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01-mybatis的dao层实现-传统实现方式

发布时间：2025-01-28 22:59:16编辑：雪饮阅读（）

基于org,apache.maven.archetypes:maven-archetype-quickstart骨架建立新的module
建立完成后在pom.xml中配置依赖如：
<dependencies>
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.32</version>
  </dependency>
  <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.4.6</version>
  </dependency>
  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
  </dependency>
</dependencies>
然后在新module中src/main/下面建立java目录
并在src/main/java中建立package如sp25.domain
然后在src/main/java/sp25.domain这个package下面建立User类如：
package sp25.domain;

public class User {
    private int id;
    private String username;
    private String password;

    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;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}
然后在新module中src/main/下面建立resources目录,然后在src/main/resources下面建立sp25目录并在该sp25目录下建立mapper,目录并在mapper下面建立UserMapper.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="userMapper">
    <!--查询操作-->
    <select id="findAll" resultType="user">
        select * from user
    </select>

</mapper>
然后制作resources根目录建立sqlMapConfig.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>
    <!--通过properties标签加载外部properties文件-->
    <properties resource="jdbc.properties"/>
    <typeAliases>
        <typeAlias type="sp25.domain.User" alias="user"/>
    </typeAliases>
    <!--数据源环境-->
    <environments default="developement">
        <environment id="developement">
            <transactionManager type="JDBC"></transactionManager>
            <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>
   

    <!--加载映射文件-->
    <mappers>
        <mapper resource="sp25/mapper/UserMapper.xml"></mapper>
    </mappers>

</configuration>
然后在src/main/java/下面建立package如sp25.dao,然后在sp25.dao下面建立UserMapper.java如：
package sp25.dao;

import sp25.domain.User;

import java.io.IOException;
import java.util.List;

public interface UserMapper {
    public List<User> findAll() throws IOException;
}
以及其实现：
package sp25.dao.impl;

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 sp25.dao.UserMapper;
import sp25.domain.User;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class UserMapperImpl implements UserMapper {
    public List<User> findAll() throws IOException {
        InputStream resourceAsStream= Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession=sqlSessionFactory.openSession();
        List<User> userList=sqlSession.selectList("userMapper.findAll");
        System.out.println(userList);
        sqlSession.close();
        return userList;
    }
}
然后我们再建立service层，如：sp25.service
然后再建立一个service的实现demo，实际上应该还有一层就是最终调用层上面才有类似main入口方法，这里应该是为了省事，直接在service层的一个ServiceDemo中进行了实现。
package sp25.service;

import sp25.dao.UserMapper;
import sp25.dao.impl.UserMapperImpl;
import sp25.domain.User;

import java.io.IOException;
import java.util.List;

public class ServiceDemo {
    public static void main(String[] args) throws IOException {
        //创建dao层对象，当前dao层实现是手动编写的
        UserMapper userMapper = new UserMapperImpl();
        List<User> all=userMapper.findAll();
        System.out.println(all);

    }
}
然后测试运行下该main方法。