Servlet 學習（三）
阿新 • • 發佈：2018-04-09
content load 分享 數據 cat exce nal charset 信息
HTTP 請求的構成
1、HTTP 請求行:
請求方式，比如 GET 、POST 等
本次請求的URI ，比如 /hello
協議和版本號
2、 HTTP 請求報頭: (頭部/首部/請求頭)
- 請求頭和請求正文之間用空行分隔
3、 HTTP 請求正文:
- 一種是 請求參數 ，比如 /hello?username=zhangsanfeng&password=wudang2017
- 一種是 針對上傳文件 等操作
HttpServletRequest 類型的對象
1、Servlet 容器響應Web 客戶端請求的時序圖
2、與HTTP請求行對應的方法
- 請求方式: String getMethod()
- URI : String getRequestURI()
- 協議: String getProtocol()
3、與HTTP請求報頭:
- String getHeader( String name ) 獲取指定名稱的請求報頭的取值
- Enumeration<String> getHeaders( String name ) 獲取指定名稱的請求報頭的取值(取值有多個，比如cookie)
- long getDateHeader( String name ) 獲取指定名稱的請求報頭的取值 ( 返回以毫秒為單位的時間 )
- int getIntHeader( String name ) 獲取指定名稱的請求報頭的取值 ( 以 int 形式返回 )
- Enumeration<String> getHeaderNames() 獲取所有的請求報頭的名稱
4、與HTTP請求正文:
獲取請求參數:
- String getParameter( String name ) 獲取指定的請求參數對應的值
- String[] getParameterValues( String name ) 獲取指定的請求參數對應的值 ( 取值有多個，比如 checkbox )
- Map< String , String[] > getParameterMap() 獲取所有的請求參數及取值( 取值是個數組 )
- Enumeration<String> getParameterNames() 獲取所有的請求參數的名稱
獲取WEB客戶端上傳的數據:
- ServletInputStream getInputStream() 在 Servlet 3.0 之前獲取上傳數據的方法 ( 以字節形流式返回 )
- BufferedReader getReader() 在 Servlet 3.0 之前獲取上傳數據的方法 ( 以字符流形式返回 )
- Part getPart( String name ) 根據 名稱 獲得 一個 multipart/form-data POST request 中指定名稱對應的 Part 對象
<input type="file" name="upfile" > =========> request.getPart( "upfile" )
- Collection<Part> getParts() 獲取 multipart/form-data POST request 中對應的所有的 Part 對象
測試案例：
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <servlet> <servlet-name>ParseRequestServlet</servlet-name> <servlet-class>ecut.request.ParseRequestServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ParseRequestServlet</servlet-name> <url-pattern>/parse</url-pattern> </servlet-mapping> <servlet> <servlet-name>FirstUploadServlet</servlet-name> <servlet-class>ecut.request.FirstUploadServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>FirstUploadServlet</servlet-name> <url-pattern>/upload/first</url-pattern> </servlet-mapping> <servlet> <servlet-name>SecondUploadServlet</servlet-name> <servlet-class>ecut.request.SecondUploadServlet</servlet-class> <!-- 啟用 Servlet 3.x 所支持的文件上傳方式 --> <multipart-config> <location>D:/files</location> </multipart-config> <!-- location 指定的是文件上傳後的存儲位置 --> </servlet> <servlet-mapping> <servlet-name>SecondUploadServlet</servlet-name> <url-pattern>/upload/second</url-pattern> </servlet-mapping> <servlet> <servlet-name>ThirdUploadServlet</servlet-name> <servlet-class>ecut.request.ThirdUploadServlet</servlet-class> <!-- 啟用 Servlet 3.x 所支持的文件上傳方式 --> <multipart-config> <location>D:/files</location> </multipart-config> <!-- location 指定的是文件上傳後的存儲位置 --> </servlet> <servlet-mapping> <servlet-name>ThirdUploadServlet</servlet-name> <url-pattern>/upload/third</url-pattern> </servlet-mapping> </web-app>
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Request</title> </head> <body> <a href="/Servlet/parse?username=Amy&password=123456" >訪問 ParseRequestServlet</a> <h5>GET</h5> <form action="/Servlet/parse" method="get" > <input type="text" name="username" placeholder="用戶名"> <br> 性別: <input type="radio" name="gender" value="女"> 我是靚女 <input type="radio" name="gender" value="男"> 我是靚仔 <br> 愛好: <input type="checkbox" name="hobby" value="eat">吃飯 <input type="checkbox" name="hobby" value="sleep">睡覺 <input type="checkbox" name="hobby" value="wc">上廁所 <br> <input type="submit" value="提交"> </form> <h5>POST</h5> <form action="/Servlet/parse" method="post" > <input type="text" name="username" placeholder="用戶名"> <br> 性別: <input type="radio" name="gender" value="女"> 我是靚女 <input type="radio" name="gender" value="男"> 我是靚仔 <br> 愛好: <input type="checkbox" name="hobby" value="eat">吃飯 <input type="checkbox" name="hobby" value="sleep">睡覺 <input type="checkbox" name="hobby" value="wc">上廁所 <br> <input type="submit" value="提交"> </form> <h5>文件上傳(古代)</h5> <!-- method 必須是 POST ，enctype 必須是 multipart/form-data enctype默認是對數據進行 application/x-www-form-urlencoded編碼--> <form action="/Servlet/upload/first" method="post" enctype="multipart/form-data"> <input type="file" name="upfile" > <input type="submit" value="上傳" > </form> <h5>文件上傳( 從 Servlet 3.0 開始 )</h5> <!-- method 必須是 POST ，enctype 必須是 multipart/form-data --> <form action="/Servlet/upload/second" method="post" enctype="multipart/form-data"> <input type="file" name="upfile" > <input type="submit" value="上傳" > </form> <h5>文件上傳( 從 Servlet 3.0 開始 )</h5> <!-- method 必須是 POST ，enctype 必須是 multipart/form-data --> <form action="/Servlet/upload/third" method="post" enctype="multipart/form-data"> <input type="file" name="upfile1" > <br> <input type="file" name="upfile2" > <br> <input type="file" name="upfile3" > <br> <input type="file" name="upfile4" > <br> <input type="submit" value="上傳" > </form> </body> </html>
package ecut.request; import java.io.IOException; import java.io.PrintWriter; import java.util.Arrays; import java.util.Enumeration; import java.util.Map; import java.util.Map.Entry; import java.util.Set; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ParseRequestServlet extends HttpServlet { private static final long serialVersionUID = 5473447295646845596L; @Override protected void service( HttpServletRequest request, HttpServletResponse response ) throws ServletException, IOException { request.setCharacterEncoding( "UTF-8" ); response.setCharacterEncoding( "UTF-8" ); response.setContentType( "text/html;charset=UTF-8" ); PrintWriter p =response.getWriter(); // 獲取 HTTP HTTP 請求行中的相關信息 String method = request.getMethod(); String uri = request.getRequestURI() ; String protocol = request.getProtocol() ; System.out.println( "HTTP 請求行:"); System.out.println("\t請求方式 = " + method); System.out.println("\tURI = " + uri); System.out.println("\t協議/版本號= " + protocol); p.println("<p>HTTP 請求行:</p>"); p.println("<p style=‘text-indent:2em;‘>請求方式 = " + method+"</p>"); p.println("<p style=‘text-indent:2em;‘>URI = " + uri+"</p>"); p.println("<p style=‘text-indent:2em;‘>協議/版本號 = " + protocol+"</p>"); // 獲取HTTP 請求報頭 Enumeration<String> headerNames = request.getHeaderNames(); System.out.println( "HTTP 請求報頭:" ); p.println( "<p>HTTP 請求報頭:"+"</p>" ); while( headerNames.hasMoreElements() ) { String name = headerNames.nextElement(); // 獲取單個的HTTP 請求報頭的名稱 String value = request.getHeader( name ) ; // 獲得指定名稱對應的HTTP 請求報頭的值 System.out.println( "\t" + name + " = " + value ); p.println("<p style=‘text-indent:2em;‘>" + name + " = " + value +"</p>"); } // 獲取HTTP 請求參數 Map<String,String[]> paramMap = request.getParameterMap(); Set< Entry<String, String[]> > entrySet = paramMap.entrySet(); System.out.println( "HTTP 請求參數:" ); p.println( "<p>HTTP 請求參數:" ); for( Entry<String, String[]> e : entrySet ){ String name = e.getKey() ; String[] value = e.getValue() ; System.out.println( "\t" + name + " : " + Arrays.toString( value ) ); p.println( "<p style=‘text-indent:2em;‘>" + name + " : " + Arrays.toString( value ) +"</p>"); } } }
運行結果如下：
控制臺輸出文件的內容。
獲取指定的請求參數對應的值取值有多個的測試案例：
運行結果如下：
HTTP 請求行:
請求方式 = GET
URI = /Servlet/parse
協議/版本號= HTTP/1.1
HTTP 請求報頭:
host = localhost:8080
user-agent = Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0
accept = text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
accept-language = zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
accept-encoding = gzip, deflate
referer = http://localhost:8080/Servlet/pages/request/index.html
connection = keep-alive
upgrade-insecure-requests = 1
HTTP 請求參數:
username : [AmyZheng]
gender : [男]
hobby : [eat, sleep]
文件上傳測試案例一：
package ecut.request; import java.io.BufferedReader; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class FirstUploadServlet extends HttpServlet { private static final long serialVersionUID = -7777691027208490971L; @Override protected void doGet( HttpServletRequest request , HttpServletResponse response ) throws ServletException, IOException { throw new RuntimeException( "不支持GET方式上傳" ); } @Override protected void doPost( HttpServletRequest request , HttpServletResponse response ) throws ServletException, IOException { request.setCharacterEncoding( "UTF-8" ); // 上傳文件時，只考慮文本文件，不考慮其它文件 BufferedReader reader = request.getReader(); //InputStream in = request.getInputStream(); String s ; while( ( s = reader.readLine() ) != null ){ System.out.println( s ); } } }
運行結果如下：
頁面跳轉到http://localhost:8080/Servlet/upload/first
控制臺輸出文件內容
-----------------------------296501829912081
Content-Disposition: form-data; name="upfile"; filename="Http.txt"
Content-Type: text/plain
文件內容省略
-----------------------------296501829912081--
文件上傳測試案例二：
package ecut.request; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.Part; public class SecondUploadServlet extends HttpServlet { private static final long serialVersionUID = 4485463572490572537L; @Override protected void doGet( HttpServletRequest request , HttpServletResponse response ) throws ServletException, IOException { throw new RuntimeException( "不支持GET方式上傳" ); } @Override protected void doPost( HttpServletRequest request, HttpServletResponse response ) throws ServletException, IOException { // String username = request.getParameter( "username" ) ; // <input type="text" name="username" > Part part = request.getPart( "upfile" ) ; // <input type="file" name="upfile" > System.out.println( part ); /* Servlet 3.0 中獲得文件名的做法 String cd = part.getHeader( "Content-Disposition" ); System.out.println( cd ); String s = "filename=\""; int index = cd.indexOf( s );//找到filename的位置 String name = cd.substring( index + s.length() , cd.length() - 1 );//獲取文件名 System.out.println( name ); */ // part.getName() ; // name="upfile" String filename = part.getSubmittedFileName(); // Servlet 3.1 開始出現的方法 part.write( filename ); } }
運行結果如下：
頁面跳轉到http://localhost:8080/Servlet/upload/second
D:\files目錄下增加了一個文件
文件上傳測試案例三：
package ecut.request; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.Part; public class ThirdUploadServlet extends HttpServlet { private static final long serialVersionUID = 4485463572490572537L; @Override protected void doGet( HttpServletRequest request , HttpServletResponse response ) throws ServletException, IOException { throw new RuntimeException( "不支持GET方式上傳" ); } @Override protected void doPost( HttpServletRequest request, HttpServletResponse response ) throws ServletException, IOException { upfile("upfile1",request); upfile("upfile2",request); upfile("upfile3",request); upfile("upfile4",request); } void upfile(String upfile,HttpServletRequest request) throws ServletException, IOException{ Part part = request.getPart( upfile) ; String filename = part.getSubmittedFileName(); part.write( filename ); } }
運行結果如下：
頁面跳轉到http://localhost:8080/Servlet/upload/third
D:\files目錄下增加了四個文件
轉載請於明顯處標明出處
http://www.cnblogs.com/AmyZheng/p/8761234.html
Servlet 學習（三）