96 lines
3.1 KiB
Java
96 lines
3.1 KiB
Java
package io.github.ehlxr.cache;
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import java.util.concurrent.Callable;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.Future;
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import java.util.concurrent.FutureTask;
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/**
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* Created by ehlxr on 2017/4/11.
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*/
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public class TestFutureCahe<K, V> {
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private final ConcurrentHashMap<K, Future<V>> cacheMap = new ConcurrentHashMap<K, Future<V>>();
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public static void main(String[] args) {
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final TestFutureCahe<String, String> TestGuaVA = new TestFutureCahe<String, String>();
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Thread t1 = new Thread(new Runnable() {
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@Override
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public void run() {
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System.out.println("T1======start========");
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Object value = TestGuaVA.getCache("key", "T1");
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System.out.println("T1 value==============" + value);
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System.out.println("T1======end========");
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}
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});
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Thread t2 = new Thread(new Runnable() {
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@Override
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public void run() {
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System.out.println("T2======start========");
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Object value = TestGuaVA.getCache("key", "T2");
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System.out.println("T2 value==============" + value);
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System.out.println("T2======end========");
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}
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});
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Thread t3 = new Thread(new Runnable() {
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@Override
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public void run() {
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System.out.println("T3======start========");
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Object value = TestGuaVA.getCache("key", "T3");
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System.out.println("T3 value==============" + value);
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System.out.println("T3======end========");
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}
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});
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t1.start();
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t2.start();
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t3.start();
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}
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public Object getCache(K keyValue, String ThreadName) {
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Future<V> value = null;
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try {
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System.out.println("ThreadName getCache==============" + ThreadName);
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//从缓存获取数据
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value = cacheMap.get(keyValue);
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//如果没有的话，把数据放到缓存
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if (value == null) {
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value = putCache(keyValue, ThreadName);
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return value.get();
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}
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return value.get();
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} catch (Exception e) {
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}
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return null;
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}
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public Future<V> putCache(K keyValue, final String ThreadName) {
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// //把数据放到缓存
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Future<V> value = null;
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Callable<V> callable = new Callable<V>() {
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@SuppressWarnings("unchecked")
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@Override
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public V call() throws Exception {
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//可以根据业务从数据库获取等取得数据,这边就模拟已经获取数据了
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System.out.println("ThreadName 执行业务数据并返回处理结果的数据（访问数据库等）==============" + ThreadName);
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return (V) "dataValue";
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}
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};
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FutureTask<V> futureTask = new FutureTask<V>(callable);
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value = cacheMap.putIfAbsent(keyValue, futureTask);
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if (value == null) {
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value = futureTask;
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futureTask.run();
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}
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return value;
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}
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} |