八、其他增强类型
2018-08-29 本文已影响0人
lifeline张
一、本课目标
- 理解更多增强类型的使用方法
二、异常抛出增强
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示例代码：
增强处理类：
package aop;
import org.apache.log4j.Logger;
import org.aspectj.lang.JoinPoint;
/**
* 定义包含增强方法的JavaBean
*/
public class ErrorLogger {
private static final Logger log = Logger.getLogger(ErrorLogger.class);
public void afterThrowing(JoinPoint jp, RuntimeException e) {
log.error(jp.getSignature().getName() + " 方法发生异常：" + e);
}
}
实体类：
package entity;
/**
* 用户实体类
*/
public class User implements java.io.Serializable {
private Integer id; // 用户ID
private String username; // 用户名
private String password; // 密码
private String email; // 电子邮件
// getter & setter
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}
dao层
package dao;
import entity.User;
/**
* 增加DAO接口,定义了所需的持久化方法
*/
public interface UserDao {
public void save(User user);
}
package dao.impl;
import dao.UserDao;
import entity.User;
/**
* 用户DAO类，实现UserDao接口，负责User类的持久化操作
*/
public class UserDaoImpl implements UserDao {
public void save(User user) {
// 这里并未实现完整的数据库操作，仅为说明问题
System.out.println("保存用户信息到数据库");
throw new RuntimeException("为测试程序运行效果抛出的异常");
}
}
service层：
package service;
import entity.User;
/**
* 用户业务接口，定义了所需的业务方法
*/
public interface UserService {
public void addNewUser(User user);
}
package service.impl;
import service.UserService;
import dao.UserDao;
import entity.User;
/**
* 用户业务类，实现对User功能的业务管理
*/
public class UserServiceImpl implements UserService {
// 声明接口类型的引用，和具体实现类解耦合
private UserDao dao;
// dao 属性的setter访问器，会被Spring调用，实现设值注入
public void setDao(UserDao dao) {
this.dao = dao;
}
public void addNewUser(User user) {
// 调用用户DAO的方法保存用户信息
dao.save(user);
}
}
配置文件：
<?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-3.2.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.2.xsd">
<bean id="dao" class="dao.impl.UserDaoImpl"></bean>
<bean id="service" class="service.impl.UserServiceImpl">
<property name="dao" ref="dao"></property>
</bean>
<!-- 声明增强方法所在的Bean -->
<bean id="errorLogger" class="aop.ErrorLogger"></bean>
<!-- 配置切面 -->
<aop:config>
<!-- 定义切入点 -->
<aop:pointcut id="pointcut" expression="execution(* service.UserService.*(..))" />
<!-- 引用包含增强方法的Bean -->
<aop:aspect ref="errorLogger">
<!-- 将afterThrowing()方法定义为异常抛出增强并引用pointcut切入点 -->
<!-- 通过throwing属性指定为名为e的参数注入异常实例 -->
<aop:after-throwing method="afterThrowing"
pointcut-ref="pointcut" throwing="e" />
</aop:aspect>
</aop:config>
</beans>
测试类：
package test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import service.UserService;
import entity.User;
public class Test {
@org.junit.Test
public void test() {
ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService service = (UserService) ctx.getBean("service");
User user = new User();
user.setId(1);
user.setUsername("test");
user.setPassword("123456");
user.setEmail("test@xxx.com");
service.addNewUser(user);
}
}
运行结果：
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三、最终增强
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增强类：
package aop;
import org.apache.log4j.Logger;
import org.aspectj.lang.JoinPoint;
public class AfterLogger {
private static Logger log = Logger.getLogger(AfterLogger.class);
public void after(JoinPoint jp) {
log.info(jp.getSignature().getName() + "方法结束了");
}
}
配置文件：
<?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-3.2.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.2.xsd">
<bean id="dao" class="dao.impl.UserDaoImpl"></bean>
<bean id="service" class="service.impl.UserServiceImpl">
<property name="dao" ref="dao"></property>
</bean>
<!-- 声明增强方法所在的Bean -->
<bean id="afterLogger" class="aop.AfterLogger"></bean>
<!-- 配置切面 -->
<aop:config>
<!-- 定义切入点 -->
<aop:pointcut id="pointcut" expression="execution(* service.UserService.*(..))" />
<!-- 引用包含增强方法的Bean -->
<aop:aspect ref="afterLogger">
<!-- 将after()方法定义为最终增强并引用pointcut切入点 -->
<aop:after method="after"
pointcut-ref="pointcut"/>
</aop:aspect>
</aop:config>
</beans>
其他的不用改动，在这种情况下，UserDaoImpl里面还有异常抛出的，这时候的运行结果如下：
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四、环绕增强
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在上面的UserDaoImpl找那个的sqve方法中去掉抛出异常语句。
增强类：
package aop;
import java.util.Arrays;
import org.apache.log4j.Logger;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
public class AroundLogger {
private static Logger log = Logger.getLogger(AroundLogger.class);
/**
* 可以通过修改这个方法的返回值来修改目标方法的返回值
* @param jp
* @return
* @throws Throwable
*/
public Object aroundLogger(ProceedingJoinPoint jp ) throws Throwable {
log.info("调用" + jp.getTarget() + "的" +
jp.getSignature() + "方法，方法参数" +
Arrays.toString(jp.getArgs()));
Object result;
try {
result = jp.proceed();
log.info("调用" + jp.getTarget() + "的" +
jp.getSignature() + "方法，方法返回值" +
result);
return result;
} catch (Throwable e) {
log.error(jp.getSignature().getName() + " 方法发生异常：" + e);
throw e;
}finally {
log.info(jp.getSignature().getName() + " 方法结束执行。");
}
}
}
配置文件：
<?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-3.2.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.2.xsd">
<bean id="dao" class="dao.impl.UserDaoImpl"></bean>
<bean id="service" class="service.impl.UserServiceImpl">
<property name="dao" ref="dao"></property>
</bean>
<!-- 声明增强方法所在的Bean -->
<bean id="aroundLogger" class="aop.AroundLogger"></bean>
<!-- 配置切面 -->
<aop:config>
<!-- 定义切入点 -->
<aop:pointcut id="pointcut" expression="execution(public void addNewUser(entity.User))" />
<!-- 引用包含增强方法的Bean -->
<aop:aspect ref="aroundLogger">
<!-- 使用aop：around标签元素定义环绕增强，引入切入点pointcut -->
<aop:around method="aroundLogger" pointcut-ref="pointcut"/>
</aop:aspect>
</aop:config>
</beans>
测试类：
package test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import service.UserService;
import entity.User;
public class Test {
@org.junit.Test
public void test() {
ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService service = (UserService) ctx.getBean("service");
User user = new User();
user.setId(1);
user.setUsername("test");
user.setPassword("123456");
user.setEmail("test@xxx.com");
service.addNewUser(user);
}
}
运行结果：
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五、小结
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