查看和修改线程优先级
1.题目
java中每个线程都有优化级属性，默认情况下，新建的线程和创建该线程的线程优先级是一样的。当线程调度器选择要运行的线程时，会选择优先级高的线程。
实现：查看和修改线程的优先级
2.解题思路
创建一个类：ThreadPriorityTest，继承了JFrame。用来界面显示当前线程组中运行的线程。
定义2个方法：
-
do_this_windowActivated():用来监听窗体激活事件
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do_button_actionPerformed() :用来单击修改按钮事件，获取用户输入的优先级和选择的行，修改线程优先级。
Thread是程序中的执行线程。JAVA虚拟机允许应用程序并发地运行多个执行线程。
3.代码详解
package com.xiaoxuzhu;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.border.EmptyBorder;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.JTableHeader;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
/**
* Description:
*
* @author xiaoxuzhu
* @version 1.0
*
* <pre>
* 修改记录:
* 修改后版本 修改人 修改日期 修改内容
* 2022/5/11.1 xiaoxuzhu 2022/5/11 Create
* </pre>
* @date 2022/5/11
*/
public class ThreadPriorityTest extends JFrame {
/**
*
*/
private static final long serialVersionUID = 1127454227002083871L;
private JPanel contentPane;
private JTable table;
private JTextField textField;
/**
* Launch the application.
*/
public static void main(String[] args) {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
} catch (Throwable e) {
e.printStackTrace();
}
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ThreadPriorityTest frame = new ThreadPriorityTest();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public ThreadPriorityTest() {
addWindowListener(new WindowAdapter() {
@Override
public void windowActivated(WindowEvent e) {
do_this_windowActivated(e);
}
});
setTitle("查看和修改线程优化级");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(0, 0));
setContentPane(contentPane);
JPanel panel = new JPanel();
contentPane.add(panel, BorderLayout.SOUTH);
JLabel label = new JLabel("新优先级（1~10）");
label.setFont(new Font("微软雅黑", Font.PLAIN, 16));
panel.add(label);
textField = new JTextField();
textField.setFont(new Font("微软雅黑", Font.PLAIN, 16));
panel.add(textField);
textField.setColumns(10);
JButton button = new JButton("修改");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
do_button_actionPerformed(e);
}
});
button.setFont(new Font("微软雅黑", Font.PLAIN, 16));
panel.add(button);
JScrollPane scrollPane = new JScrollPane();
contentPane.add(scrollPane, BorderLayout.CENTER);
table = new JTable();
table.setFont(new Font("微软雅黑", Font.PLAIN, 14));
table.setRowHeight(30);
JTableHeader header = table.getTableHeader();
header.setFont(new Font("微软雅黑", Font.PLAIN, 16));
header.setPreferredSize(new Dimension(header.getWidth(), 35));
scrollPane.setViewportView(table);
}
protected void do_this_windowActivated(WindowEvent e) {
ThreadGroup group = Thread.currentThread().getThreadGroup();// 获得当前线程所在线程组
Thread[] threads = new Thread[group.activeCount()];// 使用数组保存活动状态的线程
group.enumerate(threads);// 获得所有线程
DefaultTableModel model = (DefaultTableModel) table.getModel(); // 获得表格模型
model.setRowCount(0); // 清空表格模型中的数据
model.setColumnIdentifiers(new Object[] { "线程ID", "线程名称", "优先级" }); // 定义表头
for (Thread thread : threads) {// 增加行数据
model.addRow(new Object[] { thread.getId(), thread.getName(), thread.getPriority() });
}
table.setModel(model);// 更新表格模型
}
protected void do_button_actionPerformed(ActionEvent e) {
String text = textField.getText();
Integer priority = Integer.parseInt(text);
int selectedRow = table.getSelectedRow();
DefaultTableModel model = (DefaultTableModel) table.getModel();
model.setValueAt(priority, selectedRow, 2);
repaint();
}
}线程列表和对应优先级：
修改线程优先级：
修改结果：
