[笔记］bean注入和aop

依赖注入，由传统的 has a，改为在配置文件中注入，降低依赖。

传统方式：依赖性大

public class A{
private B data1;
.....
}
public class B{
...
}

注入

public class A{
private BParent data1;
public A(){...}
public A(int i， B b){...}
.....
}

public interface BParent{
...
}

public class B implements BParent{
...
}

<beans>
<bean id="A" class ="xx.xxx.aaa">
<constructor-arg value="15">//构造注入简单类型
<constructor-arg ref="B">//构造注入一个类

<property name="data1" ref="B"> //第二种注入方法set注入
<property name="xx">
<list>//或者set
<value>13</value>//或者<ref bean="xxx">
</list>
</property>

<property name="xx">
<map>
<entry key="xxx" value="xxx"/> //或者<entry key="xxx" value_ref="xxx"/> 
</map>
</property>

<property name="xx">
<props>
<prop key="xxx">"xxx"</prop>
<prop key="xxx"><null/></prop>//值为null的时候
</props>
</property>

</bean> <bean id="B" class ="xx.xxx.bbb"> </bean> 

</beans>

自动匹配注入

byName 根据data名自动匹配id相同的bean

byType 根据data类型自动匹配id相同的bean

byConstructor 如果使用构造函数注入

autodetect 先尝试使用byConstructor，失败尝试使用byType

aop: 在xml中配置元素

package com.springinaction.springidol;
public class Audience {
  public void takeSeats() {
    System.out.println("The audience is taking their seats.");
  }//Before performance
  public void turnOffCellPhones() {
    System.out.println("The audience is turning off their cellphones");//Before performance
}
  public void applaud() {
    System.out.println("CLAP CLAP CLAP CLAP CLAP");
}//After performance
  public void demandRefund() {
    System.out.println("Boo! We want our money back!");
}//After bad performance
 }

<bean id="audience"
      class="com.springinaction.springidol.Audience" />

  <aop:config>
          <aop:aspect ref="audience">
<aop:pointcut id="performance" expression=
"execution(* com.springinaction.springidol.Performer.perform(..))" />
    <aop:before
        pointcut-ref="performance"
        method="takeSeats" />
    <aop:before
        pointcut-ref="performance"
        method="turnOffCellPhones" />
    <aop:after-returning
        pointcut-ref="performance"
        method="applaud" />
    <aop:after-throwing
        pointcut-ref="performance"
        method="demandRefund" />
  </aop:aspect>
</aop:config>

within 在这个包内

周围通知:befor,after-returning,after-throwing的结合

public void watchPerformance(ProceedingJoinPoint joinpoint) {
  try {
    System.out.println("The audience is taking their seats.");
    System.out.println("The audience is turning off their cellphones");//Before performance
　　long start = System.currentTimeMillis();
　　joinpoint.proceed();//Proceed to advised method
    long end = System.currentTimeMillis();
    System.out.println("CLAP CLAP CLAP CLAP CLAP");
    System.out.println("The performance took " + (end - start)
        + " milliseconds.");//After performance
  } catch (Throwable t) {
    System.out.println("Boo! We want our money back!");//After bad performance
  }
}

<aop:config>
  <aop:aspect ref="audience">
<aop:pointcut id="performance2" expression=
"execution(* com.springinaction.springidol.Performer.perform(..))" />
<aop:around
        pointcut-ref="performance2"
        method="watchPerformance()" />
  </aop:aspect>
</aop:config>

传递参数给通知：使用agrs

package com.springinaction.springidol;
public interface MindReader {
  void interceptThoughts(String thoughts);
  String getThoughts();
}

package com.springinaction.springidol;
public interface MindReader {
  void interceptThoughts(String thoughts);
  String getThoughts();
}

package com.springinaction.springidol;
public interface Thinker {
  void thinkOfSomething(String thoughts);
}

package com.springinaction.springidol;
public class Volunteer implements Thinker {
  private String thoughts;
  public void thinkOfSomething(String thoughts) {
    this.thoughts = thoughts;
}
  public String getThoughts() {
    return thoughts;
}
 }

<aop:config>
  <aop:aspect ref="magician">
    <aop:pointcut id="thinking"
      expression="execution(*
      com.springinaction.springidol.Thinker.thinkOfSomething(String))
           and args(thoughts)" /> //agrs将参数定义为thoughts
    <aop:before
        pointcut-ref="thinking"
        method="interceptThoughts"
        arg-names="thoughts" />
  </aop:aspect>
</aop:config>

给通知的对象添加方法：

<aop:aspect>
  <aop:declare-parents
    types-matching="com.springinaction.springidol.Performer+" //要通知的对象(实现了performer接口)
    implement-interface="com.springinaction.springidol.Contestant" //要添加的接口
    default-impl="com.springinaction.springidol.GraciousContestant" //实现接口方法的类
    />
</aop:aspect>
或者使用

<aop:declare-parents
  types-matching="com.springinaction.springidol.Performer+"
  implement-interface="com.springinaction.springidol.Contestant"
  delegate-ref="contestantDelegate"
  />

<bean id="contestantDelegate"
      class="com.springinaction.springidol.GraciousContestant" />

使用注解方法：

package com.springinaction.springidol;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.DeclareParents;

@Aspect
public class ContestantIntroducer {

  @DeclareParents(
      value = "com.springinaction.springidol.Performer+",
      defaultImpl = GraciousContestant.class)

  public static Contestant contestant;
}

<bean class="com.springinaction.springidol.ContestantIntroducer" /> 

<aop:aspectj-autoproxy/>  //spring提供自动代理创建器类，名为AnnotationAwareaspectJAutoProxyCreator，可在spring上下文里注册为一个bean，为简化，spring在sop命名空间里提供了此自定义配置元素，自动创建bean，根据@pointcut注视定义的切点来自动代理相匹配的bean

 

aop方法2:注解

package com.springinaction.springidol;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
Annotating aspects 103
@Aspect
public class Audience {
@Pointcut(
"execution(* com.springinaction.springidol.Performer.perform(..))")
public void performance() {
}
Define pointcut
@Before("performance()") Before public void takeSeats() { performance
  System.out.println("The audience is taking their seats.");
}
@Before("performance()") Before public void turnOffCellPhones() { performance
  System.out.println("The audience is turning off their cellphones");
}
  @AfterReturning("performance()")
  public void applaud() {
    System.out.println("CLAP CLAP CLAP CLAP CLAP");
  }
  @AfterThrowing("performance()")
  public void demandRefund() {
    System.out.println("Boo! We want our money back!");
  }

@Around("performance()")
          public void watchPerformance(ProceedingJoinPoint joinpoint) {
            try {
              System.out.println("The audience is taking their seats.");
              System.out.println("The audience is turning off their cellphones");
              long start = System.currentTimeMillis();
              joinpoint.proceed();
              long end = System.currentTimeMillis();
              System.out.println("CLAP CLAP CLAP CLAP CLAP");
              System.out.println("The performance took " + (end - start)
                  + " milliseconds.");
            } catch (Throwable t) {
              System.out.println("Boo! We want our money back!");
} }
}

<bean id="audience"
      class="com.springinaction.springidol.Audience" />
<aop:aspectj-autoproxy/>