Servlet詳解(第二篇)
阿新 • • 發佈：2019-01-14
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<h2><a name="t0"></a>servlet訪問路徑</h2><p><img src="https://img-blog.csdn.net/20160422215855388" alt="這裡寫圖片描述" title=""></p><h2><a name="t1"></a><a target="_blank"></a>servletConfig的作用</h2><p><img src="https://img-blog.csdn.net/20160422215926326" alt="這裡寫圖片描述" title=""></p><h2><a name="t2"></a><a target="_blank"></a>使用者相應請求流程圖</h2><p><img src="https://img-blog.csdn.net/20160422220028177" alt="這裡寫圖片描述" title=""></p><h1><a name="t3"></a><a target="_blank"></a>response</h1><h3><a name="t4"></a><a target="_blank"></a>1，response概述</h3><pre onclick="hljs.copyCode(event)"><code class="hljs css"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-selector-tag">response</span>是<span class="hljs-selector-tag">Servlet</span><span class="hljs-selector-class">.service</span>方法的一個引數，型別為<span class="hljs-selector-tag">javax</span><span class="hljs-selector-class">.servlet</span><span class="hljs-selector-class">.http</span><span class="hljs-selector-class">.HttpServletResponse</span>。</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">在客戶端發出每個請求時，伺服器都會建立一個<span class="hljs-selector-tag">response</span>物件，並傳入給<span class="hljs-selector-tag">Servlet</span><span class="hljs-selector-class">.service</span>()方法。</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-selector-tag">response</span>物件是用來對客戶端進行響應的，這說明在<span class="hljs-selector-tag">service</span>()方法中使用<span class="hljs-selector-tag">response</span>物件可以完成對客戶端的響應工作。</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h4><a target="_blank"></a>response物件的功能分為以下四種：</h4><pre onclick="hljs.copyCode(event)"><code class="hljs"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">設定響應頭資訊；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">傳送狀態碼；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">設定響應正文；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 重定向；</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h3><a name="t5"></a><a target="_blank"></a>2 response響應正文</h3><h4><a target="_blank"></a>response是響應物件，向客戶端輸出響應正文（響應體）可以使用response的響應流，repsonse一共提供了兩個響應流物件：</h4><pre onclick="hljs.copyCode(event)"><code class="hljs vbscript"><ol class="hljs-ln" style="width:886px"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">PrintWriter out=<span class="hljs-built_in">response</span>.getWriter()：獲取字元流；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">ServletOutputStream out=<span class="hljs-built_in">response</span>.getOutputStream()：獲取位元組流；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 當然，如果響應正文內容為字元，那麼使用<span class="hljs-built_in">response</span>.getWriter()，如果響應內容是位元組，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 例如:下載時，那麼可以使用<span class="hljs-built_in">response</span>.getOutputStream()。</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 注意，在一個請求中，不能同時使用這兩個流！</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 也就是說，要麼你使用repsonse.getWriter()，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="7"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 要麼使用<span class="hljs-built_in">response</span>.getOutputStream()，但不能同時使用這兩個流。不然會丟擲IllegalStateException異常。</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h4><a target="_blank"></a>2.1字元響應流</h4><h5><a target="_blank"></a>字元編碼</h5><pre onclick="hljs.copyCode(event)"><code class="hljs vbscript"><ol class="hljs-ln" style="width:847px"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">在使用<span class="hljs-built_in">response</span>.getWriter()時需要注意預設字元編碼為ISO<span class="hljs-number">-8859</span><span class="hljs-number">-1</span>，如果希望設定字元流的字元編碼為utf<span class="hljs-number">-8</span>，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">可以使用<span class="hljs-built_in">response</span>.setCharaceterEncoding(“utf<span class="hljs-number">-8</span>”)來設定。這樣可以保證輸出給客戶端的字元都是使用UTF<span class="hljs-number">-8</span>編碼的！</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">但客戶端瀏覽器並不知道響應資料是什麼編碼的！如果希望通知客戶端使用UTF<span class="hljs-number">-8</span>來解讀響應資料，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">那麼還是使用<span class="hljs-built_in">response</span>.setContentType(<span class="hljs-string">"text/html;charset=utf-8"</span>)方法比較好，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">因為這個方法不只會呼叫<span class="hljs-built_in">response</span>.setCharaceterEncoding(“utf<span class="hljs-number">-8</span>”)，還會設定content-type響應頭，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">客戶端瀏覽器會使用content-type頭來解讀響應資料。</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h5><a target="_blank"></a>緩衝區</h5><pre onclick="hljs.copyCode(event)"><code class="hljs css"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-selector-tag">response</span><span class="hljs-selector-class">.getWriter</span>()是<span class="hljs-selector-tag">PrintWriter</span>型別，所以它有緩衝區，緩衝區的預設大小為8<span class="hljs-selector-tag">KB</span>。</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">也就是說，在響應資料沒有輸出8<span class="hljs-selector-tag">KB</span>之前，資料都是存放在緩衝區中，而不會立刻傳送到客戶端。</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">當<span class="hljs-selector-tag">Servlet</span>執行結束後，伺服器才會去重新整理流，使緩衝區中的資料傳送到客戶端。</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h6><a target="_blank"></a>如果希望響應資料馬上傳送給客戶端：</h6><pre onclick="hljs.copyCode(event)"><code class="hljs css"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">向流中寫入大於8<span class="hljs-selector-tag">KB</span>的資料；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">呼叫<span class="hljs-selector-tag">response</span><span class="hljs-selector-class">.flushBuffer</span>()方法來手動重新整理緩衝區；</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h3><a name="t6"></a><a target="_blank"></a>3設定響應頭資訊</h3><pre onclick="hljs.copyCode(event)"><code class="hljs vbscript"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">可以使用<span class="hljs-built_in">response</span>物件的setHeader()方法來設定響應頭！使用該方法設定的響應頭最終會發送給客戶端瀏覽器！</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> </div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">response</span>.setHeader(“content-type”,“text/html;charset=utf<span class="hljs-number">-8</span>”)：設定content-type響應頭，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">該頭的作用是告訴瀏覽器響應內容為html型別，編碼為utf<span class="hljs-number">-8</span>。而且同時會設定<span class="hljs-built_in">response</span>的字元流編碼為utf<span class="hljs-number">-8</span>，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">即<span class="hljs-built_in">response</span>.setCharaceterEncoding(“utf<span class="hljs-number">-8</span>”)；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">response</span>.setHeader(<span class="hljs-string">"Refresh"</span>,<span class="hljs-string">"5;URL=http://www.itcast.cn"</span>)：<span class="hljs-number">5</span>秒後自動跳轉到傳智主頁。</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h3><a name="t7"></a><a target="_blank"></a>4設定狀態碼及其他方法</h3><pre onclick="hljs.copyCode(event)"><code class="hljs vbscript"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">response</span>.setContentType(<span class="hljs-string">"text/html;charset=utf-8"</span>)：</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">等同與呼叫<span class="hljs-built_in">response</span>.setHeader(“content-type”,“text/html;charset=utf<span class="hljs-number">-8</span>”)；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> </div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">response</span>.setCharacterEncoding(“utf<span class="hljs-number">-8</span>”)：設定字元響應流的字元編碼為utf<span class="hljs-number">-8</span>；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> </div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">response</span>.setStatus(<span class="hljs-number">200</span>)：設定狀態碼；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="7"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">response</span>.sendError(<span class="hljs-number">404</span>,“您要查詢的資源不存在”)：當傳送錯誤狀態碼時，Tomcat會跳轉到固定的錯誤頁面去，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="8"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 但可以顯示錯誤資訊。</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h3><a name="t8"></a><a target="_blank"></a>5重定向</h3><h4><a target="_blank"></a>5.1什麼是重定向</h4><p>當你訪問<a href="http://www.sun.com" rel="nofollow" target="_blank">http://www.sun.com</a>時，你會發現瀏覽器位址列中的URL會變成<a href="http://www.oracle.com/us/sun/index.htm" rel="nofollow" target="_blank">http://www.oracle.com/us/sun/index.htm</a>，這就是重定向了。 <br>重定向是伺服器通知瀏覽器去訪問另一個地址，即再發出另一個請求。 <br><img src="https://img-blog.csdn.net/20160422221129707" alt="這裡寫圖片描述" title=""><br>響應碼為200表示響應成功，而響應碼為302表示重定向。所以完成重定向的第一步就是設定響應碼為302。 <br>因為重定向是通知瀏覽器再第二個請求，所以瀏覽器需要知道第二個請求的URL，所以完成重定向的第二步是設定Location頭，指定第二個請求的URL地址。</p><h4><a target="_blank"></a>5.2重定向的方法</h4><pre class="prettyprint" name="code" onclick="hljs.copyCode(event)"><code class="hljs java has-numbering"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-keyword"><span class="hljs-keyword">public</span></span> <span class="hljs-class"><span class="hljs-keyword"><span class="hljs-class"><span class="hljs-keyword">class</span></span></span><span class="hljs-class"> </span><span class="hljs-title"><span class="hljs-class"><span class="hljs-title">AServlet</span></span></span><span class="hljs-class"> </span><span class="hljs-keyword"><span class="hljs-class"><span class="hljs-keyword">extends</span></span></span><span class="hljs-class"> </span><span class="hljs-title"><span class="hljs-class"><span class="hljs-title">HttpServlet</span></span></span>{</span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-keyword"><span class="hljs-function"><span class="hljs-keyword">public</span></span></span><span class="hljs-function"> </span><span class="hljs-keyword"><span class="hljs-function"><span class="hljs-keyword">void</span></span></span><span class="hljs-function"> </span><span class="hljs-title"><span class="hljs-function"><span class="hljs-title">doGet</span></span></span><span class="hljs-function"><span class="hljs-params">(HttpServletRequest request,HttpServletResponse response)</span></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> <span class="hljs-keyword"><span class="hljs-function"><span class="hljs-keyword">throws</span></span></span><span class="hljs-function"> ServletException,IOException</span>{response.sendRedirect(<span class="hljs-string"><span class="hljs-string">"/hello/BServlet"</span></span>);}}</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> </div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h4><a target="_blank"></a>5.3重定向小結</h4><pre onclick="hljs.copyCode(event)"><code class="hljs css"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">重定向是兩次請求；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">重定向的<span class="hljs-selector-tag">URL</span>可以是其他應用，不侷限於當前應用；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">重定向的響應頭為302，並且必須要有<span class="hljs-selector-tag">Location</span>響應頭；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">重定向就不要再使用<span class="hljs-selector-tag">response</span><span class="hljs-selector-class">.getWriter</span>()或<span class="hljs-selector-tag">response</span><span class="hljs-selector-class">.getOutputStream</span>()輸出資料，不然可能會出現異常；</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h1><a name="t9"></a><a target="_blank"></a>request</h1><h5>request是Servlet.service()方法的一個引數，型別為javax.servlet.http.HttpServletRequest。在客戶端發出每個請求時，伺服器都會建立一個request物件，並把請求資料封裝到request中，然後在呼叫Servlet.service()方法時傳遞給service()方法，這說明在service()方法中可以通過request物件來獲取請求資料。</h5><h3><a name="t10"></a><a target="_blank"></a>1request的功能可以分為以下幾種：</h3><pre onclick="hljs.copyCode(event)"><code class="hljs vbscript"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">封裝了請求頭資料；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">封裝了請求正文資料，如果是<span class="hljs-keyword">GET</span>請求，那麼就沒有正文；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">request</span>是一個域物件，可以把它當成Map來新增獲取資料；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">request</span>提供了請求轉發和請求包含功能。</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h5>request是域物件！在JavaWeb中一共四個域物件，其中ServletContext就是域物件，它在整個應用中只建立一個ServletContext物件。request其中一個，request可以在一個請求中共享資料。</h5><h3><a name="t11"></a><a target="_blank"></a>2下面是request的域方法：</h3><pre onclick="hljs.copyCode(event)"><code class="hljs delphi"><ol class="hljs-ln" style="width:927px"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">void setAttribute(<span class="hljs-keyword">String</span> <span class="hljs-keyword">name</span>,<span class="hljs-keyword">Object</span> value)：用來儲存一個物件，也可以稱之為儲存一個域屬性，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">例如：servletContext.setAttribute(“xxx”,“XXX”)，在request中儲存了一個域屬性，域屬性名稱為xxx，域屬性的值為XXX。</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">請注意，如果多次呼叫該方法，並且使用相同的<span class="hljs-keyword">name</span>，那麼會覆蓋上一次的值，這一特性與Map相同；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> </div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-keyword">Object</span> getAttribute(<span class="hljs-keyword">String</span> <span class="hljs-keyword">name</span>)：用來獲取request中的資料，當前在獲取之前需要先去儲存才行，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">例如：<span class="hljs-keyword">String</span> value=(<span class="hljs-keyword">String</span>)request.getAttribute(“xxx”);，獲取名為xxx的域屬性；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="7"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> </div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="8"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">void removeAttribute(<span class="hljs-keyword">String</span> <span class="hljs-keyword">name</span>)：用來移除request中的域屬性，如果引數<span class="hljs-keyword">name</span>指定的域屬性不存在，那麼本方法什麼都不做；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="9"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">Enumeration getAttributeNames()：獲取所有域屬性的名稱；</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h3><a name="t12"></a><a target="_blank"></a>3 request獲取請求頭資料</h3><pre onclick="hljs.copyCode(event)"><code class="hljs vbscript"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">request</span>與請求頭相關的方法有：</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getHeader(<span class="hljs-built_in">String</span> name)：獲取指定名稱的請求頭；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">Enumeration getHeaderNames()：獲取所有請求頭名稱；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">int</span> getIntHeader(<span class="hljs-built_in">String</span> name)：獲取值為<span class="hljs-built_in">int</span>型別的請求頭。</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h3><a name="t13"></a><a target="_blank"></a>4 request獲取請求相關的其它方法</h3><pre onclick="hljs.copyCode(event)"><code class="hljs javascript"><ol class="hljs-ln" style="width:893px"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">request中還提供了與請求相關的其他方法，有些方法是為了我們更加便捷的方法請求頭資料而設計，有些是與請求URL相關的方法。</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">int getContentLength()：獲取請求體的位元組數，GET請求沒有請求體，沒有請求體返回<span class="hljs-number">-1</span>；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getContentType()：獲取請求型別，如果請求是GET，那麼這個方法返回<span class="hljs-literal">null</span>；如果是POST請求，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 那麼預設為application/x-www-form-urlencoded，表示請求體內容使用了URL編碼；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getMethod()：返回請求方法，例如：GET</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">Locale getLocale()：返回當前客戶端瀏覽器的Locale。java.util.Locale表示國家和言語，這個東西在國際化中很有用；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="7"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getCharacterEncoding()：獲取請求編碼，如果沒有setCharacterEncoding()，</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="8"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 那麼返回<span class="hljs-literal">null</span>，表示使用ISO<span class="hljs-number">-8859</span><span class="hljs-number">-1</span>編碼；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="9"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-keyword">void</span> setCharacterEncoding(<span class="hljs-built_in">String</span> code)：設定請求編碼，只對請求體有效！</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="10"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 注意，對於GET而言，沒有請求體！！！所以此方法只能對POST請求中的引數有效！</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="11"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getContextPath()：返回上下文路徑，例如：/hello</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="12"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getQueryString()：返回請求URL中的引數，例如：name=zhangSan</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="13"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getRequestURI()：返回請求URI路徑，例如：/hello/oneServlet</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="14"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">StringBuffer getRequestURL()：返回請求URL路徑，例如：http:<span class="hljs-comment">//localhost/hello/oneServlet，</span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="15"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 即返回除了引數以外的路徑資訊；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="16"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getServletPath()：返回Servlet路徑，例如：/oneServlet</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="17"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getRemoteAddr()：返回當前客戶端的IP地址；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="18"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getRemoteHost()：返回當前客戶端的主機名，但這個方法的實現還是獲取IP地址；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="19"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getScheme()：返回請求協議，例如：http；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="20"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in">String</span> getServerName()：返回主機名，例如：localhost</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="21"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> int getServerPort()：返回伺服器埠號</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><p><img src="https://img-blog.csdn.net/20160422221706887" alt="這裡寫圖片描述" title=""></p><h3><a name="t14"></a><a target="_blank"></a>5 request獲取請求引數</h3><h5><a target="_blank"></a>最為常見的客戶端傳遞引數方式有兩種：</h5><pre onclick="hljs.copyCode(event)"><code class="hljs vbscript"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 瀏覽器位址列直接輸入：一定是<span class="hljs-keyword">GET</span>請求；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">超連結：一定是<span class="hljs-keyword">GET</span>請求；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">表單：可以是<span class="hljs-keyword">GET</span>，也可以是POST，這取決與<form>的method屬性值；</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h5><a target="_blank"></a>GET請求和POST請求的區別：</h5><h6><a target="_blank"></a>GET請求：：</h6><pre onclick="hljs.copyCode(event)"><code class="hljs vbscript"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">請求引數會在瀏覽器的位址列中顯示，所以不安全；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">請求引數長度限制長度在<span class="hljs-number">1</span>K之內；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-keyword">GET</span>請求沒有請求體，無法通過<span class="hljs-built_in">request</span>.setCharacterEncoding()來設定引數的編碼；</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h6><a target="_blank"></a>POST請求：</h6><pre onclick="hljs.copyCode(event)"><code class="hljs"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">請求引數不會顯示瀏覽器的位址列，相對安全；</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 請求引數長度沒有限制；</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><pre class="prettyprint" name="code" onclick="hljs.copyCode(event)"><code class="hljs xml has-numbering"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-tag"><span class="hljs-tag"><</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">a</span></span></span><span class="hljs-tag"> </span><span class="hljs-attribute"><span class="hljs-tag"><span class="hljs-attr">href</span></span></span><span class="hljs-tag">=</span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-string">"/hello/ParamServlet?p1=v1&p2=v2"</span></span></span><span class="hljs-tag">></span></span>超連結<span class="hljs-tag"><span class="hljs-tag"></</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">a</span></span></span><span class="hljs-tag">></span></span><span class="hljs-tag"><span class="hljs-tag"><</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">hr</span></span></span><span class="hljs-tag">/></span></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-tag"><span class="hljs-tag"><</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">form</span></span></span><span class="hljs-tag"> </span><span class="hljs-attribute"><span class="hljs-tag"><span class="hljs-attr">action</span></span></span><span class="hljs-tag">=</span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-string">"/hello/ParamServlet"</span></span></span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-attr">method</span>=<span class="hljs-string">"post"</span></span></span><span class="hljs-tag">></span></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 引數1：<span class="hljs-tag"><span class="hljs-tag"><</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">input</span></span></span><span class="hljs-tag"> </span><span class="hljs-attribute"><span class="hljs-tag"><span class="hljs-attr">type</span></span></span><span class="hljs-tag">=</span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-string">"text"</span></span></span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-attr">name</span>=<span class="hljs-string">"p1"</span></span></span><span class="hljs-tag">/></span></span><span class="hljs-tag"><span class="hljs-tag"><</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">br</span></span></span><span class="hljs-tag">/></span></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 引數2：<span class="hljs-tag"><span class="hljs-tag"><</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">input</span></span></span><span class="hljs-tag"> </span><span class="hljs-attribute"><span class="hljs-tag"><span class="hljs-attr">type</span></span></span><span class="hljs-tag">=</span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-string">"text"</span></span></span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-attr">name</span>=<span class="hljs-string">"p2"</span></span></span><span class="hljs-tag">/></span></span><span class="hljs-tag"><span class="hljs-tag"><</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">br</span></span></span><span class="hljs-tag">/></span></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-tag"> <span class="hljs-tag"><</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">input</span></span></span><span class="hljs-tag"> </span><span class="hljs-attribute"><span class="hljs-tag"><span class="hljs-attr">type</span></span></span><span class="hljs-tag">=</span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-string">"submit"</span></span></span><span class="hljs-value"><span class="hljs-tag"><span class="hljs-attr">value</span>=<span class="hljs-string">"提交"</span></span></span><span class="hljs-tag">/></span></span><span class="hljs-tag"></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-tag"></</span><span class="hljs-title"><span class="hljs-tag"><span class="hljs-name">form</span></span></span><span class="hljs-tag">></span></div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h4><a target="_blank"></a>下面是使用request獲取請求引數的API：</h4><pre class="prettyprint" name="code" onclick="hljs.copyCode(event)"><code class="hljs vbscript has-numbering"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">{<span class="hljs-built_in"> <span class="hljs-built_in">String</span></span> v1=<span class="hljs-built_in"><span class="hljs-built_in">request</span></span>.getParameter(<span class="hljs-string"><span class="hljs-string">"p1"</span></span>);</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in"> <span class="hljs-built_in">String</span></span> v2=<span class="hljs-built_in"><span class="hljs-built_in">request</span></span>.getParameter(<span class="hljs-string"><span class="hljs-string">"p2"</span></span>);</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> System.out.println(<span class="hljs-string"><span class="hljs-string">"p1="</span></span>+v1);</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> System.out.println(<span class="hljs-string"><span class="hljs-string">"p2="</span></span>+v2);} </div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">{<span class="hljs-built_in"> <span class="hljs-built_in">String</span></span> v1=<span class="hljs-built_in"><span class="hljs-built_in">request</span></span>.getParameter(<span class="hljs-string"><span class="hljs-string">"p1"</span></span>);</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in"> <span class="hljs-built_in">String</span></span> v2=<span class="hljs-built_in"><span class="hljs-built_in">request</span></span>.getParameter(<span class="hljs-string"><span class="hljs-string">"p2"</span></span>);</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="7"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> System.out.println(<span class="hljs-string"><span class="hljs-string">"p1="</span></span>+v1);</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="8"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> System.out.println(<span class="hljs-string"><span class="hljs-string">"p2="</span></span>+v2); }</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h4><a target="_blank"></a>一次性獲取多個引數</h4><pre class="prettyprint" name="code" onclick="hljs.copyCode(event)"><code class="hljs avrasm has-numbering cs"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">{String[]names=request<span class="hljs-preprocessor">.getParameterValues</span>(<span class="hljs-string"><span class="hljs-string">"name"</span></span>)<span class="hljs-comment">;</span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">[<span class="hljs-meta">獲取所有名為name的引數值</span>]</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">System<span class="hljs-preprocessor">.<span class="hljs-keyword">out</span></span><span class="hljs-preprocessor">.println</span>(Arrays<span class="hljs-preprocessor">.toString</span>(names))<span class="hljs-comment">;</span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">[<span class="hljs-meta">列印陣列，輸出結果為：[zhangSan, liSi</span>]]}</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h4><a target="_blank"></a>一次性獲取所有引數</h4><pre class="prettyprint" name="code" onclick="hljs.copyCode(event)"><code class="hljs ocaml has-numbering javascript"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><form action=<span class="hljs-string"><span class="hljs-string">"/hello/ParamServlet"</span></span><span class="hljs-keyword">method</span>=<span class="hljs-string"><span class="hljs-string">"post"</span></span>></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 引數<span class="hljs-number"><span class="hljs-number">1</span></span>：<input <span class="hljs-class"><span class="hljs-keyword">type</span>=</span><span class="hljs-string"><span class="hljs-string">"text"</span></span>name=<span class="hljs-string"><span class="hljs-string">"p1"</span></span>/><span class="xml"><span class="hljs-tag"><<span class="hljs-name">br</span>/></span></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> 引數<span class="hljs-number"><span class="hljs-number">2</span></span>：<input <span class="hljs-class"><span class="hljs-keyword">type</span>=</span><span class="hljs-string"><span class="hljs-string">"text"</span></span>name=<span class="hljs-string"><span class="hljs-string">"p2"</span></span>/><span class="xml"><span class="hljs-tag"><<span class="hljs-name">br</span>/></span></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> <input <span class="hljs-class"><span class="hljs-keyword">type</span>=</span><span class="hljs-string"><span class="hljs-string">"submit"</span></span><span class="hljs-keyword">value</span>=<span class="hljs-string"><span class="hljs-string">"提交"</span></span>/></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="5"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="xml"><span class="hljs-tag"></<span class="hljs-name">form</span>></span></span></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="6"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">{Enumeration names=request.getParameterNames()</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="7"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">[獲取所有引數名稱，輸出結果為：p1和p2];</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="8"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-keyword"><span class="hljs-keyword">while</span></span>(names.hasMoreElements()){System.out.println(names.nextElement());}}</div></div></li></ol></code><div class="hljs-button" data-title="複製"></div></pre><h4><a target="_blank"></a>Map getParameterMap()：</h4><p>獲取所有引數封裝到Map中，其中key為引數名，value為引數值，因為一個引數名稱可能有多個值，所以引數值是String[]，而不是String。</p><pre class="prettyprint" name="code" onclick="hljs.copyCode(event)"><code class="hljs vbscript has-numbering"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><a href=<span class="hljs-string"><span class="hljs-string">"/day05_1/ParamServlet?p1=v1&p1=vv1&p2=v2&p2=vv2"</span></span>>超連結</a></div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"> </div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="3"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line">Map<<span class="hljs-built_in"><span class="hljs-built_in">String</span></span>,<span class="hljs-built_in"><span class="hljs-built_in">String</span></span>[]>paramMap=<span class="hljs-built_in"><span class="hljs-built_in">request</span></span>.getParameterMap();</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="4"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-keyword"><span class="hljs-keyword">for</span></span>(<span class="hljs-built_in"><span class="hljs-built_in">String</span></span> name:paramMap.keySet()){<span class="hljs-built_in"></span></div></div></li></ol></code><code class="hljs vbscript has-numbering"><span class="hljs-built_in"></span></code><div class="hljs-button" data-title="複製"></div></pre><pre class="prettyprint" name="code"><code class="hljs vbscript has-numbering"><ol class="hljs-ln"><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="1"></div></div><div class="hljs-ln-code"><div class="hljs-ln-line"><span class="hljs-built_in"><span class="hljs-built_in">String</span></span>[]values=paramMap.<span class="hljs-keyword"><span class="hljs-keyword">get</span></span>(name);</div></div></li><li><div class="hljs-ln-numbers"><div class="hljs-ln-line hljs-ln-n" data-line-number="2"></div></div><div class="hljs-ln-code">&l