Mybatis学习笔记一

<?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.yyb</groupId>
    <artifactId>mybitis</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.2.7</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.8</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>mybatis</finalName>
        <!--配置jdk版本为1.8-->
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

<?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>
    <!-- 和spring整合后 environments配置将废除 -->
    <environments default="development">
        <environment id="development">
            <!-- 使用jdbc事务管理 -->
            <transactionManager type="JDBC" />
            <!-- 数据库连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url"
                    value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>
</configuration>

<?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，用于隔离sql，还有一个很重要的作用，后面会讲 -->
<mapper namespace="test">
    <!-- id:statement的id 或者叫做sql的id-->
    <!-- parameterType:声明输入参数的类型 -->
    <!-- resultType:声明输出结果的类型，应该填写pojo的全路径 -->
    <!-- #{}：输入参数的占位符，相当于jdbc的？ -->
    <select id="queryUserById" parameterType="int"  resultType="com.yyb.pojo.User">
        SELECT * FROM user WHERE id  = #{id}
    </select>
</mapper>

package com.yyb.test;
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;


/**
 * Created by Administrator on 2017/8/15.
 */
public class Test {
    @org.junit.Test
    public void func1() {
        String path = "SqlMapConfig.xml";
        InputStream resourceAsStream = null;
        try {
            // 1. 加载SqlMapConfig.xml配置文件
            resourceAsStream = Resources.getResourceAsStream(path);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 2. 创建SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //3. 创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        // 4. 执行SqlSession对象执行查询，获取结果User
        // 第一个参数是User.xml的statement的id，第二个参数是执行sql需要的参数；
        Object user = sqlSession.selectOne("test.queryUserById", 1);

        // 5. 打印结果
        System.out.println(user);

        // 6. 释放资源
        sqlSession.close();
    }
}

<!-- //根据用户名称模糊查询用户列表
    #{}    select * from user where id = ？    占位符  ? ==  ‘五‘
    ${}    select * from user where username like ‘%五%‘  字符串拼接
     区别主要是单引号的问题  #{}会加单引号  ${value}不会加单引号，名字必须为value
     -->
    <select id="findByUserName" parameterType="String" resultType="com.yyb.pojo.User">
        SELECT * FROM user WHERE username  like ‘%${value}%‘
        --也可以这样，防止SQL注入：SELECT * FROM user WHERE username  like "%"#{value}"%"

    </select>

    @org.junit.Test
    public void func2() {
        String path = "SqlMapConfig.xml";
        InputStream resourceAsStream = null;
        try {
            // 1. 加载SqlMapConfig.xml配置文件
            resourceAsStream = Resources.getResourceAsStream(path);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 2. 创建SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //3. 创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        // 4. 执行SqlSession对象执行查询，获取结果User
        // 第一个参数是User.xml的statement的id，第二个参数是执行sql需要的参数；
        List<User> users = sqlSession.selectList("test.findByUserName", "五");

        // 5. 打印结果
        System.out.println(users);

        // 6. 释放资源
        sqlSession.close();
    }

org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 3
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:70)

 <insert id="addUser" parameterType="com.yyb.pojo.User" >
      INSERT into USER(username,birthday,address,sex) VALUES (#{username},#{birthday},#{address},#{sex})
    </insert>

 @org.junit.Test
    public void func3() {
        String path = "SqlMapConfig.xml";
        InputStream resourceAsStream = null;
        try {
            // 1. 加载SqlMapConfig.xml配置文件
            resourceAsStream = Resources.getResourceAsStream(path);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 2. 创建SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //3. 创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        // 4. 执行SqlSession对象执行查询，获取结果User
        // 第一个参数是User.xml的statement的id，第二个参数是执行sql需要的参数；
        User user=new  User();
        user.setUsername("yyb");
        user.setSex("男");
        user.setBirthday(new Date());
        user.setAddress("cd");
       int i = sqlSession.insert("test.addUser",user);
        sqlSession.commit();
        // 5. 打印结果
        System.out.println(i);

        // 6. 释放资源
        sqlSession.close();
    }

 <insert id="addUser" parameterType="com.yyb.pojo.User" >
        <!-- selectKey 标签实现主键返回 -->
        <!-- keyColumn:主键对应的表中的哪一列 -->
        <!-- keyProperty：主键对应的pojo中的哪一个属性 -->
        <!-- order：设置在执行insert语句前执行查询id的sql，该值在执行insert语句之后执行查询id的sql -->
        <!-- resultType：设置返回的id的类型 -->
        <selectKey keyColumn="id" keyProperty="id" order="AFTER" resultType="int">
            SELECT LAST_INSERT_ID()
        </selectKey>
      INSERT into USER(username,birthday,address,sex) VALUES (#{username},#{birthday},#{address},#{sex})
    </insert>

System.out.println(user.getId());

    <update id="updateUser" parameterType="com.yyb.pojo.User" >
      UPDATE USER SET username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} WHERE id = #{id}
    </update>

 @org.junit.Test
    public void func4() {
        String path = "SqlMapConfig.xml";
        InputStream resourceAsStream = null;
        try {
            // 1. 加载SqlMapConfig.xml配置文件
            resourceAsStream = Resources.getResourceAsStream(path);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 2. 创建SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //3. 创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        // 4. 执行SqlSession对象执行查询，获取结果User
        // 第一个参数是User.xml的statement的id，第二个参数是执行sql需要的参数；
        User user=new  User();
        user.setId(28);
        user.setUsername("rhr");
        user.setSex("女");
        user.setBirthday(new Date());
        user.setAddress("cd");
        int i = sqlSession.update("test.updateUser",user);
        sqlSession.commit();
        // 5. 打印结果
        System.out.println(i);
        // 6. 释放资源
        sqlSession.close();
    }

 <delete id="deleteUser" parameterType="Integer" >
        DELETE FROM USER  WHERE  id=#{id}
    </delete>

 @org.junit.Test
    public void func5() {
        String path = "SqlMapConfig.xml";
        InputStream resourceAsStream = null;
        try {
            // 1. 加载SqlMapConfig.xml配置文件
            resourceAsStream = Resources.getResourceAsStream(path);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 2. 创建SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //3. 创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        // 4. 执行SqlSession对象执行查询，获取结果User
        // 第一个参数是User.xml的statement的id，第二个参数是执行sql需要的参数；
        int i = sqlSession.delete("test.deleteUser",28);
        sqlSession.commit();
        // 5. 打印结果
        System.out.println(i);
        // 6. 释放资源
        sqlSession.close();
    }

SqlSession session = sqlSessionFactory.openSession();

try {
     // do work
} finally {
    session.close();
}

public interface UserMapper {

    
    //遵循四个原则
    //接口 方法名  == User.xml 中 id 名
    //返回值类型  与  Mapper.xml文件中返回值类型要一致
    //方法的入参类型 与Mapper.xml中入参的类型要一致
    //命名空间 绑定此接口
    public User findUserById(Integer id);
    
}

<?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">
<!-- 写Sql语句   -->
<mapper namespace="com.itheima.mybatis.mapper.UserMapper">
    <!-- 通过ID查询一个用户 -->
    <select id="findUserById" parameterType="Integer" resultType="User">
        select * from user where id = #{id}
    </select>
</mapper>

    @Test
    public void testMapper() throws Exception {
        //加载核心配置文件
        String resource = "sqlMapConfig.xml";
        InputStream in = Resources.getResourceAsStream(resource);
        //创建SqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
        //创建SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        
        //SqlSEssion帮我生成一个实现类  （给接口）
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        
        
        User user = userMapper.findUserById(10);
        System.out.println(user);
    }

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8
jdbc.username=root
jdbc.password=root

<?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>
    <!-- 是用resource属性加载外部配置文件 -->
    <properties resource="db.properties">
        <!-- 在properties内部用property定义属性 -->
        <!-- 如果外部配置文件有该属性，则内部定义属性被外部属性覆盖 -->
        <property name="jdbc.username" value="root123" />
        <property name="jdbc.password" value="root123" />
    </properties>

    <!-- 和spring整合后 environments配置将废除 -->
    <environments default="development">
        <environment id="development">
            <!-- 使用jdbc事务管理 -->
            <transactionManager type="JDBC" />
            <!-- 数据库连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
        </environment>
    </environments>

    <!-- 加载映射文件 -->
    <mappers>
        <mapper resource="sqlmap/User.xml" />
        <mapper resource="mapper/UserMapper.xml" />
    </mappers>
</configuration>

    <typeAliases>
        <!-- 单个别名定义 -->
        <typeAlias alias="user" type="cn.itcast.mybatis.pojo.User" />
        <!-- 批量别名定义，扫描整个包下的类，别名为类名（大小写不敏感） -->
        <package name="cn.itcast.mybatis.pojo" />
        <package name="其它包" />
    </typeAliases>