我有 MainProgramWindow GUI。该GUI有一些变量和一键调用Sql类的createExcel方法并同时启动进度条。
public class MainProgramWindow extends javax.swing.JFrame {
package AgentStatGenerator;
//Rest of code.
class Sql {
//Rest of code.
public int newvalueforpbar = 0;
SwingProgressBarExampleOLD2 progressbar = new SwingProgressBarExampleOLD2();
public void createExcel() {
try{
//Rest of code.
stmt = con.createStatement();
rs1 = stmt.executeQuery(query1);
while (rs1.next()) {
HSSFRow row2 = sheet.createRow((short) index);
Cell cell100 = row2.createCell((short) 0);
cell100.setCellValue(rs1.getString(1));
cell100.setCellStyle(stylersinfo);
Cell cell101 = row2.createCell((short) 1);
cell101.setCellValue(rs1.getInt(2));
cell101.setCellStyle(stylersthousand);
Cell cell102 = row2.createCell((short) 2);
cell102.setCellValue(rs1.getDouble(3));
cell102.setCellStyle(stylersdouble);
index++;
newvalueforpbar = 50;
progressbar.updateBar(newvalueforpbar);
}
rs2 = stmt.executeQuery(query2);
while (rs2.next()){
HSSFRow row3 = sheet.createRow((short) index);
Cell cell103 = row3.createCell((short) 0);
cell103.setCellValue(rs2.getString(1));
cell103.setCellStyle(stylersinfo);
Cell cell104 = row3.createCell((short) 1);
cell104.setCellValue(rs2.getInt(2));
cell104.setCellStyle(stylersthousand);
Cell cell105 = row3.createCell((short) 2);
cell105.setCellValue(rs2.getDouble(3));
cell105.setCellStyle(stylersdouble);
index++;
newvalueforpbar = 100;
progressbar.updateBar(newvalueforpbar);
}
catch(Exception ex){
JOptionPane.showMessageDialog(null, ex.toString());
}
}
}
}
private void createExcelButonActionPerformed(java.awt.event.ActionEvent evt) {
Sql sql1 = new Sql ();
SwingProgressBarExampleOLD2 progressbar = new SwingProgressBarExampleOLD2();
progressbar.startProgress();
sql1.createExcel();
}
}
我的 SwingProgressBarExampleOLD2 类
package AgentStatGenerator;
import java.lang.reflect.Constructor;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingUtilities;
/**
*
* @author Lacrymae_Ev
*/
public class SwingProgressBarExampleOLD2 extends JPanel {
JProgressBar pbar;
static final int MY_MINIMUM = 0;
static final int MY_MAXIMUM = 100;
public SwingProgressBarExampleOLD2() {
// initialize Progress Bar
pbar = new JProgressBar();
pbar.setMinimum(MY_MINIMUM);
pbar.setMaximum(MY_MAXIMUM);
// add to JPanel
add(pbar);
}
public void updateBar(int newValue) {
pbar.setValue(newValue);
}
public void startProgress() {
final SwingProgressBarExampleOLD2 it = new SwingProgressBarExampleOLD2();
JFrame frame = new JFrame("ProgressBar");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(it);
frame.pack();
frame.setVisible(true);
}
}
当我在MainProgramWindow GUI中按下createExcelButon时,sql1.createExcel()方法成功执行并开始工作,我的进度条也出现了。但只有进度条的 jframe 未填充 bpar,并等待 sql1.createExcel() 完全完成。
当 sql1.createExcel() 完全完成并在定义的位置创建 Excel 文件时,进度条 jframe 填充了 pbar,但进度条没有进度。但我用progressbar.updateBar(newvalueforpbar);给pbar喂食在每个 while 语句结束之后。
P.S:如果我从按钮中删除 pbar 调用,我的程序将成功运行并创建具有所需格式的 Excel 文件。我的问题是进度条喂食。
提前致谢。
最佳答案
您正在同一线程中执行所有任务The Event Dispatch Thread 。解决这个问题的一个好方法是在单独的线程中执行业务代码,这样就不会阻塞 gui,并且您可以更新 gui,而无需等待业务代码完成。 Swing 提供 SwingWorker类来实现这一点。这里有一个带有进度条的很好的例子。 Swing Worker Example .
了解更多 How to Use Progress Bars .
简单来说,您所做的就是创建一个 swingWorker 子类并重写 doInBackGround()
。
示例:
public class Worker extends SwingWorker<Void, Void> {
@Override
protected Void doInBackground() throws Exception {
//here you make heavy task this is running in another thread not in EDT
int i = 0;
setProgress(i);
// call query 1
while(i < 50){
setProgress(i++);
Thread.sleep(5); // random magic number
}
// then call query 2
while(i <= 100){
setProgress(i++);
Thread.sleep(5); // random magic number
}
return null;
}
}
在您的客户端代码中,您有进度条:
SwingWorker myWorker = new Worker();
myWorker.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(final PropertyChangeEvent event) {
switch (event.getPropertyName()) {
case "progress":
myProgressBar.setIndeterminate(false);
myProgressBar.setValue((Integer) event.getNewValue());
break;
}
}
});
//then to get start you have to use execute()
worker.execute();
关于Java 进度条反馈,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/21779825/