Java查看和修改線程優先級操作詳解
查看和修改線程優先級
1.題目
JAVA中每個線程都有優化級屬性,默認情況下,新建的線程和創建該線程的線程優先級是一樣的。當線程調度器選擇要運行的線程時,會選擇優先級高的線程。
實現:查看和修改線程的優先級
2.解題思路
創建一個類:ThreadPriorityTest,繼承瞭JFrame。用來界面顯示當前線程組中運行的線程。
定義2個方法:
- do_this_windowActivated():用來監聽窗體激活事件
- do_button_actionPerformed() :用來單擊修改按鈕事件,獲取用戶輸入的優先級和選擇的行,修改線程優先級。
Thread是程序中的執行線程。JAVA虛擬機允許應用程序並發地運行多個執行線程。
3.代碼詳解
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> * 修改記錄: * 修改後版本 修改人 修改日期 修改內容 * 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("查看和修改線程優化級"); 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("新優先級(1~10)"); label.setFont(new Font("微軟雅黑", Font.PLAIN, 16)); panel.add(label); textField = new JTextField(); textField.setFont(new Font("微軟雅黑", 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("微軟雅黑", Font.PLAIN, 16)); panel.add(button); JScrollPane scrollPane = new JScrollPane(); contentPane.add(scrollPane, BorderLayout.CENTER); table = new JTable(); table.setFont(new Font("微軟雅黑", Font.PLAIN, 14)); table.setRowHeight(30); JTableHeader header = table.getTableHeader(); header.setFont(new Font("微軟雅黑", 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();// 獲得當前線程所在線程組 Thread[] threads = new Thread[group.activeCount()];// 使用數組保存活動狀態的線程 group.enumerate(threads);// 獲得所有線程 DefaultTableModel model = (DefaultTableModel) table.getModel(); // 獲得表格模型 model.setRowCount(0); // 清空表格模型中的數據 model.setColumnIdentifiers(new Object[] { "線程ID", "線程名稱", "優先級" }); // 定義表頭 for (Thread thread : threads) {// 增加行數據 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(); } }
線程列表和對應優先級:
修改線程優先級:
修改結果:
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