Java并发编程实例--2.获取和设置线程信息

常用线程属性

ID: 每个线程的唯一标识；

Name: 线程名称；

Priority: 线程优先级，从1-10，数字越大优先级越高；不推荐改变线程优先级；

Status: 线程状态，包含6种状态：new, runnable, blocked, waiting, time waiting, terminated

本例中，我们会开发一个程序以设置线程名称和优先级并展示一些线程信息。

Calculator.java

package com.dylan.thread.ch1.c02;

/**
 * This class prints the multiplication table of a number
 * @author xusucheng
 * @create 2018-04-21
 **/
public class Calculator implements Runnable{
    private int number;
    public Calculator(int number) {
        this.number=number;
    }
    @Override
    public void run() {
        for (int i=1; i<=10; i++){
            System.out.printf("%s: %d * %d = %d\n",Thread.
                    currentThread().getName(),number,i,i*number);
        }
    }

}

Main.java

package com.dylan.thread.ch1.c02;

import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.lang.Thread.State;

/**
 * @author xusucheng
 * @create 2018-04-21
 **/
public class Main {

    /**
     * Main method of the example
     * @param args
     */
    public static void main(String[] args) {

        // Thread priority infomation
        System.out.printf("Minimum Priority: %s\n",Thread.MIN_PRIORITY);
        System.out.printf("Normal Priority: %s\n",Thread.NORM_PRIORITY);
        System.out.printf("Maximun Priority: %s\n",Thread.MAX_PRIORITY);

        Thread threads[];
        Thread.State status[];

        // Launch 10 threads to do the operation, 5 with the max
        // priority, 5 with the min
        threads=new Thread[10];
        status=new Thread.State[10];
        for (int i=0; i<10; i++){
            threads[i]=new Thread(new Calculator(i));
            if ((i%2)==0){
                threads[i].setPriority(Thread.MAX_PRIORITY);
            } else {
                threads[i].setPriority(Thread.MIN_PRIORITY);
            }
            threads[i].setName("Thread "+i);
        }

        // Wait for the finalization of the threads. Meanwhile,
        // write the status of those threads in a file
        try (FileWriter file = new FileWriter("D:\\output\\threadLog.txt");PrintWriter pw = new PrintWriter(file);){

            for (int i=0; i<10; i++){
                pw.println("Main : Status of Thread "+i+" : "+threads[i].getState());
                status[i]=threads[i].getState();
            }

            for (int i=0; i<10; i++){
                threads[i].start();
            }

            boolean finish=false;
            while (!finish) {
                for (int i=0; i<10; i++){
                    if (threads[i].getState()!=status[i]) {
                        writeThreadInfo(pw, threads[i],status[i]);
                        status[i]=threads[i].getState();
                    }
                }

                finish=true;
                for (int i=0; i<10; i++){
                    finish=finish &&(threads[i].getState()== State.TERMINATED);
                }
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     *  This method writes the state of a thread in a file
     * @param pw : PrintWriter to write the data
     * @param thread : Thread whose information will be written
     * @param state : Old state of the thread
     */
    private static void writeThreadInfo(PrintWriter pw, Thread thread, State state) {
        pw.printf("Main : Id %d - %s\n",thread.getId(),thread.getName());
        pw.printf("Main : Priority: %d\n",thread.getPriority());
        pw.printf("Main : Old State: %s\n",state);
        pw.printf("Main : New State: %s\n",thread.getState());
        pw.printf("Main : ************************************\n");
    }

}

日志文件内容：

Main : Status of Thread 0 : NEW
Main : Status of Thread 1 : NEW
Main : Status of Thread 2 : NEW
Main : Status of Thread 3 : NEW
Main : Status of Thread 4 : NEW
Main : Status of Thread 5 : NEW
Main : Status of Thread 6 : NEW
Main : Status of Thread 7 : NEW
Main : Status of Thread 8 : NEW
Main : Status of Thread 9 : NEW
Main : Id 11 - Thread 0
Main : Priority: 10
Main : Old State: NEW
Main : New State: BLOCKED
Main : ************************************
Main : Id 12 - Thread 1
Main : Priority: 1
Main : Old State: NEW
Main : New State: RUNNABLE
Main : ************************************
Main : Id 13 - Thread 2
Main : Priority: 10
Main : Old State: NEW
Main : New State: BLOCKED
Main : ************************************
Main : Id 14 - Thread 3
Main : Priority: 1
Main : Old State: NEW
Main : New State: RUNNABLE
Main : ************************************
Main : Id 15 - Thread 4
Main : Priority: 10
Main : Old State: NEW
Main : New State: RUNNABLE
Main : ************************************
Main : Id 16 - Thread 5
Main : Priority: 1
Main : Old State: NEW
Main : New State: RUNNABLE
Main : ************************************
Main : Id 17 - Thread 6
Main : Priority: 10
Main : Old State: NEW
Main : New State: RUNNABLE
Main : ************************************
Main : Id 18 - Thread 7
Main : Priority: 1
Main : Old State: NEW
Main : New State: RUNNABLE
Main : ************************************
Main : Id 19 - Thread 8
Main : Priority: 10
Main : Old State: NEW
Main : New State: BLOCKED
Main : ************************************
Main : Id 20 - Thread 9
Main : Priority: 1
Main : Old State: NEW
Main : New State: RUNNABLE
Main : ************************************
Main : Id 12 - Thread 1
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: BLOCKED
Main : ************************************
Main : Id 14 - Thread 3
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: BLOCKED
Main : ************************************
Main : Id 15 - Thread 4
Main : Priority: 10
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 16 - Thread 5
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: BLOCKED
Main : ************************************
Main : Id 17 - Thread 6
Main : Priority: 10
Main : Old State: RUNNABLE
Main : New State: BLOCKED
Main : ************************************
Main : Id 18 - Thread 7
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: BLOCKED
Main : ************************************
Main : Id 19 - Thread 8
Main : Priority: 10
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 20 - Thread 9
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: BLOCKED
Main : ************************************
Main : Id 12 - Thread 1
Main : Priority: 1
Main : Old State: BLOCKED
Main : New State: BLOCKED
Main : ************************************
Main : Id 13 - Thread 2
Main : Priority: 10
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 15 - Thread 4
Main : Priority: 10
Main : Old State: RUNNABLE
Main : New State: TERMINATED
Main : ************************************
Main : Id 13 - Thread 2
Main : Priority: 10
Main : Old State: RUNNABLE
Main : New State: TERMINATED
Main : ************************************
Main : Id 12 - Thread 1
Main : Priority: 1
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 14 - Thread 3
Main : Priority: 1
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 12 - Thread 1
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: BLOCKED
Main : ************************************
Main : Id 14 - Thread 3
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: TERMINATED
Main : ************************************
Main : Id 20 - Thread 9
Main : Priority: 1
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 20 - Thread 9
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: TERMINATED
Main : ************************************
Main : Id 18 - Thread 7
Main : Priority: 1
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 17 - Thread 6
Main : Priority: 10
Main : Old State: BLOCKED
Main : New State: TERMINATED
Main : ************************************
Main : Id 18 - Thread 7
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: TERMINATED
Main : ************************************
Main : Id 16 - Thread 5
Main : Priority: 1
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 11 - Thread 0
Main : Priority: 10
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 11 - Thread 0
Main : Priority: 10
Main : Old State: RUNNABLE
Main : New State: TERMINATED
Main : ************************************
Main : Id 16 - Thread 5
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: TERMINATED
Main : ************************************
Main : Id 12 - Thread 1
Main : Priority: 1
Main : Old State: BLOCKED
Main : New State: RUNNABLE
Main : ************************************
Main : Id 12 - Thread 1
Main : Priority: 1
Main : Old State: RUNNABLE
Main : New State: TERMINATED
Main : ************************************