如何让 Java 正确地挥杆作画？
How To Get Java Swing To Paint Properly?
我有一个最小的应用程序来显示 Java Swing GUI 更新问题，似乎它没有正确绘制组件，错误如下所示：
这是我的程序：
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import java.util.concurrent.*;
public class Java_Test extends JPanel
{
static JFrame frame=new JFrame("Java Test");
static int W=800,H=260,Executor_Count=12;
JPanel Progress_Panel=new JPanel(),Center_Panel;
JButton Do_Test_Button=new JButton("Do Test");
Get_Time Timer=new Get_Time();
ThreadPoolExecutor executor;
Progress_Bar Progress_bar;
Timer Display_Timer=new Timer(1);
public Java_Test()
{
setLayout(new BorderLayout());
JPanel Top_Panel=new JPanel();
Top_Panel.setPreferredSize(new Dimension(W-6,60));
add("North",Top_Panel);
Do_Test_Button.setFont(new Font("Times New Roman",0,16));
Do_Test_Button.setBackground(new Color(118,198,250));
Do_Test_Button.setForeground(new Color(0,28,218));
Do_Test_Button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent evt) { Do_Test(); } });
Top_Panel.add(Do_Test_Button);
JPanel Center_Panel=new JPanel();
Center_Panel.setPreferredSize(new Dimension(W-2,170));
add("Center",Center_Panel);
Progress_Panel.setPreferredSize(new Dimension(W-2,160));
Center_Panel.add(Progress_Panel);
JLabel Progress_Label=new JLabel("Progress");
Progress_Label.setFont(new Font("Times New Roman",0,20));
Progress_Label.setBackground(new Color(253,253,253));
Progress_Label.setForeground(new Color(8,68,128));
Progress_Label.setPreferredSize(new Dimension(W-20,53));
Progress_Label.setHorizontalAlignment(SwingConstants.CENTER);
Progress_Panel.add(Progress_Label);
Progress_bar=new Progress_Bar(620,26);
Progress_Panel.add(Progress_bar);
JPanel Time_Used_Panel=new JPanel(new FlowLayout(FlowLayout.CENTER,6,26));
Time_Used_Panel.setPreferredSize(new Dimension(W-20,60));
Progress_Panel.add(Time_Used_Panel);
JLabel Time_Used_Label=new JLabel("Time : ");
Time_Used_Label.setFont(new Font("Times New Roman",0,14));
Time_Used_Label.setForeground(new Color(0,0,238));
Time_Used_Label.setHorizontalAlignment(SwingConstants.CENTER);
Time_Used_Panel.add(Time_Used_Label);
Display_Timer.setFont(new Font("Times New Roman",0,14));
Display_Timer.setForeground(new Color(0,0,238));
Display_Timer.setPreferredSize(new Dimension(50,17));
Time_Used_Panel.add(Display_Timer);
Clock clock=new Clock(0);
clock.setFont(new Font("Monospaced",Font.PLAIN,16));
clock.setBackground(new Color(0,110,220));
clock.setForeground(new Color(250,250,250));
clock.setOpaque(true);
clock.setPreferredSize(new Dimension(288,30));
clock.start();
JPanel Bottom_Panel=new JPanel();
Bottom_Panel.setPreferredSize(new Dimension(W-2,50));
Bottom_Panel.add(clock);
add("South",Bottom_Panel);
setPreferredSize(new Dimension(W,H));
}
void Do_Test()
{
String Info="",Result;
Out("Do_Test");
try
{
Display_Timer.start();
Timer.Start();
Output_Time("[ 1 ]");
Progress_bar.Set_Progress(1);
int Task_Count=222;
executor=new ThreadPoolExecutor(Executor_Count,Executor_Count*2,1,TimeUnit.SECONDS,new LinkedBlockingQueue());
ArrayList<Future<String>> futures=new ArrayList<>(Task_Count);
Test_Runner A_Runner;
try
{
for (int i=0;i<Task_Count;i++)
{
A_Runner=new Test_Runner();
futures.add(executor.submit(A_Runner));
}
executor.shutdown();
while (!executor.isTerminated()) { executor.awaitTermination(100,TimeUnit.MILLISECONDS); }
for (Future<String> future : futures)
{
Result=future.get();
if (Result!=null) Info+=Result;
}
}
catch (Exception e) { e.printStackTrace(); }
}
catch (Exception e) { e.printStackTrace(); }
Output_Time("[ 2 ]");
Progress_bar.Set_Progress(100);
Out("Done");
Display_Timer.stop();
}
String Output_Time(String Id)
{
Timer.End();
String Time_Duration=Id+" : Time = "+Timer.Get_Duration_Hour_Minute_Second();
Out(Time_Duration);
return Time_Duration;
}
private static void Out(String message) { System.out.println(message); }
static void Create_And_Show_GUI()
{
final Java_Test demo=new Java_Test();
frame.add(demo);
frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } });
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { Create_And_Show_GUI(); } }); }
}
class Progress_Bar extends JPanel implements Runnable
{
int W,H,Last_Progress=-99,Progress,counter=0,Unit_Size=20;
static JProgressBar b=new JProgressBar();
boolean Started_B=false,Do_Step_B=false;
Thread Progress_Bar_Runner_Thread;
public Progress_Bar(int W,int H)
{
setPreferredSize(new Dimension(W,H));
b.setPreferredSize(new Dimension(W-20,H-8));
b.setStringPainted(true);
add(b);
start();
}
public void Set_Progress(int Progress)
{
if (Progress==1 || (this.Progress<Progress && Progress<=100))
{
this.Progress=Progress;
b.setValue(Progress);
b.paintImmediately(0,0,b.getWidth(),b.getHeight());
Out(" Progress = "+Progress+" %");
}
if (Progress==1) Started_B=true;
else if (Progress>=100)
{
Started_B=false;
Do_Step_B=false;
}
}
public void run()
{
try
{
while (Progress<=100)
{
if ((Progress==0 || Progress==50 || Progress==100 || Do_Step_B) && Last_Progress!=Progress)
{
b.setValue(Progress);
// revalidate();
b.paintImmediately(0,0,b.getWidth(),b.getHeight());
Last_Progress=Progress;
}
Thread.sleep(200); // Delay the thread
Do_Step_B=(Started_B && (counter++ % Unit_Size ==0));
if (Progress<100 && Do_Step_B) Progress++;
}
}
catch (Exception e) { e.printStackTrace(); }
}
public void start()
{
if (Progress_Bar_Runner_Thread==null)
{
Progress_Bar_Runner_Thread=new Thread(this);
Progress_Bar_Runner_Thread.setPriority(Thread.NORM_PRIORITY);
Progress_Bar_Runner_Thread.start();
}
}
public void stop() { if (Progress_Bar_Runner_Thread!=null) Progress_Bar_Runner_Thread=null; }
private static void Out(String message) { System.out.println(message); }
}
class Test_Runner implements Callable<String>
{
int Start_Index=0,End_Index=6999;
StringBuilder StrBdr=new StringBuilder();
public Test_Runner() { }
public String call() throws InterruptedException
{
try { for (int i=Start_Index;i<End_Index;i++) StrBdr.append("Test_Runner + Test_Runner + Test_Runner + Test_Runner + Test_Runner + Test_Runner"); }
catch (Exception e) {}
return StrBdr.toString();
}
}
class Timer extends JLabel implements Runnable
{
public static final long serialVersionUID=26362862L;
private Thread Timer_Thread;
String Time_Text="";
int updateInterval=1000,Format=0;
Get_Time Timer=new Get_Time();
public Timer()
{
setFont(new Font("Monospaced",Font.PLAIN,16));
setVerticalAlignment(SwingConstants.CENTER);
setHorizontalAlignment(SwingConstants.CENTER);
}
public Timer(int Format) { this.Format=Format; }
public void start()
{
Timer.Start();
if (Timer_Thread==null)
{
Timer_Thread=new Thread(this);
Timer_Thread.setPriority(Thread.NORM_PRIORITY);
Timer_Thread.start();
}
}
public void run()
{
Thread myThread=Thread.currentThread();
while (Timer_Thread==myThread)
{
switch (Format)
{
case 1 : Time_Text=Timer.Get_Duration_Hour_Minute_Second();break;
}
setText(Time_Text);
paintImmediately(0,0,getWidth(),getHeight());
revalidate();
try { Thread.sleep(updateInterval); }
catch (InterruptedException e) { }
}
}
public void stop() { if (Timer_Thread != null) Timer_Thread=null; }
}
class Clock extends JLabel implements Runnable
{
public static final long serialVersionUID=26362862L;
private Thread clockThread;
String Time_Text="";
int updateInterval=1000,Format=0;
Get_Time Timer=new Get_Time();
public Clock() { start(); }
public Clock(int Format)
{
this.Format=Format;
start();
}
public void start()
{
setVerticalAlignment(SwingConstants.CENTER);
setHorizontalAlignment(SwingConstants.CENTER);
if (clockThread==null)
{
clockThread=new Thread(this);
// clockThread.setPriority(Thread.NORM_PRIORITY);
clockThread.setPriority(Thread.MIN_PRIORITY);
clockThread.start();
}
}
public void run()
{
Thread myThread=Thread.currentThread();
while (clockThread==myThread)
{
switch (Format)
{
case 0 : Time_Text=" "+new java.util.Date().toString().substring(0,19)+" ";break;
}
setText(Time_Text);
paintImmediately(0,0,getWidth(),getHeight());
revalidate();
try { Thread.sleep(updateInterval); }
catch (InterruptedException e) { }
}
}
public void stop() { if (clockThread != null) clockThread=null; }
}
class Get_Time
{
private long start,end;
public int Hours,Minutes,Seconds,Total_Seconds;
String ST_Hours,ST_Minutes,ST_Seconds;
public Get_Time() { Reset(); }
public void Start() { start=System.currentTimeMillis(); }
public void End()
{
int half_second;
end=System.currentTimeMillis();
Total_Seconds=(int)(end-start)/1000;
half_second=(int)(end-start)%1000;
if (half_second>499) Total_Seconds++;
Hours=Total_Seconds/3600;
Minutes=(Total_Seconds%3600)/60;
Seconds=(Total_Seconds%3600)%60;
ST_Hours=new String((Hours>9)?""+Hours:"0"+Hours);
ST_Minutes=new String((Minutes>9)?""+Minutes:"0"+Minutes);
ST_Seconds=new String((Seconds>9)?""+Seconds:"0"+Seconds);
}
public String Get_Duration_Hour_Minute_Second()
{
End();
return ST_Hours+":"+ST_Minutes+":"+ST_Seconds;
}
public void Reset() { start=0;end=0; }
}
我的电脑有 12 核 3.33 GH Intel Corei7 x 980 CPU，24 GB 内存，运行 Windows 7，Java 版本 = 1.8 .0_212
问题是如何解决？
Swing线程和绘画问题列举：
以下所有代码都是从 Swing 事件分派线程 (EDT) 调用的，到目前为止一切顺利....
void Do_Test() {
String Info = "", Result;
Out("Do_Test");
try {
Display_Timer.start();
Timer.Start();
Output_Time("[ 1 ]");
Progress_bar.Set_Progress(1); // OK to call this on the event thread
int Task_Count = 222;
executor = new ThreadPoolExecutor(Executor_Count, Executor_Count * 2, 1,
TimeUnit.SECONDS, new LinkedBlockingQueue());
ArrayList<Future<String>> futures = new ArrayList<>(Task_Count);
Test_Runner A_Runner;
try {
for (int i = 0; i < Task_Count; i++) {
A_Runner = new Test_Runner();
futures.add(executor.submit(A_Runner));
}
executor.shutdown();
好的，这里我们开始看到问题，因为您在 EDT 上调用可能很长的 while 循环，可能会阻止它：
while (!executor.isTerminated()) {
executor.awaitTermination(100, TimeUnit.MILLISECONDS);
}
此处相同，因为对 Future#get() 的调用是阻塞调用：
for (Future<String> future : futures) {
Result = future.get();
if (Result != null)
Info += Result;
}
好的，现在我们开始看到一些真正不寻常的 Swing 代码，您可以在其中进行 Swing 调用，包括设置 JProgressBar 的值 关闭 EDT，然后尝试强制 EDT 执行一些操作通过 paintImmediately(....) 绘画。在 EDT 之外调用可能会导致间歇性和不可预测的错误，并可能导致绘画混乱，并且 GUI 有时会冻结：
class Progress_Bar extends JPanel implements Runnable {
// .....
public void Set_Progress(int Progress) {
if (Progress == 1 || (this.Progress < Progress && Progress <= 100)) {
this.Progress = Progress; // ****** being called off the EDT
b.paintImmediately(0, 0, b.getWidth(), b.getHeight()); // ***** Don't do this
Out(" Progress = " + Progress + " %");
}
// .....
}
public void run() {
try {
while (Progress <= 100) {
if ((Progress == 0 || Progress == 50 || Progress == 100 || Do_Step_B)
&& Last_Progress != Progress) {
// ***** called off the EDT -- don't do this
b.setValue(Progress);
// revalidate();
b.paintImmediately(0, 0, b.getWidth(), b.getHeight()); // **** and don't do this
Last_Progress = Progress;
}
Thread.sleep(200); // Delay the thread
Do_Step_B = (Started_B && (counter++ % Unit_Size == 0));
if (Progress < 100 && Do_Step_B)
Progress++;
}
} catch (Exception e) {
e.printStackTrace();
}
}
// .......
}
类似奇怪的goings-ons在这个class，定时器class，你设置一个JLabel的文本关闭的EDT：
class Timer extends JLabel implements Runnable {
// ....
public void run() {
Thread myThread = Thread.currentThread();
while (Timer_Thread == myThread) {
switch (Format) {
case 1:
Time_Text = Timer.Get_Duration_Hour_Minute_Second();
break;
}
// again this is dangerous code **********
setText(Time_Text);
paintImmediately(0, 0, getWidth(), getHeight());
// ....
时钟相同class...
解决方案：
要在 Swing GUI 中重复调用代码，请使用 javax.swing.Timer 或 "Swing Timer"。有关使用它的示例，请参阅我对您的 MCVE 的实现，但在上面的线程代码中使用了 Swing 计时器。
另一个代码，即调用 long-running 任务的代码，应该在 SwingWorker 中完成。此辅助线程通常以两种方式之一（或两种方式）与 Swing GUI 通信——使用 publish/process 方法对，或（如以下示例所示）使用附加到辅助线程的 PropertyChangeListener。 Worker 有几个 "bound" 属性，通知侦听器更改的字段，包括 progress 属性，可以保存从 0 到 100 的值，以及 SwingWorker.StateValue，或 "state" 属性:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import javax.swing.*;
@SuppressWarnings("serial")
public class JavaTest2 extends JPanel {
private static final int W = 800;
private static final int H = 260;
private Action doTestAction = new DoTestAction("Do Test");
private JProgressBar progressBar = new JProgressBar(0, 100);
private MyClockPanel clockPanel = new MyClockPanel();
private MyTimerPanel timerPanel = new MyTimerPanel();
public JavaTest2() {
JPanel topPanel = new JPanel();
topPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 35, 5));
topPanel.add(new JButton(doTestAction));
progressBar.setStringPainted(true);
JPanel progressPanel = new JPanel(new GridBagLayout());
progressPanel.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
GridBagConstraints gbc = new GridBagConstraints();
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.weightx = 1.0;
progressPanel.add(progressBar, gbc);
JLabel progressLabel = new JLabel("Progress", SwingConstants.CENTER);
progressLabel.setFont(new Font("Times New Roman", 0, 20));
progressLabel.setForeground(new Color(8, 68, 128));
JPanel centralPanel = new JPanel(new BorderLayout(5, 5));
centralPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
centralPanel.add(progressLabel, BorderLayout.PAGE_START);
centralPanel.add(progressPanel);
JPanel clockWrapper = new JPanel();
clockWrapper.add(clockPanel);
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.PAGE_AXIS));
bottomPanel.add(timerPanel, BorderLayout.PAGE_START);
bottomPanel.add(clockWrapper, BorderLayout.PAGE_END);
setLayout(new BorderLayout());
setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
add(topPanel, BorderLayout.PAGE_START);
add(bottomPanel, BorderLayout.PAGE_END);
add(centralPanel);
}
@Override
public Dimension getPreferredSize() {
Dimension superSize = super.getPreferredSize();
if (isPreferredSizeSet()) {
return superSize;
} else {
int w = Math.max(superSize.width, W);
int h = Math.max(superSize.height, H);
return new Dimension(w, h);
}
}
private class DoTestAction extends AbstractAction {
private MyWorker myWorker = null;
public DoTestAction(String name) {
super(name);
int mnemonic = (int) name.charAt(0);
putValue(MNEMONIC_KEY, mnemonic);
}
@Override
public void actionPerformed(ActionEvent e) {
if (myWorker != null && myWorker.getState() == SwingWorker.StateValue.STARTED) {
return; // still running
}
timerPanel.start();
progressBar.setValue(0);
myWorker = new MyWorker();
myWorker.addPropertyChangeListener(new WorkerListener());
myWorker.execute();
setEnabled(false);
}
}
class WorkerListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent evt) {
// if the worker is changing its progress bound property:
if (evt.getPropertyName().equals("progress")) {
int progress = (int) evt.getNewValue();
// just for safety's sake, limit progress to 100 and no more
progress = Math.min(progress, 100);
progressBar.setValue(progress);
} else if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
// else if worker is done
try {
// get the result to at least trap errors
String result = ((MyWorker) evt.getSource()).get();
// can display result in the GUI
timerPanel.stop();
} catch (Exception e) {
// worker's exception is available to the GUI if desired here
e.printStackTrace();
}
progressBar.setValue(100);
doTestAction.setEnabled(true);
}
}
}
private static class MyWorker extends SwingWorker<String, Void> {
private static final int EXECUTOR_COUNT = 12;
private static final int TASK_COUNT = 222;
@Override
protected String doInBackground() throws Exception {
ExecutorService executor = new ThreadPoolExecutor(EXECUTOR_COUNT, EXECUTOR_COUNT * 2, 1,
TimeUnit.SECONDS, new LinkedBlockingQueue<>());
List<Future<String>> futures = new ArrayList<>();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < TASK_COUNT; i++) {
Callable<String> aRunner = new ARunner();
futures.add(executor.submit(aRunner));
}
executor.shutdown();
int index = 0;
for (Future<String> future : futures) {
String result = future.get();
sb.append(result);
sb.append(" ");
index++;
int progress = (100 * index) / TASK_COUNT;
progress = Math.min(progress, 100);
setProgress(progress);
}
return sb.toString();
}
}
private static class ARunner implements Callable<String> {
private static final long SLEEP_TIME = 800;
@Override
public String call() throws Exception {
TimeUnit.MILLISECONDS.sleep(SLEEP_TIME);
return "Foo";
}
}
private static void createAndShowGui() {
JavaTest2 mainPanel = new JavaTest2();
JFrame frame = new JFrame("Java Test 2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
@SuppressWarnings("serial")
class MyClockPanel extends JPanel {
private static final Color FG = new Color(250, 250, 250);
private static final Color BG = new Color(0, 110, 220);
private static final int TIMER_DELAY = 200;
private static final Font FONT = new Font("Monospaced", Font.PLAIN, 16);
private JLabel clockLabel = new JLabel("", SwingConstants.CENTER);
private DateTimeFormatter formatter = DateTimeFormatter.ofPattern("E MMM dd yyyy kk:mm:ss");
public MyClockPanel() {
setBackground(BG);
clockLabel.setForeground(FG);
clockLabel.setFont(FONT);
displayDateTime();
setLayout(new BorderLayout());
setBorder(BorderFactory.createEmptyBorder(5, 50, 5, 50));
add(clockLabel);
new javax.swing.Timer(TIMER_DELAY, e -> {
displayDateTime();
}).start();
}
private void displayDateTime() {
LocalDateTime dateTime = LocalDateTime.now();
String text = dateTime.format(formatter);
clockLabel.setText(text);
}
}
@SuppressWarnings("serial")
class MyTimerPanel extends JPanel {
private static final Color FG = new Color(0, 0, 238);
private static final Font FONT = new Font("Times New Roman", 0, 14);
private static final int TIMER_DELAY = 40;
private static final String FORMAT_TXT = "Elapsed Time: %02d:%02d:%02d";
private JLabel timerLabel = new JLabel("", SwingConstants.CENTER);
private LocalDateTime startTime = null;
private Timer timer = null;
public MyTimerPanel() {
timerLabel.setForeground(FG);
timerLabel.setFont(FONT);
setLayout(new BorderLayout());
setBorder(BorderFactory.createEmptyBorder(5, 50, 5, 50));
timerLabel.setText(String.format(FORMAT_TXT, 0, 0, 0));
add(timerLabel);
}
public void start() {
stop();
startTime = LocalDateTime.now();
timer = new Timer(TIMER_DELAY, e -> incrementTime());
timer.start();
}
public void stop() {
if (timer != null && timer.isRunning()) {
timer.stop();
}
}
private void incrementTime() {
LocalDateTime currentTime = LocalDateTime.now();
long hours = ChronoUnit.HOURS.between(startTime, currentTime);
long minutes = ChronoUnit.MINUTES.between(startTime, currentTime) % 60;
long seconds = ChronoUnit.SECONDS.between(startTime, currentTime) % 60;
String text = String.format(FORMAT_TXT, hours, minutes, seconds);
timerLabel.setText(text);
}
}
我有一个最小的应用程序来显示 Java Swing GUI 更新问题，似乎它没有正确绘制组件，错误如下所示：
这是我的程序：
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import java.util.concurrent.*;
public class Java_Test extends JPanel
{
static JFrame frame=new JFrame("Java Test");
static int W=800,H=260,Executor_Count=12;
JPanel Progress_Panel=new JPanel(),Center_Panel;
JButton Do_Test_Button=new JButton("Do Test");
Get_Time Timer=new Get_Time();
ThreadPoolExecutor executor;
Progress_Bar Progress_bar;
Timer Display_Timer=new Timer(1);
public Java_Test()
{
setLayout(new BorderLayout());
JPanel Top_Panel=new JPanel();
Top_Panel.setPreferredSize(new Dimension(W-6,60));
add("North",Top_Panel);
Do_Test_Button.setFont(new Font("Times New Roman",0,16));
Do_Test_Button.setBackground(new Color(118,198,250));
Do_Test_Button.setForeground(new Color(0,28,218));
Do_Test_Button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent evt) { Do_Test(); } });
Top_Panel.add(Do_Test_Button);
JPanel Center_Panel=new JPanel();
Center_Panel.setPreferredSize(new Dimension(W-2,170));
add("Center",Center_Panel);
Progress_Panel.setPreferredSize(new Dimension(W-2,160));
Center_Panel.add(Progress_Panel);
JLabel Progress_Label=new JLabel("Progress");
Progress_Label.setFont(new Font("Times New Roman",0,20));
Progress_Label.setBackground(new Color(253,253,253));
Progress_Label.setForeground(new Color(8,68,128));
Progress_Label.setPreferredSize(new Dimension(W-20,53));
Progress_Label.setHorizontalAlignment(SwingConstants.CENTER);
Progress_Panel.add(Progress_Label);
Progress_bar=new Progress_Bar(620,26);
Progress_Panel.add(Progress_bar);
JPanel Time_Used_Panel=new JPanel(new FlowLayout(FlowLayout.CENTER,6,26));
Time_Used_Panel.setPreferredSize(new Dimension(W-20,60));
Progress_Panel.add(Time_Used_Panel);
JLabel Time_Used_Label=new JLabel("Time : ");
Time_Used_Label.setFont(new Font("Times New Roman",0,14));
Time_Used_Label.setForeground(new Color(0,0,238));
Time_Used_Label.setHorizontalAlignment(SwingConstants.CENTER);
Time_Used_Panel.add(Time_Used_Label);
Display_Timer.setFont(new Font("Times New Roman",0,14));
Display_Timer.setForeground(new Color(0,0,238));
Display_Timer.setPreferredSize(new Dimension(50,17));
Time_Used_Panel.add(Display_Timer);
Clock clock=new Clock(0);
clock.setFont(new Font("Monospaced",Font.PLAIN,16));
clock.setBackground(new Color(0,110,220));
clock.setForeground(new Color(250,250,250));
clock.setOpaque(true);
clock.setPreferredSize(new Dimension(288,30));
clock.start();
JPanel Bottom_Panel=new JPanel();
Bottom_Panel.setPreferredSize(new Dimension(W-2,50));
Bottom_Panel.add(clock);
add("South",Bottom_Panel);
setPreferredSize(new Dimension(W,H));
}
void Do_Test()
{
String Info="",Result;
Out("Do_Test");
try
{
Display_Timer.start();
Timer.Start();
Output_Time("[ 1 ]");
Progress_bar.Set_Progress(1);
int Task_Count=222;
executor=new ThreadPoolExecutor(Executor_Count,Executor_Count*2,1,TimeUnit.SECONDS,new LinkedBlockingQueue());
ArrayList<Future<String>> futures=new ArrayList<>(Task_Count);
Test_Runner A_Runner;
try
{
for (int i=0;i<Task_Count;i++)
{
A_Runner=new Test_Runner();
futures.add(executor.submit(A_Runner));
}
executor.shutdown();
while (!executor.isTerminated()) { executor.awaitTermination(100,TimeUnit.MILLISECONDS); }
for (Future<String> future : futures)
{
Result=future.get();
if (Result!=null) Info+=Result;
}
}
catch (Exception e) { e.printStackTrace(); }
}
catch (Exception e) { e.printStackTrace(); }
Output_Time("[ 2 ]");
Progress_bar.Set_Progress(100);
Out("Done");
Display_Timer.stop();
}
String Output_Time(String Id)
{
Timer.End();
String Time_Duration=Id+" : Time = "+Timer.Get_Duration_Hour_Minute_Second();
Out(Time_Duration);
return Time_Duration;
}
private static void Out(String message) { System.out.println(message); }
static void Create_And_Show_GUI()
{
final Java_Test demo=new Java_Test();
frame.add(demo);
frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } });
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { Create_And_Show_GUI(); } }); }
}
class Progress_Bar extends JPanel implements Runnable
{
int W,H,Last_Progress=-99,Progress,counter=0,Unit_Size=20;
static JProgressBar b=new JProgressBar();
boolean Started_B=false,Do_Step_B=false;
Thread Progress_Bar_Runner_Thread;
public Progress_Bar(int W,int H)
{
setPreferredSize(new Dimension(W,H));
b.setPreferredSize(new Dimension(W-20,H-8));
b.setStringPainted(true);
add(b);
start();
}
public void Set_Progress(int Progress)
{
if (Progress==1 || (this.Progress<Progress && Progress<=100))
{
this.Progress=Progress;
b.setValue(Progress);
b.paintImmediately(0,0,b.getWidth(),b.getHeight());
Out(" Progress = "+Progress+" %");
}
if (Progress==1) Started_B=true;
else if (Progress>=100)
{
Started_B=false;
Do_Step_B=false;
}
}
public void run()
{
try
{
while (Progress<=100)
{
if ((Progress==0 || Progress==50 || Progress==100 || Do_Step_B) && Last_Progress!=Progress)
{
b.setValue(Progress);
// revalidate();
b.paintImmediately(0,0,b.getWidth(),b.getHeight());
Last_Progress=Progress;
}
Thread.sleep(200); // Delay the thread
Do_Step_B=(Started_B && (counter++ % Unit_Size ==0));
if (Progress<100 && Do_Step_B) Progress++;
}
}
catch (Exception e) { e.printStackTrace(); }
}
public void start()
{
if (Progress_Bar_Runner_Thread==null)
{
Progress_Bar_Runner_Thread=new Thread(this);
Progress_Bar_Runner_Thread.setPriority(Thread.NORM_PRIORITY);
Progress_Bar_Runner_Thread.start();
}
}
public void stop() { if (Progress_Bar_Runner_Thread!=null) Progress_Bar_Runner_Thread=null; }
private static void Out(String message) { System.out.println(message); }
}
class Test_Runner implements Callable<String>
{
int Start_Index=0,End_Index=6999;
StringBuilder StrBdr=new StringBuilder();
public Test_Runner() { }
public String call() throws InterruptedException
{
try { for (int i=Start_Index;i<End_Index;i++) StrBdr.append("Test_Runner + Test_Runner + Test_Runner + Test_Runner + Test_Runner + Test_Runner"); }
catch (Exception e) {}
return StrBdr.toString();
}
}
class Timer extends JLabel implements Runnable
{
public static final long serialVersionUID=26362862L;
private Thread Timer_Thread;
String Time_Text="";
int updateInterval=1000,Format=0;
Get_Time Timer=new Get_Time();
public Timer()
{
setFont(new Font("Monospaced",Font.PLAIN,16));
setVerticalAlignment(SwingConstants.CENTER);
setHorizontalAlignment(SwingConstants.CENTER);
}
public Timer(int Format) { this.Format=Format; }
public void start()
{
Timer.Start();
if (Timer_Thread==null)
{
Timer_Thread=new Thread(this);
Timer_Thread.setPriority(Thread.NORM_PRIORITY);
Timer_Thread.start();
}
}
public void run()
{
Thread myThread=Thread.currentThread();
while (Timer_Thread==myThread)
{
switch (Format)
{
case 1 : Time_Text=Timer.Get_Duration_Hour_Minute_Second();break;
}
setText(Time_Text);
paintImmediately(0,0,getWidth(),getHeight());
revalidate();
try { Thread.sleep(updateInterval); }
catch (InterruptedException e) { }
}
}
public void stop() { if (Timer_Thread != null) Timer_Thread=null; }
}
class Clock extends JLabel implements Runnable
{
public static final long serialVersionUID=26362862L;
private Thread clockThread;
String Time_Text="";
int updateInterval=1000,Format=0;
Get_Time Timer=new Get_Time();
public Clock() { start(); }
public Clock(int Format)
{
this.Format=Format;
start();
}
public void start()
{
setVerticalAlignment(SwingConstants.CENTER);
setHorizontalAlignment(SwingConstants.CENTER);
if (clockThread==null)
{
clockThread=new Thread(this);
// clockThread.setPriority(Thread.NORM_PRIORITY);
clockThread.setPriority(Thread.MIN_PRIORITY);
clockThread.start();
}
}
public void run()
{
Thread myThread=Thread.currentThread();
while (clockThread==myThread)
{
switch (Format)
{
case 0 : Time_Text=" "+new java.util.Date().toString().substring(0,19)+" ";break;
}
setText(Time_Text);
paintImmediately(0,0,getWidth(),getHeight());
revalidate();
try { Thread.sleep(updateInterval); }
catch (InterruptedException e) { }
}
}
public void stop() { if (clockThread != null) clockThread=null; }
}
class Get_Time
{
private long start,end;
public int Hours,Minutes,Seconds,Total_Seconds;
String ST_Hours,ST_Minutes,ST_Seconds;
public Get_Time() { Reset(); }
public void Start() { start=System.currentTimeMillis(); }
public void End()
{
int half_second;
end=System.currentTimeMillis();
Total_Seconds=(int)(end-start)/1000;
half_second=(int)(end-start)%1000;
if (half_second>499) Total_Seconds++;
Hours=Total_Seconds/3600;
Minutes=(Total_Seconds%3600)/60;
Seconds=(Total_Seconds%3600)%60;
ST_Hours=new String((Hours>9)?""+Hours:"0"+Hours);
ST_Minutes=new String((Minutes>9)?""+Minutes:"0"+Minutes);
ST_Seconds=new String((Seconds>9)?""+Seconds:"0"+Seconds);
}
public String Get_Duration_Hour_Minute_Second()
{
End();
return ST_Hours+":"+ST_Minutes+":"+ST_Seconds;
}
public void Reset() { start=0;end=0; }
}
我的电脑有 12 核 3.33 GH Intel Corei7 x 980 CPU，24 GB 内存，运行 Windows 7，Java 版本 = 1.8 .0_212
问题是如何解决？
Swing线程和绘画问题列举：
以下所有代码都是从 Swing 事件分派线程 (EDT) 调用的，到目前为止一切顺利....
void Do_Test() {
String Info = "", Result;
Out("Do_Test");
try {
Display_Timer.start();
Timer.Start();
Output_Time("[ 1 ]");
Progress_bar.Set_Progress(1); // OK to call this on the event thread
int Task_Count = 222;
executor = new ThreadPoolExecutor(Executor_Count, Executor_Count * 2, 1,
TimeUnit.SECONDS, new LinkedBlockingQueue());
ArrayList<Future<String>> futures = new ArrayList<>(Task_Count);
Test_Runner A_Runner;
try {
for (int i = 0; i < Task_Count; i++) {
A_Runner = new Test_Runner();
futures.add(executor.submit(A_Runner));
}
executor.shutdown();
好的，这里我们开始看到问题，因为您在 EDT 上调用可能很长的 while 循环，可能会阻止它：
while (!executor.isTerminated()) {
executor.awaitTermination(100, TimeUnit.MILLISECONDS);
}
此处相同，因为对 Future#get() 的调用是阻塞调用：
for (Future<String> future : futures) {
Result = future.get();
if (Result != null)
Info += Result;
}
好的，现在我们开始看到一些真正不寻常的 Swing 代码，您可以在其中进行 Swing 调用，包括设置 JProgressBar 的值 关闭 EDT，然后尝试强制 EDT 执行一些操作通过 paintImmediately(....) 绘画。在 EDT 之外调用可能会导致间歇性和不可预测的错误，并可能导致绘画混乱，并且 GUI 有时会冻结：
class Progress_Bar extends JPanel implements Runnable {
// .....
public void Set_Progress(int Progress) {
if (Progress == 1 || (this.Progress < Progress && Progress <= 100)) {
this.Progress = Progress; // ****** being called off the EDT
b.paintImmediately(0, 0, b.getWidth(), b.getHeight()); // ***** Don't do this
Out(" Progress = " + Progress + " %");
}
// .....
}
public void run() {
try {
while (Progress <= 100) {
if ((Progress == 0 || Progress == 50 || Progress == 100 || Do_Step_B)
&& Last_Progress != Progress) {
// ***** called off the EDT -- don't do this
b.setValue(Progress);
// revalidate();
b.paintImmediately(0, 0, b.getWidth(), b.getHeight()); // **** and don't do this
Last_Progress = Progress;
}
Thread.sleep(200); // Delay the thread
Do_Step_B = (Started_B && (counter++ % Unit_Size == 0));
if (Progress < 100 && Do_Step_B)
Progress++;
}
} catch (Exception e) {
e.printStackTrace();
}
}
// .......
}
类似奇怪的goings-ons在这个class，定时器class，你设置一个JLabel的文本关闭的EDT：
class Timer extends JLabel implements Runnable { // ....
public void run() {
Thread myThread = Thread.currentThread();
while (Timer_Thread == myThread) {
switch (Format) {
case 1:
Time_Text = Timer.Get_Duration_Hour_Minute_Second();
break;
}
// again this is dangerous code **********
setText(Time_Text);
paintImmediately(0, 0, getWidth(), getHeight());
// ....
时钟相同class...
解决方案：
要在 Swing GUI 中重复调用代码，请使用 javax.swing.Timer 或 "Swing Timer"。有关使用它的示例，请参阅我对您的 MCVE 的实现，但在上面的线程代码中使用了 Swing 计时器。
另一个代码，即调用 long-running 任务的代码，应该在 SwingWorker 中完成。此辅助线程通常以两种方式之一（或两种方式）与 Swing GUI 通信——使用 publish/process 方法对，或（如以下示例所示）使用附加到辅助线程的 PropertyChangeListener。 Worker 有几个 "bound" 属性，通知侦听器更改的字段，包括 progress 属性，可以保存从 0 到 100 的值，以及 SwingWorker.StateValue，或 "state" 属性:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import javax.swing.*;
@SuppressWarnings("serial")
public class JavaTest2 extends JPanel {
private static final int W = 800;
private static final int H = 260;
private Action doTestAction = new DoTestAction("Do Test");
private JProgressBar progressBar = new JProgressBar(0, 100);
private MyClockPanel clockPanel = new MyClockPanel();
private MyTimerPanel timerPanel = new MyTimerPanel();
public JavaTest2() {
JPanel topPanel = new JPanel();
topPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 35, 5));
topPanel.add(new JButton(doTestAction));
progressBar.setStringPainted(true);
JPanel progressPanel = new JPanel(new GridBagLayout());
progressPanel.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
GridBagConstraints gbc = new GridBagConstraints();
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.weightx = 1.0;
progressPanel.add(progressBar, gbc);
JLabel progressLabel = new JLabel("Progress", SwingConstants.CENTER);
progressLabel.setFont(new Font("Times New Roman", 0, 20));
progressLabel.setForeground(new Color(8, 68, 128));
JPanel centralPanel = new JPanel(new BorderLayout(5, 5));
centralPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
centralPanel.add(progressLabel, BorderLayout.PAGE_START);
centralPanel.add(progressPanel);
JPanel clockWrapper = new JPanel();
clockWrapper.add(clockPanel);
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.PAGE_AXIS));
bottomPanel.add(timerPanel, BorderLayout.PAGE_START);
bottomPanel.add(clockWrapper, BorderLayout.PAGE_END);
setLayout(new BorderLayout());
setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
add(topPanel, BorderLayout.PAGE_START);
add(bottomPanel, BorderLayout.PAGE_END);
add(centralPanel);
}
@Override
public Dimension getPreferredSize() {
Dimension superSize = super.getPreferredSize();
if (isPreferredSizeSet()) {
return superSize;
} else {
int w = Math.max(superSize.width, W);
int h = Math.max(superSize.height, H);
return new Dimension(w, h);
}
}
private class DoTestAction extends AbstractAction {
private MyWorker myWorker = null;
public DoTestAction(String name) {
super(name);
int mnemonic = (int) name.charAt(0);
putValue(MNEMONIC_KEY, mnemonic);
}
@Override
public void actionPerformed(ActionEvent e) {
if (myWorker != null && myWorker.getState() == SwingWorker.StateValue.STARTED) {
return; // still running
}
timerPanel.start();
progressBar.setValue(0);
myWorker = new MyWorker();
myWorker.addPropertyChangeListener(new WorkerListener());
myWorker.execute();
setEnabled(false);
}
}
class WorkerListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent evt) {
// if the worker is changing its progress bound property:
if (evt.getPropertyName().equals("progress")) {
int progress = (int) evt.getNewValue();
// just for safety's sake, limit progress to 100 and no more
progress = Math.min(progress, 100);
progressBar.setValue(progress);
} else if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
// else if worker is done
try {
// get the result to at least trap errors
String result = ((MyWorker) evt.getSource()).get();
// can display result in the GUI
timerPanel.stop();
} catch (Exception e) {
// worker's exception is available to the GUI if desired here
e.printStackTrace();
}
progressBar.setValue(100);
doTestAction.setEnabled(true);
}
}
}
private static class MyWorker extends SwingWorker<String, Void> {
private static final int EXECUTOR_COUNT = 12;
private static final int TASK_COUNT = 222;
@Override
protected String doInBackground() throws Exception {
ExecutorService executor = new ThreadPoolExecutor(EXECUTOR_COUNT, EXECUTOR_COUNT * 2, 1,
TimeUnit.SECONDS, new LinkedBlockingQueue<>());
List<Future<String>> futures = new ArrayList<>();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < TASK_COUNT; i++) {
Callable<String> aRunner = new ARunner();
futures.add(executor.submit(aRunner));
}
executor.shutdown();
int index = 0;
for (Future<String> future : futures) {
String result = future.get();
sb.append(result);
sb.append(" ");
index++;
int progress = (100 * index) / TASK_COUNT;
progress = Math.min(progress, 100);
setProgress(progress);
}
return sb.toString();
}
}
private static class ARunner implements Callable<String> {
private static final long SLEEP_TIME = 800;
@Override
public String call() throws Exception {
TimeUnit.MILLISECONDS.sleep(SLEEP_TIME);
return "Foo";
}
}
private static void createAndShowGui() {
JavaTest2 mainPanel = new JavaTest2();
JFrame frame = new JFrame("Java Test 2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
@SuppressWarnings("serial")
class MyClockPanel extends JPanel {
private static final Color FG = new Color(250, 250, 250);
private static final Color BG = new Color(0, 110, 220);
private static final int TIMER_DELAY = 200;
private static final Font FONT = new Font("Monospaced", Font.PLAIN, 16);
private JLabel clockLabel = new JLabel("", SwingConstants.CENTER);
private DateTimeFormatter formatter = DateTimeFormatter.ofPattern("E MMM dd yyyy kk:mm:ss");
public MyClockPanel() {
setBackground(BG);
clockLabel.setForeground(FG);
clockLabel.setFont(FONT);
displayDateTime();
setLayout(new BorderLayout());
setBorder(BorderFactory.createEmptyBorder(5, 50, 5, 50));
add(clockLabel);
new javax.swing.Timer(TIMER_DELAY, e -> {
displayDateTime();
}).start();
}
private void displayDateTime() {
LocalDateTime dateTime = LocalDateTime.now();
String text = dateTime.format(formatter);
clockLabel.setText(text);
}
}
@SuppressWarnings("serial")
class MyTimerPanel extends JPanel {
private static final Color FG = new Color(0, 0, 238);
private static final Font FONT = new Font("Times New Roman", 0, 14);
private static final int TIMER_DELAY = 40;
private static final String FORMAT_TXT = "Elapsed Time: %02d:%02d:%02d";
private JLabel timerLabel = new JLabel("", SwingConstants.CENTER);
private LocalDateTime startTime = null;
private Timer timer = null;
public MyTimerPanel() {
timerLabel.setForeground(FG);
timerLabel.setFont(FONT);
setLayout(new BorderLayout());
setBorder(BorderFactory.createEmptyBorder(5, 50, 5, 50));
timerLabel.setText(String.format(FORMAT_TXT, 0, 0, 0));
add(timerLabel);
}
public void start() {
stop();
startTime = LocalDateTime.now();
timer = new Timer(TIMER_DELAY, e -> incrementTime());
timer.start();
}
public void stop() {
if (timer != null && timer.isRunning()) {
timer.stop();
}
}
private void incrementTime() {
LocalDateTime currentTime = LocalDateTime.now();
long hours = ChronoUnit.HOURS.between(startTime, currentTime);
long minutes = ChronoUnit.MINUTES.between(startTime, currentTime) % 60;
long seconds = ChronoUnit.SECONDS.between(startTime, currentTime) % 60;
String text = String.format(FORMAT_TXT, hours, minutes, seconds);
timerLabel.setText(text);
}
}