The http post method connects to the server, sends data to the server, and obtains data from the server. The post Server

The http post method connects to the server, sends data to the server, and obtains data from the server. The post Server

The general process is: the client fills in the user name and password and makes a judgment on the server. If the verification password is correct, the logon is successful. If the password is incorrect, the logon failure is returned.

The client is a java program with the following code:

Package lgx. java. test; import java. io. byteArrayOutputStream; import java. io. IOException; import java. io. inputStream; import java. io. outputStream; import java. io. unsupportedEncodingException; import java.net. httpURLConnection; import java.net. malformedURLException; import java.net. URL; import java.net. URLEncoder; import java. util. hashMap; import java. util. map; public class HttpPostDemo {private static String PA TH = "http: // 192.168.1.48: 8080/myapp2/LoginAction"; private static URL url; static {try {url = new URL (PATH);} catch (MalformedURLException e) {e. printStackTrace () ;}/ *** @ param args */public static void main (String [] args) {Map <String, String> param = new HashMap <String, string> (); param. put ("username", "admin"); param. put ("password", "123"); String result = sendPostMessage (param, "UTF-8"); System. out. Println ("result is" + result);} private static String sendPostMessage (Map <String, String> param, String encode) {StringBuffer buffer = new StringBuffer (); if (param! = Null &&! Param. isEmpty () {for (Map. entry <String, String> entry: param. entrySet () {try {buffer. append (entry. getKey ()). append ("= "). append (URLEncoder. encode (entry. getValue (), encode )). append ("&");} catch (UnsupportedEncodingException e) {e. printStackTrace () ;}try {HttpURLConnection connection = (HttpURLConnection) url. openConnection (); connection. setRequestMethod ("POST"); connection. setDoInput (true); connectio N. setDoOutput (true); byte [] data = buffer. toString (). getBytes (); // set the request type to text, and the string in it is the default connection. setRequestProperty ("Content-Tyte", "application/x-www-form-urlencoded"); connection. setRequestProperty ("Content-Length", String. valueOf (data. length); // output stream, which sends data to the server OutputStream outputStream = connection. getOutputStream (); outputStream. write (data); int requestCode = connection. getResponseCode (); if (requ EstCode = 200) {// input stream, get the server data return StreamToString (connection. getInputStream (), encode) ;}} catch (IOException e) {// TODO Auto-generated catch blocke. printStackTrace () ;}} return "";} /*** convert an input stream to a specified encoded String ** @ param inputStream input stream * @ param encode encoding format * @ return String */private static String StreamToString (InputStream inputStream, string encode) {ByteArrayOutputStream arrayOutputStream = new ByteA RrayOutputStream (); byte [] data = new byte [1024]; String result = ""; int len = 0; try {while (len = inputStream. read (data ))! =-1) {arrayOutputStream. write (data, 0, len);} result = new String (arrayOutputStream. toByteArray (), encode);} catch (IOException e) {// TODO Auto-generated catch blocke. printStackTrace ();} return result ;}}

The server is a tomcat server. In the project, you have created a servlet. The code in the servlet is as follows:

package com.login.manager;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class LoginAction */public class LoginAction extends HttpServlet {private static final long serialVersionUID = 1L;    /**     * Default constructor.      */    public LoginAction() {        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubthis.doPost(request, response);}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=utf-8");request.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");PrintWriter out=response.getWriter();String username=request.getParameter("username");String password=request.getParameter("password");System.out.println(username+"---->username");System.out.println(password+"----->password");if(username.equals("admin")&&password.equals("123")){out.print("longin is success");}else{out.print("login is failed");}}}

Use these two codes to enable the server first and then run the client. If both the user name and password are correct,

The console of the client is:

The result is longin is success.

The console of the server is:

Admin ----> username
123 -----> password