Guice 学习（八）AOP (面向切面的编程)

Guice支持AOP的条件是：

类必须是public或者package (default)

类不能是final类型的

方法必须是public,package或者protected

方法不能使final类型的

实例必须通过Guice的@Inject注入或者有一个无參数的构造函数

---

且看演示样例代码

1、定义接口

package com.guice.AOP;

import com.google.inject.ImplementedBy;

@ImplementedBy(ServiceImpl.class)

public interface Service {

    public void sayHello();

}

2、定义实现类

package com.guice.AOP;

import com.google.inject.Singleton;

import com.google.inject.name.Named;

@Singleton

public class ServiceImpl implements Service {

    @Named("log")

    @Override

    public void sayHello() {

        System.out.println(String.format("[%s#%d] execute %s at %d", this.getClass().getSimpleName(), hashCode(), "sayHello", System.nanoTime()));

    }

}

3、定义切面

package com.guice.AOP;

import org.aopalliance.intercept.MethodInterceptor;

import org.aopalliance.intercept.MethodInvocation;

/**

 *  TODO :自己定义的方法拦截器。用于输出方法的运行时间

 *

 * @author E468380

 */

public class LoggerMethodInterceptor implements MethodInterceptor {

    @Override

    public Object invoke(MethodInvocation invocation) throws Throwable {

        String name = invocation.getMethod().getName();

        long startTime = System.nanoTime();

        System.out.println(String.format("before method[%s] at %s", name, startTime));

        Object obj = null;

        try {

            obj = invocation.proceed();// 运行服务

        } finally {

            long endTime = System.nanoTime();

            System.out.println(String.format("after method[%s] at %s, cost(ns):%d", name, endTime, (endTime - startTime)));

        }

        return obj;

    }

}

4、測试类

package com.guice.AOP;

import com.google.inject.Binder;

import com.google.inject.Guice;

import com.google.inject.Inject;

import com.google.inject.Injector;

import com.google.inject.Module;

import com.google.inject.matcher.Matchers;

import com.google.inject.name.Names;

public class AopTest {

    @Inject

    private Service service;

    public static void main(String[] args) {

        Injector injector = Guice.createInjector(new Module() {

            @Override

            public void configure(Binder binder) {

                binder.bindInterceptor(Matchers.any(), Matchers.annotatedWith(Names.named("log")), new LoggerMethodInterceptor());

            }

        });

        injector.getInstance(AopTest.class).service.sayHello();

        injector.getInstance(AopTest.class).service.sayHello();

        injector.getInstance(AopTest.class).service.sayHello();

    }

}

输出结果：

 before method[sayHello] at 18832801981960

 [ServiceImpl$$EnhancerByGuice$$d4244950#1109685565] execute sayHello at 18832817170768

 after method[sayHello] at 18832817378285, cost(ns):15396325

 before method[sayHello] at 18832817542181

 [ServiceImpl$$EnhancerByGuice$$d4244950#1109685565] execute sayHello at 18832817640327

 after method[sayHello] at 18832817781772, cost(ns):239591

 before method[sayHello] at 18832817920651

 [ServiceImpl$$EnhancerByGuice$$d4244950#1109685565] execute sayHello at 18832818013023

 after method[sayHello] at 18832818132657, cost(ns):212006

5、切面注入依赖

在这里我们声明一个前置服务。输出全部调用的方法名称。

①定义接口

package com.guice.AOP;

import org.aopalliance.intercept.MethodInvocation;

import com.google.inject.ImplementedBy;

@ImplementedBy(BeforeServiceImpl.class)

public interface BeforeService {

    void before(MethodInvocation invocation);

}

②定义实现类

package com.guice.AOP;

import org.aopalliance.intercept.MethodInvocation;

public class BeforeServiceImpl implements BeforeService {

    @Override

    public void before(MethodInvocation invocation) {

        System.out.println("Before--->" + invocation.getClass().getName());

    }

}

③定义切面

package com.guice.AOP;

import org.aopalliance.intercept.MethodInterceptor;

import org.aopalliance.intercept.MethodInvocation;

import com.google.inject.Inject;

//这个切面依赖前置服务

public class AfterMethodIntercepter implements MethodInterceptor {

    @Inject

    private BeforeService beforeService;

    @Override

    public Object invoke(MethodInvocation invocation) throws Throwable {

        beforeService.before(invocation);

        Object obj = null;

        try {

            obj = invocation.proceed();

        } finally {

            System.out.println("after--->" + invocation.getClass().getName());

        }

        return obj;

    }

}

④编写測试类

package com.guice.AOP;

import com.google.inject.Binder;

import com.google.inject.Guice;

import com.google.inject.Inject;

import com.google.inject.Injector;

import com.google.inject.Module;

import com.google.inject.matcher.Matchers;

import com.google.inject.name.Names;

public class AopTest2 {

    @Inject

    private Service service;

    public static void main(String[] args) {

        Injector injector = Guice.createInjector(new Module() {

            @Override

            public void configure(Binder binder) {

                AfterMethodIntercepter after = new AfterMethodIntercepter();

                binder.requestInjection(after);

                binder.bindInterceptor(Matchers.any(), Matchers.annotatedWith(Names.named("log")), after);

            }

        });

        injector.getInstance(AopTest2.class).service.sayHello();

    }

}

输出结果：

 Before--->com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation

 [ServiceImpl$$EnhancerByGuice$$618294e9#506575947] execute sayHello at 20140444543338

 after--->com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation

说明

Binder绑定一个切面的API是：

com.google.inject.Binder.bindInterceptor(Matcher<? super Class<?

>>, Matcher<? super Method>, MethodInterceptor...)

第一个參数是匹配类，第二个參数是匹配方法，第三个数组參数是方法拦截器。也就是说眼下为止Guice只能拦截到方法，然后才做一些切面工作。

注意