mybatis_day01

第一章、认识框架

1. MyBatis框架介绍

　　Mybatis最大的特点是把Sql语句写在XML配置文件当中。而且Mybatis执行完Sql语句之后可以以对象形式返回（POJO/POJO集合等）。

2. 从 XML 中构建 SqlSessionFactory

　　SqlSessionFactory 的实例可以通过 SqlSessionFactoryBuilder 获得。而 SqlSessionFactoryBuilder 则可以从 XML 配置文件或一个预先配置的 Configuration 实例来构建出 SqlSessionFactory 实例。

String resource = "org/mybatis/example/mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

3. 从 SqlSessionFactory 中获取 SqlSession

SqlSession session = sqlSessionFactory.openSession()

第二章、Mybatis框架快速入门案例

1. 添加依赖、配置编译环境

   <dependencies>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>
        <!--log4j-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>


    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.2</version>
                <!--编译插件,配置信息-->
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>utf-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>

2. 添加 db.properties、log4.j.properties、mybatis-config.xml、EmployeeMapper.xml

　　(1) db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf8&useSSL=false
username=root
password=root

　　(2)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>
    <!--
        properties标签：引入外部配置文件
            resource：配置properties配置文件的路径
    -->
    <properties resource="db.properties"/>

    <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:配置SQL语句配置文件的路径，resource配置SQL语句的文件路径和文件名
        -->
        <mapper resource="EmployeeMapper.xml"/>
    </mappers>
</configuration>

　　(3) EmployeeMapper.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:命名空间，值可以随意写
    当有多个xxxMapper时，需要确保namespace唯一性
-->
<mapper namespace="com.atguigu.pojo.EmployeeMapper">
    <select id="queryEmployeeById" parameterType="Integer" resultType="com.atguigu.pojo.Employee">
        select * from employee where id = 1
    </select>
</mapper>

3. 创建pojo类

@Data
public class Employee {
    private Integer id;
    private String name;
    private Double salary;
}

4. 测试类

@Test
    public void testQueryEmployeeById() throws IOException {
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Object o = sqlSession.selectOne("com.atguigu.pojo.EmployeeMapper.queryEmployeeById");
        System.out.println(o);
    }

 

第三章、Mybatis框架实现数据的CURD

1. 导入依赖和maven编译环境插件

<dependencies>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
        </dependency>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.3</version>
        </dependency>
        <!--lombook-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.8</version>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <!--log4j-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>utf-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>

2. 添加配置文件

　　db.properties、EmployeeMapper.xml、log4j.properties、mybatis-config.xml

　　(1) db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf8&useSSL=false
username=root
password=root

　　(2) EmployeeMapper.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">
<mapper namespace="employeeMapper">
    <!--1.1查询所有员工信息-->
    <!--
        select标签：配置查询语句
          resultType属性:"查询数据表后的结果集"
          parameterType属性:"SQL语句的参数的数据类型"，8个基本数据类,及其包装类,和字符串类型,直接写类名即可 (不区分大小写)

          SQL语句的参数: 有2种写法 #{}  ${}
            #{} 防止SQL的注入攻击,提供SQL的执行效率
            ${} 一般不使用,${}直接做了字符串拼接
  -->
    <select id="queryEmployee" resultType="Employee">
        select * from employee
    </select>
    <!--1.2查询员工信息，根据id刷选-->
    <select id="queryEmployeeById" parameterType="Integer" resultType="Employee">
        select * from employee where id = #{id}
    </select>
    <!--1.3查询员工，根据名字模糊查询-->
    <select id="queryEmployeeByLikeName" parameterType="String" resultType="Employee">
        select * from employee where name like #{name}
    </select>
    <!--2.1修改员工数据-->
    <update id="updateEmployeeById" parameterType="Employee">
        update employee set name = #{name},salary = #{salary} where id = #{id}
    </update>
    <!--3.1删除员工数据-->
    <update id="deleteEmployeeById" parameterType="Integer">
        delete from employee where id = #{id}
    </update>
    <!--
        insert：配置新增的SQL语句
            insert,update,delete 执行结果都是行数,数据类型固定位int无需配置结果集
            parameterType属性: SQL语句有参数的,参数存储在JavaBean对象
        注意: SQL语句的参数占位符 #{}，参数是引用数据类型, JavaBean对象的字段名字
    -->
    <!--4.1 插入数据-->
    <insert id="insertEmployee" parameterType="Employee">
        insert into Employee values(#{id},#{name},#{salary})
    </insert>
    <!--4.2 插入数据获取自动增长的主键列-->
    <!--
          配置新增的SQL语句，获取新增的主键值，MySQL支持自动增长
          useGeneratedKeys属性: 是否使用新增的主键，属性的默认值是false,写成true
          keyProperty属性: 获取新增主键的存储位置,填写"javaBean对象的字段名"
    -->
    <insert id="insertEmployeeGetAutoKey" parameterType="Employee" keyProperty="id" useGeneratedKeys="true">
        insert into Employee values(#{id},#{name},#{salary})
    </insert>
    <!--4.3 插入数据，获取不自动增长的主键列-->
    <!--
        selectKey：配置获取新增的主键,数据库不支持自动增长的配置方式
            keyProperty属性: 获取新增主键的存储位置,填写"javaBean对象的字段名"
            resultType属性: 配置新增主键的数据类型
            order属性:顺序,获取新增主键的SQL语句的执行顺序,在insert之前还是之后
    -->
    <insert id="insertEmployeeGetNoAutoKey" parameterType="Employee">
        <selectKey keyProperty="id" resultType="Integer" order="AFTER" >
            select last_insert_id()
        </selectKey>
        insert into employee values(#{id},#{name},#{salary})
    </insert>
    
</mapper>

 

　　(3) 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>
    <!--引入外部配置文件-->
    <properties resource="db.properties"></properties>
    <!--配置包扫描-->
    <typeAliases>
        <package name="com.atguigu.pojo"/>
        <!--<typeAlias type="com.atguigu.pojo.Employee" alias="Employee"/>-->
    </typeAliases>
    <!--
        environments：配置数据源环境
            数据源环境分为：开发环境(development)、测试环境(test)、生产环境(produce)
            default属性：配置默认的数据源环境
    -->
    <environments default="development">
        <!--
            environments：配置单个开发环境
            id属性：配置开发环境
        -->
        <environment id="development">
            <!--
                transactionManager：事务管理器
                    type属性：
                        type="JDBC"：配置含义,MyBatis框架使用的是最原始的JDBC事务管理
                            Connection接口的方法：setAutoCommit,commit,rollback

                    type="MANAGERED"：的含义：MyBaits框架不使用事物
                        将框架事务管理抛出去，交给其他框架处理，Spring框架AOP,切面编程
            -->
            <transactionManager type="JDBC"/>
            <!--
                dataSource：配置连接池
                    type="POOLED" 使用连接池
                    type="UNPOOLED" 不使用连接池，使用第三方连接池，druid,c3p0,dbcp
            -->
            <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>
        <!--配置Mapper映射文件路径-->
        <mapper resource="EmployeeMapper.xml"/>
    </mappers>
</configuration>

2. 创建pojo类

package com.atguigu.pojo;

import lombok.Data;

@Data
public class Employee {
    private Integer id;
    private String name;
    private Double salary;
}

3. 测试类

public class MainTest {
    private SqlSessionFactory sqlSessionFactory;
    @Before
    public void test() throws IOException {
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }
    //1.1查询所有员工信息
    @Test
    public void queryEmployee(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<Employee> employeeList = sqlSession.selectList("employeeMapper.queryEmployee");
        for (Employee employee : employeeList) {
            System.out.println("employee = " + employee);
        }
        sqlSession.close();
    }
    //1.2查询员工信息，根据id刷选
    @Test
    public void queryEmployeeById(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Employee employee = sqlSession.selectOne("employeeMapper.queryEmployeeById", 1);
        System.out.println("employee = " + employee);
        sqlSession.close();
    }
    //1.3查询员工，根据名字模糊查询
    @Test
    public void queryEmployeeByLikeName(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<Employee> employeeList = sqlSession.selectList("employeeMapper.queryEmployeeByLikeName", "%o%");
        for (Employee employee : employeeList) {
            System.out.println("employee = " + employee);
        }
        sqlSession.close();
    }
    //2.1修改员工数据
    @Test
    public void updateEmployeeById(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Employee employee = new Employee();
        employee.setId(6);
        employee.setName("孙尚香");
        employee.setSalary(890D);
        sqlSession.insert("employeeMapper.updateEmployeeById",employee);
        sqlSession.commit();
        sqlSession.close();
    }
    //3.1删除员工数据
    @Test
    public void deleteEmployeeById(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        sqlSession.delete("employeeMapper.deleteEmployeeById",11);
        sqlSession.commit();
        sqlSession.close();
    }
    //4.1 插入数据
    @Test
    public void insertEmployee(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Employee employee = new Employee();
        employee.setName("孙权");
        employee.setSalary(6879D);
        sqlSession.insert("employeeMapper.insertEmployee",employee);
        System.out.println("employee = " + employee);
        sqlSession.commit();
        sqlSession.close();
    }
    //4.2 插入数据获取自动增长的主键列
    @Test
    public void insertEmployeeGetAutoKey(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Employee employee = new Employee();
        employee.setName("孙权");
        employee.setSalary(6879D);
        sqlSession.insert("employeeMapper.insertEmployeeGetAutoKey",employee);
        System.out.println("employee = " + employee);
        sqlSession.commit();
        sqlSession.close();
    }
    //4.3 插入数据，获取不自动增长的主键列
    @Test
    public void insertEmployeeGetNoAutoKey(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Employee employee = new Employee();
        employee.setName("孙权");
        employee.setSalary(6879D);
        sqlSession.insert("employeeMapper.insertEmployeeGetNoAutoKey",employee);
        System.out.println("employee = " + employee);
        sqlSession.commit();
        sqlSession.close();
    }
}

  原文：

https://www.cnblogs.com/pdjdghrs/p/15509278.html