MyBatis快速入门(简明浅析易懂)

create database mybatis;use mybatis;create table users(id int primary key auto_increment, name varchar(20), age int);insert into users (name,age) values('Tom',12);insert into users (name, age) values('Jack',11);

<?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/mybatis" /><property name="username" value="root" /><property name="password" value="root" /></dataSource></environment></environments></configuration>

public class User {private int id;private String name;private int age;//get,set方法}

<?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.atguigu.mybatis_test.test1.userMapper"><select id="getUser" parameterType="int"resultType="com.atguigu.mybatis_test.test1.User">select * from users where id=#{id}</select></mapper>

<mappers><mapper resource="com/atguigu/mybatis_test/test1/userMapper.xml"/></mappers>

public class Test {public static void main(String[] args) throws IOException {String resource = "conf.xml";//加载mybatis的配置文件（它也加载关联的映射文件）Reader reader = Resources.getResourceAsReader(resource);//构建sqlSession的工厂SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);//创建能执行映射文件中sql的sqlSessionSqlSession session = sessionFactory.openSession();//映射sql的标识字符串String statement = "com.atguigu.mybatis.bean.userMapper"+".selectUser";//执行查询返回一个唯一user对象的sqlUser user = session.selectOne(statement, 1);System.out.println(user);}}

<insert id="insertUser" parameterType="com.atguigu.ibatis.bean.User">insert into users(name, age) values(#{name}, #{age});</insert><delete id="deleteUser" parameterType="int">delete from users where id=#{id}</delete><update id="updateUser" parameterType="com.atguigu.ibatis.bean.User">update users set name=#{name},age=#{age} where id=#{id}</update><select id="selectUser" parameterType="int" resultType="com.atguigu.ibatis.bean.User">select * from users where id=#{id}</select><select id="selectAllUsers" resultType="com.atguigu.ibatis.bean.User">select * from users</select>

<mapper resource=" com/atguigu/ibatis/bean/userMapper.xml"/>

public User getUserById(int id) {SqlSession session = sessionFactory.openSession();User user = session.selectOne(URI+".selectUser", id);return user;}

public interface UserMapper {@Insert("insert into users(name, age) values(#{name}, #{age})")public int insertUser(User user);@Delete("delete from users where id=#{id}")public int deleteUserById(int id);@Update("update users set name=#{name},age=#{age} where id=#{id}")public int updateUser(User user);@Select("select * from users where id=#{id}")public User getUserById(int id);@Select("select * from users")public List<User> getAllUser();}

<mapper class="com.atguigu.ibatis.crud.ano.UserMapper"/>

public User getUserById(int id) {SqlSession session = sessionFactory.openSession();UserMapper mapper = session.getMapper(UserMapper.class);User user = mapper.getUserById(id);return user;}

## db.properties<br><properties resource="db.properties"/><property name="driver" value="${driver}" /><property name="url" value="${url}" /><property name="username" value="${username}" /><property name="password" value="${password}" />

<typeAliases><typeAlias type="com.atguigu.ibatis.bean.User" alias="_User"/></typeAliases>

log4j.properties，log4j.rootLogger=DEBUG, Console#Consolelog4j.appender.Console=org.apache.log4j.ConsoleAppenderlog4j.appender.Console.layout=org.apache.log4j.PatternLayoutlog4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%nlog4j.logger.java.sql.ResultSet=INFOlog4j.logger.org.apache=INFOlog4j.logger.java.sql.Connection=DEBUGlog4j.logger.java.sql.Statement=DEBUGlog4j.logger.java.sql.PreparedStatement=DEBUG

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"><log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/"><appender name="STDOUT" class="org.apache.log4j.ConsoleAppender"><layout class="org.apache.log4j.PatternLayout"><param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) /n" /></layout></appender><logger name="java.sql"><level value="debug" /></logger><logger name="org.apache.ibatis"><level value="debug" /></logger><root><level value="debug" /><appender-ref ref="STDOUT" /></root></log4j:configuration>

CREATE TABLE orders(order_id INT PRIMARY KEY AUTO_INCREMENT,order_no VARCHAR(20),order_price FLOAT);INSERT INTO orders(order_no, order_price) VALUES('aaaa', 23);INSERT INTO orders(order_no, order_price) VALUES('bbbb', 33);INSERT INTO orders(order_no, order_price) VALUES('cccc', 22);

public class Order {private int id;private String orderNo;private float price;}

<select id="selectOrder" parameterType="int" resultType="_Order">select order_id id, order_no orderNo,order_price price from orders where order_id=#{id}</select>

<select id="selectOrderResultMap" parameterType="int" resultMap="orderResultMap">select * from orders where order_id=#{id}</select><resultMap type="_Order" id="orderResultMap"><id property="id" column="order_id"/><result property="orderNo" column="order_no"/><result property="price" column="order_price"/></resultMap>

CREATE TABLE teacher(t_id INT PRIMARY KEY AUTO_INCREMENT,t_name VARCHAR(20));CREATE TABLE class(c_id INT PRIMARY KEY AUTO_INCREMENT,c_name VARCHAR(20),teacher_id INT);ALTER TABLE class ADD CONSTRAINT fk_teacher_id FOREIGN KEY (teacher_id) REFERENCES teacher(t_id); INSERT INTO teacher(t_name) VALUES('LS1');INSERT INTO teacher(t_name) VALUES('LS2');INSERT INTO class(c_name, teacher_id) VALUES('bj_a', 1);INSERT INTO class(c_name, teacher_id) VALUES('bj_b', 2);

public class Teacher {private int id;private String name;}public class Classes {private int id;private String name;private Teacher teacher;}

<!--方式一: 嵌套结果: 使用嵌套结果映射来处理重复的联合结果的子集SELECT * FROM class c, teacher t,student s WHERE c.teacher_id=t.t_id AND c.C_id=s.class_id AND c.c_id=1--><select id="getClass3" parameterType="int" resultMap="ClassResultMap3">select * from class c, teacher t,student s where c.teacher_id=t.t_id and c.C_id=s.class_id and c.c_id=#{id}</select><resultMap type="_Classes" id="ClassResultMap3"><id property="id" column="c_id"/><result property="name" column="c_name"/><association property="teacher" column="teacher_id" javaType="_Teacher"><id property="id" column="t_id"/><result property="name" column="t_name"/></association><!-- ofType指定students集合中的对象类型 --><collection property="students" ofType="_Student"><id property="id" column="s_id"/><result property="name" column="s_name"/></collection></resultMap><!--方式二：嵌套查询：通过执行另外一个SQL映射语句来返回预期的复杂类型SELECT * FROM class WHERE c_id=1;SELECT * FROM teacher WHERE t_id=1 //1 是上一个查询得到的teacher_id的值SELECT * FROM student WHERE class_id=1 //1是第一个查询得到的c_id字段的值--><select id="getClass4" parameterType="int" resultMap="ClassResultMap4">select * from class where c_id=#{id}</select><resultMap type="_Classes" id="ClassResultMap4"><id property="id" column="c_id"/><result property="name" column="c_name"/><association property="teacher" column="teacher_id" javaType="_Teacher" select="getTeacher2"></association><collection property="students" ofType="_Student" column="c_id" select="getStudent"></collection></resultMap><select id="getTeacher2" parameterType="int" resultType="_Teacher">SELECT t_id id, t_name name FROM teacher WHERE t_id=#{id}</select><select id="getStudent" parameterType="int" resultType="_Student">SELECT s_id id, s_name name FROM student WHERE class_id=#{id}</select>

@Testpublic void testOO() {SqlSession sqlSession = factory.openSession();Classes c = sqlSession.selectOne("com.atguigu.day03_mybatis.test5.OOMapper.getClass", 1);System.out.println(c);}@Testpublic void testOO2() {SqlSession sqlSession = factory.openSession();Classes c = sqlSession.selectOne("com.atguigu.day03_mybatis.test5.OOMapper.getClass2", 1);System.out.println(c);}

CREATE TABLE student(s_id INT PRIMARY KEY AUTO_INCREMENT,s_name VARCHAR(20),class_id INT);INSERT INTO student(s_name, class_id) VALUES('xs_A', 1);INSERT INTO student(s_name, class_id) VALUES('xs_B', 1);INSERT INTO student(s_name, class_id) VALUES('xs_C', 1);INSERT INTO student(s_name, class_id) VALUES('xs_D', 2);INSERT INTO student(s_name, class_id) VALUES('xs_E', 2);INSERT INTO student(s_name, class_id) VALUES('xs_F', 2);

public class Student {private int id;private String name;}public class Classes {private int id;private String name;private Teacher teacher;private List<Student> students;}

<!--方式一: 嵌套结果: 使用嵌套结果映射来处理重复的联合结果的子集SELECT * FROM class c, teacher t,student s WHERE c.teacher_id=t.t_id AND c.C_id=s.class_id AND c.c_id=1--><select id="getClass3" parameterType="int" resultMap="ClassResultMap3">select * from class c, teacher t,student s where c.teacher_id=t.t_id and c.C_id=s.class_id and c.c_id=#{id}</select><resultMap type="_Classes" id="ClassResultMap3"><id property="id" column="c_id"/><result property="name" column="c_name"/><association property="teacher" column="teacher_id" javaType="_Teacher"><id property="id" column="t_id"/><result property="name" column="t_name"/></association><!-- ofType指定students集合中的对象类型 --><collection property="students" ofType="_Student"><id property="id" column="s_id"/><result property="name" column="s_name"/></collection></resultMap><!--方式二：嵌套查询：通过执行另外一个SQL映射语句来返回预期的复杂类型SELECT * FROM class WHERE c_id=1;SELECT * FROM teacher WHERE t_id=1 //1 是上一个查询得到的teacher_id的值SELECT * FROM student WHERE class_id=1 //1是第一个查询得到的c_id字段的值--><select id="getClass4" parameterType="int" resultMap="ClassResultMap4">select * from class where c_id=#{id}</select><resultMap type="_Classes" id="ClassResultMap4"><id property="id" column="c_id"/><result property="name" column="c_name"/><association property="teacher" column="teacher_id" javaType="_Teacher" select="getTeacher2"></association><collection property="students" ofType="_Student" column="c_id" select="getStudent"></collection></resultMap><select id="getTeacher2" parameterType="int" resultType="_Teacher">SELECT t_id id, t_name name FROM teacher WHERE t_id=#{id}</select><select id="getStudent" parameterType="int" resultType="_Student">SELECT s_id id, s_name name FROM student WHERE class_id=#{id}</select>

@Testpublic void testOM() {SqlSession sqlSession = factory.openSession();Classes c = sqlSession.selectOne("com.atguigu.day03_mybatis.test5.OOMapper.getClass3", 1);System.out.println(c);}@Testpublic void testOM2() {SqlSession sqlSession = factory.openSession();Classes c = sqlSession.selectOne("com.atguigu.day03_mybatis.test5.OOMapper.getClass4", 1);System.out.println(c);}

create table d_user( id int primary key auto_increment, name varchar(10),age int(3));insert into d_user(name,age) values('Tom',12); insert into d_user(name,age) values('Bob',13); insert into d_user(name,age) values('Jack',18);7.3.ConditionUser(查询条件实体类)private String name;private int minAge;private int maxAge;

private int id;private String name;private int age;

<?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.atguigu.day03_mybatis.test6.userMapper"><select id="getUser" parameterType="com.atguigu.day03_mybatis.test6.ConditionUser" resultType="com.atguigu.day03_mybatis.test6.User">select * from d_user where age>=#{minAge} and age<=#{maxAge}<if test='name!="%null%"'>and name like #{name}</if></select></mapper>

public class UserTest {public static void main(String[] args) throws IOException {Reader reader = Resources.getResourceAsReader("conf.xml");SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);SqlSession sqlSession = sessionFactory.openSession();String statement = "com.atguigu.day03_mybatis.test6.userMapper.getUser";List<User> list = sqlSession.selectList(statement, new ConditionUser("%a%", 1, 12));System.out.println(list);}}

create table p_user( id int primary key auto_increment, name varchar(10),sex char(2));insert into p_user(name,sex) values('A',"男"); insert into p_user(name,sex) values('B',"女"); insert into p_user(name,sex) values('C',"男"); #创建存储过程(查询得到男性或女性的数量, 如果传入的是0就女性否则是男性)DELIMITER $CREATE PROCEDURE mybatis.ges_user_count(IN sex_id INT, OUT user_count INT)BEGIN IF sex_id=0 THENSELECT COUNT(*) FROM mybatis.p_user WHERE p_user.sex='女' INTO user_count;ELSESELECT COUNT(*) FROM mybatis.p_user WHERE p_user.sex='男' INTO user_count;END IF;END$#调用存储过程DELIMITER ;SET @user_count = 0;CALL mybatis.ges_user_count(1, @user_count);SELECT @user_count;

public class User {private String id;private String name;private String sex;}

<mapper namespace="com.atguigu.mybatis.test7.userMapper"><!--查询得到男性或女性的数量, 如果传入的是0就女性否则是男性CALL mybatis.get_user_count(1, @user_count);--><select id="getCount" statementType="CALLABLE" parameterMap="getCountMap">call mybatis.get_user_count(?,?)</select><parameterMap type="java.util.Map" id="getCountMap"><parameter property="sex_id" mode="IN" jdbcType="INTEGER"/><parameter property="user_count" mode="OUT" jdbcType="INTEGER"/></parameterMap></mapper>

Map<String, Integer> paramMap = new HashMap<>();paramMap.put("sex_id", 0);session.selectOne(statement, paramMap);Integer userCount = paramMap.get("user_count");System.out.println(userCount);

CREATE TABLE c_user(id INT PRIMARY KEY AUTO_INCREMENT,NAME VARCHAR(20),age INT);INSERT INTO c_user(NAME, age) VALUES('Tom', 12);INSERT INTO c_user(NAME, age) VALUES('Jack', 11);

public class User implements Serializable{private int id;private String name;private int age;

<?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.atguigu.mybatis.test8.userMapper"><select id="getUser" parameterType="int" resultType="_CUser">select * from c_user where id=#{id}</select><update id="updateUser" parameterType="_CUser">update c_user setname=#{name}, age=#{age} where id=#{id}</update></mapper>

/** 一级缓存: 也就Session级的缓存(默认开启)*/@Testpublic void testCache1() {SqlSession session = MybatisUtils.getSession();String statement = "com.atguigu.mybatis.test8.userMapper.getUser";User user = session.selectOne(statement, 1);System.out.println(user);/** 一级缓存默认就会被使用*//*user = session.selectOne(statement, 1);System.out.println(user);*//*1. 必须是同一个Session,如果session对象已经close()过了就不可能用了*//*session = MybatisUtils.getSession();user = session.selectOne(statement, 1);System.out.println(user);*//*2. 查询条件是一样的*//*user = session.selectOne(statement, 2);System.out.println(user);*//*3. 没有执行过session.clearCache()清理缓存*//*session.clearCache();user = session.selectOne(statement, 2);System.out.println(user);*//*4. 没有执行过增删改的操作(这些操作都会清理缓存)*//*session.update("com.atguigu.mybatis.test8.userMapper.updateUser",new User(2, "user", 23));user = session.selectOne(statement, 2);System.out.println(user);*/}

<mapper namespace="com.atguigu.mybatis.test8.userMapper"><cache/>

/** 测试二级缓存*/@Testpublic void testCache2() {String statement = "com.atguigu.mybatis.test8.userMapper.getUser";SqlSession session = MybatisUtils.getSession();User user = session.selectOne(statement, 1);session.commit();System.out.println("user="+user);SqlSession session2 = MybatisUtils.getSession();user = session2.selectOne(statement, 1);session.commit();System.out.println("user2="+user);}

<cacheeviction="FIFO" //回收策略为先进先出flushInterval="60000" //自动刷新时间60ssize="512" //最多缓存512个引用对象readOnly="true"/> //只读

CREATE TABLE s_user(user_id INT AUTO_INCREMENT PRIMARY KEY,user_name VARCHAR(30),user_birthday DATE,user_salary DOUBLE)

public class User {private int id;private String name;private Date birthday;private double salary;//set,get方法}

public interface UserMapper {void save(User user);void update(User user);void delete(int id);User findById(int id);List<User> findAll();}

<?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.atguigu.mybatis.test9.UserMapper"><resultMap type="User" id="userResult"><result column="user_id" property="id"/><result column="user_name" property="name"/><result column="user_birthday" property="birthday"/><result column="user_salary" property="salary"/></resultMap><!-- 取得插入数据后的id --><insert id="save" keyColumn="user_id" keyProperty="id" useGeneratedKeys="true">insert into s_user(user_name,user_birthday,user_salary)values(#{name},#{birthday},#{salary})</insert><update id="update">update s_userset user_name = #{name},user_birthday = #{birthday},user_salary = #{salary}where user_id = #{id}</update><delete id="delete">delete from s_userwhere user_id = #{id}</delete><select id="findById" resultMap="userResult">select *from s_userwhere user_id = #{id}</select><select id="findAll" resultMap="userResult">select *from s_user</select></mapper>

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context"xmlns:tx="http://www.springframework.org/schema/tx"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-3.2.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-3.2.xsdhttp://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx-3.2.xsd"><!-- 1. 数据源 : DriverManagerDataSource --><bean id="dataSource"class="org.springframework.jdbc.datasource.DriverManagerDataSource"><property name="driverClassName" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/mybatis"/><property name="username" value="root"/><property name="password" value="root"/></bean><!--2. mybatis的SqlSession的工厂: SqlSessionFactoryBeandataSource / typeAliasesPackage--><bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"><property name="dataSource" ref="dataSource"/><property name="typeAliasesPackage" value="com.atuigu.spring_mybatis2.domain"/></bean><!--3. mybatis自动扫描加载Sql映射文件 : MapperScannerConfigurersqlSessionFactory / basePackage--><bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"><property name="basePackage" value="com.atuigu.spring_mybatis2.mapper"/><property name="sqlSessionFactory" ref="sqlSessionFactory"/></bean><!-- 4. 事务管理 : DataSourceTransactionManager --><bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"><property name="dataSource" ref="dataSource"/></bean><!-- 5. 使用声明式事务 --><tx:annotation-driven transaction-manager="txManager" /></beans>

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><!-- Spring整合myBatis后，这个配置文件基本可以不要了--><!-- 设置外部配置文件 --><!-- 设置类别名 --><!-- 设置数据库连接环境 --><!-- 映射文件 --></configuration>

@RunWith(SpringJUnit4ClassRunner.class) //使用Springtest测试框架@ContextConfiguration("/beans.xml") //加载配置public class SMTest {@Autowired //注入private UserMapper userMapper;@Testpublic void save() {User user = new User();user.setBirthday(new Date());user.setName("marry");user.setSalary(300);userMapper.save(user);System.out.println(user.getId());}@Testpublic void update() {User user = userMapper.findById(2);user.setSalary(2000);userMapper.update(user);}@Testpublic void delete() {userMapper.delete(3);}@Testpublic void findById() {User user = userMapper.findById(1);System.out.println(user);}@Testpublic void findAll() {List<User> users = userMapper.findAll();System.out.println(users);}}