使用線程創建的三種方法實現j2me聯網（PS：我想做android！NND！）

在j2me聯網時，在eclipse控制檯下有一個警告：“若要避免潛在的死鎖，應該在commandAction()處理程序之外的其他線程中執行可能會阻塞的，操作（如網絡連接）。
爲了避免潛在的死鎖，我們經常把把聯網的代碼部分寫到一個線程中去執行。
而實際應用中，網絡連接的事務也都是使用一個單獨的線程進行的。

線程的創建可以使用Runnable接口來實現，也可以使用Thread類實現，還可以以匿名內部類的方式創建。在本文中，分別用這三種方式給出了j2me聯網的例子。
代碼均測試通過。可以直接使用。
1.通過繼承Thread類創建

/**
* 測試Thread類線程
* @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 {
        // 創建Runnable類
        OpenConn openConn = new
 OpenConn(
"http://www.google.com"
);
        // 創建線程
        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("連接網絡成功..."
);
            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("超時錯誤,連接網絡失敗..."
);
        }
    }
}

/** 
* 測試Thread類線程 
* @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 {
		// 創建Runnable類
		OpenConn openConn = new OpenConn("http://www.google.com");
		// 創建線程
		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("連接網絡成功...");
			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("超時錯誤,連接網絡失敗...");
		}
	}
}

 
2.通過引用Runnable接口創建

/**
* 測試Runnable接口線程
* @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("連接網絡成功..."
);
            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("超時錯誤,連接網絡失敗..."
);
        }
    }
}

/** 
* 測試Runnable接口線程 
* @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("連接網絡成功...");
			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("超時錯誤,連接網絡失敗...");
		}
	}
}

3.以匿名內部類的方式創建
即在一個方法中創建線程，當方法被調用時，線程即啓動，如下：

/**
* 測試匿名線程線程創建
* @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("連接網絡成功..."
);
            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("超時錯誤,連接網絡失敗..."
);
        }

     }
}
轉自javaeye mfcai