spring boot系列（六）spring boot 配置mybatis(xml简化版)

    orm框架的本质是简化编程中操作数据库的编码，发展到现在基本上就剩两家了，一个是宣称可以不用写一句SQL的hibernate，一个是可以灵活调试动态sql的mybatis,两者各有特点，在企业级系统开发中可以根据需求灵活使用。发现一个有趣的现象：传统企业大都喜欢使用hibernate,互联网行业通常使用mybatis。
    hibernate特点就是所有的sql都用Java代码来生成，不用跳出程序去写（看）sql，有着编程的完整性，发展到最顶端就是spring data jpa这种模式了，基本上根据方法名就可以生成对应的sql了
    mybatis初期使用比较麻烦，需要各种配置文件、实体类、dao层映射关联、还有一大推其它配置。当然mybatis也发现了这种弊端，初期开发了generator可以根据表结果自动生产实体类、配置文件和dao层代码，可以减轻一部分开发量；后期也进行了大量的优化可以使用注解了，自动管理dao层和配置文件等

0 pom.xml增加

<dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.1</version>
</dependency>

1 配置

application.properties新增以下配置：

mybatis.config-locations=classpath:mybatis/mybatis-config.xml
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml
mybatis.type-aliases-package=com.cfj.ceshi.entit

指定了mybatis基础配置文件和实体类映射文件的地址

mybatis-config.xml 配置

<?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>
    <typeAliases>
        <typeAlias alias="Integer" type="java.lang.Integer" />
        <typeAlias alias="Long" type="java.lang.Long" />
        <typeAlias alias="HashMap" type="java.util.HashMap" />
        <typeAlias alias="LinkedHashMap" type="java.util.LinkedHashMap" />
        <typeAlias alias="ArrayList" type="java.util.ArrayList" />
        <typeAlias alias="LinkedList" type="java.util.LinkedList" />
    </typeAliases>
</configuration>

2 添加User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="com.cfj.ceshi.mapper.UserMapper" >
    <resultMap id="BaseResultMap" type="com.cfj.ceshi.entity.UserEntity" >
        <id column="id" property="id" jdbcType="BIGINT" />
        <result column="user_name" property="userName" jdbcType="VARCHAR" />
        <result column="pass_word" property="passWord" jdbcType="VARCHAR" />
        <result column="user_sex" property="userSex" javaType="com.cfj.ceshi.enums.UserSexEnum"/>
        <result column="nick_name" property="nickName" jdbcType="VARCHAR" />
    </resultMap>
    
    <sql id="Base_Column_List" >
        id, user_name, pass_word, user_sex, nick_name
    </sql>

    <select id="getAll" resultMap="BaseResultMap"  >
       SELECT 
       <include refid="Base_Column_List" />
       FROM users
    </select>

    <select id="getOne" parameterType="java.lang.Long" resultMap="BaseResultMap" >
        SELECT 
       <include refid="Base_Column_List" />
       FROM users
       WHERE id = #{id}
    </select>

    <insert id="insert" parameterType="com.cfj.ceshi.entity.UserEntity" >
       INSERT INTO 
               users
               (user_name,pass_word,user_sex) 
           VALUES
               (#{userName}, #{passWord}, #{userSex})
    </insert>
    
    <update id="update" parameterType="com.cfj.ceshi.entity.UserEntity" >
       UPDATE 
               users 
       SET 
           <if test="userName != null">user_name = #{userName},</if>
           <if test="passWord != null">pass_word = #{passWord},</if>
           nick_name = #{nickName}
       WHERE 
               id = #{id}
    </update>
    
    <delete id="delete" parameterType="java.lang.Long" >
       DELETE FROM
                users 
       WHERE 
                id =#{id}
    </delete>

</mapper>

3 实体层

package com.cfj.ceshi.entity;

import com.cfj.ceshi.enums.UserSexEnum;

public class UserEntity {
    
    private static final long serialVersionUID = 1L;
    private Long id;
    private String userName;
    private String passWord;
    private UserSexEnum userSex;
    private String nickName;

    public UserEntity() {
        super();
    }

    public UserEntity(String userName, String passWord, UserSexEnum userSex) {
        super();
        this.passWord = passWord;
        this.userName = userName;
        this.userSex = userSex;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long 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 UserSexEnum getUserSex() {
        return userSex;
    }

    public void setUserSex(UserSexEnum userSex) {
        this.userSex = userSex;
    }

    public String getNickName() {
        return nickName;
    }

    public void setNickName(String nickName) {
        this.nickName = nickName;
    }

    @Override
    public String toString() {
        // TODO Auto-generated method stub
        return "userName " + this.userName + ", pasword " + this.passWord + "sex " + userSex.name();
    }

}

4 Dao层（mapper层）

package com.cfj.ceshi.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.cfj.ceshi.entity.UserEntity;
import com.cfj.ceshi.enums.UserSexEnum;

public interface UserMapper {
    
List<UserEntity> getAll();
    
    UserEntity getOne(Long id);

    void insert(UserEntity user);

    void update(UserEntity user);

    void delete(Long id);

}

 5 control层（web层）暂时简化掉了service层

package com.cfj.ceshi.web;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.cfj.ceshi.entity.UserEntity;
import com.cfj.ceshi.mapper.UserMapper;

@RestController
public class UserController {
    
    @Autowired
    private UserMapper userMapper;
    
    @RequestMapping("/getUsers")
    public List<UserEntity> getUsers() {
        List<UserEntity> users=userMapper.getAll();
        return users;
    }
    
    @RequestMapping("/getUser")
    public UserEntity getUser(Long id) {
        UserEntity user=userMapper.getOne(id);
        return user;
    }
    
    @RequestMapping("/add")
    public void save(UserEntity user) {
        userMapper.insert(user);
    }
    
    @RequestMapping(value="update")
    public void update(UserEntity user) {
        userMapper.update(user);
    }
    
    @RequestMapping(value="/delete/{id}")
    public void delete(@PathVariable("id") Long id) {
        userMapper.delete(id);
    }

}