[MyBatis]注解

在抽象接口编辑注解

@Select("select * from user")
    List<User> getUsers();

 

在mybatis-config.xml即mybatis核心配置文件中绑定接口

 <!--绑定接口-->
    <mappers>
        <mapper class="com.zlc.dao.UserMapper"/>
    </mappers>

注意：简单sql语句推荐使用注解，复杂sql语句使用xml配置文件方式

 

 

目录结构

 

 

 

接口

package com.zlc.dao;

import com.zlc.pojo.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface UserMapper {

    @Select("select * from user")
    List<User> getUsers();
}

实体类

package com.zlc.pojo;

import org.apache.ibatis.type.Alias;

//实体类
@Alias("user")
public class User {
    private int id;
    private String name;
    private String pwd;

    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
}

工具类

package com.zlc.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;

//sqlSessionFactory-->sqlSession
public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static{
        try {
            //第一步：获取sqlSessionFactory对象
            String resource="mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //SqlSession完全包含了面向数据库执行SQL命令的所有方法
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }

}

mybatis-config.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核心配置文件-->
<configuration>
    <!--引入外部配置文件-->
    <properties resource="db.properties"/>

    <!--日志工厂  STDOUT_LOGGING -->
    <settings>
        <setting name="logImpl" value="LOG4J"/>
    </settings>

    <!--属性别名-->
    <!--<typeAliases>
        <typeAlias type="com.User" alias="User"/>
    </typeAliases>-->
    <typeAliases>
        <package name="com.zlc.pojo"/>
    </typeAliases>


    <environments default="development">
        <environment id="development">
            <!--数据库-->
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>

    <!--绑定接口-->
    <mappers>
        <mapper class="com.zlc.dao.UserMapper"/>
    </mappers>
</configuration>

db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=UTF-8
username=root
password=364624