httpUrlConnection连接网络的用法(用到了handle传递消息,在主线程中更新UI)

由于httpclient在Android5.0以后已经过时,所以官方推荐使用httpUrlConnection来连接网络,现将该连接的基本方法展示,如下

注意:记得加入<uses-permission android:name="android.permission.INTERNET" />

另外,本例用到了handle来处理消息,跟新UI在主线程中,访问网络在子线程中

客户端代码:

 package imqsl.com.testhttp;

 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.support.v7.app.AppCompatActivity;
 import android.view.View;
 import android.widget.Button;
 import android.widget.EditText;
 import android.widget.TextView;
 import android.widget.Toast;

 import java.io.BufferedReader;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLEncoder;

 public class MainActivity extends AppCompatActivity {
     Button button = null;
     EditText edit = null;
     TextView textView = null;
     String result="";
     Handler handler=null;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         button= (Button) findViewById(R.id.button);
         edit= (EditText) findViewById(R.id.edit);
         textView= (TextView) findViewById(R.id.text_display);
         button.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View view) {
                 if ("".equals(edit.getText().toString())){
                     Toast.makeText(MainActivity.this,"请输入要发送的内容",Toast.LENGTH_SHORT).show();
                     return;
                 }
                 new Thread(new Runnable() {
                     @Override
                     public void run() {
                         send();
                         Message msg=handler.obtainMessage();//子线程中的handle用来给主线程传递消息,虽然本例中的msg没有使用,
但是主线程中的handle也要等待该Message,否则不会继续,然后更新UI
                         handler.sendMessage(msg);
                     }
                 }).start();
             }
         });
         handler=new Handler(){//主线程中的handle用来接收子线程中的Message以便更新UI
             @Override
             public void handleMessage(Message msg) {
                 Toast.makeText(MainActivity.this,result,Toast.LENGTH_SHORT).show();
                 if (result!=null){
                     textView.setText(result);
                     edit.setText("");
                 }
                 super.handleMessage(msg);
             }
         };

     }

     private void send() {
         URL url;
         String target = "http://192.168.1.152:8080/flightcheck/testservlet";
         try {
             url=new URL(target);
             HttpURLConnection urlConn= (HttpURLConnection) url.openConnection();//注意:httpURLconnetion的创建是这样自的
             urlConn.setRequestMethod("POST");//设置连接方式,post必须设置,get可以不用设置,因为默认的就是get
             urlConn.setUseCaches(false);//是指是否缓存
             urlConn.setDoInput(true);//设置是否输入
             urlConn.setDoOutput(true);//设置是否输出
             DataOutputStream out=new DataOutputStream(urlConn.getOutputStream());
             String param="content="+ URLEncoder.encode(edit.getText().toString(),"utf-8");//使用URLEncoder.encode转换为utf-8以防止中文乱码
             out.writeBytes(param);//writeBytes写字节到输出流中,服务器端也是接收的bytes
             out.flush();//记得刷一下
             out.close();
             System.out.println("responsecode:"+urlConn.getResponseCode());
             if (urlConn.getResponseCode()==HttpURLConnection.HTTP_OK){//连接成功,则相等,httpURLConnection.http_ok=200
                 BufferedReader bufferedReader=new BufferedReader(new  //处理流,转换流,节点流
                         InputStreamReader(urlConn.getInputStream()));
                 String line=null;
                 System.out.println("bufferedReader.readLine():"+bufferedReader.readLine());
                 while ((line=bufferedReader.readLine())!=null){
                     result+=line+"\n";                              //加了个"\n"相当于换到了下一行
                 }
             }
         } catch (MalformedURLException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }

     }
 }

xml文件代码:

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:orientation="vertical"
     >
     <EditText
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:id="@+id/edit"
         />
     <Button
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="发表"
         android:id="@+id/button"
         />
     <TextView
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:id="@+id/text_display"
         />

 </LinearLayout>

服务器端代码:

 package test;

 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;

 public class testservlet extends HttpServlet {
     private static final long serialVersionUID = 1L;

     public testservlet() {
         super();
     }

     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         String content = new String(request.getParameter("content").getBytes("ISO-8859-1"), "UTF-8");//客户端writeBytes,服务器端就getBytes并转码
         System.out.println(content);
         response.setContentType("text/plain");
         response.setCharacterEncoding("utf-8");//加入本步设置客户端就可以得到服务器端发来的正确的中文了

         PrintWriter out=response.getWriter();//打印流,输出流,向客户端输入的意思
         out.print(content);//输出流,向客户端输入的意思
         out.flush();//打印流记得刷一下,不然不行
         out.close();
     }

     protected void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         doGet(request, response);
     }

 }