Spring AOP 学习�W�记

Jxi — Sun, 23 Aug 2009 14:52:00 GMT

AOP Aspect Oriented Programing 面向斚w��~�程
AOP 术语
�q�接�?(Joinpoint)    �E�序执行的特定位�|?�c�d��始初始化前、类初始化后、调用前后、异常抛出后)
切点:   (PointCut)     �E�序�c�M��客观存在的事物（�c�M��的方法）
增强 :  (Advice)        �|�入到目标类Joinpint的一�D�代�?br /> 目标对象:(Target)   引介(Introduction) �l�入(Weaving) 代理(Proxy) 切面(Aspect):切点和增强的�l�成

基础知识: Spring Aop :使用动态代理技术在�q�行期间�l�入增强代码
ProxyFactory 代理工厂采用JDK代理或CGLib代理技�?br /> JDK 动态代�?
1.定义UserService接口函数:

public interface UserService {
public void addUser(int id);
}

2.UserServiceImpl

public class UserServiceImpl implements UserService{
public void addUser(int id){
System.out.println("��d��一个用户中 �Q?/span>"+id);
}
}

3.ProxyHandler

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

public class ProxyHandler implements InvocationHandler{
   private Object target;
   public  ProxyHandler(Object target){
       this.target=target;
   }

public Object invoke(Object proxy, Method method, Object[] args)
        throws Throwable {
       System.out.println("��d��用户�?/span>");
       Object obj=method.invoke(target,args);
       System.out.println("��d��用户�?/span>");
       return obj;
}
}

TestProxyHandler

import java.lang.reflect.Proxy;

public class ProxyHandlerTest {
  public static void main(String args[]){
      UserService target=new UserServiceImpl();
      ProxyHandler handler=new ProxyHandler(target);
      UserService proxy=(UserService)Proxy.newProxyInstance(
        target.getClass().getClassLoader(),
        target.getClass().getInterfaces(),
        handler);
      proxy.addUser(100);
  }
}

CGLib 代理:
AddUserService接口:

package CGlib.Text.Service;

public interface AddUserService {
public void addUser(int id);
}

AddUserServiceImpl 实现�c?

package CGlib.Text.Service;

public class AddUserServiceImpl implements AddUserService {

    public void addUser(int id) {
        System.out.println("��d��用户ID�?"+id);
    }
}

CglibProxy 代理�c?

package CGlib.Text.Service;

import java.lang.reflect.Method;

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

public class CglibProxy implements MethodInterceptor{
    private Enhancer enhancer=new Enhancer();
    @SuppressWarnings("unchecked")
    public Object getProxy(Class clazz){
        enhancer.setSuperclass(clazz);
        enhancer.setCallback(this);
        return enhancer.create();
    }

    public Object intercept(Object obj, Method method, Object[] args,
            MethodProxy proxy) throws Throwable {
        System.out.println("��d��用户之前");
        System.out.print(method.getName());
        System.out.print(obj.getClass().getName()+"外加");
        System.out.print(args.getClass().getName());
        Object result=proxy.invokeSuper(obj, args);
        System.out.println("外加的参�?/span>"+args.toString());
        System.out.println("��d��用户之后");
        // TODO Auto-generated method stub
        return result;
    }


}

CglibProxyTest:��试�c?br />

package CGlib.Text.Service;

public class CglibProxyTest {
    public static void main(String[] args){
        CglibProxy proxy=new CglibProxy();
        AddUserServiceImpl userService=
            (AddUserServiceImpl)proxy.getProxy(AddUserServiceImpl.class);
      userService.addUser(100);
    }

}

对JDK动态代理和Cglib动态代理的理解�Q?br /> JDK 代理时性能高，但生成代理对象时�q�行性能较低
Cglib 代理时性能低，但生成代理对象时�q�行性能较高
所以：单例Singleton 旉��用CGLib代理�?br />

Jxi 2009-08-23 22:52 发表评论

Spring

Jxi — Sat, 25 Jul 2009 06:57:00 GMT

Spring

Important

Spring is an application framework. Unlike single-tier frameworks such as Struts or Hibernate, Spring aims to help structure whole applications in a consistent, productive manner, pulling together best-of-breed single-tier frameworks to create a coherent architecture.

Problems with the Traditional Approach to J2EE

传统J2EE�Ҏ��存在的问�?/span>

J2EE applications tend to contain excessive amounts of "plumbing" code.�?/span>
Many J2EE applications use a distributed object model where this is inappropriate.�?/span>
The EJB component model is unduly complex.不当
EJB is overused.�q�度使用
Many "J2EE design patterns" are not, in fact, design patterns, but workarounds for technology limitations.技术跟不上
J2EE applications are hard to unit test.��试�?/span>
Certain J2EE technologies have simply failed.

Enter Spring

接触Spring

Inversion of Control container:倒置控制
Aspect-Oriented Programming (AOP) framework:
Data access abstraction:
JDBC simplification:
Transaction management:
MVC web framework:
Simplification for working with JNDI, JTA, and other J2EE APIs:
Lightweight remoting:
JMS support:
JMX support:
Support for a comprehensive testing strategy for application developers:

The key Spring values can be summarized as follows:

· Spring is a non-invasive framework.非��R�?

· Spring provides a consistent programming model, usable in any environment.

· Spring aims to promote code reuse.复用

· Spring aims to facilitate Object Oriented design in J2EE applications.

· Spring aims to facilitate good programming practice, such as programming to interfaces, rather than classes.面向接口

· Spring promotes pluggability.性能

· Spring facilitates the extraction of configuration values from Java code into XML or properties files.

· Spring is designed so that applications using it are as easy as possible to test.

· Spring is consistent.

· Spring promotes architectural choice.

· Spring does not reinvent the wheel.

Jxi 2009-07-25 14:57 发表评论

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Spring AOP 学习�W�记

Spring