Java多線程系列二——Thread類的方法

標籤：標記   over   integer   org   結束   ext   span   exception   while   

Thread實現Runnable介面並實現了大量實用的方法

public static native void yield();

此方法釋放CPU，但並不釋放已獲得的鎖，其它就緒的線程將可能得到執行機會，它自己也有可能再次得到執行機會

public static native void sleep(long millis) throws InterruptedException;

此方法釋放CPU，但並不釋放已獲得的鎖，其它就緒的線程將得到執行機會，在休眠時間結束後，當前線程繼續執行

public final void join() throws InterruptedException;

一旦調用後宿主線程將阻塞，待當前線程結束後繼續

public final synchronized void join(long millis)throws InterruptedException;

一旦調用後宿主線程將阻塞，待millis時間結束後繼續

public void interrupt();

中斷線程

public final void setDaemon(boolean on);

on=true表示線程標記為守護線程(例如GC線程)，若正在啟動並執行所有線程都是守護線程，JVM將退出

import java.util.Map;import java.util.concurrent.ConcurrentHashMap;import java.util.concurrent.atomic.AtomicInteger;import org.junit.Assert;import org.junit.Test;/** * @Description: 測試Thread的方法 */public class ThreadMethodsTest {    static String SLEEP = "sleep";    static String YIELD = "yield";    static String JOIN = "join";    private Map<String, ThreadMethodEnum> map = new ConcurrentHashMap<>();    class TheadSleep implements Runnable {        private int millis;        public TheadSleep(int millis) {            this.millis = millis;        }        @Override        public void run() {            long threadId = Thread.currentThread().getId();            ThreadMethodEnum sleep = ThreadMethodEnum.SLEEP;            sleep.init(threadId);            try {                Thread.sleep(millis);            } catch (InterruptedException e) {                e.printStackTrace();            }            sleep.stop();            map.put(sleep.getMethod(), sleep);        }    }    class TheadYield implements Runnable {        @Override        public void run() {            long threadId = Thread.currentThread().getId();            ThreadMethodEnum yield = ThreadMethodEnum.YIELD;            yield.init(threadId);            Thread.yield();            yield.stop();            map.put(yield.getMethod(), yield);        }    }    class TheadJoin implements Runnable {        private Thread thread;        private int millis = 0;        public TheadJoin(Thread thread) {            this.thread = thread;        }        public TheadJoin(Thread thread, int millis) {            this.thread = thread;            this.millis = millis;        }        @Override        public void run() {            try {                long threadId = Thread.currentThread().getId();                ThreadMethodEnum join = ThreadMethodEnum.JOIN;                join.init(threadId);                if (millis > 0) {                    this.thread.join(millis);                } else {                    this.thread.join();                }                join.stop();                map.put(join.getMethod(), join);            } catch (InterruptedException e) {                e.printStackTrace();            }        }    }    final AtomicInteger interruptCount = new AtomicInteger(0);    final int interruptIndex = 100;    class ThreadInterrupt extends Thread {        @Override        public void run() {            while (!isInterrupted()) {                interruptCount.incrementAndGet();                if (interruptCount.intValue() == interruptIndex) {                    interrupt();                }            }        }    }    @Test    public void testSleep() throws InterruptedException {        int millis = 1000;        Thread sleep = new Thread(new TheadSleep(millis));        sleep.start();        sleep.join();        ThreadMethodEnum tme = map.get(SLEEP);        // 預期sleep時間與millis相近        Assert.assertEquals(1, Math.round((tme.getStopTimeMillis() - tme.getStartTimeMillis()) * 1.0 / millis));    }    @Test    public void testYield() throws InterruptedException {        Thread yield = new Thread(new TheadYield());        yield.start();        yield.join();        ThreadMethodEnum tme = map.get(YIELD);        // 預期yield消耗時間幾乎為0        Assert.assertEquals(1, Math.round(tme.getStartTimeMillis() * 1.0 / tme.getStopTimeMillis()));    }    @Test    public void testJoin() throws InterruptedException {        int millis = 1000;        Thread sleep = new Thread(new TheadSleep(millis));        sleep.start();        Thread join = new Thread(new TheadJoin(sleep));        join.start();        join.join();        ThreadMethodEnum tme = map.get(SLEEP);        // 預期sleep時間與millis相近        Assert.assertEquals(1, Math.round((tme.getStopTimeMillis() - tme.getStartTimeMillis()) * 1.0 / millis));        tme = map.get(JOIN);        // 預期join阻塞時間與millis相近        Assert.assertEquals(1, Math.round((tme.getStopTimeMillis() - tme.getStartTimeMillis()) * 1.0 / millis));    }    @Test    public void testJoinMillis() throws InterruptedException {        int millis = 500;        Thread sleep = new Thread(new TheadSleep(millis * 2));        sleep.start();        Thread join = new Thread(new TheadJoin(sleep, millis));        join.start();        join.join();        ThreadMethodEnum tme = map.get(SLEEP);        // 預期sleep不能在join阻塞結束前設定，故為null        Assert.assertTrue(tme == null);        tme = map.get(JOIN);        // 預期join阻塞時間與millis相近        Assert.assertEquals(1, Math.round((tme.getStopTimeMillis() - tme.getStartTimeMillis()) / millis));    }    @Test    public void testInterrupt() throws InterruptedException {        ThreadInterrupt interrupt = new ThreadInterrupt();        interrupt.start();        interrupt.join();        Assert.assertEquals(interruptIndex, interruptCount.intValue());    }}enum ThreadMethodEnum {    SLEEP(ThreadMethodsTest.SLEEP) {        @Override        public void init(long threadId) {            super.start(threadId);        }    },    YIELD(ThreadMethodsTest.YIELD) {        @Override        public void init(long threadId) {            super.start(threadId);        }    },    JOIN(ThreadMethodsTest.JOIN) {        @Override        public void init(long threadId) {            super.start(threadId);        }    };    private String method;    private long threadId;    private long startTimeMillis;    private long stopTimeMillis = 0;    private ThreadMethodEnum(String method) {        this.method = method;    }    public void stop() {        this.stopTimeMillis = System.currentTimeMillis();    }    public String getMethod() {        return method;    }    public long getThreadId() {        return threadId;    }    public long getStartTimeMillis() {        return startTimeMillis;    }    public long getStopTimeMillis() {        return stopTimeMillis;    }    private void start(long threadId) {        this.threadId = threadId;        this.startTimeMillis = System.currentTimeMillis();    }    public abstract void init(long threadId);}

 

Java多線程系列二——Thread類的方法