模拟手机客户端与Web应用的交互[URL和HttpURLConnection的使用]

URL和HttpURLConnection的使用

　　java.lang.Object

　　　　|--java.net.URL

　　java.lang.Object

　　　　|--java.net.URLConnection

　　　　　　|--java.net.HttpURLConnection

　　1、模拟手机端

import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;

//模拟手机客户端
public class Phone {
    public static void main(String[] args) throws Exception {
        //建立与服务端的连接
        URL url = new URL("http://localhost:8080/day26/Server");
        //取得与服务端的连接
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        conn.setDoOutput(true);//防止报Exception in thread "main" java.net.ProtocolException: cannot write to a URLConnection if doOutput=false - call setDoOutput(true)
        //向服务端发送请求
        OutputStream os = conn.getOutputStream();
        PrintWriter pw = new PrintWriter(os);
        String username = "杰克";
        username = URLEncoder.encode(username,"UTF-8");
        pw.write("username="+username+"&password=12346");
        pw.flush();
        pw.close();
        //通知服务端客户端已发送请求完毕
        int code = conn.getResponseCode();
        System.out.println("code=" + code);
        
        /*接收服务端的输出
        InputStream is = conn.getInputStream();
        byte[] buf = new byte[1024];
        int len = 0;
        while((len=is.read(buf))>0){
            System.out.println(new String(buf,0,len));
        }
        //关闭
        is.close();
        */
    }
}

 　　2、服务端

import java.io.IOException;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Server extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
        //输出到客户端
        response.setContentType("text/html;charset=GBK");
        response.getWriter().write("当前时间为[GET]:" + new Date().toLocaleString());
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
        //接收客户端的请求
        request.setCharacterEncoding("UTF-8");
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        System.out.println("username[POST]="+username);
        System.out.println("password[POST]="+password);
    }
}

 总结：

1)服务端[GET]->手机--GET方式

(1)手机先发送请求，再接收服务端的响应
(2)在服务端写到GET方式中

　　2)手机->服务端[POST]--POST方式
　　　　(1)在服务端写到POST方式中

　　3)对于中文方式

(1)通过URLEncoder进行URL编码，
　　String username = "杰克";
　　username = URLEncoder.encode(username,"UTF-8");
(2)在服务端进行编码设置：
　　request.setCharacterEncoding("UTF-8");
(3)必须确保URL编码和解析一致