mybatis动态代理模式crud

实现方法步骤：

1.引入依赖
2.建立pojo类和dao层 dao层里面的接口目录 和下面的mapper.xml映射文件保持一致
3.编写propertes文件 写jdbc的driver url和用户名密码 以便在核心配置文件中引用
4.编写核心配置文件 引入properties中的密码 账户 url等数据
注意：
在核心配置文件中 可以使用类名映射
下图中会详细讲解类名映射
5 编写映射文件 映射文件中的mapper namespace要和对应的接口名保持一致，select update delete insert 中id要和接口的方法名保持一致

6.编写测试类
a. 先写出初始方法 获得sqlSessionFactory
b.在下面的测试方法中 使用sqlSessionFactory获得sqlSession
c.使用sqlSession.getMapper(接口名.class)方法 建立连接
d.调用接口中的方法执行

类名映射详解：

示例目录结构：

执行具体代码块：

1.引入依赖 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>cn.cfg</groupId>
    <artifactId>mybatis_day02</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>


</project>

2.建立pojo类和dao层
pojo类：

package cn.cfg.pojo;

public class User {
    private Integer id;
    private String username;
    private String sex;
    private String pws;
    private String address;

    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 getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getPws() {
        return pws;
    }

    public void setPws(String pws) {
        this.pws = pws;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", sex='" + sex + '\'' +
                ", pws='" + pws + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

dao类 （接口，对应映射文件和test类）

package cn.cfg.dao;

import cn.cfg.pojo.User;

import java.util.List;

public interface UserDao {
    //查询所有
    public List<User> findAll();
    //更改信息
    public void update(User user);
    //根据id查询
    public List<User> selectByID(Integer id);

}

3.编写propertes文件(jdbc.properties)

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=root

4.编写核新配置文件（SqlMapConfig.xml）

<?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>
    <!--引入外部文件-->
    <properties resource="jdbc.properties"></properties>

    <!--即把下面的cn.cfg.pojo.User 在映射文件里面替换为user-->
    <typeAliases>
        <typeAlias type="cn.cfg.pojo.User" alias="user"></typeAlias>
        <typeAlias type="cn.cfg.dao.UserDao" alias="userdao"></typeAlias>
    </typeAliases>
    <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>
        <!--传统写法-->
        <!--<mapper resource="cn/cfg/dao/UserDao.xml"/>-->

        <!--引入映射文件时  映射文件目录和接口目录一致  可以用package标签直接写接口路径-->
        <package name="cn.cfg.dao"></package>
    </mappers>
</configuration>

5.映射文件

<?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="cn.cfg.dao.UserDao">
    <!--查询所有-->
    <select id="findAll" resultType="user">
        select * from user
    </select>

    <!--更改信息-->
    <update id="update" parameterType="user">
        UPDATE user set username=#{username},address=#{address} where id=#{id}
    </update>

    <!--通过id查询-->
    <select id="selectByID" parameterType="java.lang.Integer" resultType="user">
        SELECT * from user where id=#{id}
    </select>


</mapper>

6.测试类

package cn.cfg.test;

import cn.cfg.dao.UserDao;
import cn.cfg.pojo.User;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.List;

public class TestMybatis {
    SqlSessionFactory sqlSessionFactory=null;
    @Before
    public void init(){
        InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("SqlMapConfig.xml");
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }



    @Test
    public void findAllMyBaits(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List<User> userList = userDao.findAll();
        for (User user:userList){
            System.out.println(user);
        }
        sqlSession.close();
    }

//    更改信息 更改第是个小龙女为龙姑娘
    @Test
    public void upateMyBatis(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);

        User user = new User();
        user.setUsername("龙姑娘");
        user.setAddress("绝情谷底");
        user.setId(10);
        userDao.update(user);
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void testById(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List<User> users = userDao.selectByID(9);
        System.out.println(users);
    }
}