20241223:回调学习-1

李成 · 李成 · commit fe20abeeec07 · 2024-12-23T17:33:18.000+08:00
diff --git a/pom.xml b/pom.xml
@@ -69,6 +69,12 @@
                 </exclusion>
             </exclusions>
         </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.2</version>
+            <scope>compile</scope>
+        </dependency>
     </dependencies>
 
     <build>
diff --git a/src/main/java/javaStudy/basic/callBack/CallBack.java b/src/main/java/javaStudy/basic/callBack/CallBack.java
@@ -0,0 +1,50 @@
+package javaStudy.basic.callBack;
+
+import org.junit.Test;
+
+import java.util.Random;
+import java.util.concurrent.*;
+
+public class CallBack {
+    //这里简单地使用future和callable实现了线程执行完后
+    public static void main(String[] args) throws ExecutionException, InterruptedException {
+        // 创建一个可缓存的线程池，用于执行异步任务
+        ExecutorService executor = Executors.newCachedThreadPool();
+        Future<String> future = executor.submit(new Callable<String>() {
+            @Override
+            public String call() throws Exception {
+                System.out.println("call");
+                TimeUnit.SECONDS.sleep(1);
+                return "str";
+            }
+        });
+        //手动阻塞调用get通过call方法获得返回值。
+        System.out.println(future.get());
+        //需要手动关闭，不然线程池的线程会继续执行。
+        executor.shutdown();
+
+        //使用futuretask同时作为线程执行单元和数据请求单元。
+        FutureTask<Integer> futureTask = new FutureTask(new Callable<Integer>() {
+            @Override
+            public Integer call() throws Exception {
+                System.out.println("dasds");
+                return new Random().nextInt();
+            }
+        });
+        new Thread(futureTask).start();
+        //阻塞获取返回值
+        System.out.println(futureTask.get());
+    }
+
+    @Test
+    public void test() {
+        Callable callable = new Callable() {
+            @Override
+            public Object call() throws Exception {
+                return null;
+            }
+        };
+        FutureTask futureTask = new FutureTask(callable);
+
+    }
+}
diff --git a/src/main/java/javaStudy/basic/callBack/demo/BottomService.java b/src/main/java/javaStudy/basic/callBack/demo/BottomService.java
@@ -0,0 +1,21 @@
+package javaStudy.basic.callBack.demo;
+
+public class BottomService {
+
+    public String bottom(String param) {
+
+        try { //  模拟底层处理耗时，上层服务需要等待
+
+            Thread.sleep(3000);
+
+        } catch (InterruptedException e) {
+
+            e.printStackTrace();
+
+        }
+
+        return param +" BottomService.bottom() execute -->";
+
+    }
+
+}
diff --git a/src/main/java/javaStudy/basic/callBack/demo/Test.java b/src/main/java/javaStudy/basic/callBack/demo/Test.java
@@ -0,0 +1,25 @@
+package javaStudy.basic.callBack.demo;
+
+import java.util.Date;
+
+public class Test {
+
+    public static void main(String[] args) {
+
+        BottomService bottomService = new BottomService();
+
+        UpperService upperService = new UpperServiceImpl(bottomService);
+
+        System.out.println("=============== callBottomService start ==================:" + new Date());
+
+        String result = upperService.callBottomService("callBottomService start --> ");
+
+        //upperTaskAfterCallBottomService执行必须等待callBottomService()调用BottomService.bottom()方法返回后才能够执行
+
+        upperService.upperTaskAfterCallBottomService(result);
+
+        System.out.println("=============== callBottomService end ====================:" + new Date());
+
+    }
+
+}
diff --git a/src/main/java/javaStudy/basic/callBack/demo/UpperService.java b/src/main/java/javaStudy/basic/callBack/demo/UpperService.java
@@ -0,0 +1,9 @@
+package javaStudy.basic.callBack.demo;
+
+public interface UpperService {
+
+    public void upperTaskAfterCallBottomService(String upperParam);
+
+    public String callBottomService(final String param);
+
+}
diff --git a/src/main/java/javaStudy/basic/callBack/demo/UpperServiceImpl.java b/src/main/java/javaStudy/basic/callBack/demo/UpperServiceImpl.java
@@ -0,0 +1,29 @@
+package javaStudy.basic.callBack.demo;
+
+public class UpperServiceImpl implements UpperService {
+
+    private BottomService bottomService;
+
+    @Override
+
+    public void upperTaskAfterCallBottomService(String upperParam) {
+
+        System.out.println(upperParam + " upperTaskAfterCallBottomService() execute.");
+
+    }
+
+    public UpperServiceImpl(BottomService bottomService) {
+
+        this.bottomService = bottomService;
+
+    }
+
+    @Override
+
+    public String callBottomService(final String param) {
+
+        return bottomService.bottom(param + " callBottomService.bottom() execute --> ");
+
+    }
+
+}
