Spring整合MyBatis案例练习笔记

需求:

　用户登录

技术需求:

　　Servlet+Spring+Mybatis+MVC+jsp+css+html+jquery

数据库设计:

　　用户表

Sql语句设计:

　　select * from t_user where uname=#{0} and pwd=#{1}

实现:

　　mapper层

package com.bjsxt.mapper;

import com.bjsxt.pojo.User;

public interface UserMapper {

    //用户登录

    User selUser(String uname,String pwd);

}

　　UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE mapper

  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

  <mapper namespace="com.bjsxt.mapper.UserMapper">

    <!-- 用户登录sql配置 -->

      <select id="selUser" resultType="com.bjsxt.pojo.User">

          select * from t_user where uname=#{arg0} and pwd=#{arg1}

      </select>

  </mapper>

　　pojo层

package com.bjsxt.pojo;

/**

 * 用户实体类

 * @author Yancy

 *

 */

public class User {

    private int uid;//用户ID

    private String uname;//用户名称

    private String pwd;//用户密码

    public int getUid() {

        return uid;

    }

    public void setUid(int uid) {

        this.uid = uid;

    }

    public String getUname() {

        return uname;

    }

    public void setUname(String uname) {

        this.uname = uname;

    }

    public String getPwd() {

        return pwd;

    }

    public void setPwd(String pwd) {

        this.pwd = pwd;

    }

    public User(int uid, String uname, String pwd) {

        super();

        this.uid = uid;

        this.uname = uname;

        this.pwd = pwd;

    }

    @Override

    public String toString() {

        return "User [uid=" + uid + ", uname=" + uname + ", pwd=" + pwd + "]";

    }

    @Override

    public int hashCode() {

        final int prime = 31;

        int result = 1;

        result = prime * result + ((pwd == null) ? 0 : pwd.hashCode());

        result = prime * result + uid;

        result = prime * result + ((uname == null) ? 0 : uname.hashCode());

        return result;

    }

    @Override

    public boolean equals(Object obj) {

        if (this == obj)

            return true;

        if (obj == null)

            return false;

        if (getClass() != obj.getClass())

            return false;

        User other = (User) obj;

        if (pwd == null) {

            if (other.pwd != null)

                return false;

        } else if (!pwd.equals(other.pwd))

            return false;

        if (uid != other.uid)

            return false;

        if (uname == null) {

            if (other.uname != null)

                return false;

        } else if (!uname.equals(other.uname))

            return false;

        return true;

    }

    public User() {

        super();

        // TODO Auto-generated constructor stub

    }

}

　　service层

package com.bjsxt.service;

import com.bjsxt.pojo.User;

public interface UserService {

    //用户登录

    User checkUserInfoService(String uname,String pwd);

}

　　service.impl层

package com.bjsxt.service.impl;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.bjsxt.mapper.UserMapper;

import com.bjsxt.pojo.User;

import com.bjsxt.service.UserService;

public class UserServiceImpl implements UserService {

    private UserMapper um;

    public UserMapper getUm() {

        return um;

    }

    public void setUm(UserMapper um) {

        this.um = um;

    }

    //用户登录

    @Override

    public User checkUserInfoService(String uname, String pwd) {

        //使用对象完成数据库操作

        return um.selUser(uname, pwd);

    }

}

　　servlet层

package com.bjsxt.servlet;

import java.io.IOException;

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.support.WebApplicationContextUtils;

import com.bjsxt.pojo.User;

import com.bjsxt.service.UserService;

public class UserServlet extends HttpServlet{

    UserService us;

    @Override

    public void init() throws ServletException {

        //传统方式

//        //获取Spring容器对象

//        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");

//        //获取业务层对象

//        us = (UserService) ac.getBean("us");

        //优化方式

        ApplicationContext ac=WebApplicationContextUtils.getWebApplicationContext(this.getServletContext());

        us = (UserService) ac.getBean("us");

    }

    @Override

    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //请求编码格式

        req.setCharacterEncoding("utf-8");

        //设置响应编码格式

        resp.setCharacterEncoding("utf-8");

        resp.setContentType("text/html;charset=utf-8");

        //获取请求信息

        String uname=req.getParameter("uname");

        String pwd=req.getParameter("pwd");

        //处理请求信息

            //调用方法处理请求

            User u = us.checkUserInfoService(uname, pwd);

        //处理响应结果

            if(u!=null) {

                resp.sendRedirect(req.getContextPath()+"/success.jsp");

            }

    }

}

　　配置文件src目录下

　　applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

      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-4.2.xsd">

      <!-- 配置数据源 -->

      <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">

          <property name="driverClassName" value="com.mysql.jdbc.Driver" />

          <property name="url" value="jdbc:mysql://localhost:3306/mybatis"></property>

          <property name="username" value="root"></property>

          <property name="password" value="123456"></property>

      </bean>

      <!-- 配置工厂bean -->

      <bean id="factory" class="org.mybatis.spring.SqlSessionFactoryBean">

          <property name="dataSource" ref="dataSource"></property>

      </bean>

      <!-- 配置mapper扫描bean -->

      <bean id="mapper" class="org.mybatis.spring.mapper.MapperScannerConfigurer">

          <property name="sqlSessionFactory" ref="factory"></property>

          <property name="basePackage" value="com.bjsxt.mapper"></property>

      </bean>

      <!-- 配置业务层bean -->

      <bean id="us" class="com.bjsxt.service.impl.UserServiceImpl">

          <property name="um" ref="userMapper"></property>

      </bean>

</beans>

log4j.properties

# Global logging configuration

log4j.rootLogger=ERROR, stdout

# MyBatis logging configuration...

log4j.logger.com.bjsxt=DEBUG

# Console output...

log4j.appender.stdout=org.apache.log4j.ConsoleAppender

log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

　　web.xml在WEB-INF下

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">

  <!-- 配置Spring文件路径 -->

    <context-param>

        <param-name>contextConfigLocation</param-name>

        <param-value>classpath:applicationContext.xml</param-value>

    </context-param>

  <!-- 配置监听器 -->

  <listener>

      <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>

  </listener>

  <!-- 配置Servlet -->

  <servlet>

      <servlet-name>user</servlet-name>

      <servlet-class>com.bjsxt.servlet.UserServlet</servlet-class>

      <load-on-startup>1</load-on-startup>

  </servlet>

  <servlet-mapping>

      <servlet-name>user</servlet-name>

      <url-pattern>/user</url-pattern>

  </servlet-mapping>

</web-app>

整合问题及其解决方案:

　　问题一:

　　　　传统方式是在service层直接通过mybatis对象完成数据的操作,业务层和mapper层的耦合性非常高.

　　解决一:

　　　　使用SpringIOC技术和service层和mapper层进行解耦.

　　方案一:

　　　　直接从Spring容器对象中获取Mapper对象

　　　　　　--->Spring容器还管理SqlSession对象

　　　　　　　　--->Spring容器还管理DataSource对象

　　实现一:

　　　　参照配置文件

　　问题二:

　　　　如果在Servlet层中直接new创建业务层对象,虽然可以正常使用,但是会造成Servlet层和业务层的耦合性较高,不易于后期的的迭代升级.

　　解决二:

　　　　使用SpringIOC将Servlet层和service层进行解耦.

　　实现二:

　　　　将Service对象配置成bean,交由Spring容器管理.在Servlet中通过Spring容器对象获取业务层对象

　　问题三:

　　　　我们实现的登录代码,如果放在高并发环境,我们发现Spring容器对象一个线程中会被创建两次,这样造成占据的内存过多.

　　解决三:

　　　　①在service层中我们使用Spring容器对象获取Mapper接口对象,Mapper接口对象本身就在Spring容器中,但是我们把Service也配置成bean了,那么是不是可以使用依赖注入呢.直接在Spring的配置文件中通过依赖注入将Mapper对象注入给service对象

　　　　②使用init方法,将获取us对象的动作放到服务器启动是完成.

　　问题四:

　　　　Spring容器在获取的代码的路径在init方法中耦合性较高.

　　解决四:

　　　　将Spring容器相关路径信息配置到web.xml中

　　实现四:

　　　　在web.xml中配置全局参数表明Spring路径

　　　　配置Spring监听器

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Spring整合MyBatis案例练习笔记

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