Android三种网络通讯方式及Android的网络通讯机制

2020-04-11 11:17:46

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Android平台有三种网络接口可以使用，他们分别是：java.net.*(标准Java接口)、Org.apache接口和Android.net.*(Android网络接口)。下面分别介绍这些接口的功能和作用。

1.标准Java接口

java.net.*提供与联网有关的类，包括流、数据包套接字(socket)、Internet协议、常见Http处理等。比如：创建URL，以及URLConnection/HttpURLConnection对象、设置链接参数、链接到服务器、向服务器写数据、从服务器读取数据等通信。这些在Java网络编程中均有涉及，我们看一个简单的socket编程，实现服务器回发客户端信息。

下面用个例子来说明：

A、客户端：

新建Android项目工程：SocketForAndroid（这个随意起名字了吧，我是以这个建立的！）

下面是main_activity.xml的代码：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical"> <TextView  android:layout_width="fill_parent"  android:layout_height="wrap_content"  android:text="@string/hello" /> <EditText  android:id="@+id/message"  android:layout_width="match_parent"  android:layout_height="wrap_content"  android:hint="@string/hint" /> <Button  android:id="@+id/send"  android:layout_width="fill_parent"  android:layout_height="wrap_content"  android:text="@string/send" /></LinearLayout>

MainActivity.java的代码入下：

package com.yaowen.socketforandroid;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.EditText;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.net.Socket;public class MainActivity extends AppCompatActivity { private EditText message; private Button send; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  //初始化两个UI控件  message = (EditText) findViewById(R.id.message);  send = (Button) findViewById(R.id.send);  //设置发送按钮的点击事件响应  send.setOnClickListener(new View.OnClickListener() {   @Override   public void onClick(View v) {    Socket socket = null;    //获取message输入框里的输入的内容    String msg = message.getText().toString() + "/r/n";    try {     //这里必须是192.168.3.200，不可以是localhost或者127.0.0.1     socket = new Socket("192.168.3.200", 18888);     PrintWriter out = new PrintWriter(       new BufferedWriter(         new OutputStreamWriter(           socket.getOutputStream()         )       ), true);     //发送消息     out.println(msg);     //接收数据     BufferedReader in = new BufferedReader(      new InputStreamReader(       socket.getInputStream()      )     );     //读取接收的数据     String msg_in = in.readLine();     if (null != msg_in) {      message.setText(msg_in);      System.out.println(msg_in);     } else {      message.setText("接收的数据有误!");     }     //关闭各种流     out.close();     in.close();    } catch (IOException e) {     e.printStackTrace();    } finally {     try {      if (null != socket) {       //socket不为空时，最后记得要把socket关闭       socket.close();      }     } catch (IOException e) {      e.printStackTrace();     }    }   }  }); }}

最后别忘记添加访问网络权限：

<uses-permission android:name="android.permission.INTERNET" />

B、服务端：

package service;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.net.ServerSocket;import java.net.Socket;public class ServerAndroid implements Runnable { @Override public void run() { Socket socket = null; try { ServerSocket server = new ServerSocket(18888); // 循环监听客户端链接请求 while (true) { System.out.println("start..."); // 接收请求 socket = server.accept(); System.out.println("accept..."); // 接收客户端消息 BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream())); String message = in.readLine(); System.out.println(message); // 发送消息，向客户端 PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),  true); out.println("Server:" + message); // 关闭流 in.close(); out.close(); } } catch (IOException e) { e.printStackTrace(); } finally { if (null != socket) { try {  socket.close(); } catch (IOException e) {  e.printStackTrace(); } } } } // 启动服务器 public static void main(String[] args) { Thread server = new Thread(new ServerAndroid()); server.start(); }}

C、启动服务器，控制台会打印出“start...”字符串！

D、运行Android项目文件，如下图：

在输入框里输入如下字符串，点发送按钮：

服务器收到客户端发来的消息并打印到控制台：

2、Apache接口

对于大部分应用程序而言JDK本身提供的网络功能已远远不够，这时就需要Android提供的Apache HttpClient了。它是一个开源项目，功能更加完善，为客户端的Http编程提供高效、最新、功能丰富的工具包支持。
下面我们以一个简单例子来看看如何使用HttpClient在Android客户端访问Web。
首先，要在你的机器上搭建一个web应用test，有两个很简单的PHP文件：hello_get.php和hello_post.php！
内容如下：

hello_get.php的代码如下：

<html> <body> Welcome <?php echo $_GET["name"]; ?><br> You connected this page on : <?php echo $_GET["get"]; ?> </body></html>

hello_post.php的代码如下：

<html><body>Welcome <?php echo $_POST["name"]; ?><br>You connected this page on : <?php echo $_POST["post"]; ?></body></html>

在原来的Android项目里新建一个Apache活动类：Apache.java，代码如下：

package com.yaowen.socketforandroid;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.TextView;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicNameValuePair;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.UnsupportedEncodingException;import java.util.ArrayList;import java.util.List;/** * Created by YAOWEN on 2015/11/10. */public class ApacheActivity extends AppCompatActivity implements View.OnClickListener { private TextView textView; private Button get1, post1; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.apache);  textView = (TextView) findViewById(R.id.textView);  get1 = (Button) findViewById(R.id.get);  post1 = (Button) findViewById(R.id.post);  get1.setOnClickListener(this);  post1.setOnClickListener(this); } @Override public void onClick(View v) {  if (v.getId() == R.id.get) {   //注意：此处ip不能用127.0.0.1或localhost,Android模拟器已将它自己作为了localhost   String url = "http://192.168.3.200/test/hello_get.php?name=yaowen&get=GET";   textView.setText(get(url));  }  if (v.getId() == R.id.post) {   String url="http://192.168.3.200/test/hello_post.php";   textView.setText(post(url));  } } /**  * 以post方式发送请求，访问web  *  * @param url web地址  * @return 响应数据  */ private String post(String url) {  BufferedReader reader = null;  StringBuffer sb = null;  String result = "";  HttpClient client = new DefaultHttpClient();  HttpPost requset = new HttpPost(url);  //保存要传递的参数  List<NameValuePair> params = new ArrayList<NameValuePair>();  //添加参数  params.add(new BasicNameValuePair("name", "yaowen"));  params.add(new BasicNameValuePair("post","POST"));  try {   HttpEntity entity = new UrlEncodedFormEntity(params, "utf-8");   requset.setEntity(entity);   HttpResponse response = client.execute(requset);   if (response.getStatusLine().getStatusCode() == 200) {    System.out.println("post success");    reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));    sb = new StringBuffer();    String line = "";    String NL = System.getProperty("line.separator");    while ((line = reader.readLine()) != null) {     sb.append(line);    }   }  } catch (UnsupportedEncodingException e) {   e.printStackTrace();  } catch (ClientProtocolException e) {   e.printStackTrace();  } catch (IOException e) {   e.printStackTrace();  } finally {   if (null != reader) {    try {     reader.close();    } catch (IOException e) {     e.printStackTrace();    }   }   if (null != sb) {    result = sb.toString();   }  }  return result; } /**  * 以get方式发送请求，访问web  *  * @param url web地址  * @return 响应数据  */ private static String get(String url) {  BufferedReader bufferedReader = null;  StringBuffer sb = null;  String result = "";  HttpClient client = new DefaultHttpClient();  HttpGet request = new HttpGet(url);  //发送请求，得到响应  try {   HttpResponse response = client.execute(request);   //请求成功   if (response.getStatusLine().getStatusCode() == 200) {    bufferedReader = new BufferedReader(      new InputStreamReader(        response.getEntity()          .getContent()      )    );    sb = new StringBuffer();    String line = "";    String NL = System.getProperty("line.separator");    while ((line = bufferedReader.readLine()) != null) {     sb.append(line);    }   }  } catch (IOException e) {   e.printStackTrace();  } finally {   if (null != bufferedReader) {    try {     bufferedReader.close();     //bufferedReader=null;    } catch (IOException e) {     e.printStackTrace();    }   }   if (null != sb) {    result = sb.toString();   }  }  return result; }}

新建一个apache.XML文件，如下：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical"> <TextView  android:id="@+id/textView"  android:layout_width="fill_parent"  android:layout_height="wrap_content"  android:gravity="center"  android:text="通过按钮选择不同方式访问网页" /> <Button  android:id="@+id/get"  android:layout_width="match_parent"  android:layout_height="wrap_content"  android:text="get" /> <Button  android:id="@+id/post"  android:layout_width="match_parent"  android:layout_height="wrap_content"  android:text="post" /></LinearLayout>

结果运行如下：