基于Schema配置切面

时间 2019-11-06

标签基于 schema 配置切面繁體版

原文原文链接

使用基于Schema的切面定义后，切点、加强类型的注解信息从切面类中剥离出来，原来的切面类也就蜕变为真正意义上的POJO了。

一、一个简单切面的配置java

基于Schema配置的切面示例：

<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
    <aop:config proxy-target-class="true">
        <aop:aspect ref="adviceMethods">
            <aop:before pointcut="target(com.yyq.schema.NaiveWaiter) and execution(* greetTo(..))"
                        method="preGreeting"/>
        </aop:aspect>
    </aop:config>
    <bean id="adviceMethods" class="com.yyq.schema.AdviceMethods"/>
    <bean id="naiveWaiter" class="com.yyq.schema.NaiveWaiter"/>
    <bean id="naughtyWaiter" class="com.yyq.schema.NaughtyWaiter"/>
</beans>

　　使用一个<aop:aspect>元素标签订义切面，其内部能够定义多个加强。在<aop:config>元素中能够定义多个切面。经过<aop:before>声明了一个前置加强，并经过pointcut属性定义切点表达式，切点表达式的语法和@AspectJ中所用的语法彻底相同，因为&&在XML中使用不便，因此通常用and操做符代替。经过method属性指定加强的方法，该方法应该是adviceMethods Bean中的方法。spring

加强方法所在的类：

package com.baobaotao.schema;
import org.aspectj.lang.ProceedingJoinPoint;

public class AdviceMethods {
    public void preGreeting(String name) {
        System.out.println("--how are you!--");
        System.out.println(name);
    }
    //后置加强对应方法
    public void afterReturning(int retVal){
       System.out.println("----afterReturning()----");
       System.out.println("returnValue:"+retVal);
       System.out.println("----afterReturning()----");
    }
    //环绕加强对应方法
    public void aroundMethod(ProceedingJoinPoint pjp){
       System.out.println("----aroundMethod()----");
       System.out.println("args[0]:"+pjp.getArgs()[0]);
       System.out.println("----aroundMethod()----");
    }
    //抛出异常加强
    public void afterThrowingMethod(IllegalArgumentException iae){
       System.out.println("----afterThrowingMethod()----");
       System.out.println("exception msg:"+iae.getMessage());
       System.out.println("----afterThrowingMethod()----");
    }
    //final加强
    public void afterMethod(){
       System.out.println("----afterMethod()----");
    }
        
      //------------绑定链接点参数----------//
    public void bindParams(int num,String name){
       System.out.println("----bindParams()----");
       System.out.println("name:"+name);
       System.out.println("num:"+num);
       System.out.println("----bindParams()----");
    }
}

NaiveWaiter类：express

package com.yyq.schema;
public class NaiveWaiter implements Waiter {
    @Override
    public void greetTo(String name) {
        System.out.println("NaiveWaiter：greet to " + name + "...");
    }
    @Override
    public void serveTo(String name) {
        System.out.println("NaiveWaiter：serving to " + name + "...");
    }
    public void smile(String clientName,int times){
        System.out.println("NaiveWaiter:smile to  "+clientName+ times+"times...");
    }
}

NaughtyWaiter类：ide

package com.yyq.schema;
public class NaughtyWaiter implements Waiter {
    public void greetTo(String clientName) {
        System.out.println("NaughtyWaiter:greet to " + clientName + "...");
    }
    public void serveTo(String clientName) {
        System.out.println("NaughtyWaiter:serving " + clientName + "...");
    }
    public void joke(String clientName, int times) {
        System.out.println("NaughtyWaiter:play " + times + " jokes to " + clientName + "...");
    }
}

测试方法：函数

package com.yyq;
import com.yyq.schema.Waiter;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SchemaTest {
    @Test
    public void schemaTest(){
        String configPath = "com\\yyq\\schema\\beans.xml";
        ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath);
        Waiter naiveWaiter = (Waiter)ctx.getBean("naiveWaiter");
        Waiter naughtyWaiter = (Waiter)ctx.getBean("naughtyWaiter");
        naiveWaiter.greetTo("John");
        naughtyWaiter.greetTo("Tom");
    }
}

输出结果：

---How are you !---

John

NaiveWaiter：greet to John...

NaughtyWaiter:greet to Tom...

二、配置命名切点

经过pointcut属性声明的切点时匿名切点，它不能被其余加强或其余切面引用。Spring提供了命名切点的配置方式。

命名切点配置：

  <aop:config proxy-target-class="true">
        <aop:aspect ref="adviceMethods">
            <aop:pointcut id="greetToPointcut" expression="target(com.yyq.schema.NaiveWaiter) and execution(* greetTo(..))"/>
            <aop:before method="preGreeting" pointcut-ref="greetToPointcut"/>
        </aop:aspect>
    </aop:config>

　　使用<aop:pointcut>定义了一个切点，并经过id属性进行命名，经过pointcut-ref引用这个命名的切点。和<aop:before>同样，除了引介加强外，其余任意加强类型都拥有pointcut、pointcut-ref和method这3个属性。post

若是想要让一个切点为全部加强访问，定义以下：

 <aop:config proxy-target-class="true">
        <aop:pointcut id="greetToPointcut2" expression="target(com.yyq.schema.NaiveWaiter) and execution(* greetTo(..))"/>
        <aop:aspect ref="adviceMethods">
            <aop:before method="preGreeting" pointcut-ref="greetToPointcut2"/>
        </aop:aspect>
        <aop:aspect ref="adviceMethods">
            <aop:after method="postGreeting" pointcut-ref="greetToPointcut2"/>
        </aop:aspect>
    </aop:config>

三、各类加强类型的配置测试

1）后置加强

<aop:config proxy-target-class="true">
        <aop:aspect ref="adviceMethods">
            <aop:after-returning method="afterReturning"
                                 pointcut="target(com.baobaotao.SmartSeller)" returning="retVal" />
        </aop:aspect>
    </aop:config>

2）环绕加强spa

 <aop:config proxy-target-class="true">
        <aop:aspect ref="adviceMethods">
            <aop:around method="aroundMethod"
                        pointcut="execution(* serveTo(..)) and within(com.baobaotao.Waiter)" />
        </aop:aspect>
    </aop:config>

3）抛出异常加强code

<aop:config proxy-target-class="true">
        <aop:aspect ref="adviceMethods">
            <aop:after-throwing method="afterThrowingMethod"
                                pointcut="target(com.baobaotao.SmartSeller) and execution(* checkBill(..))"
                                throwing="iae" />
        </aop:aspect>
    </aop:config>

4）Final加强xml

 <aop:config proxy-target-class="true">
        <aop:aspect ref="adviceMethods">
            <aop:after method="afterMethod"
                       pointcut="execution(* com..*.Waiter.greetTo(..))" />
        </aop:aspect>
    </aop:config>

5）引介加强

<aop:config proxy-target-class="true">
        <aop:aspect ref="adviceMethods">
            <aop:declare-parents
                    implement-interface="com.baobaotao.Seller"
                    default-impl="com.baobaotao.SmartSeller"
                    types-matching="com.baobaotao.Waiter+" />
        </aop:aspect>
    </aop:config>

四、绑定链接点信息

基于Schema配置的加强方法绑定链接点信息和基于@AspectJ绑定链接点信息所使用的方式没有区别。

1）全部加强类型对应的方法第一个入参均可以声明为JoinPoint（环绕加强可声明为ProceedingJoinPoint）访问链接点信息；

2）<aop:after-returning>（后置加强）能够经过returning属性绑定链接点方法的返回值，<aop:after-throwing>（抛出异常加强）能够经过throwing属性绑定链接点方法所抛出的异常；

3）全部加强类型均可以经过可绑定参数的切点函数绑定链接点方法的入参。

绑定链接点采纳数到加强方法：

 <aop:config proxy-target-class="true">
        <aop:aspect ref="adviceMethods">
            <aop:before method="bindParams"
                        pointcut="target(com.yyq.schema.NaiveWaiter) and args(name,num,..)"/>
        </aop:aspect>
    </aop:config>

AdviceMethods绑定参数的加强方法：

//------------绑定链接点参数----------//
    public void bindParams(int num,String name){
        System.out.println("----bindParams()----");
        System.out.println("name:"+name);
        System.out.println("num:"+num);
        System.out.println("----bindParams()----");
    }

五、Advisor配置

Advisor是Spring中切面概念的对应物，是切点和加强的复合体，不过仅包含一个切点和一个加强。在AspectJ中没有对应的等价物，在aop Schema配置样式中，能够经过<aop:advisor>配置一个Advisor。经过advice-ref属性引用基于接口定义的加强，经过pointcut定义切点表达式，或者经过pointcut-ref引用一个命名的切点。

  <aop:config proxy-target-class="true">
        <aop:advisor advice-ref="testAdvice"  pointcut="execution(* com..*.Waiter.greetTo(..))"/>
    </aop:config>
    <bean id="testAdvice" class="com.yyq.schema.TestBeforeAdvice"/>

加强类：

package com.yyq.schema;
import java.lang.reflect.Method;
import org.springframework.aop.MethodBeforeAdvice;
public class TestBeforeAdvice implements MethodBeforeAdvice {
    public void before(Method method, Object[] args, Object target)
            throws Throwable {
        System.out.println("------TestBeforeAdvice------");
        System.out.println("clientName:"+args[0]);
        System.out.println("------TestBeforeAdvice------");
    }
}