Mybatis基于接口代理的方式来开发Dao(一)

Mybatis的简单介绍：Mybatis是一个操作数据库的框架。最开始叫做ibatis，从apache基金会脱离，加入googleCode正式更名为MyBatis。最终现在mybatis的代码托管在github
首先我们创建一个Maven的项目mybatis02，其中配置文件pom.xml如下：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.yida.mybatis</groupId>
  <artifactId>mybatis02</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>

   <dependencies>
    <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.38</version>
</dependency>

  <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.2.7</version>
</dependency>

  <dependency>
        <groupId>org.bgee.log4jdbc-log4j2</groupId>
        <artifactId>log4jdbc-log4j2-jdbc4.1</artifactId>
        <version>1.16</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.13</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.5</version>
    </dependency>

  <!-- https://mvnrepository.com/artifact/log4j/log4j -->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.16</version>
    </dependency>


  </dependencies>





  <build>
    <plugins>
    <!-- maven的编译插件，用于指定我们jdk的版本 -->
          <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>

    </plugins>
</build>

</project>

这里使用了日志，其中日志的配置文件log4j.properties如下：

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# 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

定义一个user实体类用于对应数据库的user 表，

package com.yida.mybatis.pojo;

import java.util.Date;

public class User {
    private int id;
    private String username;
    private Date birthday;
    private String sex;
    private String address;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }

    public User() {
        super();
        // TODO Auto-generated constructor stub
    }
    public User(int id, String username, Date birthday, String sex, String address) {
        super();
        this.id = id;
        this.username = username;
        this.birthday = birthday;
        this.sex = sex;
        this.address = address;
    }

}

然后定义一个接 口UserMapper.java的文件，如下：

package com.yida.mybatis.demo01;

import java.util.List;

import com.yida.mybatis.pojo.User;

public interface UserMapper {
    //根据id来查询User
    User getUserMapperById(int id);
    //根据地址来进行模糊查询
    List<User> getUserMapperByAddress(String address);
    //更新User
    void updateUserMapper(User user);
    //插入User
    void insertUerMapper(User user);
    //根据id删除User
    void deleteUserMapper(int id);
}

在UserMapper.java的同级目录下创建UserMapper.xml配置文件：

<?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.yida.mybatis.demo01.UserMapper">
  <select id="getUserMapperById" parameterType="int" resultType="com.yida.mybatis.pojo.User" >
    select * from user where id = #{id}
  </select>
  <select id="getUserMapperByAddress" parameterType="string" resultType="com.yida.mybatis.pojo.User" >
    select * from user where address like '%${value}%'
  </select>
  <update id="updateUserMapper" parameterType="com.yida.mybatis.pojo.User">
  update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id = #{id}
  </update>
  <insert id="insertUerMapper" parameterType="com.yida.mybatis.pojo.User">
  insert into user (username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address});
  </insert>
  <delete id="deleteUserMapper" parameterType="int">
    delete from user  where id = #{id}
  </delete>

</mapper>

创建mybatis的核心配置文件SqlMapperConfig.xml,如下：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

<!-- 配置数据库链接的信息  -->
<!-- <properties resource="db.properties"> -->
<properties>
    <property name="jdbc.driver" value="com.mysql.jdbc.Driver" />
    <property name="jdbc.url"
        value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />
    <property name="jdbc.username" value="root" />
    <property name="jdbc.password" value="root" />
</properties>

  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
   <!--  <mapper class="com.yida.mybatis.demo01.UserMapper"/> -->
    <package name="com.yida.mybatis.demo01"/>
  </mappers>
</configuration>

创建测试类进行增删改查：UserMapperTest.java如下 ：

package com.yida.mybatis.demo01;


import java.util.Date;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.yida.mybatis.pojo.User;


public class UserMapperTest {
    /**
     * 实现对User表的增删改查
     * @throws Exception 
     */
    SqlSession sqlSession = null;
    @Before
    public void initMethod() throws Exception{
        System.out.println(888);
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        //根据SqlSessionFactoryBuilder来获取SqlSessionFactory
        SqlSessionFactory build = builder.build(Resources.getResourceAsStream("SqlMapperConfig.xml"));
        //通过SqlSessionFactory来获取我们的SqlSession
        sqlSession = build.openSession(false);
    }
    /**
     * 根据id查找User
     */
    @Test
    public void getUserMapperById(){
        System.out.println(666);
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.getUserMapperById(16);
        System.out.println(user.getAddress());
    }
    /**
     * 根据地址进行模糊搜索
     */
    @Test
    public void getUserMapperByAddress(){
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<User> list = mapper.getUserMapperByAddress("河南");
        for (User user : list) {
            System.out.println(user.getAddress());
        }
    }
    /**
     * 更新User
     */
    @Test
    public void updateUserMapper(){
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = new User();
        user.setId(32);
        user.setUsername("大大66666666");
        user.setBirthday(new Date());
        user.setSex("0");
        user.setAddress("武汉888888");
        mapper.updateUserMapper(user);
        sqlSession.commit();
    }
    /**
     * 插入操作
     */
    @Test
    public void insertUerMapper(){
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = new User();
        user.setUsername("大大66666666");
        user.setBirthday(new Date());
        user.setSex("0");
        user.setAddress("武汉888888");
        mapper.insertUerMapper(user);
        sqlSession.commit();
    }
    /**
     * 根据 id删除User
     */
    @Test
    public void deleteUserMapper(){
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.deleteUserMapper(41);
        sqlSession.commit();
    }
    @After
    public void finalMethod(){
        sqlSession.close();
    }
}

ok，完成！下一篇待我整理一下，讲讲动态sql及多表查询等