MyBatis 簡單介紹及快速入門

簡單介紹

MyBatis是支援普通SQL查詢，儲存過程和高階對映的優秀持久層框架。MyBatis消除了幾乎所有的JDBC程式碼和引數的手工設定以及對結果集的檢索封裝。MyBatis可以使用簡單的XML或註解用於配置和原始對映，將介面和Java的POJO（Plain Old Java Objects，普通的Java物件）對映成資料庫中的記錄.

JDBC->dbutils(自動封裝)->MyBatis->Hibernate

快速入門

1.新增 jar包：mybatis-3.1.1.jar， mysql-connector-java-5.1.7-bin.jar
2.建庫+表

create database mybatis;
use mybatis;
CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(20), age INT);
INSERT INTO users(NAME, age) VALUES('Tom', 12);
INSERT INTO users(NAME, age) VALUES('Jack', 11);

3.編寫表 實體類並給出對映檔案

User.java

package com.wsb.mybatis.test;

public class User
 
 {

    private Integer id;
    private String name;
    private int age;

    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this
 
.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
    }

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">

<!--namespace相當於id，對應一個對映-->
<mapper namespace="com.wsb.mybatis.test.UserMapper">
    <select id="getUser" parameterType="int" resultType="com.wsb.mybatis.test.User">
        select * from users where id = #{id} <!-- #{id}佔位符,#{}固定 -->
    </select>
</mapper>

4.編寫 MyBatis 的配置檔案 mybatis-config.xml

<configuration>
    <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:///mybatis" />
                <property name="username" value="root" />
                <property name="password" value="admin" />
            </dataSource>
        </environment>
    </environments>

<!-- 將UserMapper.xml 註冊到 mybatis-config.xml -->
    <mappers>
        <mapper resource="com/wsb/mybatis/test/UserMapper.xml" />
    </mappers>
</configuration>

5.測試

public static void main(String[] args) {

        //通過類載入器獲取配置檔案的輸入流
        InputStream inputStream = TestUser.class.getClassLoader().getResourceAsStream("mybatis-config.xml");

        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream)；
        SqlSession session = factory.openSession();
        Object user = session.selectOne("com.wsb.mybatis.test.UserMapper.getUser", 1);
        System.out.println(user);

        session.close();

    }

結果： User [id=1, name=Tom, age=12]