這篇文章主要講解了“Java線程池的使用實(shí)例”，文中的講解內(nèi)容簡(jiǎn)單清晰，易于學(xué)習(xí)與理解，下面請(qǐng)大家跟著小編的思路慢慢深入，一起來研究和學(xué)習(xí)“Java線程池的使用實(shí)例”吧！
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TestThreadPool.java
重慶分公司
重慶分公司
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class TestThreadPool {
public static void main(String[] args) {
long startTime = System.currentTimeMillis(); //獲取開始時(shí)間
ExecutorService fixedThreadPool = Executors.newFixedThreadPool(5);//設(shè)置線程池的最大線程數(shù)
for (int i = 0; i < 10; i++) {
final int index = i;//一般多線程并發(fā)都用final
fixedThreadPool.execute(new Runnable() {
public void run() {
System.out.println(index + " " + Thread.currentThread().getName());
}
});
}
long endTime = System.currentTimeMillis(); //獲取結(jié)束時(shí)間
System.out.println("程序運(yùn)行時(shí)間：" + (endTime - startTime) + "ms");
}
}輸出結(jié)果： 
（當(dāng)然輸出結(jié)果不是固定的，不過線程數(shù)一定不會(huì)超過5個(gè)）
可以看到 Thread.currentThread().getName() 拿到的name只有5種，說明最大線程數(shù)控制在 5 個(gè)
工作隊(duì)列用了LinkedBlockingQueue ，無界隊(duì)列，當(dāng)任務(wù)多而線程數(shù)少時(shí)，任務(wù)會(huì)存在隊(duì)列里，容易內(nèi)存溢出。
TestThreadPool1.java
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class TestThreadPool1 {
public static void main(String[] args) {
ExecutorService cachedThreadPool = Executors.newCachedThreadPool();
for (int i = 0; i < 10000; i++) {
final int index = i;
cachedThreadPool.execute(new Runnable() {
public void run() {
System.out.println(index + " " + Thread.currentThread().getName());
}
});
}
}
}輸出結(jié)果的 Thread.currentThread().getName() 拿到的name有一兩千種（當(dāng)然不同環(huán)境和配置的機(jī)器的結(jié)果最大線程數(shù)是不同的）
工作隊(duì)列使用SynchronousQueue同步隊(duì)列。會(huì)根據(jù)任務(wù)數(shù)創(chuàng)建線程，數(shù)量太大容易導(dǎo)致cpu使用率100% 99%
TestThreadPool2.java
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class TestThreadPool2 {
public static void main(String[] args) {
ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor();
for (int i = 0; i < 10000; i++) {
final int index = i;
singleThreadExecutor.execute(new Runnable() {
public void run() {
System.out.println(index + " " + Thread.currentThread().getName());
}
});
}
}
}輸出結(jié)果：無論循環(huán)100次還是100000次，輸出結(jié)果Thread.currentThread().getName()的值都會(huì)是
pool-1-thread-1
TestThreadPool3.java
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class TestThreadPool3 {
public static void main(String[] args) {
ExecutorService singleThreadExecutor = Executors.newCachedThreadPool();
for (int i = 0; i < 10; i++) {
final int index = i;
singleThreadExecutor.execute(new Runnable() {
public void run() {
try {
while(true) {
System.out.println(index + " " + Thread.currentThread().getName());
Thread.sleep(10 * 1000);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
}
}
}輸出結(jié)果：每隔10s就會(huì)輸出10行結(jié)果
**使用 ScheduledExecutorService 的 scheduleAtFixedRate方法可以設(shè)置延時(shí)和執(zhí)行間隔
scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit)
Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on.
意思是創(chuàng)建并執(zhí)行一個(gè)在給定初始延遲后首次啟用的定期操作，后續(xù)操作具有給定的周期；也就是將在 initialDelay 后開始執(zhí)行，然后在 initialDelay+period 后執(zhí)行，接著在 initialDelay + 2 * period 后執(zhí)行，依此類推。
TestThreadPool4.java
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
public class TestThreadPool4 {
public static void main(String[] args) {
ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5);
System.out.println(System.currentTimeMillis());
scheduledThreadPool.scheduleAtFixedRate(new Runnable() {
public void run() {
System.out.println(System.currentTimeMillis());
}
}, 5, 10, TimeUnit.SECONDS);
}
}從輸出結(jié)果可以看出，延時(shí)5s后每隔10s會(huì)輸出一次當(dāng)前時(shí)間。
**使用ScheduledExecutorService的schedule可以設(shè)置首次執(zhí)行延時(shí)
schedule(Runnable command, long delay, TimeUnit unit)
Creates and executes a one-shot action that becomes enabled after the given delay.
創(chuàng)建并執(zhí)行在給定延遲后啟用的一次性操作。
TestThreadPool5.java
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
public class TestThreadPool5 {
public static void main(String[] args) {
ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5);
for (int i = 0; i < 10; i++) {
final int index = i;
scheduledThreadPool.schedule(new Runnable() {
public void run() {
System.out.println(index + " " + Thread.currentThread().getName());
}
}, 3, TimeUnit.SECONDS);
}
}
}輸出結(jié)果：運(yùn)行3s后會(huì)輸出10行結(jié)果，而不會(huì)每隔3s輸出一行。
感謝各位的閱讀，以上就是“Java線程池的使用實(shí)例”的內(nèi)容了，經(jīng)過本文的學(xué)習(xí)后，相信大家對(duì)Java線程池的使用實(shí)例這一問題有了更深刻的體會(huì)，具體使用情況還需要大家實(shí)踐驗(yàn)證。這里是創(chuàng)新互聯(lián)，小編將為大家推送更多相關(guān)知識(shí)點(diǎn)的文章，歡迎關(guān)注！
