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，
^_^
。
?
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
，當調用線程類的
start()
方法，本質是調用
run()
，線程執行。
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());
?????? }
?
}
輸出結果：
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
的線程和
JDK
的有點區別
?
當啟動一個
SWT
的線程時候，要回過來操作
shell
上的控件
必須要調用
Display
的
SyncExec
同步或者
asyncExec
異步，來重新取得
shell
舉個例子
如下：
?
我們新建
SWT Application
，加一個
button
啟動另一個線程，
?
代碼如下所示：
?
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() {//
這段代碼很重要
?
??????????????????????????????????
public void run() {
?
??????????????????????????????????
?????? MessageDialog.openInformation(null, "fd", "fd");
?
?????????????????????????????????? }
?
??????????????????????????? });
???????????????????? }
?
????????????? }
?????? }
?
}
?
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
?
好了
有問題
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QQ 4384919
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