mybatis入门案例
pom.xml,mybatis.xml,db.properties,UserDao.xml文件配置
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>MybatisTest</artifactId>
<version>1.0-SNAPSHOT</version>
<!-- 解决 File encoding has not been set, using platform encoding UTF-8,
i.e. build is platform dependent!-->
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<!--配置maven阿里云仓库开始,不用去改maven的setting-->
<repositories>
<repository>
<id>public</id>
<name>localprivatenexus</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>public</id>
<name>localprivatenexus</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
<!--配置maven阿里云结束-->
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.5</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.6</version>
</dependency>
</dependencies>
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
</resources>
</build>
</project>
mybatis.xml
<?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>
<!-- stdout logging 标准输出日志
settings 控制mybatis全局行为的
-->
<!--<settings>
<setting name="logImpl" value="STDOUT_LOGGING"/>
</settings>-->
<!-- 环境配置 数据库的连接信息
default: 与environment 中某个id值保持一致 表示你默认要用到那个数据库
-->
<!-- 加载数据库配置文件 -->
<properties resource="db.properties"/>
<environments default="development">
<!-- environment :一个数据库的信息配置，环境 environments表示多个环境
id: 一个唯一值 可自定义 表示环境的名称
-->
<environment id="development">
<!-- transactionManager ：mybatis的事务类型
type: JDBC(表示使用jdbc中connection对象的commit,rollback 做事务处理
dataSource : 表示数据源 用来连接数据库的
type： POOLED (连接池 例如c3p0 Druid)
-->
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<!-- 一个mapper标签指定一个文件的位置
从类路径开始的路径信息。 target/classes(类路径) -->
<mappers>
<mapper resource="Dao\UserDao.xml"/>
</mappers>
</configuration>
UserDao.xml
<?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="Dao.UserDao">
<!-- id 为接口中查询方法的方法名 也可自定义
resultType:表示结果类型，遍历resultSet得到的java类型 ==全限定名称== ！
-->
<select id="userList" resultType="entity.User">
select id,username,password from test01 order by id
</select>
<insert id="insertUser">
insert into test01 values (#{id},#{username},#{password})
</insert>
<delete id="deleteUser" >
delete from test01 where id=#{id}
</delete>
</mapper>
db.properties
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3307/mybatis?useUnicode=true&characterEncoding=utf-8
jdbc.username=root
jdbc.password=33333333
创建实体类和dao层
entity.User
package entity;
/**
* Created with IntelliJ IDEA.
*
* @author Administrator
* @Auther: 风离
* @Date: 2021/03/06/10:56
* @Description:
*/
public class User {
private String username,password;
private int id;
public int getId() {
return id;
}
public void setId(int 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 User(String username, String password, int id) {
this.username = username;
this.password = password;
this.id = id;
}
public User() {
}
@Override
public String toString() {
return "User{" +
"username='" + username + '\'' +
", password='" + password + '\'' +
", id=" + id +
'}';
}
}
Dao.UserDao
package Dao;
import entity.User;
import java.io.IOException;
import java.util.List;
/**
* Created with IntelliJ IDEA.
*
* @Auther: 风离
* @Date: 2021/03/06/11:00
* @Description: 使用jdk动态代理 不用写实现类
*/
public interface UserDao {
//查询所有账号数据
public List<User> userList() throws IOException;
//插入一条数据: user 表示要插入数据库的数据
// int 表示影响的行数
public int insertUser(User user) throws IOException;
public int deleteUser(User user) throws IOException;
}
实现类
package Dao;
import entity.User;
import org.apache.ibatis.session.SqlSession;
import utils.MybatisUtils;
import java.io.IOException;
import java.util.List;
/**
* Created with IntelliJ IDEA.
*
* @Auther: 风离
* @Date: 2021/03/09/0:12
* @Description:
*/
public class UserDaoImpl implements UserDao {
@Override
public List<User> userList() throws IOException {
SqlSession sqlSession= MybatisUtils.getSqlSession();
String sqlId="Dao.UserDao."+"userList";
return sqlSession.selectList(sqlId);
//sqlSession.close();
}
@Override
public int insertUser(User user) throws IOException {
SqlSession sqlSession=MybatisUtils.getSqlSession();
String sqlId="Dao.UserDao."+"insertUser";
return sqlSession.insert(sqlId,user);
//sqlSession.close();
}
@Override
public int deleteUser(User user) throws IOException {
SqlSession sqlSession=MybatisUtils.getSqlSession();
String sqlId="Dao.UserDao."+"deleteUser";
return sqlSession.delete(sqlId,user.getId());
//sqlSession.close();
}
}
重复步骤则封装成工具类
MybatisUtils
package 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 java.io.IOException;
import java.io.InputStream;
/**
* Created with IntelliJ IDEA.
*
* @Auther: 风离
* @Date: 2021/03/08/21:13
* @Description:
*/
public class MybatisUtils {
public static SqlSessionFactory sqlSessionFactory=null;
static {
//1.定义mybatis主配置文件的名称，从类路径的根target/classes
String config="mybatis.xml";
//2.读取这个config表示的文件
try {
InputStream in= Resources.getResourceAsStream(config);
//3.创建SqlSessionFactoryBuilder对象
SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder();
//4.创建SqlSessionFactory对象
sqlSessionFactory=builder.build(in);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSqlSession() throws IOException {
//5【重要】.获取SqlSession对象，从SqlSessionFactory中获取 带参数true 默认自动提交事务
if (sqlSessionFactory != null) {
return sqlSessionFactory.openSession(true);
}
return null;
}
}
测试类
import Dao.UserDao;
import Dao.UserDaoImpl;
import entity.User;
import org.apache.ibatis.session.SqlSession;
import utils.MybatisUtils;
import java.io.IOException;
import java.util.List;
/**
* Created with IntelliJ IDEA.
*
* @Auther: 风离
* @Date: 2021/03/06/15:03
* @Description:第一个访问通过mybatis访问数据库案例
*/
public class Test {
public static void main(String[] args) throws IOException {
//User user=new User("伍六七","rewq4321",777);
//System.out.println(user.toString());
UserDao userDao=new UserDaoImpl();
userDao.userList().forEach(user -> System.out.println(user));
//System.out.println("插入数据的条数为："+userDao.insertUser(user));
}
}
看看是否能查出来~~
完美！！ 下一篇 为：利用jdk动态代理来简化查询过程，即省略手动实现类