谈谈Android的三种网络通信方式

2019-12-12 04:08:11

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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。

服务端：

public class Server 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();         //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 Server());     server.start();   } }

客户端，MainActivity

public class MainActivity extends Activity {   private EditText editText;   private Button button;   /** Called when the activity is first created. */   @Override   public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.main);          editText = (EditText)findViewById(R.id.editText1);     button = (Button)findViewById(R.id.button1);          button.setOnClickListener(new OnClickListener() {       @Override       public void onClick(View v) {         Socket socket = null;         String message = editText.getText().toString()+ "/r/n" ;         try {           //创建客户端socket,注意:不能用localhost或127.0.0.1，Android模拟器把自己作为localhost           socket = new Socket("<span style="font-weight: bold;">10.0.2.2</span>",18888);           PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter               (socket.getOutputStream())),true);           //发送数据           out.println(message);                      //接收数据           BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));           String msg = in.readLine();           if (null != msg){             editText.setText(msg);             System.out.println(msg);           }           else{             editText.setText("data error");           }           out.close();           in.close();         } catch (UnknownHostException e) {           e.printStackTrace();         } catch (IOException e) {           e.printStackTrace();         }         finally{           try {             if (null != socket){               socket.close();             }           } catch (IOException e) {             e.printStackTrace();           }         }       }     });   } }

布局文件：

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"   android:orientation="vertical" android:layout_width="fill_parent"   android:layout_height="fill_parent">   <TextView android:layout_width="fill_parent"     android:layout_height="wrap_content" android:text="@string/hello" />   <EditText android:layout_width="match_parent" android:id="@+id/editText1"     android:layout_height="wrap_content"     android:hint="input the message and click the send button"     ></EditText>   <Button android:text="send" android:id="@+id/button1"     android:layout_width="fill_parent" android:layout_height="wrap_content"></Button> </LinearLayout>

启动服务器：

javac com/test/socket/Server.java java com.test.socket.Server

运行客户端程序：

结果如图：

注意：服务器与客户端无法链接的可能原因有：

没有加访问网络的权限：<uses-permission android:name="android.permission.INTERNET"></uses-permission>

IP地址要使用：10.0.2.2

模拟器不能配置代理。

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myapp，只有很简单的一个http.jsp

内容如下：

<%@page language="java" import="java.util.*" pageEncoding="utf-8"%> <html> <head> <title> Http Test </title> </head> <body> <% String type = request.getParameter("parameter"); String result = new String(type.getBytes("iso-8859-1"),"utf-8"); out.println("<h1>" + result + "</h1>"); %> </body> </html>

然后实现Android客户端，分别以post、get方式去访问myapp,代码如下：

布局文件：

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

资源文件：

strings.xml

<?xml version="1.0" encoding="utf-8"?> <resources>   <string name="hello">通过按钮选择不同方式访问网页</string>   <string name="app_name">Http Get</string> </resources>

主Activity:

public class MainActivity extends Activity {   private TextView textView;   private Button get,post;   /** Called when the activity is first created. */   @Override   public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.main);          textView = (TextView)findViewById(R.id.textView);     get = (Button)findViewById(R.id.get);     post = (Button)findViewById(R.id.post);          //绑定按钮监听器     get.setOnClickListener(new OnClickListener() {       @Override       public void onClick(View v) {         //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 uri = "http://192.168.22.28:8080/myapp/http.jsp?parameter=以Get方式发送请求";         textView.setText(get(uri));       }     });     //绑定按钮监听器     post.setOnClickListener(new OnClickListener() {       @Override       public void onClick(View v) {         String uri = "http://192.168.22.28:8080/myapp/http.jsp";         textView.setText(post(uri));       }     });   }   /**    * 以get方式发送请求，访问web    * @param uri web地址    * @return 响应数据    */   private static String get(String uri){     BufferedReader reader = null;     StringBuffer sb = null;     String result = "";     HttpClient client = new DefaultHttpClient();     HttpGet request = new HttpGet(uri);     try {       //发送请求，得到响应       HttpResponse response = client.execute(request);              //请求成功       if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){         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 (ClientProtocolException e) {       e.printStackTrace();     } catch (IOException e) {       e.printStackTrace();     }     finally{       try {         if (null != reader){           reader.close();           reader = null;         }       } catch (IOException e) {         e.printStackTrace();       }     }     if (null != sb){       result = sb.toString();     }     return result;   }   /**    * 以post方式发送请求，访问web    * @param uri web地址    * @return 响应数据    */   private static String post(String uri){     BufferedReader reader = null;     StringBuffer sb = null;     String result = "";     HttpClient client = new DefaultHttpClient();     HttpPost request = new HttpPost(uri);          //保存要传递的参数     List<NameValuePair> params = new ArrayList<NameValuePair>();     //添加参数     params.add(new BasicNameValuePair("parameter","以Post方式发送请求"));          try {       //设置字符集       HttpEntity entity = new UrlEncodedFormEntity(params,"utf-8");       //请求对象       request.setEntity(entity);       //发送请求       HttpResponse response = client.execute(request);              //请求成功       if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){         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 (ClientProtocolException e) {       e.printStackTrace();     } catch (IOException e) {       e.printStackTrace();     }     finally{       try {         //关闭流         if (null != reader){           reader.close();           reader = null;         }       } catch (IOException e) {         e.printStackTrace();       }     }     if (null != sb){       result = sb.toString();     }     return result;   } }

运行结果如下：