[英]JavaFX version of ExecutorService
我创建了一个Java实用程序,在x内部的x花式zip文件(twx)中搜索XML。
最初这是一个命令行实用程序,没有线程。
当我将其移动到使用JavaFX时,我遇到了冻结问题,然后将所有搜索移动到Task对象中进行修复。
我需要一些方法来跟踪进度,所以我实现了Progress属性和ProgressBar来跟踪。
它工作得很好,但由于我已经是多线程,为什么不为每个Zip搜索创建一个线程。 不幸的是,这种方法效果不佳。
为了跟踪我创建一个任务数组,然后创建一个处理它们的主任务。 我使用处理所有更新的进度和总属性。
这是代码
public class TextSearch {
final private SimpleDoubleProperty progress = new SimpleDoubleProperty();
final private SimpleDoubleProperty total = new SimpleDoubleProperty();
/**
*
* Kicks off a search. Creates a Task/Thread for each twx search.
* @return A task object that maintains all of the twx searches.
*
* @throws ZipException If the zip file is unreadable.
* @throws IOException If the file is unreadable.
* @throws JDOMException If the xml in the files are unreadable.
* @throws InvalidTWXFile If the twx is corrupt.
*/
public Task<?> executeSearch() throws ZipException, IOException, JDOMException, InvalidTWXFile {
//Loop through all registered twx files.
Iterator<TWExport> rit = registered.iterator();
Integer t = 0;
//Create a task for each search
final ArrayList<Task<?>> tasks = new ArrayList<Task<?>>();
while(rit.hasNext())
{
final TWExport twx = rit.next();
//Only run search if user selects to search it.
if(twx.getSearchEnabled())
{
Task<Void> task = new Task<Void>() {
@Override public Void call() {
informUser("Searching " + twx);
SearchResults proj = new SearchResults(twx);
searchResult.add(proj);
searchTwx(proj,twx);
twx.setResultCount(proj.getTotalCount());
informUser("Finished Searching " + twx);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
if (isCancelled()) {
updateMessage("Cancelled");
}
}
return null;
}
};
tasks.add(task);
t += twx.getObjects().size();
} else
{
informUser("Skipping " + twx);
}
}
total.setValue(t);
//Create the main thread that will hold all individual searches.
Task<Void> main = new Task<Void>() {
@Override
protected Void call() throws Exception {
startTime = new Date();
Iterator<Task<?>> it = tasks.iterator();
while(it.hasNext())
{
Thread t = new Thread(it.next());
t.start();
}
//Sometimes I get a hung thread in this loop
while(!progress.getValue().equals(total.getValue()))
{
updateProgress(progress.getValue(), total.getValue());
Thread.sleep(5000);
}
setEndTime(new Date());
return null;
}
};
new Thread(main).start();
return main;
}
/**
* Search through a twx file and add results to the project search results
* @param proj The parent SearchResults
* @param twx The TWExport to search
*/
private void searchTwx(SearchResults proj, TWExport twx) {
Iterator<TWObject> it = twx.getObjects().iterator();
//Iterate through the files and get the result
while(it.hasNext())
{
TWObject object = it.next();
progress.setValue(progress.getValue() + 1);
if(searchArtifacts.matcher(object.getName()).find())
{
SearchResults result = object.searchContents(searchStr);
if(result != null)
{
proj.add(result);
}
}
}
}
使用主线程看起来非常笨重,有时它会在一次搜索10个以上的zip文件时挂在该循环中。
有没有更好的方法来执行此操作,具有未知数量的任务? 有没有类似JavaFX ExecutorService的地方,我可以添加一堆任务,启动它并监控progressProperty?
不需要特定于JavaFX的执行器服务:常规的java.util.concurrent.ExecutorService
工作得很好,因为Task
是FutureTask
的子类。
获得任务列表后,您可以根据每个任务的进度计算总体进度。 例如,它可能只是所有进度的总和除以任务数。 如果每个任务都有不同数量的项目要处理,您可能可以做一些更复杂的事情。
这是一个简单的SSCCE:
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.stream.Collectors;
import javafx.application.Application;
import javafx.beans.binding.DoubleBinding;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.concurrent.Task;
import javafx.concurrent.Worker;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ProgressBar;
import javafx.scene.control.TextArea;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class MultipleTaskTest extends Application {
private final ExecutorService exec = Executors.newFixedThreadPool(5, r -> {
Thread t = new Thread(r);
t.setDaemon(true);
return t ;
});
private final Random rng = new Random();
@Override
public void start(Stage primaryStage) {
Label pendingTasksLabel = new Label();
Button button = new Button("Launch tasks");
TextArea log = new TextArea();
DoubleProperty progress = new SimpleDoubleProperty(1);
ProgressBar progressBar = new ProgressBar();
progressBar.progressProperty().bind(progress);
IntegerProperty pendingTasks = new SimpleIntegerProperty(0);
pendingTasksLabel.textProperty().bind(pendingTasks.asString("Pending Tasks: %d"));
button.disableProperty().bind(pendingTasks.greaterThan(0));
button.setOnAction(e -> {
int numTasks = rng.nextInt(5) + 4 ;
List<Task<Void>> tasks = new ArrayList<>();
for (int i = 0; i < numTasks; i++) {
tasks.add(createRandomTask());
}
// rebind progress:
progress.unbind();
progress.bind( new DoubleBinding() {
{
for (Task<Void> task : tasks) {
bind(task.progressProperty());
}
}
@Override
public double computeValue() {
return tasks.stream().collect(Collectors.summingDouble(
task -> Math.max(task.getProgress(), 0)
)) / numTasks;
}
});
log.appendText("Submitting "+numTasks+" tasks\n");
pendingTasks.set(numTasks);
// log state of each task:
tasks.forEach(task ->
task.stateProperty().addListener((obs, oldState, newState) -> {
log.appendText("\tTask "+newState+"\n");
// update pendingTasks if task moves out of running state:
if (oldState == Worker.State.RUNNING) {
pendingTasks.set(pendingTasks.get() - 1);
}
}));
tasks.forEach(exec::execute);
});
VBox root = new VBox(10, pendingTasksLabel, progressBar, log, button);
root.setAlignment(Pos.CENTER);
root.setPadding(new Insets(10));
VBox.setVgrow(log, Priority.ALWAYS);
primaryStage.setScene(new Scene(root, 400, 400));
primaryStage.show();
}
@Override
public void stop() {
exec.shutdownNow() ;
}
private Task<Void> createRandomTask() {
int numSteps = 100 + rng.nextInt(100);
return new Task<Void>() {
@Override
public Void call() throws Exception {
for (int i = 1; i <= numSteps; i++) {
Thread.sleep(50);
updateProgress(i, numSteps);
}
return null ;
}
};
}
public static void main(String[] args) {
launch(args);
}
}
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