Android中socket初體驗

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　　最近要做一個Android的項目，用到socket和伺服器之間互動，研究了一個小demo。主要遇到了以下幾個問題：

　　1.用戶端建立socket對象時一直失敗NetworkOnMainThreadException，查了一下，原因是4.0之後在主線程中執行http請求會報這個錯。解決辦法是將代碼放到了一個新線程中，問題就解決了。

　　2.伺服器接收到用戶端資訊後反饋給用戶端資訊，將該資訊表示在用戶端UI上時報“android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.”異常。該問題原因是，在主線線程之外的線程中直接更新頁面顯示常會報錯。解決辦法是通過runOnUiThread方法將線程對象傳過去，這樣在主線程中就能執行該線程的內容了，當然還有其他辦法。可參考連結http://blog.csdn.net/shenyuemei/article/details/11030679。

　　

　　下面是程式碼：

　　布局檔案

<?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="match_parent"    android:orientation="vertical" >        <EditText        android:id="@+id/content"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:hint="@string/et_hint" />    <Button        android:id="@+id/send"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="@string/txt_send" />           <TextView        android:id="@+id/tv"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>

服務端代碼

package testDemo;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.net.ServerSocket;import java.net.Socket;public class Server implements Runnable {    public static void main(String[] args) {        Thread desktopServerThread = new Thread(new Server());        desktopServerThread.start();    }    @Override    public void run() {        try {            ServerSocket serverSocket = new ServerSocket(8888);            while (true) {                                // 阻塞，等待接收客戶請求。                Socket client = serverSocket.accept();                System.out.println("接受到用戶端的請求。");                try {                    BufferedReader in = new BufferedReader(                            new InputStreamReader(client.getInputStream()));                    // 讀取用戶端發過來的資訊                    String read = in.readLine();                    System.out.println("用戶端發送訊息為 : " + read);                    // 向用戶端返回資訊                    PrintWriter out = new PrintWriter(new BufferedWriter(                            new OutputStreamWriter(client.getOutputStream())));                    if (read != null) {                        out.println("你發送給伺服器的資訊為 : " + read);                        out.flush();                    }                        out.close();                    in.close();                } catch (Exception e) {                    e.printStackTrace();                } finally {                    client.close();                }            }        } catch (Exception e) {            e.printStackTrace();        }    }}

用戶端代碼

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.InetAddress;import java.net.Socket;import java.net.UnknownHostException;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;public class ClientActivity extends Activity {    private Button send = null;    private EditText content = null;    private TextView tv = null;    String msg = null;        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.socket2);                send = (Button)findViewById(R.id.send);        content = (EditText)findViewById(R.id.content);        tv = (TextView)findViewById(R.id.tv);                send.setOnClickListener(new OnClickListener(){            @Override            public void onClick(View v) {                setTitle("socket");                new Thread(thread1).start();            }                    });    }        /*Handler myHandler = new Handler() {                @Override        public void handleMessage(Message msg) {            myHandler.post(thread1);        }    };*/        /**     * 該線程主要是向伺服器發送訊息和接收訊息     */    Runnable thread1 = new Runnable() {        @Override        public void run() {            Socket socket = null;            try {                InetAddress serverAddr = InetAddress.getByName("192.168.1.110");                                socket = new Socket(serverAddr, 8888);                //想伺服器發送訊息                PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())));                out.println(content.getText().toString());                out.flush();                                //讀取伺服器返回的訊息                BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));                msg = in.readLine();                //把該子線程當做參數傳遞，這樣在主UI線程就可更新UI                ClientActivity.this.runOnUiThread(updateThread);                            } catch (UnknownHostException e) {                e.printStackTrace();            } catch (IOException e) {                e.printStackTrace();            }        }            };        Runnable updateThread = new Runnable() {        @Override        public void run() {            if (msg != null) {                tv.setText(msg);            } else {                tv.setText("data error.");            }        }            };}