使用线程创建的三种方法实现j2me联网（PS：我想做android！NND！）

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..." );
        }
    }
}

/** 
* 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..." );
        }
    }
}

/** 
* 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..." );
        }

     }
}
转自javaeye mfcai