2006-9-12

前天把 SWT 的多線程終于搞定，本來想寫點心得，苦于沒時間，今天剛好有時間，就寫了如下拙作， ^_^ 。

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1 ．先看看 JAVA JDK 里的多線程：

JDK 里的多項程里有兩種方式： extends Thread 和 implements Runnable ，當調(diào)用線程類的 start() 方法，本質(zhì)是調(diào)用 run() ，線程執(zhí)行。

e.g.

package com.javathread;

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public class TestThread {

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?????? /**

?????? ?* @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();

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??????????????????????????? t2.start();

??????????????????????????? Thread.sleep(1000);

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???????????????????? }

????????????? } catch (InterruptedException e) {

???????????????????? // TODO Auto-generated catch block

???????????????????? e.printStackTrace();

????????????? }

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

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?????? }

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}

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/*

?* create a Thread class

?*/

class NewThread extends Thread {

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?????? public void run() {

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

?????? }

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} 輸出結(jié)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!

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Implements Runnable()

package com.javathread;

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public class TestThread {

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?????? /**

?????? ?* @param args

?????? ?*/

?????? public static void main(String[] args) {

????????????? // TODO Auto-generated method stub

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

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????????????? new NewThread("two");

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

????????????? try {

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???????????????????? Thread.sleep(10000);

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????????????? } catch (InterruptedException e) {

???????????????????? // TODO Auto-generated catch block

???????????????????? e.printStackTrace();

????????????? }

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

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?????? }

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}

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/*

?* create a Thread class

?*/

class NewThread implements Runnable {

?????? String name;

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?????? Thread t;

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?????? NewThread(String name) {

????????????? this.name = name;

????????????? t = new Thread(this, name);

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

????????????? t.start();

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?????? }

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?????? 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();

????????????? }

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?????? }

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}

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但是 SWT 的線程和 JDK 的有點區(qū)別

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當啟動一個 SWT 的線程時候，要回過來操作 shell 上的控件

必須要調(diào)用 Display 的 SyncExec 同步或者 asyncExec 異步，來重新取得 shell

舉個例子

如下：

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我們新建 SWT Application ，加一個 button 啟動另一個線程，

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代碼如下所示：

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package com;

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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;

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public class Test {

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?????? private static Display display = Display.getDefault();

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?????? private static Shell shell = new Shell();

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?????? public static void main(String[] args) {

????????????? Test test = new Test();

????????????? test.open();

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????????????? // final Shell shell = new Shell();

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?????? }

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?????? public void open() {

????????????? shell.setSize(500, 375);

????????????? shell.setText("SWT Application");

????????????? shell.open();

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

????????????? startnewthreadButton.addSelectionListener(new SelectionAdapter() {

???????????????????? public void widgetSelected(SelectionEvent e) {

??????????????????????????? new TestThread().start();

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???????????????????? }

????????????? });

????????????? startnewthreadButton.setText("startnewthread");

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

????????????? shell.layout();

????????????? while (!shell.isDisposed()) {

???????????????????? if (!display.readAndDispatch())

??????????????????????????? display.sleep();

????????????? }

?????? }

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?????? /*

?????? ?* create a new Thread class

?????? ?*/

?????? private class TestThread extends Thread {

????????????? public void run() {

???????????????????? /*

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

???????????????????? ?*/

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

??????????????????????????? Test.display.syncExec(new Runnable() {// 這段代碼很重要

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?????????????????????????????????? public void run() {

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

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?????????????????????????????????? }

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??????????????????????????? });

???????????????????? }

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????????????? }

?????? }

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}

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如果不加加紅這段代碼 直接 MessageDialog.openInformation(null,”fd”,”fd”);

程序會拋出異常： ja va.lang.ExceptionInInitializerError

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好了 有問題 聯(lián)系 edsionchen002@163.com

QQ 4384919

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