1、任务执行和调度
spring用taskexecutor和taskscheduler接口提供了异步执行和调度任务的抽象。
spring的taskexecutor和java.util.concurrent.executor接口时一样的，这个接口只有一个方法execute(runnable task)。
1.1、taskexecutor类型
spring已经内置了许多taskexecutor的实现，你没有必要自己去实现：
- simpleasynctaskexecutor 这种实现不会重用任何线程，每次调用都会创建一个新的线程。
- synctaskexecutor 这种实现不会异步的执行
- concurrenttaskexecutor 这种实现是java.util.concurrent.executor的一个adapter。
- simplethreadpooltaskexecutor 这种实现实际上是quartz的simplethreadpool的一个子类，它监听spring的声明周期回调。
- threadpooltaskexecutor 这是最常用最通用的一种实现。它包含了java.util.concurrent.threadpoolexecutor的属性，并且用taskexecutor进行包装。
1.2、注解支持调度和异步执行
to enable support for @scheduled and @async annotations add @enablescheduling and @enableasync to one of your
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@configuration classes:@configuration@enableasync@enableschedulingpublic class appconfig {} |
特别注意
the default advice mode for processing @async annotations is "proxy" which allows for interception of calls through the proxy only; local calls within the same class cannot get intercepted that way. for a more advanced mode of interception, consider switching to "aspectj" mode in combination with compile-time or load-time weaving.
默认是用代理去处理@async的，因此，相同类中的方法调用带@async的方法是无法异步的，这种情况仍然是同步。
举个例子：下面这种，在外部直接调用sayhi()是可以异步执行的，而调用sayhello()时sayhi()仍然是同步执行
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public class a { public void sayhello() { sayhi(); } @async public void sayhi() { } } |
1.3、@async注解
在方法上加@async注解表示这是一个异步调用。换句话说，方法的调用者会立即得到返回，并且实际的方法执行是想spring的taskexecutor提交了一个任务。
in other words, the caller will return immediately upon invocation and the actual execution of the method will occur in a task that has been submitted to a spring taskexecutor.
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@asyncvoid dosomething() { // this will be executed asynchronously} |
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@asyncvoid dosomething(string s) { // this will be executed asynchronously} |
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@asyncfuture<string> returnsomething(int i) { // this will be executed asynchronously} |
注意：
@async methods may not only declare a regular java.util.concurrent.future return type but also spring's org.springframework.util.concurrent.listenablefuture or, as of spring 4.2, jdk 8's java.util.concurrent.completablefuture: for richer interaction with the asynchronous task and for immediate composition with further processing steps.
1.4、@async限定executor
默认情况下，当在方法上加@async注解时，将会使用一个支持注解驱动的executor。然而，@async注解的value值可以指定一个别的executor
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@async("otherexecutor")void dosomething(string s) { // this will be executed asynchronously by "otherexecutor"} |
这里，otherexecutor是spring容器中任意executor bean的名字。
1.5、@async异常管理
当一个@async方法有一个future类型的返回值时，就很容易管理在调future的get()方法获取任务的执行结果时抛出的异常。如果返回类型是void，那么异常是不会被捕获到的。
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public class myasyncuncaughtexceptionhandler implements asyncuncaughtexceptionhandler { @override public void handleuncaughtexception(throwable ex, method method, object... params) { // handle exception }} |
2、线程池配置
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import org.springframework.context.annotation.bean;import org.springframework.context.annotation.configuration;import org.springframework.scheduling.annotation.enableasync;import org.springframework.scheduling.concurrent.threadpooltaskexecutor;@configuration@enableasyncpublic class taskexecutorconfig { private integer corepoolsize = 30; private integer maxpoolsize = 50; private integer keepaliveseconds = 300;// private integer queuecapacity = 2000; @bean("mythreadpooltaskexecutor") public threadpooltaskexecutor mythreadpooltaskexecutor() { threadpooltaskexecutor executor = new threadpooltaskexecutor(); executor.setcorepoolsize(corepoolsize); executor.setmaxpoolsize(maxpoolsize); executor.setkeepaliveseconds(keepaliveseconds);// executor.setqueuecapacity(queuecapacity); executor.setwaitfortaskstocompleteonshutdown(true); executor.initialize(); return executor; }} |
调用
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@async("mythreadpooltaskexecutor") @override public void present(couponpresentlogentity entity) { try { couponbaseresponse rst = couponsendrpcservice.send(entity.getuserid(), entity.getcouponbatchkey(), "1", entity.getvendorid()); if (null != rst && rst.issuccess()) { entity.setstatus(presentstatusenum.success.gettype()); }else { string reason = (null == rst) ? "响应异常" : rst.getmsg(); entity.setfailurereason(reason); entity.setstatus(presentstatusenum.failure.gettype()); } }catch (exception ex) { log.error(ex.getmessage(), ex); entity.setfailurereason(ex.getmessage()); entity.setstatus(presentstatusenum.failure.gettype()); } couponpresentlogdao.update(entity); } |
结果
[info ] 2018-05-09 16:27:39.887 [mythreadpooltaskexecutor-1] [com.ourhours.coupon.rpc.dubbo.receivelogfilter] - receive method-name:send; arguments:[10046031,"4d7cc32f8f7e4b00bca56f6bf4b3b658","1",10001]
[info ] 2018-05-09 16:27:39.889 [mythreadpooltaskexecutor-2] [com.ourhours.coupon.rpc.dubbo.receivelogfilter] - receive method-name:send; arguments:[10046031,"4d7cc32f8f7e4b00bca56f6bf4b3b658","1",10001]
参考：
spring framework reference documentation 4.3.17.release
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：http://www.cnblogs.com/cjsblog/p/9016657.html
