mybatis

什么是MyBatis?

MyBatis是一款优秀的持久层框架，用于简化JDBC开发
MyBatis本是Apache的一个开源项目iBatis,.2010年这个项目由apache software
foundation迁移到了google code,并且改名为MyBatis。2013年11月迁移到Github
官网

mybatis快速入门

导入mybatis

    <dependencies>

        <dependency>
            <groupId>org.mybatisgroupId>
            <artifactId>mybatisartifactId>
            <version>3.5.5version>
        dependency>

        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>5.1.45version>
        dependency>

        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>3.8.2version>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>org.slf4jgroupId>
            <artifactId>slf4j-apiartifactId>
            <version>1.7.16version>
        dependency>
        <dependency>
            <groupId>ch.qos.logbackgroupId>
            <artifactId>logback-coreartifactId>
            <version>1.2.3version>
        dependency>
        <dependency>
            <groupId>ch.qos.logbackgroupId>
            <artifactId>logback-classicartifactId>
            <version>1.2.3version>
        dependency>
    dependencies>
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1.创建user表，添加数据

CREATE DATABASE mybatis;
USE mybatis;
DROP TABLE IF EXISTS tb_user;
CREATE TABLE tb_user(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(20),
PASSWORD VARCHAR(20),
gender VARCHAR(20),
addr VARCHAR(30)
);

ALTER DATABASE mybatis CHARACTER SET utf8;
ALTER TABLE tb_user CHARACTER SET utf8;


INSERT INTO tb_user VALUES(1,'zhangsan','123','男','北京');
INSERT INTO tb_user VALUES(2,'李四','234','女','天津');
INSERT INTO tb_user VALUES(3,'王五','11','男','西安');

SELECT * FROM tb_user

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2.创建模块，导入坐标

在 main 目录下的 resoures 配置文件目录下创建一个名为 logback.xml 的配置文件，粘贴一下内容：

<configuration>
    
    <appender name="Console" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>【%level】 %blue(%d{HH:mm:ss.SSS}) %cyan(【%thread】) %boldGreen(%logger{15}) - %msg %npattern>
        encoder>
    appender>

    <logger name="com.itheima" level="DEBUG" additivity="false">
        <appender-ref ref="Console"/>
    logger>

    <root level="DEBUG">
        <appender-ref ref="Console"/>
    root>
configuration>
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3.编写MyBatis核心配置文件->替换连接信息解决硬编码问题

在 main 目录下的 resoures 配置文件目录下创建一个名为 mybatis-config.xml 的配置文件，内容			在MyBatis官网
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模板

DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
  <environments default="development">
    <environment id="development">
      <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>
  <mappers>
    <mapper resource="org/mybatis/example/BlogMapper.xml"/>
  mappers>
configuration>
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修改后

DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<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://localhost:3306/mybatis?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="lqx"/>
            dataSource>
        environment>
    environments>
    <mappers>
        <mapper resource="UserMapper.xml"/>
    mappers>
configuration>
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4.编写SQL映射文件->统一管理sq语句，解决硬编码问题

在 main 目录下的 resoures 配置文件目录下创建一个名为 UserMapper.xml 的配置文件，内容在MyBatis官网
模板

DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.mybatis.example.BlogMapper">
   <select id="selectBlog" resultType="Blog">
 		select * from Blog where id = #{id}
  select>
mapper>
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修改后

DOCTYPE mapper
     PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
     "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="test">
 <select id="selectAll" resultType="com.lqx.pojo.User">
     select * from tb_user;
 select>
mapper>
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5.编码

1.定义P0J0类

package com.lqx.pojo;

public class User {
    private Integer id;
    private String username;
    private String PASSWORD;
    private String gender;
    private String addr;

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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 String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getAddr() {
        return addr;
    }

    public void setAddr(String addr) {
        this.addr = addr;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", PASSWORD='" + PASSWORD + '\'' +
                ", gender='" + gender + '\'' +
                ", addr='" + addr + '\'' +
                '}';
    }
}
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2.加载核心配置文件，获取SqlSessionFactory对象
3.获取SqlSession对象，执行SQL语句
4.释放资源
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package com.lqx;

import com.lqx.pojo.User;
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;
import java.util.List;

public class MyBatisDemo {
    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<User> users = sqlSession.selectList("test.selectAll");

        System.out.println(users);
        sqlSession.close();

    }
}
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解决SQL映射文件的警告提示

产生原因：ldea和数据库没有建立连接，不识别表信息
解决方式：在ldea中配置MySQL数据库连接
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其他内容这里不做了

Mapperf代理开发
核心配置文件
参数传递
注解开发
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