前天把 SWT 的多线程终于搞定，本来想写点心得，苦于没时间，今天刚好有时间，就写了如下拙作， ^_^ 。

1 ．先看看 JAVA JDK 里的多线程：

JDK 里的多项程里有两种方式： extends Thread 和 implements Runnable ，当调用线程类的 start() 方法，本质是调用 run() ，线程执行。

e.g.

package com.javathread;

public class TestThread {

       /**

        * @param args

        */

       public static void main(String[] args) {

              // TODO Auto-generated method stub

              Thread t1 = new NewThread();// Create two new Thread

              t1.setName("t1");

              Thread t2 = new NewThread();

              t2.setName("t2");

              // new NewThread().start();//call the newThread

              try {

                     for (int i = 5; i > 0; i--) {

                            System.out.println("main Thread " + i);

                            t1.start();

                            t2.start();

                            Thread.sleep(1000);

                     }

              } catch (InterruptedException e) {

                     // TODO Auto-generated catch block

                     e.printStackTrace();

              }

              System.out.println("Exiting main Thread!");

       }

}

/*

 * create a Thread class

 */

class NewThread extends Thread {

       public void run() {

              System.out.println("new  Thread " + this.getName());

       }

} 输出结果：

main Thread 5

new  Thread t1

new  Thread t2

main Thread 4

main Thread 3

main Thread 2

main Thread 1

Exiting main Thread!

Implements Runnable()

package com.javathread;

public class TestThread {

       /**

        * @param args

        */

       public static void main(String[] args) {

              // TODO Auto-generated method stub

              new NewThread("one");// Create two new Thread

              new NewThread("two");

              // new NewThread().start();//call the newThread

              try {

                     Thread.sleep(10000);

              } catch (InterruptedException e) {

                     // TODO Auto-generated catch block

                     e.printStackTrace();

              }

              System.out.println("Exiting main Thread!");

       }

}

/*

 * create a Thread class

 */

class NewThread implements Runnable {

       String name;

       Thread t;

       NewThread(String name) {

              this.name = name;

              t = new Thread(this, name);

              System.out.println("New Thread " + t);

              t.start();

       }

       public void run() {

              try {

                     for (int i = 5; i > 0; i--) {

                            System.out.println(name + ":" + i);

                            Thread.sleep(1000);

                     }

              } catch (InterruptedException e) {

                     // TODO Auto-generated catch block

                     e.printStackTrace();

              }

       }

}

但是 SWT 的线程和 JDK 的有点区别

当启动一个 SWT 的线程时候，要回过来操作 shell 上的控件

必须要调用 Display 的 SyncExec 同步或者 asyncExec 异步，来重新取得 shell

举个例子

如下：

我们新建 SWT Application ，加一个 button 启动另一个线程，

代码如下所示：

package com;

import org.eclipse.jface.dialogs.MessageDialog;

import org.eclipse.swt.SWT;

import org.eclipse.swt.events.SelectionAdapter;

import org.eclipse.swt.events.SelectionEvent;

import org.eclipse.swt.widgets.Button;

import org.eclipse.swt.widgets.Display;

import org.eclipse.swt.widgets.Shell;

public class Test {

       private static Display display = Display.getDefault();

       private static Shell shell = new Shell();

       public static void main(String[] args) {

              Test test = new Test();

              test.open();

              // final Shell shell = new Shell();

       }

       public void open() {

              shell.setSize(500, 375);

              shell.setText("SWT Application");

              shell.open();

              final Button startnewthreadButton = new Button(shell, SWT.NONE);

              startnewthreadButton.addSelectionListener(new SelectionAdapter() {

                     public void widgetSelected(SelectionEvent e) {

                            new TestThread().start();

                     }

              });

              startnewthreadButton.setText("startnewthread");

              startnewthreadButton.setBounds(135, 116, 90, 25);

              shell.layout();

              while (!shell.isDisposed()) {

                     if (!display.readAndDispatch())

                            display.sleep();

              }

       }

       /*

        * create a new Thread class

        */

       private class TestThread extends Thread {

              public void run() {

                     /*

                      * call Swt controls must use Dispaly.syncExec or Display.asyncExec

                      */

                     if (!Test.display.isDisposed()) {

                            Test.display.syncExec(new Runnable() {// 这段代码很重要

                                   public void run() {

                                          MessageDialog.openInformation(null, "fd", "fd");

                                   }

                            });

                     }

              }

       }

}

如果不加加红这段代码 直接 MessageDialog.openInformation(null,”fd”,”fd”);

程序会抛出异常： ja va.lang.ExceptionInInitializerError

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