Mybatis官方文档：
https://mybatis.org/mybatis-3/zh/index.html
1. 为什么需要MyBatis
帮助程序员将数据存入到数据库中
方便
传统的JDBC代码太复杂了，简化，框架，自动化
不用MyBatis也可以，技术没有高低之分
优点：
- 简单易学
- 灵活
- sql和代码的分离，提高了可维护性。
- 提供映射标签，支持对象与数据库的orm字段关系映射
- 提供对象关系映射标签，支持对象关系组建维护
- 提供xml标签，支持编写动态sql
2、第一个Mybatis程序
思路：搭建环境 --> 导入MyBatis --> 编写代码 --> 测试
.2.1导入maven依赖配置
<dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.5</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.21</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13</version> <scope>test</scope> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.12</version> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> </resources> </build>
2.2目录结构
2.3mybatis-config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核心配置文件-->
<configuration>
<properties resource="db-config.properties"/>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mapper/UserDao.xml" />
</mappers>
</configuration>注意点:这里url的value需要使用${jdbc.url}否则在编译的时候回出现错误，value值回自动替换成www.example.com
2.4 db-config.properties配置
====
2.5 编写mybatisUtil工具类
package com.zhangpan.utils;
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.apache.ibatis.session.SqlSessionManager;
import java.io.IOException;
import java.io.InputStream;
public class MybatisUtil {
static SqlSessionFactory sqlSessionFactory = null;
static {
try {
String MybatisConfig = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(MybatisConfig);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession();
}
}2.6编写dao接口
package com.zhangpan.mapper;
import com.zhangpan.pojo.User;
import java.util.List;
public interface UserDao {
public List<User> getUserList();
public void addUser(User user);
}2.7编写接口实现UserDao.xml(由原来的接口实现类变成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">
<!--namespace=绑定一个指定的Dao/Mapper接口-->
<mapper namespace="com.zhangpan.mapper.UserDao">
<select id="getUserList" resultType="com.zhangpan.pojo.User">
select * from USER
</select>
<select id="addUser" parameterType="com.zhangpan.pojo.User">
insert into USER (username,sex,birthday,address) value (#{username},#{sex},#{birthday},#{address})
</select>
</mapper>2.8 Junit测试
package com.zhangpan;
import com.zhangpan.mapper.UserDao;
import com.zhangpan.pojo.User;
import com.zhangpan.utils.MybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.Date;
import java.util.List;
public class test {
@Test
public void test1(){
SqlSession sqlSession = MybatisUtil.getSqlSession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
List<User> userList = userDao.getUserList();
for (User user:userList){
System.out.println(user);
}
sqlSession.close();
}
@Test
public void addUser_test(){
SqlSession sqlSession = MybatisUtil.getSqlSession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
User user = new User();
user.setUsername("关二爷");
user.setSex("1");
user.setBirthday(new Date());
user.setAddress("光棍屯18号");
userDao.addUser(user);
sqlSession.commit();
sqlSession.close();
}
}3、通过配置文件实现CURD
1. namespace**
namespace中的包名要和Dao/Mapper接口的包名一致
选择，查询语句；
id：就是对应的namespace中的方法名；
resultType : Sql语句执行的返回值；
parameterType : 参数类型；
import com.zhangpan.pojo.User;
import org.omg.CORBA.PUBLIC_MEMBER;
import java.util.List;
import java.util.Map;
public interface UserDao {
public List<User> getUserList();
public void addUser(User user);
public void addUserMap(Map<String,Object> map);
public List<User> getUserLike(String username);
public List<User> getUserByLimit(Map<String,Integer> map);
public List<User> getUserByRowBounds();
}userDao.xml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">
<!--namespace=绑定一个指定的Dao/Mapper接口-->
<mapper namespace="com.zhangpan.mapper.UserDao">
<resultMap id="UserMap" type="User">
<result column="username" property="username"/>
<result column="address" property="address"/>
</resultMap>
<select id="getUserList" resultType="User">
select * from USER
</select>
<select id="addUser" parameterType="User">
insert into USER (username,sex,birthday,address) value (#{username},#{sex},#{birthday},#{address})
</select>
<select id="addUserMap" parameterType="map">
insert into USER (username,sex,birthday,address) value (#{username},#{sex},#{birthday},#{address})
</select>
<select id="getUserLike" parameterType="String" resultMap="UserMap">
select * from USER where username like "%"#{username}"%"
</select>
<select id="getUserByLimit" parameterType="map" resultMap="UserMap">
select * from user limit #{startIndex},#{pageSize}
</select>
<select id="getUserByRowBounds" resultMap="UserMap">
select * from user
</select>
</mapper>测试类
package com.zhangpan;
import com.zhangpan.mapper.UserDao;
import com.zhangpan.pojo.User;
import com.zhangpan.utils.MybatisUtil;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.Test;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class test {
Logger logger = Logger.getLogger(test.class);
@Test
public void test1(){
SqlSession sqlSession = MybatisUtil.getSqlSession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
List<User> userList = userDao.getUserList();
for (User user:userList){
System.out.println(user);
}
sqlSession.close();
}
@Test
public void addUser_test(){
SqlSession sqlSession = MybatisUtil.getSqlSession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
User user = new User();
user.setUsername("关二爷");
user.setSex("1");
user.setBirthday(new Date());
user.setAddress("光棍屯18号");
userDao.addUser(user);
sqlSession.commit();
sqlSession.close();
}
@Test
public void addUser_map(){
SqlSession sqlSession = MybatisUtil.getSqlSession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
HashMap<String,Object> map = new HashMap<String, Object>();
map.put("username","python1223423");
map.put("sex","0");
map.put("birthday",new Date());
map.put("address","yangguangdadao 13hao");
userDao.addUserMap(map);
sqlSession.commit();
sqlSession.close();
}
@Test
public void getUserLike(){
SqlSession sqlSession = MybatisUtil.getSqlSession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
List<User> users = userDao.getUserLike("python");
for (User user:users){
System.out.println(user);
}
logger.info("info:稳得一匹");
sqlSession.close();
}
@Test
public void getUserByLimit(){
SqlSession sqlSession = MybatisUtil.getSqlSession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
HashMap<String,Integer> map = new HashMap<String, Integer>();
map.put("startIndex",0);
map.put("pageSize",3);
List<User> list = userDao.getUserByLimit(map);
for (User user:list){
System.out.println(user);
}
}
@Test
public void getUserByRowBounds(){
SqlSession sqlSession = MybatisUtil.getSqlSession();
RowBounds rowBounds = new RowBounds(2,2);
List<User> userList = sqlSession.selectList("com.zhangpan.mapper.UserDao.getUserByRowBounds",null,rowBounds);
for (User user:userList){
System.out.println(user);
}
}
}未完待续。。。。。
