http協議從客戶端提交資料給伺服器並返回資料
阿新 • • 發佈：2019-01-10
老羅視訊學習。
本例從客戶端提交資料給伺服器，伺服器接收到資料之後，看是否匹配，匹配返回字串“login is success!”，失敗返回“login is error!”
一.客戶端。
初始化url地址
private static String path = "http://192.168.10.102:8080/myhttp/servlet/LoginActivity"; private static URL url; static{ try { url = new URL(path); } catch (MalformedURLException e) { // TODO Auto-generated catch block e.printStackTrace(); } }
setPostMessage函式
getOutputStream是向伺服器傳遞資料用的。
getInputStream是從伺服器獲取資料用的。
向伺服器輸入資料傳遞圖片之類的，要用HttpUrlConnection類
doInput預設值是true，doOutput預設值是false。
private static String sendPostMessage(Map<String, String> params,String encode) { //請求體封裝在StringBuffer中 StringBuffer buffer = new StringBuffer(); //buffer.append("?"); try { //判斷是否為空 if(params!=null && !params.isEmpty()){ //迭代for迴圈 for(Map.Entry<String, String> entry : params.entrySet()){ //append，追加字串 buffer.append(entry.getKey()) .append("=") .append(URLEncoder.encode(entry.getValue(),encode)) .append("&"); } } //刪掉最後多餘的那個“&” buffer.deleteCharAt(buffer.length()-1); System.out.print(buffer.toString()); //接下來是http協議內容 //開啟連結 HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection(); //設定伺服器斷開重連時間 urlConnection.setConnectTimeout(3000); //設定提交方式 urlConnection.setRequestMethod("POST"); //設定從伺服器讀取資料 urlConnection.setDoInput(true); //設定向伺服器寫資料 urlConnection.setDoOutput(true); //接下來需要把url的請求的內容，封裝到一個請求體中 //獲得上傳資訊的位元組大小 byte[] data = buffer.toString().getBytes(); //設定請求體的型別 //設定請求體型別為文字型別，暫時不涉及圖片及二進位制資料 urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); //設定請求體的長度 urlConnection.setRequestProperty("Content-Length", String.valueOf(data.length)); //獲得輸出流，向伺服器輸出資料 OutputStream outputStream = urlConnection.getOutputStream(); outputStream.write(data,0,data.length); outputStream.close(); //獲得伺服器響應的結果和狀態碼 int responseCode = urlConnection.getResponseCode(); if (responseCode == 200) { //把inputStream改為String傳遞出來 return ChangeInputStream(urlConnection.getInputStream(),encode); } }catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } return path; }
changeInputStream函式如下：
把InputStream以encode格式轉換為String
private static String ChangeInputStream(InputStream inputStream, String encode) { // TODO Auto-generated method stub ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); byte[] data = new byte[1024]; int len = 0; String resultString = ""; if(inputStream!=null) { try { //資料迴圈儲存在outputStream中 while ((len=inputStream.read(data))!=-1) { outputStream.write(data,0,len); } //首先轉換為位元組陣列，然後以encode編碼格式轉換為字串 resultString = new String(outputStream.toByteArray(),encode); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return resultString; }
測試main函式如下：
public static void main(String[] args) {
Map<String, String> params = new HashMap<String, String>();
params.put("username", "admin");
params.put("password", "123");
String encode = "utf-8";
String resString = HttpUrils.sendPostMessage(params, encode);
System.out.print("------>"+resString);
}二.伺服器端，還用get方式例子裡用到的伺服器。
LoginActivity繼承自HttpServlet
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
super.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
//設定編碼格式
resp.setContentType("text/html;charset=utf-8");
req.setCharacterEncoding("utf-8");
resp.setCharacterEncoding("utf-8");
//獲取使用者名稱username，密碼password
PrintWriter out = resp.getWriter();
String usernameString = req.getParameter("username");
String pswdString = req.getParameter("password");
System.out.print(usernameString);
System.out.print(pswdString);
//匹配成功
if(usernameString.equals("admin")&&pswdString.equals("123")){
out.print("login is success!");
}//匹配不成功
else {
out.print("login is error!");
}
out.flush();
out.close();