worker.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"><html> <head> <title>Worker Threads and SwingWorker (The Java™ Tutorials > Creating a GUI with JFC/Swing > Concurrency in Swing)</title><style type="text/css"> .FigureCaption { margin-left: 1in; margin-right: 1in; font-family: sans-serif; font-size: smaller; text-align: justify; } #TopBar_bl { background: url(../../images/java_bar_bl.gif) 0 100% no-repeat; width: 100%; height: 60px; } #TopBar_br { background: url(../../images/java_bar_br.gif) 100% 100% no-repeat; width: 100%; height: 60px; } #TopBar_tl { background: url(../../images/java_bar_tl.gif) 0 0 no-repeat; width: 100%; height: 60px; } #TopBar_tr { background: url(../../images/java_bar_tr.gif) 100% 0 no-repeat; width: 100%; height: 60px; } #TopBar { background: #35556B url(../../images/java_bar.gif); margin: 10px 10px 0 10px; height:60px; min-width:700px; color: white; font-family: sans-serif; font-weight: bold; } @media print { #BreadCrumbs, #Download { display: none; } } #TopBar_right { line-height: 14px; 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var main = document.getElementById("MainFlow"); var toggle = document.getElementById("ToggleLeft"); if (b) { contents.className = "LeftBar_shown"; main.className = "MainFlow_indented"; toggle.innerHTML = "Hide the TOC"; document.cookie = 'tutorial_showLeftBar=yes; path=/'; } else { contents.className = "LeftBar_hidden"; main.className = "MainFlow_wide"; toggle.innerHTML = "Show the TOC"; document.cookie = 'tutorial_showLeftBar=no; path=/'; } } function toggleLeft() { showLeft(document.getElementById("LeftBar").className == "LeftBar_hidden"); document.getElementById("ToggleLeft").blur(); } function load() { showLeft(leftBar()); document.getElementById("ToggleLeft").style.display="inline"; } </script> </head><body onload="load()"> <div id=TopBar> <div id=TopBar_tr> <div id=TopBar_tl> <div id=TopBar_br> <div id=TopBar_bl> <div id=TopBar_right> <a target="_blank" href="http://java.sun.com/javase/6/download.jsp">Download the JDK</a> <br> <a href="../../search.html" target="_blank">Search the Tutorials</a> <br> <a href="javascript:toggleLeft()" id="ToggleLeft">Hide the TOC</a> </div> </div> </div> </div> </div> </div> <div class=PrintHeaders> <b>Trail:</b> Creating a GUI with JFC/Swing <br><b>Lesson:</b> Concurrency in Swing </div> <div id=LeftBar class=LeftBar_shown> <div id=Contents> <div class="linkLESSON"><a href="index.html">Concurrency in Swing</a></div><div class="linkAHEAD"><a href="initial.html">Initial Threads</a></div><div class="linkAHEAD"><a href="dispatch.html">The Event Dispatch Thread</a></div><div class="nolinkAHEAD">Worker Threads and SwingWorker</div><div class="linkBHEAD"><a href="simple.html">Simple Background Tasks</a></div><div class="linkBHEAD"><a href="interim.html">Tasks that Have Interim Results</a></div><div class="linkBHEAD"><a href="cancel.html">Canceling Background Tasks</a></div><div class="linkBHEAD"><a href="bound.html">Bound Properties and Status Methods</a></div></div> </div> <div id=MainFlow class=MainFlow_indented> <span id=BreadCrumbs> <a href=../../index.html target=_top>Home Page</a> > <a href=../index.html target=_top>Creating a GUI with JFC/Swing</a> > <a href=index.html target=_top>Concurrency in Swing</a> </span> <div class=NavBit> <a target=_top href=dispatch.html>« Previous</a> • <a target=_top href=../TOC.html>Trail</a> • <a target=_top href=simple.html>Next »</a> </div> <div id=PageTitle>Worker Threads and SwingWorker</div> <blockquote>When a Swing program needs to execute a long-running task, it usuallyuses one of the <i>worker threads</i>, also known as the <i>background threads</i>. Each task running on a worker thread isrepresented by an instance of<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/SwingWorker.html"><code>javax.swing.SwingWorker</code></a>. <code>SwingWorker</code> itself is an abstract class; you mustdefine a subclass in order to create a <code>SwingWorker</code>object; anonymous inner classes are often useful for creating verysimple <code>SwingWorker</code> objects.<p><code>SwingWorker</code> provides a number ofcommunication and control features:<ul> <li>The <code>SwingWorker</code> subclass can define a method, <code>done</code>, which is automatically invoked on the event dispatch thread when the background task is finished. <li><code>SwingWorker</code> implements<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/util/concurrent/Future.html"><code>java.util.concurrent.Future</code></a>. This interface allows the background task to provide a return value to the other thread. Other methods in this interface allow cancellation of the background task and discovering whether the background task has finished or been cancelled. <li>The background task can provide intermediate results by invoking <code>SwingWorker.publish</code>, causing <code>SwingWorker.process</code> to be invoked from the event dispatch thread. <li>The background task can define bound properties. Changes to these properties trigger events, causing event-handling methods to be invoked on the event dispatch thread.</ul>These features are discussed in the following subsections.<blockquote><hr><strong>Note:</strong> The <code>javax.swing.SwingWorker</code> class was added to the Javaplatform in Java SE 6. Prior to this, another class, also called<code>SwingWorker</code>, was widely used for some of the samepurposes. The old <code>SwingWorker</code> was not part of the Javaplatform specification, and was not provided as part of the JDK.<p>The new <code>javax.swing.SwingWorker</code> is a completly newclass. Its functionality is not a strict supersetof the old <code>SwingWorker</code>. Methods in the two classes thathave the same function do not have the same names. Also, instances ofthe old <code>SwingWorker</code> class were reusable, while a new instanceof <code>javax.swing.SwingWorker</code> is needed for each newbackground task.<p>Throughout the Java Tutorials, any mention of <code>SwingWorker</code>now refers to <code>javax.swing.SwingWorker</code>.<hr></blockquote> </blockquote> <div class=NavBit> <a target=_top href=dispatch.html>« Previous</a> • <a target=_top href=../TOC.html>Trail</a> • <a target=_top href=simple.html>Next »</a> </div> </div> <div id=Footer><div id=TagNotes> Problems with the examples? Try <a target="_blank" href=../../information/run-examples.html>Compiling and Running the Examples: FAQs</a>. <br> Complaints? Compliments? Suggestions? <a target="_blank" href="http://developer.sun.com/contact/tutorial_feedback.jsp">Give us your feedback</a>.<br><br> <a target="_blank" href="../../information/copyright.html">Copyright</a> 1995-2006 Sun Microsystems, Inc. All rights reserved. <span id=Download></span></div> </div> <div class=PrintHeaders> <b>Previous page:</b> The Event Dispatch Thread <br><b>Next page:</b> Simple Background Tasks </div> </body></html> ⌨️ 快捷键说明
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