标签：java calls 并行操作 util 线程 new import public ThreadPoolExecutor
日常工作中很多地方很多效率极低的操作，往往可以改串行为并行，执行效率往往提高数倍，废话不多说先上代码
1、用到的guava坐标
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>18.0</version>
</dependency>
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2、创建一个枚举保证线程池是单例
package com.hao.service;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
public enum ExecutorManager {
INSTANCE;
private ExecutorManager() {
}
private static int AVAILABLEPROCESSORS = Runtime.getRuntime().availableProcessors();
public static final ThreadPoolExecutor threadPoolExecutor =
new ThreadPoolExecutor(AVAILABLEPROCESSORS * 50, AVAILABLEPROCESSORS * 80, 0L, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<Runnable>(AVAILABLEPROCESSORS * 2000),
new ThreadFactoryBuilder().setNameFormat("ExecutorManager-pool-Thread-%d").build());
}
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3、创建一个方法类
package com.hao.service;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import javax.annotation.PostConstruct;
import org.springframework.stereotype.Service;
import com.google.common.base.Preconditions;
@Service
public class ExecutorContext {
public ExecutorService executorService;
private int DEFAULT_WAIT_SECONDS = 2;
@PostConstruct
public void init() {
executorService = ExecutorManager.threadPoolExecutor;
}
public <T> List<T> waitAllFutures(List<Callable<T>> calls, int milliseconds) throws Exception {
Preconditions.checkArgument(null != calls && !calls.isEmpty(), "callable empty.");
LatchedCallables<T> latchAndCallables = wrapCallables(calls);
List<Future<T>> futurres = new LinkedList<>();
for (CountdownedCallable<T> callable : latchAndCallables.wrappedCallables) {
if (null != callable) {
futurres.add(executorService.submit(callable));
}
}
List<T> rets = new ArrayList<>();
if (latchAndCallables.latch.await(milliseconds, TimeUnit.MILLISECONDS)) {
for (CountdownedCallable<T> call : latchAndCallables.wrappedCallables) {
rets.add(call.getResult());
}
} else {
for (Future<T> future : futurres) {
if (!future.isDone()) {
future.cancel(true);
}
}
}
return rets;
}
public <T> List<T> waitAllCallables(List<Callable<T>> calls, int seconds) throws Exception {
Preconditions.checkArgument(null != calls && !calls.isEmpty(), "callable empty.");
LatchedCallables<T> latchAndCallables = wrapCallables(calls);
for (CountdownedCallable<T> callable : latchAndCallables.wrappedCallables) {
executorService.submit(callable);
}
List<T> rets = new ArrayList<>();
if (latchAndCallables.latch.await(seconds, TimeUnit.SECONDS)) {
for (CountdownedCallable<T> call : latchAndCallables.wrappedCallables) {
rets.add(call.getResult());
}
}
return rets;
}
public <T> List<T> waitAllCallables(@SuppressWarnings("unchecked") Callable<T>... calls) throws Exception {
Preconditions.checkNotNull(calls, "callable empty.");
return waitAllCallables(Arrays.asList(calls), DEFAULT_WAIT_SECONDS);
}
private static <T> LatchedCallables<T> wrapCallables(List<Callable<T>> callables) {
CountDownLatch latch = new CountDownLatch(callables.size());
List<CountdownedCallable<T>> wrapped = new ArrayList<>(callables.size());
for (Callable<T> callable : callables) {
wrapped.add(new CountdownedCallable<>(callable, latch));
}
LatchedCallables<T> returnVal = new LatchedCallables<>();
returnVal.latch = latch;
returnVal.wrappedCallables = wrapped;
return returnVal;
}
public static class LatchedCallables<T> {
public CountDownLatch latch;
public List<CountdownedCallable<T>> wrappedCallables;
}
public static class CountdownedCallable<T> implements Callable<T> {
private final Callable<T> wrapped;
private final CountDownLatch latch;
private T result;
public CountdownedCallable(Callable<T> wrapped, CountDownLatch latch) {
this.wrapped = wrapped;
this.latch = latch;
}
@Override
public T call() throws Exception {
try {
result = wrapped.call();
return result;
} finally {
latch.countDown();
}
}
public T getResult() {
return result;
}
}
}
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4、创建一个测试类
package com.hao;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import com.hao.bean.Employee;
import com.hao.service.EmployeeService;
import com.hao.service.ExecutorContext;
public class ExecutorTest extends BaseTest {
@Autowired
ExecutorContext executorContext;
@Autowired
EmployeeService employeeService;
@Test
public void test01() {
long t0 = System.currentTimeMillis();
List<Employee> employees = new ArrayList<Employee>();
try {
List<Callable<Integer>> calls = new ArrayList<Callable<Integer>>();
Callable<Integer> able1 = new Callable<Integer>() {
@Override
public Integer call() throws Exception {
Thread.sleep(5000);
Employee employee = employeeService.getById(1L);
employees.add(employee);
return 1;
}
};
calls.add(able1);
Callable<Integer> able2 = new Callable<Integer>() {
@Override
public Integer call() throws Exception {
Thread.sleep(5000);
Employee employee = employeeService.getById(2L);
employees.add(employee);
return 2;
}
};
calls.add(able2);
Callable<Integer> able3 = new Callable<Integer>() {
@Override
public Integer call() throws Exception {
Thread.sleep(5000);
Employee employee = employeeService.getById(3L);
employees.add(employee);
return 3;
}
};
calls.add(able3);
executorContext.waitAllCallables(calls, 5000);
} catch (Exception e) {
e.printStackTrace();
}
for (Employee employee : employees) {
System.out.println(employee);
}
System.out.println(System.currentTimeMillis() - t0);
}
}
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5、执行结果如下
次工具类的好处在于能够像使用普通 service一样使用线程池完成并行操作，当然不要忘记将 ExecutorContext 置于能被sping扫描到的地方，
否则不能直接使用@Autowired 依赖注入
标签：java,calls,并行操作,util,线程,new,import,public,ThreadPoolExecutor 来源： https://www.cnblogs.com/zhanh247/p/12576491.html
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