Mybatis学习（一）

1.ORM模型简介：

2.传统jdbc的缺陷

3.mybatis的概述：

4.mybatis的说明文档官网http://www.mybatis.org/mybatis-3/zh/getting-started.html；

要使用 MyBatis， 只需将 mybatis-x.x.x.jar 文件置于 classpath 中即可。

如果使用 Maven 来构建项目，则需将下面的 dependency 代码置于 pom.xml 文件中和测试的junit包：

<?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>com.xiaoqiang,mybatis</groupId>
    <artifactId>mybatisDemo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

</project>

创建数据库表中的映射实体类：

package com.xiaoqiang.entity;

public class User {

      private int id;
      private String name;
      private String className;
      private String score;

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

    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 getClassName() {
        return className;
    }

    public void setClassName(String className) {
        this.className = className;
    }

    public String getScore() {
        return score;
    }

    public void setScore(String score) {
        this.score = score;
    }
}

设置mybatis.xml中的配置

<?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>
    <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/student"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/UserMapper.xml"/>
    </mappers>
</configuration>

创建mapper.xml映射关联

<?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="com.xiaoqiang.entity.User">

    <select id="selectBlog" resultType="com.xiaoqiang.entity.User">
    select * from user;
  </select>
    <insert id="insertUser"  parameterType="com.xiaoqiang.entity.User">

        insert into user (id,name,className,score) values  (#{nane},#{className},#{score});
    </insert>
</mapper>

通过Test来测试下插入跟查询

import com.xiaoqiang.entity.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 Test {

    @org.junit.Test
    public  void ceshi() throws IOException {
        String resource="mybatis.xml";
        InputStream inputStream= Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession=sqlSessionFactory.openSession();
        User user=new User();
        user.setName("黄豪强");
        user.setClassName("软件工程2班");
        user.setScore("100");
        user.setId(1);
        int success=sqlSession.insert("insertUser",user);
        sqlSession.commit();
        System.out.println(success);
      /*  List<User> list=sqlSession.selectList("selectBlog");

        for(User user:list)
        {
            System.out.println(user);
        }*/
        sqlSession.close();
    }


}

mybatis整个流程图，主要操作部分为图中蓝色部分,SqlSessionFactory会话工厂只需执行一次:

 

 mybatis整个架构流程：