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:

1 package imqsl.com.testhttp;
2
3 import android.os.Bundle;
4 import android.os.Handler;
5 import android.os.Message;
6 import android.support.v7.app.AppCompatActivity;
7 import android.view.View;
8 import android.widget.Button;
9 import android.widget.EditText;
10 import android.widget.TextView;
11 import android.widget.Toast;
12
13 import java.io.BufferedReader;
14 import java.io.DataOutputStream;
15 import java.io.IOException;
16 import java.io.InputStreamReader;
17 import java.net.HttpURLConnection;
18 import java.net.MalformedURLException;
19 import java.net.URL;
20 import java.net.URLEncoder;
21
22 public class MainActivity extends AppCompatActivity {
23     Button button = null;
24     EditText edit = null;
25     TextView textView = null;
26     String result="";
27     Handler handler=null;
28     @Override
29     protected void onCreate(Bundle savedInstanceState) {
30         super.onCreate(savedInstanceState);
31         setContentView(R.layout.activity_main);
32         button= (Button) findViewById(R.id.button);
33         edit= (EditText) findViewById(R.id.edit);
34         textView= (TextView) findViewById(R.id.text_display);
35         button.setOnClickListener(new View.OnClickListener() {
36             @Override
37             public void onClick(View view) {
38                 if ("".equals(edit.getText().toString())){
39                     Toast.makeText(MainActivity.this,"请输入要发送的内容",Toast.LENGTH_SHORT).show();
40                     return;
41                 }
42                 new Thread(new Runnable() {
43                     @Override
44                     public void run() {
45                         send();
46                         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
47                         handler.sendMessage(msg);
48                     }
49                 }).start();
50             }
51         });
52         handler=new Handler(){//主线程中的handle用来接收子线程中的Message以便更新UI
53             @Override
54             public void handleMessage(Message msg) {
55                 Toast.makeText(MainActivity.this,result,Toast.LENGTH_SHORT).show();
56                 if (result!=null){
57                     textView.setText(result);
58                     edit.setText("");
59                 }
60                 super.handleMessage(msg);
61             }
62         };
63
64     }
65
66     private void send() {
67         URL url;
68         String target = "http://192.168.1.152:8080/flightcheck/testservlet";
69         try {
70             url=new URL(target);
71             HttpURLConnection urlConn= (HttpURLConnection) url.openConnection();//注意:httpURLconnetion的创建是这样自的
72             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
73             urlConn.setUseCaches(false);//是指是否缓存
74             urlConn.setDoInput(true);//设置是否输入
75             urlConn.setDoOutput(true);//设置是否输出
76             DataOutputStream out=new DataOutputStream(urlConn.getOutputStream());
77             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
78             out.writeBytes(param);//writeBytes写字节到输出流中,服务器端也是接收的bytes
79             out.flush();//记得刷一下
80             out.close();
81             System.out.println("responsecode:"+urlConn.getResponseCode());
82             if (urlConn.getResponseCode()==HttpURLConnection.HTTP_OK){//连接成功,则相等,httpURLConnection.http_ok=200
83                 BufferedReader bufferedReader=new BufferedReader(new  //处理流,转换流,节点流
84                         InputStreamReader(urlConn.getInputStream()));
85                 String line=null;
86                 System.out.println("bufferedReader.readLine():"+bufferedReader.readLine());
87                 while ((line=bufferedReader.readLine())!=null){
88                     result+=line+"\n";                              //加了个"\n"相当于换到了下一行
89                 }
90             }
91         } catch (MalformedURLException e) {
92             e.printStackTrace();
93         } catch (IOException e) {
94             e.printStackTrace();
95         }
96
97
98     }
99 }

xml文件代码:

1 <?xml version="1.0" encoding="utf-8"?>
2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
3     android:layout_width="match_parent"
4     android:layout_height="wrap_content"
5     android:orientation="vertical"
6     >
7     <EditText
8         android:layout_width="match_parent"
9         android:layout_height="wrap_content"
10         android:id="@+id/edit"
11         />
12     <Button
13         android:layout_width="wrap_content"
14         android:layout_height="wrap_content"
15         android:text="发表"
16         android:id="@+id/button"
17         />
18     <TextView
19         android:layout_width="match_parent"
20         android:layout_height="wrap_content"
21         android:id="@+id/text_display"
22         />
23
24 </LinearLayout>

服务器端代码:

1 package test;
2
3 import java.io.IOException;
4 import java.io.PrintWriter;
5
6 import javax.servlet.ServletException;
7 import javax.servlet.http.HttpServlet;
8 import javax.servlet.http.HttpServletRequest;
9 import javax.servlet.http.HttpServletResponse;
10
11
12 public class testservlet extends HttpServlet {
13     private static final long serialVersionUID = 1L;
14
15     public testservlet() {
16         super();
17     }
18
19     protected void doGet(HttpServletRequest request, HttpServletResponse response)
20             throws ServletException, IOException {
21         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
22         System.out.println(content);
23         response.setContentType("text/plain");
24         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
25
26         PrintWriter out=response.getWriter();//打印流,输出流,向客户端输入的意思
27         out.print(content);//输出流,向客户端输入的意思
28         out.flush();//打印流记得刷一下,不然不行
29         out.close();
30     }
31
32     protected void doPost(HttpServletRequest request, HttpServletResponse response)
33             throws ServletException, IOException {
34         doGet(request, response);
35     }
36
37 }