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目录
1、Maven导入Mybatis依赖包
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.49</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.4</version>
</dependency>
2、数据库配置文件 db.properties
db.driver=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/db?useSSL=false&useUnicode=true&characterEncoding=utf8
db.username=root
db.password=123456
3、Mybatis配置文件 SqlMapConfig.xml
核心配置文件名是可以改的，一般是放在资源文件夹根目录
<?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>
<!-- 一种写法，以${driver}引用，注意 & 要变成 & 详情请百度 -->
<!--<properties>
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/db?useSSL=false&useUnicode=true&characterEncoding=utf8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</properties>-->
<!-- 引入db.properties文件配置 -->
<properties resource="db.properties"/>
<settings>
<!-- 控制台打印日志，包括查询语句 -->
<setting name="logImpl" value="STDOUT_LOGGING"/>
</settings>
<!-- 开发环境，可以配置多个，default：指定采用哪个环境 -->
<environments default="development">
<environment id="development">
<!-- 事务管理器，由mybatis进行管理，事务管理类型：JDBC、MANAGED -->
<transactionManager type="JDBC"></transactionManager>
<!-- 数据源，池类型的数据源，类型：POOLED、UNPOOLED、JNDI -->
<dataSource type="POOLED">
<property name="driver" value="${db.driver}"/>
<property name="url" value="${db.url}"/>
<property name="username" value="${db.username}"/>
<property name="password" value="${db.password}"/>
</dataSource>
</environment>
</environments>
<!-- 加载映射文件 mapper -->
<mappers>
<!-- 资源路径下 -->
<mapper resource="mappers/table1.xml"/>
<!-- 该方式是加载指定包下的所有映射文件 -->
<!--<package name="com.mybatis.dao"/>-->
</mappers>
</configuration>
4、映射文件 table1Mapper.xml
映射文件一般是放在资源文件根目录的mapper目录下
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- namespace：命名空间，随便写，一般保证命名空间唯一，用动态代理必需写接口的全限定名 -->
<mapper namespace="table1">
<select id="findAll" resultType="com.mybatis.pojo.Table1">
select * from table1
</select>
</mapper>
mapper其他写法
<!-- #{}、${}都是占位符，#{}带有''，${}不带''，优先使用#{}，因为后者会导致sql注入的问题 -->
<select id="selectone" resultType="com.mybatis.user.testEnpity">
select * from user id=#{id} and title=${title}
</select>
<!-- resultMap 建立 SQL 查询结果字段与实体属性的映射关系信息 -->
<resultMap id="BaseResultMap" type="com.mybatis.student.model.Student">
<id property="id" column="id" />
<result column="NAME" property="name" />
<result column="HOBBY" property="hobby" />
<result column="MAJOR" property="major" />
<result column="BIRTHDAY" property="birthday" />
<result column="AGE" property="age" />
</resultMap>
<!--查询时resultMap引用该resultMap -->
<select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="Object">
select id,name,hobby,major,birthday,age from student where id=#{id}
</select>
5、实体类 Table1.java
package com.database.pojo;
public class Table1 {
private int id;
private int col1;
private String col2;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getCol1() {
return col1;
}
public void setCol1(int col1) {
this.col1 = col1;
}
public String getCol2() {
return col2;
}
public void setCol2(String col2) {
this.col2 = col2;
}
@Override
public String toString() {
return "Table1{" +
"id=" + id +
", col1=" + col1 +
", col2=" + col2 +
'}';
}
}
通常写法：接口+实现+调用
简单项目目录图
1、接口 Table1Dao.java
package com.mybatis.dao;
import com.mybatis.pojo.Table1;
import java.util.List;
public interface Table1Dao {
List<Table1> findAll();
}
2、实现类 Table1DaoImpl.java
package com.mybatis.dao.impl;
import com.mybatis.dao.Table1Dao;
import com.mybatis.pojo.Table1;
import org.apache.ibatis.session.SqlSession;
import java.util.List;
public class Table1DaoImpl implements Table1Dao {
public SqlSession sqlSession;
public Table1DaoImpl(SqlSession sqlSession) {
this.sqlSession = sqlSession;
}
public List<Table1> findAll() {
// 操作CRUD，第一个参数：指定statement，规则：命名空间.statementId，后面的参数是sql对应的参数
return sqlSession.selectList("test1.findAll");
}
}
3、调用
import com.mybatis.dao.Table1Dao;
import com.mybatis.dao.impl.Table1DaoImpl;
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 java.io.IOException;
import java.io.InputStream;
public class Test {
@org.junit.Test
public void test() throws IOException {
// 读取配置文件
InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
// 构建sqlSessionFactory
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
// 获取sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
// 创建
Table1Dao table1Dao = new Table1DaoImpl(sqlSession);
// 调用
List<Table1> list = table1Dao.findAll();
sqlSession.close();
}
}
动态代理
1、接口Table1Dao.java
只需写接口，不用写实现
package com.database.mybatis.dao;
import com.database.pojo.Table1;
import java.util.List;
public interface Table1Dao {
List<Table1> findAll();
}
2、table1Mapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- namespace：动态代理必需写接口的全限定名 -->
<mapper namespace="com.database.mybatis.dao.Table1Dao">
<select id="findAll" resultType="com.database.pojo.Table1">
select * from table1 where 100>id
</select>
</mapper>
3、调用
@org.junit.Test
public void MybatisTest2() throws IOException {
// 读取配置文件
InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
// 构建sqlSessionFactory
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
// 获取sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
// 创建
Table1Dao table1Dao = sqlSession.getMapper(Table1Dao.class);
// 调用
List<Table1> list = table1Dao.findAll();
sqlSession.close();
}
动态sql
<!-- 定义sql片段，用于可重用的sql片段 -->
<sql id="whereClause">
<!-- if标签：可以对输入的参数进行判断 -->
<!-- test:指定判断表达式 -->
<if test="user!=null">
<if test="user.username!=null and user.username!=''">
AND username LIKE '%${user.username}%'
</if>
<if test="user.address!=null and user.address!=''">
AND address=#{user.address}
</if>
</if>
<if test="idList!=null">
AND id IN
<!-- foreach标签： 可以循环传入参数值 -->
<!-- collenction：标示pojo中集合属性的属性名称 -->
<!-- item:每次遍历出来的对象 -->
<!--open开始遍历时拼接的串-->
<!--close结束遍历时拼接的串-->
<!--separator遍历每个对象之间需要拼接字符-->
<foreach collection="idList" item="item" open="(" close=")" separator=",">
#{item}
</foreach>
</if>
</sql>
<select id="findUserList" parameterType="userVO" resultType="user">
SELECT * FROM USER
<!-- where标签： 默认去掉第一个AND，如果没有参数就去掉where自己-->
<where>
<!--引用sql语句片段-->
<include refid="whereClause"></include>
</where>
</select>
<!-- set标签可解决多余逗号拼接的问题 -->
<update id="updateStudent" parameterType="Object">
UPDATE STUDENT
<set>
<if test="name!=null and name!='' ">
NAME = #{name},
</if>
<if test="hobby!=null and hobby!='' ">
MAJOR = #{major},
</if>
<if test="hobby!=null and hobby!='' ">
HOBBY = #{hobby}
</if>
</set>
WHERE ID = #{id};
</update>
<!-- trim标记是一个格式化的标记，主要用于拼接sql的条件语句（前缀或后缀的添加或忽略） -->
<!-- prefix：在trim标签内sql语句加上前缀 -->
<!-- suffix：在trim标签内sql语句加上后缀 -->
<!-- prefixOverrides：指定去除多余的前缀内容，如：prefixOverrides=“AND | OR”，去除trim标签内sql语句多余的前缀"and"或者"or" -->
<!-- suffixOverrides：指定去除多余的后缀内容 -->
<update id="updateByPrimaryKey" parameterType="Object">
update student set
<trim suffixOverrides=",">
<if test="name != null">
NAME=#{name},
</if>
<if test="hobby != null">
HOBBY=#{hobby},
</if>
</trim>
where id=#{id}
</update>
Mybatis详细教程：https://blog.csdn.net/hellozpc/article/details/80878563