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Eric.Zhou — Thu, 05 Jul 2007 06:28:00 GMT

如果把位于不同方面中的相同类型的通知应用于同一个连接点�Q�则可以使用declare precedence语句来控刉��知的优先��。语法：
declare precedence : TypePattern, TypePattern, ..;
如果相同�c�d��的通知位于同一个方面中�Q�那么在把通知应用于共享的�q�接�Ҏ��Q�可以��用通知声明的位�|�来指示其优先��。按在方面中声明before()和around()通知�c�d��的次序，按先后顺序执行。而after()相反�Q�声明在后面的执行优先�?img src ="http://www.aygfsteel.com/rain1102/aggbug/128334.html" width = "1" height = "1" />

Eric.Zhou 2007-07-05 14:28 发表评论

主要的pointcuts�c�d��

Eric.Zhou — Wed, 04 Jul 2007 08:39:00 GMT

分类pointcuts
遵��@特定的语法用于捕��h��一个种�cȝ��可��用连接点�?br> 主要的种�c�：

�Ҏ��执行�Q�execution(MethodSignature)
�Ҏ��调用�Q�call(MethodSignature)
构造器执行�Q�execution(ConstructorSignature)
构造器调用�Q�call(ConstructorSignature)
�c�d��始化�Q�staticinitialization(TypeSignature)
属性读操作�Q�get(FieldSignature)
属性写操作�Q�set(FieldSignature)
例外处理执行�Q�handler(TypeSignature)
对象初始化：initialization(ConstructorSignature)
对象预先初始化：preinitialization(ConstructorSignature)
Advice执行�Q�adviceexecution()

   ��Z��控制��的pointcuts
   主要包括两种�c�d��的控制流�Q?br>   cflow(Pointcut)�Q�捕��h��有的�q�接点在指定的方法执行中�Q�包括执行方法本�w��?br>   cflowbelow(Pointcut)�Q�捕��h��有的�q�接点在指定的方法执行中�Q�除了执行方法本�w��?br>
   如以下的例子�Q?br>   cflow(call(* Account.debit(..))
   所有的debit�Ҏ��中的�q�接点，包括debit�Ҏ��本��n
   cflowbelow(call(* Account.debit(..))
   所有debit�Ҏ��中的�q�接点，除了debit�Ҏ��本��n
   cflow(transactedOperations())
   所有由transactedOperations捕获的连接点
   cflowbelow(execution(Account.new(..))
   所有在Account 构造器中执行的�q�接�?br>
   ��Z��词汇�l�构的连接点
   源代码片断。，如within()和withincode()
   within �Q�捕获在指定�c�L��者方面中的程序体中的所有连接点�Q�包括内部类�?br>   Withincode�Q�用于捕获在构造器或者方法中的所有连接点�Q�包括在其中的本地类

   执行对象�q�接�?/strong>
   匚w��this,和target对象�Q�作为方法被调用的对象�?br>   this(Account)�Q�所有Account的实例的执行点，匚w��所有的�q�接点，如方法调用，属性设�|�，当前的执行对象�ؓAccount�Q�或者其子类�?br>   target(Account)�Q�匹配所有的�q�接点，目标对象为Account或其子类�?br>
   必须执行相应的类型，不能使用*,或�?.通配�W�。当前静态方法，不能被匹配�?br>
   在within()和this()中的区别�Q?br>   一个是�E�序体，而另一个�ؓ对象执行�?br>
   参数pointcuts
   用于捕获参数�c�d��的连接点�?br>   args(String,..,int)
   args(RemoteException)

   条�g��pointcuts
   if(System.currentTimeMillis()>triggerTime)

Eric.Zhou 2007-07-04 16:39 发表评论

捕获�E�序作用域内的连接点

Eric.Zhou — Wed, 04 Jul 2007 07:37:00 GMT
1.   捕获特定�c�M��的所有连接点
      使用within(TypePattern)切入点，利用TypePattern指定特定�cȝ��型模式。语法：
      pointcut () : within();
2.    捕获特定�Ҏ��内的所有连接点
      使用withincode(Signature)切入炏V��语法：
      pointcut () : withincode( .());

Eric.Zhou 2007-07-04 15:37 发表评论

捕获属性上的连接点

Eric.Zhou — Wed, 04 Jul 2007 06:31:00 GMT

捕获何时讉K��对象的属�?/strong>
      pointcut () : get( .);

      get(Signature)切入点不能捕获对静态属性的讉K��Q�尽��从AspectJ的语法角度讲以这�U�方式定义切入点是完全合法的�?br>      使用after() returning()形式的通知�Q�它在声明的returning()部分中带有一个标识符�Q�用于包含访问过的倹{�?br>捕获何时修改对象的字�D?/strong>
      pointcut () : set( .);

package com.eric.aspectj;

public aspect GetRecipe {
pointcut getNamePointcut() : get(String MyClass.name);
before() : getNamePointcut() {
  System.out.println("-------------- Aspect Advice Logic ---------------");
  System.out.println("In the advice picked by " + "getNamePointcut()");
  System.out.println("Signature: " + thisJoinPoint.getStaticPart().getSignature());
  System.out.println("Source Line: " + thisJoinPoint.getStaticPart().getSourceLocation());
  System.out.println("--------------------------------------------------");
}
after() returning(String value) : getNamePointcut() {
  System.out.println("Value being accessed is " + value);
}
}

package com.eric.aspectj;

public class MyClass {
public static final String CONSTANT = "CONSTANT STRING";
private int number;
private String name;

public String getName()
{
  System.out.println("In the getName() method");
  return this.name;
}

public void setName(String name)
{
  System.out.println("In the setName(String) method");
  this.name = name;
  System.out.println("The name field has been set");
}

public int getNumber()
{
  System.out.println("In the getNumber() method");
  return this.number;
}

public void setNumber(int number)
{
  System.out.println("In the setNumber(int) method");
  this.number = number;
  System.out.println("The number field has been set");
}

public static final void main(String args[])
{
  MyClass myObject = new MyClass();

  myObject.setName("Eric Chau");
  System.out.println("The name has been set");

  myObject.setNumber(88888888);
  System.out.println("The number has been set");
  System.out.println("Name Stored = " + myObject.getName());
  System.out.println("Number Stored = " + myObject.getNumber());

  System.out.println("The constant value is " + MyClass.CONSTANT);

}
}

�q�行�l�果�Q?br>In the setName(String) method
The name field has been set
The name has been set
In the setNumber(int) method
The number field has been set
The number has been set
In the getName() method
-------------- Aspect Advice Logic ---------------
In the advice picked by getNamePointcut()
Signature: String com.eric.aspectj.MyClass.name
Source Line: MyClass.java:11
--------------------------------------------------
Value being accessed is Eric Chau
Name Stored = Eric Chau
In the getNumber() method
Number Stored = 88888888
The constant value is CONSTANT STRING

Eric.Zhou 2007-07-04 14:31 发表评论

捕获�c�d��对象构造上的连接点

Eric.Zhou — Wed, 04 Jul 2007 05:56:00 GMT

1.   捕获�Ҏ��造函数的调用
       pointcut () : call( .new());

2.   在执行构造函数时捕获�?/strong>
      pointcut () : execution( .new());

3.   捕获何时初始化对�?/strong>
      pointcut () : initialization( .new());
      initialization(Signature)切入点必��d��含new关键字，Signature必须解析成特定类的构造函敎ͼ�而不是一个简单的�Ҏ��?br>      �׃��AspectJ�~�译器中的编译器限制�Q�当与around()通知兌��Ӟ��不能使用initialization(Signature)切入炏V�?br>      与execution(Signature)切入点相比，使用initialization(Signature)切入�Ҏ��大优�Ҏ��Q�它提供了编译时��查，以确保签名实际上制定了一个构造函数�?br>
4.   捕获何时��要初始化一个对�?/strong>
      pointcut () : preinitialization( .new());

5.   捕获何时初始化类
      pointcut () : staticinitialization();

package com.eric.aspectj;

public aspect CallNewRecipe {
pointcut myClassConstructorWithIntAndStringPointcutStaticinitialization() : staticinitialization(MyClass);
pointcut myClassConstructorWithIntAndStringPointcutCall() : call(MyClass.new(int, String));
pointcut myClassConstructorWithIntAndStringPointcutExecution() : execution(MyClass.new(int, String));
pointcut myClassConstructorWithIntAndStringPointcutPreinitialization() : preinitialization(MyClass.new(int, String));
pointcut myClassConstructorWithIntAndStringPointcutInitialization() : initialization(MyClass.new(int, String));

before() : myClassConstructorWithIntAndStringPointcutExecution() {
  System.out.println("-------------- Aspect Advice Logic Execution ---------------");
  System.out.println("In the advice picked by " + "myClassConstructorWithIntAndOthersPointcut()");
  System.out.println("The current type of object under construction is: ");
  System.out.println("getThis: " + thisJoinPoint.getThis());
  System.out.println("getTarget: " + thisJoinPoint.getTarget());
  System.out.println("getKind: " + thisJoinPoint.getKind());
  System.out.println("Signature: " + thisJoinPoint.getSignature());
  System.out.println("getName: " + thisJoinPoint.getSignature().getName());
  System.out.println("getDeclaringTypeName: " + thisJoinPoint.getSignature().getDeclaringTypeName());
  System.out.println("getDeclaringType: " + thisJoinPoint.getSignature().getDeclaringType());
  System.out.println("getModifiers: " + thisJoinPoint.getSignature().getModifiers());
  System.out.println("Source Line: " + thisJoinPoint.getSourceLocation());
  System.out.println("toString: " + thisJoinPoint.toString());
  System.out.println("--------------------------------------------------");
}
before() : myClassConstructorWithIntAndStringPointcutStaticinitialization() {
  System.out.println("--------------- Staticinitialization ------------------");
}
before() : myClassConstructorWithIntAndStringPointcutCall() {
  System.out.println("--------------- Call ------------------");
}
before() : myClassConstructorWithIntAndStringPointcutPreinitialization() {
  System.out.println("--------------- Preinitialization ------------------");
}
before() : myClassConstructorWithIntAndStringPointcutInitialization() {
  System.out.println("--------------- Initialization ------------------");
}
}

package com.eric.aspectj;

public class MyClass {

private int number;
private String name;

public MyClass(int number, String name) {
  this.number = number;
  this.name = name;
}
/**
* @param args
*/
public static void main(String[] args) {
  // TODO Auto-generated method stub
  MyClass myObject = new MyClass(123, "Eric Chau");
}

}

�q�行�l�果�Q?br>--------------- Staticinitialization ------------------
--------------- Call ------------------
--------------- Preinitialization ------------------
--------------- Initialization ------------------
-------------- Aspect Advice Logic Execution ---------------
In the advice picked by myClassConstructorWithIntAndOthersPointcut()
The current type of object under construction is:
getThis: com.eric.aspectj.MyClass@10d448
getTarget: com.eric.aspectj.MyClass@10d448
getKind: constructor-execution
Signature: com.eric.aspectj.MyClass(int, String)
getName:
getDeclaringTypeName: com.eric.aspectj.MyClass
getDeclaringType: class com.eric.aspectj.MyClass
getModifiers: 1
Source Line: MyClass.java:8
toString: execution(com.eric.aspectj.MyClass(int, String))
--------------------------------------------------

Eric.Zhou 2007-07-04 13:56 发表评论

AspectJ�q�行时API

Eric.Zhou — Wed, 04 Jul 2007 03:12:00 GMT

AspectJ�q�行�?/span>API的主要包包括:

org.aspectj.lang�?/span>提供了接口和支持�c�，用于发现关于�q�接点的�q�行时信息�?/span>

org.aspectj.lang.reflect�?/span>包含一些接口，它们提供了关于连接点�{�֐�的更�Ҏ��化的信息�?/span>

org.aspectj.weaver.tools�?/span>提供了一些接口，用于支持JVM�c�d��载器执行加蝲时织入�?/span>

Eric.Zhou 2007-07-04 11:12 发表评论

Eric.Zhou — Tue, 03 Jul 2007 09:18:00 GMT
adviceexecution()切入点用于捕获在应用�E�序内执行�Q何通知的连接点。语法：
pointcut () : adviceexecution();

public aspect AdviceExecutionRecipe {
pointcut adviceExecutionPointcut() : adviceexecution();
before() : adviceExecutionPointcut() && !within(AdviceExecutionRecipe +) {
  System.out.println("-------------- Aspect Advice Logic ---------------");
  System.out.println("In the advice picked by ExecutionRecipe");
  System.out.println("Signature: " + thisJoinPoint.getStaticPart().getSignature());
  System.out.println("Source Line: " + thisJoinPoint.getStaticPart().getSourceLocation());
  System.out.println("--------------------------------------------------");
}
}

Eric.Zhou 2007-07-03 17:18 发表评论

Eric.Zhou — Tue, 03 Jul 2007 08:32:00 GMT

使用handler(TypePattern)切入炏V��语法：
pointcut () : handler() ;
handler(TypePattern)切入点只支持vbefore()形式的通知。这意味着不能使用像around()�q�样的通知来重写catch块的正常行�ؓ�?br>
public aspect HandlerRecipe {
pointcut myExceptionHandlerPointcut() : handler(ServiceException);
before() : myExceptionHandlerPointcut() {
  System.out.println("------------ Aspect Advice Logic --------------");
  System.out.println("Signature: " + thisJoinPoint.getStaticPart().getSignature());
  System.out.println("Source Line: " + thisJoinPoint.getStaticPart().getSourceLocation());
  System.out.println("-----------------------------------------------");
}
}

public class ServiceException extends Exception {

/**
* Create a new ServiceException with the specified message.
* @param msg the detail message
*/
public ServiceException(String msg) {
  super(msg);
}

/**
* Create a new ServiceException with the specified message
* and root cause.
* @param msg the detail message
* @param ex the root cause
*/
public ServiceException(String msg, Throwable ex) {
  super(msg, ex);
}
}

public class ExceptionClass {

public void triggerMyException() throws ServiceException
    {
  ServiceException myException = new ServiceException("A service exception has occured");
       System.out.println("About to throw a ServiceException");
       throw myException;
    }
/**
* @param args
*/
public static void main(String[] args) {
  ExceptionClass myObject = new ExceptionClass();
   try
       {
          myObject.triggerMyException();
       } catch (ServiceException me)
       {
          System.out.println("A ServiceException has been caught");
       }
}

}

�q�行�l�果�Q?br>About to throw a ServiceException
------------ Aspect Advice Logic --------------
Signature: catch(ServiceException)
Source Line: ExceptionClass.java:19
-----------------------------------------------
A ServiceException has been caught

获取抛出的异�?br>public aspect HandlerRecipe {
pointcut myExceptionHandlerPointcut(ServiceException exception) : handler(ServiceException) && args(exception);
before(ServiceException exception) : myExceptionHandlerPointcut(exception) {
  System.out.println("------------ Aspect Advice Logic --------------");
  System.out.println("Signature: " + thisJoinPoint.getStaticPart().getSignature());
  System.out.println("Source Line: " + thisJoinPoint.getStaticPart().getSourceLocation());
  System.out.println("Exception caught:");
  exception.printStackTrace();
  System.out.println("-----------------------------------------------");
}
}

Eric.Zhou 2007-07-03 16:32 发表评论

Eric.Zhou — Tue, 03 Jul 2007 07:56:00 GMT
1.起个有意义的名字
2.军_��要匹配的�U�类:call、execution,, , , 3.军_��要匹配的上下文：, , or 4.军_��要匹配的范围:within,withincode,cflow,cflowbelow 定义��的pointcut,由小的简单的pointcut构造复杂的pointcut

Eric.Zhou 2007-07-03 15:56 发表评论

this,target,args与call,execution区别

Eric.Zhou — Tue, 03 Jul 2007 07:53:00 GMT
this,target,args均�ؓ�q�行时类型检�?包括该类型的子类,有两�U�用法：
a. this( Type),target(Type),args(Type)只判断是否是Type�c�d��
b. this(id),target(id),args(id):id是Type�c�d��且绑定pointcut中的声明
call,execution均�ؓ静态类型检查�?img src ="http://www.aygfsteel.com/rain1102/aggbug/127869.html" width = "1" height = "1" />

Eric.Zhou 2007-07-03 15:53 发表评论

Eric.Zhou — Tue, 03 Jul 2007 07:38:00 GMT

execution(Signature)切入点的语法是：
pointcut () : execution( .());
它与call(Signature)切入点类��|��但重要的区别是：在什么地方调用通知�Q�以及它的环境是什么？
��call(Signature)切入�Ҏ��_��在调用方法的地方调用通知。调用通知的环境是调用�c�R��一旦进入方法，因而调用的环境是正在执行的�Ҏ��Ӟ��׃��调用execution(Signature)切入炏V�?br>另外�Q�call(Signature)切入点和execution(Signature)切入点在捕获�l�承�?或重写（依赖于对象的静态和动态类型）的对象方法上的连接点时它们有一些奇怪的行�ؓ�?br>
package com.eric.aspectj;

public aspect MyAspectj {
pointcut callPointCut(My myClass, int age, String name) : execution(void com.eric.aspectj.My.foo(int, String)) && this(myClass) && args(age, name);
before(My myClass, int age, String name) : callPointCut(myClass, age, name) {
  System.out.println("signature: " + thisJoinPoint.getStaticPart().getSignature());
  System.out.println("Source Line: " + thisJoinPoint.getStaticPart().getSourceLocation());
  System.out.println("before...name : " + name + " age : " + age);
}
after(My myClass, int age, String name) returning: callPointCut(myClass, age, name) {
  System.out.println("after...");
}
}

Eric.Zhou 2007-07-03 15:38 发表评论

Eric.Zhou — Tue, 03 Jul 2007 07:10:00 GMT

call(Signature)切入点的语法是：
pointcut () : call( .());

package com.eric.aspectj;

public aspect MyAspectj {
pointcut callPointCut(MyClass myClass, int age, String name) : call(void com.eric.aspectj.MyClass.foo(int, String)) && target(myClass) && args(age, name);
before(MyClass myClass, int age, String name) : callPointCut(myClass, age, name) {
  System.out.println("before...name : " + name + " age : " + age);
}
after(MyClass myClass, int age, String name) returning: callPointCut(myClass, age, name) {
  System.out.println("after...");
}
}

package com.eric.aspectj;

public class MyClass {

public void foo(int age, String name) {
  System.out.println("foo " + name + " age is " + age);
}
public static void main(String[] args) {
  MyClass object = new MyClass();
  object.foo(24, "Eric Chau");
}
}

�q�行�l�果�Q?br>before...name : Eric Chau age : 24
foo Eric Chau age is 24
after...

Eric.Zhou 2007-07-03 15:10 发表评论