---Mybatis3学习笔记

Posted 2020-08-31

1.先来一个最简单的mybatis操作mysql数据库的例子

　　

//(1)定义一个实体类(com.ggzhang.mybatis.pojo.Student)
package com.ggzhang.mybatis.pojo;

public class Student {

    private Integer id;
    private String name;
    private int age;
    private double score;
    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;
    }
    public double getScore() {
        return score;
    }
    public void setScore(double score) {
        this.score = score;
    }
    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", age=" + age
                + ", score=" + score + "]";
    }
    public Student() {
        super();
        // TODO Auto-generated constructor stub
    }
    public Student(Integer id, String name, int age, double score) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
        this.score = score;
    }
    
}

生成一个简单的表Student

SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `student`
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
  `id` int(5) NOT NULL,
  `name` varchar(20) DEFAULT NULL,
  `age` int(3) DEFAULT NULL,
  `score` double DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

 1 package com.ggzhang.mybatis.dao;
 2 
 3 import com.ggzhang.mybatis.pojo.Student;
 4 
 5 /**
 6  * 定义dao接口
 7  * 
 8  * @author zhang
 9  * 
10  */
11 public interface StudentDao {
12     void insertStudent(Student student);
13 }

定义映射文件:注意:#{}中写入的是Student类的属性名.对于paramterType属性,框架会自定根据用户执行的SqlSession方法中的参数自动检测到,所以也可以不用指定parameterType属性

<?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.ggzhang.myabtis.dao.StudentDao">
    <insert id="insertStudent" parameterType="com.ggzhang.mybatis.pojo.Student">
        insert into student(id,name,age,score) values(#{id},#{name},#{age},#{score})
    </insert>
</mapper>

定义主配置文件.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>
<!-- 主配置文件: 1)数据库连接信息, 事务配置; 2)加载映射文件 -->

    <!-- 默认使用的环境信息 -->
    <environments  default="developer">
        <!-- 开发环境 -->
        <environment id="developer">
            <!-- 事务管理: 
               type:事务类型   JDBC:使用的Connection的事务管理 commit, rollback 
                            MANAGED: 由容器管理事务(Spring是容器)
               -->
            <transactionManager type="JDBC" />
            
            <!-- 数据源 type:数据源类型
                POOLED : 使用数据库连接池
                UNPOOLED: 不使用数据库的连接池. 每次操作的创建连接, 使用完毕后关闭连接.
                JNDI:  外部数据源
             -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatistest"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
        <!-- 线上环境 -->
        <environment id="online">
            <!-- 事务管理: 
               type:事务类型   JDBC:使用的Connection的事务管理 commit, rollback 
                            MANAGED: 由容器管理事务(Spring是容器)
               -->
            <transactionManager type="JDBC" />
            
            <!-- 数据源配置
                type:数据源类型
                POOLED : 使用数据库连接池
                UNPOOLED: 不使用数据库的连接池. 每次操作的创建连接, 使用完毕后关闭连接.
                JDNI:  外部数据源
             -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatistest"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    
    <!-- 加载sql映射文件 -->
    <mappers>
        <mapper  resource="com/ggzhang/mybatis/dao/StudentDao.xml"/> 
        <!--  <mapper  url="file:///d:/studentMapper.xml" /> -->
    </mappers>

</configuration>

定义Dao实现类

package com.ggzhang.mybatis.dao;

import java.io.IOException;
import java.io.InputStream;

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 com.ggzhang.mybatis.pojo.Student;

public class StudentDaoImpl implements StudentDao {

    private SqlSession session;

    @Override
    public void insertStudent(Student student) {
        try {
            // 读取配置文件
            InputStream inputStream = Resources
                    .getResourceAsStream("mybatis-config.xml");
            // 创建SqlSessionFactory
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
                    .build(inputStream);
            // 创建SqlSession对象
            session = sqlSessionFactory.openSession();
            session.insert("insertStudent", student);
            // 提交
            session.commit();

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();

        } finally {
            if (session != null) {
                session.close();
            }
        }

    }

}

定义测试类

package com.ggzhang.mybatis.test;

import org.junit.Test;

import com.ggzhang.mybatis.dao.StudentDao;
import com.ggzhang.mybatis.dao.StudentDaoImpl;
import com.ggzhang.mybatis.pojo.Student;

public class MybatisTest {

    @Test
    public void testInsert(){
        StudentDao studentDao = new StudentDaoImpl();
        Student student = new Student(3,"赵六",26,96.5);
        studentDao.insertStudent(student);
        
    }
}

就可以成功的插入数据了,底下是log4j打印出来的信息.包括生成的Sql,

DEBUG [main] - Logging initialized using ‘class org.apache.ibatis.logging.slf4j.Slf4jImpl‘ adapter.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - Opening JDBC Connection
DEBUG [main] - Created connection 1189752912.
DEBUG [main] - Setting autocommit to false on JDBC Connection [[email protected]]
DEBUG [main] - ==>  Preparing: insert into student(id,name,age,score) values(?,?,?,?) 
DEBUG [main] - ==> Parameters: 3(Integer), 赵六(String), 26(Integer), 96.5(Double)
DEBUG [main] - <==    Updates: 1
DEBUG [main] - Committing JDBC Connection [[email protected]]
DEBUG [main] - Resetting autocommit to true on JDBC Connection [[email protected]]
DEBUG [main] - Closing JDBC Connection [[email protected]]
DEBUG [main] - Returned connection 1189752912 to pool.