Mybatis基本配置

小鱼儿 2022-06-06 12:25 161阅读 0赞

1，新建java项目，导入jar包。

2，创建User实体com.entity.User生成set，get方法，数据库建表。

3，创建com.entity.UserMapper.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">

//指定唯一的命名空间namespace，一般不要.xml后缀  
<mapper namespace="com.entity.UserMapper">

//id随意起，最好见名思意，parameterType为主键类型，resultType为返回类型  
<select id="selectUser" parameterType="int" resultType="com.entity.User">

//sql语句  
SELECT \* FROM USER where id=\#\{id\}  
</select>

//配置集合  
<resultMap type="com.entity.User" id="userlist">  
<result property="id" column="id"/>  
<result property="username" column="username"/>  
<result property="password" column="password"/>  
</resultMap>  
<select id="selectAll" resultMap="userlist">  
select \* from user  
</select>  
<select id="delete" parameterType="int" resultMap="userlist">  
delete from user where id=\#\{id\}  
</select>  
<select id="add" parameterType="com.entity.User">  
INSERT INTO \`user\`(username,password) VALUES(\#\{username\},\#\{password\})  
</select>  
<select id="update" parameterType="com.entity.User">  
update set(username=\#\{username\},password=\#\{password\}) where id=\#\{id\}  
</select>  
</mapper>

4，在src下创建mybatis-config.xml连接数据库。

<?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>  
<environments default="development">  
<environment id="development">  
<transactionManager type="JDBC"/>  
<dataSource type="POOLED">  
<property name="driver" value="com.mysql.jdbc.Driver"/>

//连接数据库，解决数据库乱码?characterEncoding=utf8  
<property name="url" value="jdbc:mysql://localhost:3306/数据库名?characterEncoding=utf8"/>  
<property name="username" value="root"/>  
<property name="password" value="root"/>  
</dataSource>  
</environment>  
</environments>  
<mappers>

//指定映射文件路径  
<mapper resource="com/entity/UserMapper.xml"/>  
</mappers>  
</configuration>

5，创建测试文件Test.java

package com.util;  
import java.io.InputStream;  
import java.util.ArrayList;  
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 com.entity.User;  
  
  
public class Test \{  
  
public static void main(String\[\] args) throws Exception \{

//获取数据源  
String resource = "mybatis-config.xml";  
InputStream inputStream = Resources.getResourceAsStream(resource);  
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();  
SqlSessionFactory factory = builder.build(inputStream);

//打开session  
SqlSession session=factory.openSession();  
//查询一条  
//User user=session.selectOne("selectUser", 3);  
//System.out.println(user);  
  
List<User> list2=new ArrayList<>();  
//删除  
//int id=9;  
//user.setId(id);  
//session.delete("delete",user);  
//增加  
//String username="kjll";  
//String password="123";  
//user.setUsername(username);  
//user.setPassword(password);  
//session.insert("add",user);  
//查询多条  
List <User>list=session.selectList("selectAll");  
for (User user : list) \{  
System.out.println(user);  
\}  
\}  
\}