JAVAEE之Spring学习(三)---通过aop切面实现事务处理

需求：通过切面给项目中的service添加事务处理，让数据库表1添加用户失败后回滚，表2无法添加数据

思想：通过aop切面拦截service下的reg()方法，在拦截之前开启事务再进行dao调用，进行事务处理

需要注意的地方：在spring方式下获得到的datasource中的getconnection方法还没有进行拦截，在dao层，是通过queryrunner自动调用getconnection()进行提交，所以要将getconnection()做成单线程形式

service：

package cn.hncu.stud.service;import java.sql.SQLException;import cn.hncu.stud.dao.IStudaoa;import cn.hncu.stud.domain.User;public class serviceimpl implements IStudentService {    IStudaoa dao1 = null;    IStudaoa dao2 = null;    public IStudaoa getDao1() {        return dao1;    }    public void setDao1(IStudaoa dao1) {        this.dao1 = dao1;    }    public IStudaoa getDao2() {        return dao2;    }    public void setDao2(IStudaoa dao2) {        this.dao2 = dao2;    }    // 注入    @Override    public void reg(User user) throws SQLException {        dao1.reg(user);        dao2.reg(user);    }}

web.xml:将Spring容器放入servletContext中

<?xml version="1.0" encoding="UTF-8"?><web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee     http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">    <display-name></display-name>    <context-param>        <param-name>contextConfigLocation</param-name>        <param-value>            <!-- 如果有路径要用"/"开始 -->            classpath:beans.xml,            /WEB-INF/applicationContext.xml        </param-value>    </context-param>    <listener>        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>    </listener>    <servlet>        <servlet-name>StudServlet</servlet-name>        <servlet-class>cn.hncu.stud.servlet.StudServlet</servlet-class>    </servlet>    <servlet-mapping>        <servlet-name>StudServlet</servlet-name>        <url-pattern>/StudServlet</url-pattern>    </servlet-mapping>    <welcome-file-list>        <welcome-file>index.jsp</welcome-file>    </welcome-file-list></web-app>

servlet:通过ApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(getServletContext());获取spring容器

package cn.hncu.stud.servlet;import java.io.IOException;import java.io.PrintWriter;import java.sql.SQLException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import org.springframework.web.context.WebApplicationContext;import org.springframework.web.context.support.WebApplicationContextUtils;import cn.hncu.stud.domain.User;import cn.hncu.stud.service.IStudentService;public class StudServlet extends HttpServlet {    private IStudentService service = null;    @Override    public void init() throws ServletException {        // 获取web项目中的spring容器        ApplicationContext ctx = WebApplicationContextUtils                .getWebApplicationContext(getServletContext());        service = ctx.getBean("service", IStudentService.class);    }    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doPost(request, response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        String name = request.getParameter("name");        User user = new User();        user.setName(name);        try {            service.reg(user);            request.getSession().setAttribute("user", user);            request.getRequestDispatcher("/jsps/show.jsp").forward(request,                    response);        } catch (SQLException e) {            e.printStackTrace();        }    }}

applicationContext:用于配置dataSource和拦截getconnection的公共Spring容器配置文件

<?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:context="http://www.springframework.org/schema/context"    xmlns:aop="http://www.springframework.org/schema/aop"    xsi:schemaLocation="http://www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/spring-beans.xsd        http://www.springframework.org/schema/context        http://www.springframework.org/schema/context/spring-context.xsd        http://www.springframework.org/schema/aop        http://www.springframework.org/schema/aop/spring-aop.xsd        ">    <bean        class="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator">    </bean>    <!-- 切面=切点+通知 -->    <bean id="advisor"        class="org.springframework.aop.aspectj.AspectJExpressionPointcutAdvisor">        <!-- 切点 -->        <property name="expression">            <value>                execution( void cn.hncu.stud..serviceimpl.reg(..) )            </value>        </property>        <property name="advice">            <bean class="cn.hncu.stud.utils.AroundAdvice">                <property name="data" ref="dataSource"></property>            </bean>        </property>    </bean>    <!-- 切面=切点+通知 -->    <bean id="advisor1"        class="org.springframework.aop.aspectj.AspectJExpressionPointcutAdvisor">        <!-- 切点 -->        <property name="expression">            <value>execution(* *..*.getConnection())            </value>        </property>        <property name="advice">            <bean class="cn.hncu.stud.utils.ConAdvice">            </bean>        </property>    </bean>    <context:property-placeholder location="WEB-INF/conf/jdbc.properties" />    <bean id="dataSource"        class="org.springframework.jdbc.datasource.SimpleDriverDataSource">        <property name="driverClass" value="${driver}">        </property>        <property name="url" value="${url}"></property>        <!-- ${username}是系统默认的变量-->        <property name="username" value="${uname}"></property>        <property name="password" value="${password}"></property>    </bean></beans>

用于拦截getconnection方法的切面：

package cn.hncu.stud.utils;import java.lang.reflect.Method;import java.sql.Connection;import javax.sql.DataSource;import net.sf.cglib.proxy.Callback;import net.sf.cglib.proxy.Enhancer;import net.sf.cglib.proxy.MethodProxy;import org.aopalliance.intercept.MethodInterceptor;import org.aopalliance.intercept.MethodInvocation;public class ConAdvice implements MethodInterceptor {    private ThreadLocal<Connection> t1 = new ThreadLocal<Connection>();    DataSource data = null;    public DataSource getData() {        return data;    }    public void setData(DataSource data) {        this.data = data;    }    @Override    public Object invoke(MethodInvocation inv) throws Throwable {        Connection con = t1.get();        if (con == null) {            // 往本地线程池中放一个被屏蔽掉close()方法的con对象            final Connection con0 = ((Connection) inv.proceed());// 当前被拦截的是getconnection返回的是一个con            // 对con0进行代理(屏蔽close())            Callback callback = new net.sf.cglib.proxy.MethodInterceptor() {                @Override                public Object intercept(Object proxiedObj, Method method,                        Object[] args, MethodProxy proxy) throws Throwable {                    if (method.getName().equals("close")) {                        return null;                    }                    return method.invoke(con0, args);                }            };            // 生成代理后的对象            con = (Connection) Enhancer.create(Connection.class, callback);            t1.set(con);// 把代理后的对象放进去        }        return con;    }}

beans.xml:用于配置stud模块下的类的关联

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"    xmlns:context="http://www.springframework.org/schema/aop" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">    <bean id="studDao" class="cn.hncu.stud.dao.IStuJDBCDAO">        <property name="dataSource" ref="dataSource"></property>    </bean>    <bean id="studDao2" class="cn.hncu.stud.dao.IStuJDBCDAO2">        <property name="dataSource" ref="dataSource"></property>    </bean>    <bean id="service" class="cn.hncu.stud.service.serviceimpl">        <property name="dao1" ref="studDao"></property>        <property name="dao2" ref="studDao2"></property>    </bean></beans>   

AroundAdvice:进行service类的拦截：

package cn.hncu.stud.utils;import java.sql.Connection;import javax.sql.DataSource;import org.aopalliance.intercept.MethodInterceptor;import org.aopalliance.intercept.MethodInvocation;import org.springframework.beans.BeansException;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;public class AroundAdvice implements MethodInterceptor, ApplicationContextAware {    ApplicationContext ctx = null;    DataSource data = null;    public DataSource getData() {        return data;    }    public void setData(DataSource data) {        this.data = data;    }    @Override    public Object invoke(MethodInvocation invocation) throws Throwable {        Connection con = data.getConnection();        con.setAutoCommit(false);        System.out.println("开启事务");        // 放行        try {            Object returnValue = invocation.proceed();            con.commit();            return returnValue;        } catch (Exception e) {            con.rollback();            System.out.println("事务回滚");        } finally {            con.setAutoCommit(true);        }        return null;    }    @Override    public void setApplicationContext(ApplicationContext ctx)            throws BeansException {        this.ctx = ctx;    }}

这样就成功通过spring实现数据库的事务处理