談談Android的三種網絡通信方式

2019-12-12 04:08:11

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Android平臺有三種網絡接口可以使用，他們分別是：java.net.*(標準Java接口)、Org.apache接口和Android.net.*(Android網絡接口)。下面分別介紹這些接口的功能和作用。

1.標準Java接口

java.net.*提供與聯網有關的類，包括流、數據包套接字(socket)、Internet協議、常見Http處理等。比如：創建URL，以及URLConnection/HttpURLConnection對象、設置鏈接參數、鏈接到服務器、向服務器寫數據、從服務器讀取數據等通信。這些在Java網絡編程中均有涉及，我們看一個簡單的socket編程，實現服務器回發客戶端信息。

服務端：

public class Server implements Runnable{   @Override   public void run() {     Socket socket = null;     try {       ServerSocket server = new ServerSocket(18888);       //循環監聽客戶端鏈接請求       while(true){         System.out.println("start...");         //接收請求         socket = server.accept();         System.out.println("accept...");         //接收客戶端消息         BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));         String message = in.readLine();         //發送消息，向客戶端         PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true);         out.println("Server:" + message);         //關閉流         in.close();         out.close();       }     } catch (IOException e) {       e.printStackTrace();     }finally{       if (null != socket){         try {           socket.close();         } catch (IOException e) {           e.printStackTrace();         }       }     }        }   //啟動服務器   public static void main(String[] args){     Thread server = new Thread(new Server());     server.start();   } }

客戶端，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 {           //創建客戶端socket,注意:不能用localhost或127.0.0.1，Android模擬器把自己作為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);           //發送數據           out.println(message);                      //接收數據           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>

啟動服務器：

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

運行客戶端程序：

結果如圖：

注意：服務器與客戶端無法鏈接的可能原因有：

沒有加訪問網絡的權限：<uses-permission android:name="android.permission.INTERNET"></uses-permission>

IP地址要使用：10.0.2.2

模擬器不能配置代理。

2。Apache接口

對于大部分應用程序而言JDK本身提供的網絡功能已遠遠不夠，這時就需要Android提供的Apache HttpClient了。它是一個開源項目，功能更加完善，為客戶端的Http編程提供高效、最新、功能豐富的工具包支持。

下面我們以一個簡單例子來看看如何使用HttpClient在Android客戶端訪問Web。

首先，要在你的機器上搭建一個web應用myapp，只有很簡單的一個http.jsp

內容如下：

<%@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>

然后實現Android客戶端，分別以post、get方式去訪問myapp,代碼如下：

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>

資源文件：

strings.xml

<?xml version="1.0" encoding="utf-8"?> <resources>   <string name="hello">通過按鈕選擇不同方式訪問網頁</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);          //綁定按鈕監聽器     get.setOnClickListener(new OnClickListener() {       @Override       public void onClick(View v) {         //注意：此處ip不能用127.0.0.1或localhost,Android模擬器已將它自己作為了localhost         String uri = "http://192.168.22.28:8080/myapp/http.jsp?parameter=以Get方式發送請求";         textView.setText(get(uri));       }     });     //綁定按鈕監聽器     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方式發送請求，訪問web    * @param uri web地址    * @return 響應數據    */   private static String get(String uri){     BufferedReader reader = null;     StringBuffer sb = null;     String result = "";     HttpClient client = new DefaultHttpClient();     HttpGet request = new HttpGet(uri);     try {       //發送請求，得到響應       HttpResponse response = client.execute(request);              //請求成功       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方式發送請求，訪問web    * @param uri web地址    * @return 響應數據    */   private static String post(String uri){     BufferedReader reader = null;     StringBuffer sb = null;     String result = "";     HttpClient client = new DefaultHttpClient();     HttpPost request = new HttpPost(uri);          //保存要傳遞的參數     List<NameValuePair> params = new ArrayList<NameValuePair>();     //添加參數     params.add(new BasicNameValuePair("parameter","以Post方式發送請求"));          try {       //設置字符集       HttpEntity entity = new UrlEncodedFormEntity(params,"utf-8");       //請求對象       request.setEntity(entity);       //發送請求       HttpResponse response = client.execute(request);              //請求成功       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 {         //關閉流         if (null != reader){           reader.close();           reader = null;         }       } catch (IOException e) {         e.printStackTrace();       }     }     if (null != sb){       result = sb.toString();     }     return result;   } }

運行結果如下：