运用线程创建的三种方式实现j2me联网功能

使用线程创建的三种方式实现j2me联网功能
在j2me联网时，在eclipse控制台下有一个警告：“若要避免潜在的死锁，应该在commandAction()处理程序之外的其他线程中执行可能会阻塞的，操作（如网络连接）。
为了避免潜在的死锁，我们经常把把联网的代码部分写到一个线程中去执行。
而实际应用中，网络连接的事务也都是使用一个单独的线程进行的。

线程的创建可以使用Runnable接口来实现，也可以使用Thread类实现，还可以以匿名内部类的方式创建。在本文中，分别用这三种方式给出了j2me联网的例子。
代码均测试通过。可以直接使用。
1.通过继承Thread类创建

/** * 测试Thread类线程 * @author mfcai */   import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.Reader;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;public class OpenConn implements Runnable {	private HttpURLConnection conn;	private URL url;	// Thread thread1;	public OpenConn(String url) throws MalformedURLException {		this.url = new URL(url);	}	public void run() {		try {			conn = (HttpURLConnection) url.openConnection();		} catch (IOException e) {			e.printStackTrace();			url = null;		}	}	public HttpURLConnection getConn() {		return conn;	}	public static void main(String[] args) throws Exception {		// 创建Runnable类		OpenConn openConn = new OpenConn("http://www.google.com");		// 创建线程		Thread thread = new Thread(openConn);		// openConn.thread1=thread;		thread.start();		thread.join(10000);// wait 10 seconds		HttpURLConnection c = openConn.getConn();		if (c != null) {			System.out.println("连接网络成功...");			BufferedReader r = new BufferedReader(new InputStreamReader(c					.getInputStream()));			String s = r.readLine();			while (s != null) {				System.out.println(s);				s = r.readLine();			}		} else {			System.out.println("超时错误,连接网络失败...");		}	}}

 
2.通过引用Runnable接口创建

/** * 测试Runnable接口线程 * @author mfcai */ import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.Reader;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;public class OpenConn2 extends Thread {	private HttpURLConnection conn;	private URL url;	public OpenConn2(String url) throws MalformedURLException {		this.url = new URL(url);	}	public void run() {		try {			conn = (HttpURLConnection) url.openConnection();		} catch (IOException e) {			e.printStackTrace();			url = null;		}	}	public HttpURLConnection getConn() {		return conn;	}	public static void main(String[] args) throws Exception {		OpenConn2 openConn = new OpenConn2("http://www.google.com");		openConn.start();		openConn.join(10000);// wait 10 seconds		HttpURLConnection c = openConn.getConn();		if (c != null) {			System.out.println("连接网络成功...");			BufferedReader r = new BufferedReader(new InputStreamReader(c					.getInputStream()));			String s = r.readLine();			while (s != null) {				System.out.println(s);				s = r.readLine();			}		} else {			System.out.println("超时错误,连接网络失败...");		}	}}

3.以匿名内部类的方式创建
即在一个方法中创建线程，当方法被调用时，线程即启动，如下：

/** * 测试匿名线程线程创建 * @author mfcai */ import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.net.HttpURLConnection;import java.net.URL;public class OpenConn3 {	private HttpURLConnection conn;	private URL url;		public static void main(String[] args){		try{			OpenConn3 open3= new OpenConn3();			open3.strartMyThread();		}catch(Exception ex){			System.out.println(ex.toString());		}	}	 public void strartMyThread() throws Exception{ 		 this.url =new URL("http://www.google.com");         java.lang.Runnable runner=new Runnable(){        	 public void run(){         		 try {        				conn = (HttpURLConnection) url.openConnection();        			} catch (IOException e) {        				e.printStackTrace();        				url = null;        			}        	 }         };         Thread openConn=new Thread(runner);          openConn.start();          openConn.join(10000);// wait 10 seconds 		if (conn != null) { 			System.out.println("连接网络成功..."); 			BufferedReader r = new BufferedReader(new InputStreamReader(conn 					.getInputStream())); 			String s = r.readLine(); 			while (s != null) { 				System.out.println(s); 				s = r.readLine(); 			} 		} else { 			System.out.println("超时错误,连接网络失败..."); 		}	 }}

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