MyBatis框架一 Li.063

MyBatis 介绍

MyBatis 是一个优秀的基于Java 的特久层框架，它内部封装了JDBC，使开发者只需要关注SQL语句本身，而不需要花费精力去处理加载驱动、创建连接、创建执行者等复杂的操作。
MyBatis通过xml 或注解的方式将要执行的各种Statement 配置起来，并通过Java对象和 Statement中 SQL 的动态参数进行映射生成最终要执行的SQL 语句。
最后MyBatis 框架执行完 SQL 并将结果映射为 Java 对象并返回。采用ORM 思想解决了实体和数据库映射的问题，对JDBC 进行了封装，屏蔽了 JDBC API 底层访问细节，使我们不用与JDBC API打交道，就可以完成对数据库的持久化操作。

MyBatis 使用示例

导入mariadb-java-client-2.7.4.jar和mybatis-3.5.7.jar

CREATE DATABASE db1;
use db1;
create table student(
   id int auto_increment primary key ,
   NAME VARCHAR(20),
   age int
);
INSERT INTO student VALUES
(null,'张三',23),(null,'李四',24),(null,'王五',25);

public class Student {
    private Integer id;
    private String name;
    private Integer age;
    ...略
}

package com.lizicai.dao;

import com.lizicai.bean.Student;
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 StudentTest01 {
    /**
     * 查询全部
     */
    public static void main(String[] args) throws IOException {
        StudentTest01 s = new StudentTest01();
        s.selectAll() ;
    }
    public void selectAll() throws IOException {
        // 1. 加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        // 2.获取sqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        // 3.获取sqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        // 4. 获取执行结果
        List<Student>  list = sqlSession.selectList("StudentMapper.selectAll");

        // 5.打印结果
        for(Student stu : list){
            System.out.println(stu);
        }

        // 6. 关闭资源
        sqlSession.close();
        is.close();
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTA Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="mariadb">
        <environment id="mariadb">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="org.mariadb.jdbc.Driver"/>
                <property name="url" value="jdbc:mariadb://192.168.0.100:3306/db1"/>
                <property name="username" value="root"/>
                <property name="password" value="rootPassword"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="StudentMapper.xml" />
    </mappers>
</configuration>

MyBatis 相关API

Resources: org.apache.ibatis.io.Resources
核心方法

返回值      方法名                               说明
InputStream getResourceAsStream(String.fileName) 通过类加载器返回指定资源的字节输入流

SqlSessionFactoryBuilder: org.apache.ibatis.session.SqlSessionFactoryBuilder 获取SqlSessionFactory工厂对象的功能类
核心方法

返回值            方法名                说明
SqlSessionFactory build(InputStream.is) 通过指定资源字节输入流获取SqlSession工厂对象

SqlSessionFactory: org.apache.ibatis.session.SqlSessionFactory: 获取SqlSession构建者对象的工厂接口
核心方法

返回值 方法名 说明
SqlSession openSession() 获取SqlSession构建对象,并开户手动提交事务
SqlSession openSession(boolean.autoCommit) 获取SqlSession构建者对象,如果参数为true,则开户自动提交事务

SqlSession: org.apache.ibatis.session.SqlSession 构建者对象接口. 用于执行SQL, 管理事务, 接口代理.

返回值  方法名                                       说明
List<E> selectList(String.statement,Object.paramter) 执行查询语句,返回List集合
T       selectOne(String.statement,Object.paramter)  执行查询语句,返回一个结果对象
int     insert(String.statement,Object.paramter)     执行新增语句,返回影响行数
int     update(String.statement,Object.paramter)     执行修改语句,返回影响行数
int     delete(String.statement,Object.paramter)     执行删除语句,返回影响行数
void    commit()                                     提交事务
void    rollback()                                   回滚事务
T       getMapper(Class<T>.cls)                      获取指定接口的代理实现类对象
void    close()                                      释放资源

public class Student { private Integer id; private String name; private Integer age;

public Student(){}

public Student(Integer id, String name, Integer age) {
    this.id = id;
    this.name = name;
    this.age = age;
}
...get set略...

}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTA Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--
mapper: 核心根标签
namespace属性: 名称空间
-->
<mapper namespace="StudentMapper">
<!--
    select: 查询功能的标签
    id属性: 唯一标识
    resultType属性: 指定结果映射对象类型
    parameterType属性: 指定参数映射对象类型
-->
    <select id="selectAll" resultType="com.lizicai.bean.Student">
        SELECT * FROM student
    </select>

    <select id="selectById" resultType="com.lizicai.bean.Student" parameterType="java.lang.Integer">
        SELECT * FROM student WHERE id = #{id}
    </select>

    <insert id="insert" parameterType="com.lizicai.bean.Student">
        INSERT INTO student VALUES (#{id},#{name},#{age})
    </insert>

    <update id="updateById" parameterType="com.lizicai.bean.Student">
        UPDATE student SET name=#{name},age=#{age} WHERE id=#{id}
    </update>

    <delete id="deleteById" parameterType="java.lang.Integer">
        DELETE FROM student WHERE id=#{id};
    </delete>
</mapper>

package com.lizicai.dao;

import com.lizicai.bean.Student;
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 org.junit.jupiter.api.Test;

import java.io.IOException;
import java.io.InputStream;
import java.lang.invoke.SwitchPoint;
import java.util.List;

public class StudentTest01 {
    /**
     * id查询
     */

    @Test
    public void selectById() throws IOException {

        // 1. 加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        // 2.获取sqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        // 3.获取sqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        Student stu = sqlSession.selectOne("StudentMapper.selectById",1);

        System.out.println(stu);
        sqlSession.close();
        is.close();
    }

    /**
     * 更新用户信息
     */

    @Test
    public void updateById() throws IOException {
        // 1. 加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        // 2.获取sqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        // 3.获取sqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 4. 获取执行结果
        Student stu = new Student(2,"张三",24);
        int update = sqlSession.update("StudentMapper.updateById", stu);
        sqlSession.commit();
        System.out.println(update);
        sqlSession.close();
        is.close();
    }


    /**
     * 插入数据
     * @throws IOException
     */
    @Test
    public void insert() throws IOException {

        // 1. 加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        // 2.获取sqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        // 3.获取sqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        Student stu = new Student(4,"赵六",26);

        int insert = sqlSession.insert("StudentMapper.insert", stu);

        sqlSession.commit();

        System.out.println(insert);

        // 6. 关闭资源
        sqlSession.close();
        is.close();
    }
    /**
     * 删除数据
     */

    @Test
    public void delete() throws IOException {
        // 1. 加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        // 2.获取sqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        // 3.获取sqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        int delete = sqlSession.delete("StudentMapper.deleteById", 4);

        System.out.println(delete);

        sqlSession.commit();

        sqlSession.close();
        is.close();

    }

    /**
     * 查询全部
     */
    @Test
    public void selectAll() throws IOException {
        // 1. 加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");

        // 2.获取sqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

        // 3.获取sqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        // 4. 获取执行结果
        List<Student>  list = sqlSession.selectList("StudentMapper.selectAll");

        // 5.打印结果
        for(Student stu : list){
            System.out.println(stu);
        }

        // 6. 关闭资源
        sqlSession.close();
        is.close();
    }
}

引入数据库连接配置

jdbc.properties

driver=org.mariadb.jdbc.Driver
url=jdbc:mariadb://192.168.0.100:3306/db1
username=root
password=rootPassword

MyBatisConfig.xml

<configuration>
    <properties resource="jdbc.properties"></properties>
    <environments default="mariadb">
        <environment id="mariadb">
            <!-- 事务管理, 默认采用JDBC默认的事务-->
            <transactionManager type="JDBC"></transactionManager>
<!--            dataSource数据源信息 type属性 连接池-->
            <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>
            <mappers>
<!--        引入指定的映射配置文件 resource属性指定映射配置文件的名称-->
        <mapper resource="StudentMapper.xml" />
    </mappers>
</configuration>

起别名

<configuration>
    <properties resource="jdbc.properties"></properties>

    <!-- 起别名 -->
     <typeAliases>
        <typeAlias type="com.lizicai.bean.Student" alias="student"></typeAlias>
        <package name="com.lizicai.bean"/>
    </typeAliases>

    <environments default="mariadb">
        <environment id="mariadb">
            <!-- 事务管理, 默认采用JDBC默认的事务-->
            <transactionManager type="JDBC"></transactionManager>
<!--            dataSource数据源信息 type属性 连接池-->
            <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>
            <mappers>
<!--        引入指定的映射配置文件 resource属性指定映射配置文件的名称-->
        <mapper resource="StudentMapper.xml" />
    </mappers>
</configuration>

<select id="selectAll" resultType="student">
    SELECT * FROM student
</select>
<select id="selectById" resultType="com.lizicai.bean.Student" parameterType="int">
    SELECT * FROM student WHERE id = #{id}
</select>

常见别名

别名    数据类型
string  java.lang.String
long    java.lang.Long
int     java.lang.Integer
double  java.lang.Double
boolean java.lang.Boolean

dao层实现

package com.lizicai.mapper;

import com.lizicai.bean.Student;

import java.util.List;

public interface StudentMapper {
    // 查询全部
    public abstract List<Student> selectAll();

    // 根据id查询
    public abstract Student selectById(Integer id);

    // 新增数据
    public abstract Integer insert(Student stu);

    // 修改数据
    public abstract Integer update(Student stu);

    // 删除数据
    public abstract Integer delete(Integer id);
}

package com.lizicai.mapper.impl;

import com.lizicai.bean.Student;
import com.lizicai.mapper.StudentMapper;
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 StudentMapperImpl implements StudentMapper {
    // 查询所有学生
    @Override
    public List<Student> selectAll() {
        List<Student> list =null;
        InputStream is = null;
        SqlSessionFactory sqlSessionFactory = null;
        SqlSession sqlSession = null;

        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");

            sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

            sqlSession = sqlSessionFactory.openSession();

            list = sqlSession.selectList("StudentMapper.selectAll");
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if( is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if( sqlSession != null){
                sqlSession.close();
            }
        }

        return list;
    }

    // 根据id查询
    @Override
    public Student selectById(Integer id) {
        Student stu = null;
        InputStream is = null;
        SqlSessionFactory sqlSessionFactory = null;
        SqlSession sqlSession = null;

        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");

            sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

            sqlSession = sqlSessionFactory.openSession();

            stu = sqlSession.selectOne("StudentMapper.selectById",id);
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if( is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if( sqlSession != null){
                sqlSession.close();
            }
        }

        return stu;
    }

    // 新增数据
    @Override
    public Integer insert(Student stu) {
        Integer result = null;

        InputStream is = null;
        SqlSessionFactory sqlSessionFactory = null;
        SqlSession sqlSession = null;

        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");

            sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

            sqlSession = sqlSessionFactory.openSession();

            result = sqlSession.insert("StudentMapper.insert", stu);

            sqlSession.commit();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if( is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if( sqlSession != null){
                sqlSession.close();
            }
        }
        return result;
    }

    // 新增数据
    @Override
    public Integer update(Student stu) {
        Integer result = null;
        InputStream is = null;
        SqlSessionFactory sqlSessionFactory = null;
        SqlSession sqlSession = null;

        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");

            sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

            sqlSession = sqlSessionFactory.openSession();

            result = sqlSession.update("StudentMapper.updateById", stu);

            sqlSession.commit();

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if( is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if( sqlSession != null){
                sqlSession.close();
            }
        }

        return result;
    }

    // 删除数据
    @Override
    public Integer delete(Integer id) {
        Integer result = null;

        InputStream is = null;
        SqlSessionFactory sqlSessionFactory = null;
        SqlSession sqlSession = null;

        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");

            sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);

            // 默认提交事务提交
            sqlSession = sqlSessionFactory.openSession(true);

            result = sqlSession.delete("StudentMapper.deleteById", id);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if( is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if( sqlSession != null){
                sqlSession.close();
            }
        }

        return result;
    }
}

package com.lizicai.service;

import com.lizicai.bean.Student;

import java.util.List;

public interface StudentService {
    List<Student> selectAll();

    // 根据id查询
    Student selectById(Integer id);

    // 新增数据
    Integer insert(Student stu);

    // 修改数据
    Integer update(Student stu);

    // 删除数据
    Integer delete(Integer id);
}

package com.lizicai.service.impl;

import com.lizicai.bean.Student;
import com.lizicai.mapper.StudentMapper;
import com.lizicai.mapper.impl.StudentMapperImpl;
import com.lizicai.service.StudentService;

import java.util.List;

public class StudentServiceImpl implements StudentService {

    private StudentMapper mapper = new StudentMapperImpl();

    // 查询全部
    @Override
    public List<Student> selectAll() {
        return mapper.selectAll();
    }

    // 根据id查询
    @Override
    public Student selectById(Integer id) {
        return mapper.selectById(id);
    }

    @Override
    public Integer insert(Student stu) {
        return mapper.insert(stu);
    }

    @Override
    public Integer update(Student stu) {
        return mapper.update(stu);
    }

    @Override
    public Integer delete(Integer id) {
        return mapper.delete(id);
    }
}

package com.lizicai.controller;

import com.lizicai.bean.Student;
import com.lizicai.service.StudentService;
import com.lizicai.service.impl.StudentServiceImpl;
import org.junit.jupiter.api.Test;

import java.util.ArrayList;
import java.util.List;

public class StudentController {
    // 创建业务层对象
    private StudentService service = new StudentServiceImpl();

    // 查询全部功能测试
    @Test
    public void selectAll(){
        List<Student> list = service.selectAll();
        for(Student stu : list){
            System.out.println(stu);
        }
    }

    // 根据id查询学生
    @Test
    public void selectById(){
        Student stu = service.selectById(1);
        System.out.println(stu);
    }

    // 新增学生
    @Test
    public void insert(){
        Student stu = new Student(4,"赵六",26);
        Integer insert = service.insert(stu);
        System.out.println(insert);
    }

    //  更新学生信息
    @Test
    public void update(){
       Student stu = new Student(3,"王五五",25);
       int update = service.update(stu);
        System.out.println(update );
    }

    //删除学生信息
    @Test
    public void delete(){
        int delete = service.delete(4);
        System.out.println(delete);
    }
}

LOG4J

下载log4j-1.2.17.jar版本

加入libs中

在MyBatisConfig.xml中引用log4j

<configuration>
<!--    数据库账号配置-->
    <properties resource="jdbc.properties"></properties>

<!--    配置log4j-->
    <settings>
        <setting name="logImpl" value="log4j"/>
    </settings>
<configuration>

log4j.properties

# Global logging configuration
# ERROR WARN INFO DEBUG
log4j.rootLogger=DEBUG, stdout
#Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

MyBatis 介绍#

MyBatis 使用示例#

MyBatis 相关API#

引入数据库连接配置#

起别名#

dao层实现#

LOG4J#