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从零开始Mybatis连接数据库
创建Maven文件
File-->new-->project-->maven,点击next
配置
在出现的pom.xml文件中<project>标签之间加入以下内容
<!--打包方式-->
<packaging>jar</packaging>
<dependencies>
<!--加载Mybatis核心-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.7</version>
</dependency>
<!--Junit测试-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<!--mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.3</version>
</dependency>
</dependencies>在src-->main-->resources下创建文件mybatis-config.xml
在该文件中加入以下内容:
<?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>
<!--配置连接数据库环境-->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/test"/>
<property name="username" value="自己的用户名"/>
<property name="password" value="自己的密码"/>
</dataSource>
</environment>
</environments>
</configuration>注意将username和password的value值改成自己的,且在自己的数据库中创建test库
创建实体类
在main的java下创建我们需要与表中对应的实体类,这里我们写user类
public class User {
//实体类
//属性与表中的各项对应,加入相应的get,set方法
int userid;
String username;
String userpass;
String usertel;
int usercarad;
public User() {
}
public User(int userid, String username, String userpass, String usertel, int usercarad) {
this.userid = userid;
this.username = username;
this.userpass = userpass;
this.usertel = usertel;
this.usercarad = usercarad;
}
public int getUserid() {
return userid;
}
public void setUserid(int userid) {
this.userid = userid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getUserpass() {
return userpass;
}
public void setUserpass(String userpass) {
this.userpass = userpass;
}
public String getUsertel() {
return usertel;
}
public void setUsertel(String usertel) {
this.usertel = usertel;
}
public int getUsercarad() {
return usercarad;
}
public void setUsercarad(int usercarad) {
this.usercarad = usercarad;
}
}创建com.mapper包,并在包下创建UserMapper接口
这里我们简单做一个添加内容示例
package com.mapper;
public interface UserMapper {
int insertUser();//返回值为改变的行数
}创建UserMapper.xml映射文件
在resources文件夹下创建mapper文件夹(包)并在其中创建UserMapper.xml
并在其中加入以下内容,这里要保证两个一致
<?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">
<!--第一个一致,namespace对应UserMapper接口全类名-->
<mapper namespace="com.mapper.UserMapper">
<!--第二个一致,id对应方法名 int insertUser(); -->
<insert id="insertUser">
insert into user values (null,"tom","1234","111",22)
</insert>
</mapper>在mybatis-config.xml下<configuration>标签中最下面加入
<!--引入映射文件-->
<mappers>
<mapper resource="mapper/UserMapper.xml"/>
</mappers>创建测试类
创建Test类进行测试
import com.mapper.UserMapper;
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.Reader;
public class Test {
public static void main(String[] args) throws IOException {
//获取配置文件
Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
// 获取SqlSessionFactoryBuilder获取SqlSessionFactory工厂
SqlSessionFactoryBuilder sqlSessionFactoryBuilder=new SqlSessionFactoryBuilder();
//获取SqlSessionFactory工厂
SqlSessionFactory sqlSessionFactory= sqlSessionFactoryBuilder.build(reader);
//利用工厂获取sqlSession
SqlSession sqlSession=sqlSessionFactory.openSession();//openSession()加入参数true,即可实现自动提交事务
//利用sqlSession的方法获取接口的对象
UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
//调用接口方法,从而调用映射文件的sql语句
int num= userMapper.insertUser();
//提交事务
sqlSession.commit();
System.out.println("改变行数"+num);
}
}运行结果:
