• JAVA mybatis操作mysql——批量增加，批量删除，多条件模糊搜索，新增时返回id和常用的增删查改

    目录

    1 Moven配置文件

    2 mybatis.xml

    3 实体类

    4 SqlSessionUtils工具类 

    5 UserMapper.xml文件 

    6 UserMapper接口

    7 UserMapperTest测试类 

    8 表SQL文件 

    9 项目结构 

    10 将数据库配置从mybatis中抽离出来 

    11 关系（一对一，一对多，多对多）

    12 注解开发 

    13 一级二级缓存

    自己写个清单，比较基础但是也可能有不对的地方

    1 Moven配置文件

    1.  
    2.  
    3.     <dependencies>
    5.         <dependency>
    6.             <groupId>org.mybatisgroupId>
    7.             <artifactId>mybatisartifactId>
    8.             <version>3.5.11version>
    9.         dependency>
    10.         
    11.         
    12.         <dependency>
    13.             <groupId>mysqlgroupId>
    14.             <artifactId>mysql-connector-javaartifactId>
    15.             <version>8.0.28version>
    16.         dependency>
    17.         <dependency>
    18.             <groupId>junitgroupId>
    19.             <artifactId>junitartifactId>
    20.             <version>RELEASEversion>
    21.             <scope>testscope>
    22.         dependency>
    23.     dependencies>
    24.  
    25.     <build>
    26.         <resources>
    27.             <resource>
    28.                 <directory>src/main/javadirectory>
    29.                 <includes>
    30.                     <include>**/*.propertiesinclude>
    31.                     <include>**/*.xmlinclude>
    32.                 includes>
    33.                 <filtering>truefiltering>
    34.             resource>
    35.             <resource>
    36.                 <directory>src/main/resourcesdirectory>
    37.                 <includes>
    38.                     <include>**/*.propertiesinclude>
    39.                     <include>**/*.xmlinclude>
    40.                 includes>
    41.                 <filtering>truefiltering>
    42.             resource>
    43.         resources>
    44.     build>

    2 mybatis.xml

    1. "1.0" encoding="UTF-8" ?>
    2.  
    4. configuration
    5.         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    6.         "http://mybatis.org/dtd/mybatis-3-config.dtd">
    8. <configuration>
    10.     <environments default="development">
    11.         <environment id="development">
    15.             <transactionManager type="JDBC"/>
    17.             <dataSource type="POOLED">
    19.                 <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
    20.                 <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
    21.                 <property name="username" value="root"/>
    22.                 <property name="password" value="scm13503905942"/>
    23.             dataSource>
    24.         environment>
    25.     environments>
    26.  
    27.     <mappers>
    30.         <package name="com.learn.mapper"/>
    31.     mappers>
    32. configuration>

    3 实体类

    User实体类

    1. package com.learn.entity;
    2.  
    3. import java.util.Date;
    4. import java.util.List;
    5.  
    6. public class User {
    7.     private Integer id;
    8.     private String username;// 用户姓名
    9.     private String sex;// 性别
    10.     private Date birthday;// 生日
    11.     private String address;// 地址
    12.  
    13.     public User() {
    14.     }
    15.  
    16.     public User(Integer id, String username, String sex, Date birthday, String address) {
    17.         this.id = id;
    18.         this.username = username;
    19.         this.sex = sex;
    20.         this.birthday = birthday;
    21.         this.address = address;
    22.     }
    23.  
    24.     /**
    25.      * 获取
    26.      * @return id
    27.      */
    28.     public Integer getId() {
    29.         return id;
    30.     }
    31.  
    32.     /**
    33.      * 设置
    34.      * @param id
    35.      */
    36.     public void setId(Integer id) {
    37.         this.id = id;
    38.     }
    39.  
    40.     /**
    41.      * 获取
    42.      * @return username
    43.      */
    44.     public String getUsername() {
    45.         return username;
    46.     }
    47.  
    48.     /**
    49.      * 设置
    50.      * @param username
    51.      */
    52.     public void setUsername(String username) {
    53.         this.username = username;
    54.     }
    55.  
    56.     /**
    57.      * 获取
    58.      * @return sex
    59.      */
    60.     public String getSex() {
    61.         return sex;
    62.     }
    63.  
    64.     /**
    65.      * 设置
    66.      * @param sex
    67.      */
    68.     public void setSex(String sex) {
    69.         this.sex = sex;
    70.     }
    71.  
    72.     /**
    73.      * 获取
    74.      * @return birthday
    75.      */
    76.     public Date getBirthday() {
    77.         return birthday;
    78.     }
    79.  
    80.     /**
    81.      * 设置
    82.      * @param birthday
    83.      */
    84.     public void setBirthday(Date birthday) {
    85.         this.birthday = birthday;
    86.     }
    87.  
    88.     /**
    89.      * 获取
    90.      * @return address
    91.      */
    92.     public String getAddress() {
    93.         return address;
    94.     }
    95.  
    96.     /**
    97.      * 设置
    98.      * @param address
    99.      */
    100.     public void setAddress(String address) {
    101.         this.address = address;
    102.     }
    103.  
    104.     public String toString() {
    105.         return "User{id = " + id + ", username = " + username + ", sex = " + sex + ", birthday = " + birthday + ", address = " + address + "}";
    106.     }
    107.  
    108. }

    UserExt实体类

    1. package com.learn.entity;
    2.  
    3. //如果传入的参数够多，可以将参数再包装一次
    4. public class UserExt {
    5.     private User user;
    6.     private String characteristic;
    7.  
    8.  
    9.     public UserExt() {
    10.     }
    11.  
    12.     public UserExt(User user, String characteristic) {
    13.         this.user = user;
    14.         this.characteristic = characteristic;
    15.     }
    16.  
    17.     /**
    18.      * 获取
    19.      * @return user
    20.      */
    21.     public User getUser() {
    22.         return user;
    23.     }
    24.  
    25.     /**
    26.      * 设置
    27.      * @param user
    28.      */
    29.     public void setUser(User user) {
    30.         this.user = user;
    31.     }
    32.  
    33.     /**
    34.      * 获取
    35.      * @return characteristic
    36.      */
    37.     public String getCharacteristic() {
    38.         return characteristic;
    39.     }
    40.  
    41.     /**
    42.      * 设置
    43.      * @param characteristic
    44.      */
    45.     public void setCharacteristic(String characteristic) {
    46.         this.characteristic = characteristic;
    47.     }
    48.  
    49.     public String toString() {
    50.         return "UserExt{user = " + user + ", characteristic = " + characteristic + "}";
    51.     }
    52. }

    4 SqlSessionUtils工具类 

    1. package com.learn.utils;
    2.  
    3. import org.apache.ibatis.io.Resources;
    4. import org.apache.ibatis.session.SqlSession;
    5. import org.apache.ibatis.session.SqlSessionFactory;
    6. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    7.  
    8. import java.io.IOException;
    9. import java.io.InputStream;
    10.  
    11. public class SqlSessionUtils {
    12.     static SqlSessionFactory sqlSessionFactory;
    13.  
    14.     static {
    15.  
    16.         String path = "mybatis.xml";
    17.         InputStream ins = null;
    18.         try {
    19.             ins = Resources.getResourceAsStream(path);
    20.         } catch (IOException e) {
    21.             throw new RuntimeException(e);
    22.         }
    23.         sqlSessionFactory = new SqlSessionFactoryBuilder().build(ins);
    24.     }
    25.  
    26.     public static SqlSession getSqlSes() {
    27.         return sqlSessionFactory.openSession();
    28.     }
    29.  
    30.     public static void closeSqlSes(SqlSession sqlSession) {
    31.         if (sqlSession != null) {
    32.             sqlSession.close();
    33.         }
    34.     }
    35. }

    5 UserMapper.xml文件 

    1. "1.0" encoding="UTF-8"?>
    2. mapper
    3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    5. <mapper namespace="com.learn.mapper.UserMapper">
    6.     
    7.     <select id="selectUserById" resultType="com.learn.entity.User">
    8.         select * from user
    9.         <where>
    10.             id=#{id}
    11.         where>
    12.     select>
    13.  
    14.     
    15.     <select id="selectUserBySexAndAddress" resultType="com.learn.entity.User">
    16.         select *
    17.         from user
    18.         where sex = #{sex}
    19.           and address = #{address}
    20.     select>
    21.  
    22.     
    23.     <select id="selectUserByUserNameAndSexDim" resultType="com.learn.entity.User">
    24.         select * from user
    25.         <where>
    26.             <if test="null!=username">
    27.                 and username like concat('%',#{username},'%')
    28.             if>
    29.             <if test="null!=sex">
    30.                 and sex like concat('%',#{sex},'%')
    31.             if>
    32.         where>
    33.     select>
    34.  
    35.     
    36.     <select id="selectAll" resultType="com.learn.entity.User">
    37.         select *
    38.         from user
    39.     select>
    40.  
    41.     
    42.     <select id="selectUserBySexAndNameDim2" parameterType="com.learn.entity.UserExt" resultType="com.learn.entity.User">
    43.         select * from user
    44.         <where>
    45.             <if test="null!=user.sex">
    46.                 and sex like '%${user.sex}%'
    47.             if>
    48.             <if test="null!=user.username">
    49.                 and username like '%${user.username}%'
    50.             if>
    51.         where>
    52.     select>
    53.  
    54.  
    62.  
    64.     
    65.     
    66.     <update id="updateUser" parameterType="com.learn.entity.User">
    67.         update user
    68.         <set>
    69.             <if test="username!=null">
    70.                 username=#{username},
    71.             if>
    72.             <if test="username!=null">
    73.                 birthday=#{birthday},
    74.             if>
    75.             <if test="sex!=null">
    76.                 sex=#{sex},
    77.             if>
    78.             <if test="address!=null">
    79.                 address=#{address}
    80.             if>
    81.         set>
    82.         where id=#{id}
    83.     update>
    84.  
    85.     
    86.     <insert id="insertUser" parameterType="com.learn.entity.User" useGeneratedKeys="true" keyProperty="AffeectIdList">
    87.         insert into user(id, username, birthday, sex, address)
    88.         values (#{id}, #{username}, #{birthday}, #{sex}, #{address})
    89.         
    90.         <selectKey keyProperty="id" order="AFTER" resultType="int">
    91.             SELECT LAST_INSERT_ID()
    92.         selectKey>
    93.     insert>
    94.  
    95.     
    96.     <insert id="insertMultitudeUser" parameterType="com.learn.entity.User">
    97.         insert into user(id, username, birthday, sex, address)
    98.         values
    99.         
    100.         <foreach collection="list" separator="," item="item">
    101.             (null, #{item.username}, #{item.birthday}, #{item.sex}, #{item.address})
    102.         foreach>
    103.     insert>
    104.  
    105.     
    106.     <delete id="removeUserById" parameterType="int">
    107.         delete
    108.         from user
    109.         <where>
    110.             id = #{id}
    111.         where>
    112.     delete>
    113.  
    114.  
    115.     
    116. mapper>

    6 UserMapper接口

    1. package com.learn.mapper;
    2.  
    3. import com.learn.entity.User;
    4. import com.learn.entity.UserExt;
    5. import org.apache.ibatis.annotations.Param;
    6.  
    7. import java.util.List;
    8.  
    9. public interface UserMapper {
    10.    //通过id查询
    11.    User selectUserById(int userId);
    12.    //通过性别和地址查询
    13.    List selectUserBySexAndAddress(@Param("sex") String sex, @Param("address") String address);
    14.    //通过用户名和性别模糊查询
    15.    List selectUserByUserNameAndSexDim(@Param("username") String userName,@Param("sex") String sex);
    16.    //通过传递包装类模糊查询
    17.    List  selectUserBySexAndNameDim2(UserExt userExt);
    18.    //查询所有
    19.    List selectAll();
    20.    //修改
    21.    int updateUser(User user);
    22.    //插入数据，返回插入id
    23.    int insertUser(User user);
    24.    //删除
    25.    int removeUserById(int userId);
    26.    //批量插入
    27.    int insertMultitudeUser(List user);
    28.    //批量删除
    29.    int removeMultitudeUser(int[] userIdArr);
    30.  
    31. }

    7 UserMapperTest测试类 

    1. package com.learn.test;
    2. import com.learn.entity.User;
    3. import com.learn.entity.UserExt;
    4. import com.learn.mapper.UserMapper;
    5. import com.learn.utils.SqlSessionUtils;
    6. import org.apache.ibatis.session.SqlSession;
    7. import org.junit.AfterClass;
    8. import org.junit.BeforeClass;
    9. import org.junit.Test;
    10. import java.util.ArrayList;
    11. import java.util.Date;
    12. import java.util.List;
    13.  
    14. public class UserMapperTest {
    15.     static SqlSession session ;
    16.     //在所有测试方法执行之前执行（只执行一次）
    17.     @BeforeClass
    18.     public static void init() {
    19.         System.out.println("初始化完成！");
    20.         session=SqlSessionUtils.getSqlSes();
    21.     }
    22.     //在所有测试方法执行完成之后执行（只执行一次）
    23.     @AfterClass
    24.     public static void end()
    25.     {
    26.         SqlSessionUtils.closeSqlSes(session);
    27.     }
    28.     @Test
    29.     public void testSelectUserById() {
    30.         UserMapper userMapper = session.getMapper(UserMapper.class);
    31.         User user = userMapper.selectUserById(10);
    32.         System.out.println("根据ID查询");
    33.         System.out.println(user.toString());
    34.     }
    35.  
    36.     @Test
    37.     public void testSelectUserBySexAndAddress() {
    38.         UserMapper userMapper = session.getMapper(UserMapper.class);
    39.         userMapper.selectAll();
    40.         List users = userMapper.selectUserBySexAndAddress("女","河南郑州");
    41.         System.out.println("根据性别和地址查询");
    42.         for (User user : users) {
    43.             System.out.println(user.toString());
    44.         }
    45.     }
    46.  
    47.     @Test
    48.     public void testselectUserByUserNameAndSexDim() {
    49.         UserMapper userMapper = session.getMapper(UserMapper.class);
    50.         List users = userMapper.selectUserByUserNameAndSexDim("孙","男");
    51.         System.out.println("根据查询用户名和性别模糊查询");
    52.         for (User user : users) {
    53.             System.out.println(user.toString());
    54.         }
    55.     }
    56.     @Test
    57.     public void testselectUserBySexAndNameDim2() {
    58.         UserMapper userMapper = session.getMapper(UserMapper.class);
    59.         UserExt userExt=new UserExt(new User(null,"孙悟空","男",new Date(),"手机鞥"),"火");
    60.         List users = userMapper.selectUserBySexAndNameDim2(userExt);
    61.         System.out.println("通过传递包装类的方式根据查询用户名和性别模糊查询");
    62.         users.forEach(System.out::println);
    63.     }
    64.  
    65.     @Test
    66.     public void testSelectAll()
    67.     {
    68.         UserMapper userMapper = session.getMapper(UserMapper.class);
    69.         List users = userMapper.selectAll();
    70.         System.out.println("查询所有数据");
    71.         for (User user : users) {
    72.             System.out.println(user.toString());
    73.         }
    74.     }
    75.  
    76.     @Test
    77.     public void testUpdateUser()
    78.     {
    79.         UserMapper userMapper = session.getMapper(UserMapper.class);
    80.         User user=new User();
    81.         user.setId(30);
    82.         user.setSex("男");
    83.         user.setUsername("微微");
    84.         user.setBirthday(new Date());
    85.         int row = userMapper.updateUser(user);
    86.         //注意事务提交
    87.         session.commit();
    88.         System.out.println("更新数据");
    89.     }
    90.  
    91.     @Test
    92.     public void testInsertUser()
    93.     {
    94.         UserMapper userMapper = session.getMapper(UserMapper.class);
    95.         User user = new User();
    96.         user.setSex("女");
    97.         user.setUsername("梦鸽");
    98.         user.setBirthday(new Date());
    99.         System.out.println("插入数据："+userMapper.insertUser(user)+"条");
    100.         session.commit();
    101.         //注意这里，只有插入完成后必须通过对象.属性才能获取到新增id值
    102.         System.out.println("插入数据的id为:"+user.getId());
    103.     }
    104.     @Test
    105.     public void testInsertMultitudeUser()
    106.     {
    107.         UserMapper userMapper = session.getMapper(UserMapper.class);
    108.         List userList=new ArrayList<>();
    109.         userList.add(new User(null,"分割","男",new Date(),"七彩祥云1号楼"));
    110.         userList.add(new User(null,"茶几上的","男",new Date(),"七彩祥云2号楼"));
    111.         userList.add(new User(null,"所开发的","男",new Date(),"七彩祥云3号楼"));
    112.         userList.add(new User(null,"哦怕","男",new Date(),"七彩祥云4号楼"));
    113.         userList.add(new User(null,"说的","男",new Date(),"七彩祥云5号楼"));
    114.         int row=userMapper.insertMultitudeUser(userList);
    115.         session.commit();
    116.         System.out.println("批量插入数据："+row+"条");
    117.     }
    118.     @Test
    119.     public void testRemoveUserById()
    120.     {
    121.         UserMapper userMapper = session.getMapper(UserMapper.class);
    122.         int row = userMapper.removeUserById(36);
    123.         session.commit();
    124.         System.out.println("删除数据："+row+"条");
    125.     }
    126.  
    127.     @Test
    128.     public void testRemoveMultitudeUser()
    129.     {
    130.         List idArray = new ArrayList();
    131.         idArray.add(30);
    132.         idArray.add(31);
    133.         idArray.add(32);
    134.         UserMapper userMapper = session.getMapper(UserMapper.class);
    135.         for (Integer integer : idArray) {
    136.             userMapper.removeUserById(integer);
    137.         }
    138.         session.commit();
    139.         System.out.println("删除数据"+idArray.size()+"条");
    140.     }
    141. }

    8 表SQL文件 

    1.  
    2.  
    3. SET NAMES utf8mb4;
    4. SET FOREIGN_KEY_CHECKS = 0;
    5.  
    6. -- ----------------------------
    7. -- Table structure for user
    8. -- ----------------------------
    9. DROP TABLE IF EXISTS `user`;
    10. CREATE TABLE `user`  (
    11.   `id` int(11) NOT NULL AUTO_INCREMENT,
    12.   `username` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '用户名称',
    13.   `birthday` date NULL DEFAULT NULL COMMENT '生日',
    14.   `sex` char(1) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '性别',
    15.   `address` varchar(256) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '地址',
    16.   PRIMARY KEY (`id`) USING BTREE
    17. ) ENGINE = InnoDB AUTO_INCREMENT = 48 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
    18.  
    19. -- ----------------------------
    20. -- Records of user
    21. -- ----------------------------
    22. INSERT INTO `user` VALUES (1, '盛世名', NULL, '2', NULL);
    23. INSERT INTO `user` VALUES (10, '张三大牙', '2014-07-10', '女', '北京市');
    24. INSERT INTO `user` VALUES (16, '张吉东', NULL, '女', '河南郑州');
    25. INSERT INTO `user` VALUES (22, '孙训', NULL, '女', '河南郑州');
    26. INSERT INTO `user` VALUES (24, '周芷若', NULL, '女', '河南郑州');
    27. INSERT INTO `user` VALUES (28, '孙悟空', '2022-11-07', '男', '花果山1号');
    28. INSERT INTO `user` VALUES (29, '孙悟空', '2022-11-07', '男', '花果山1号');
    29. INSERT INTO `user` VALUES (33, '茶几上的', '2022-11-08', '男', '七彩祥云2号楼');
    30. INSERT INTO `user` VALUES (34, '所开发的', '2022-11-08', '男', '七彩祥云3号楼');
    31. INSERT INTO `user` VALUES (35, '哦怕', '2022-11-08', '男', '七彩祥云4号楼');
    32. INSERT INTO `user` VALUES (37, '梦鸽', '2022-11-08', '女', NULL);
    33. INSERT INTO `user` VALUES (38, '梦鸽', '2022-11-08', '女', NULL);
    34. INSERT INTO `user` VALUES (39, '梦鸽', '2022-11-08', '女', NULL);
    35. INSERT INTO `user` VALUES (41, '分割', '2022-11-08', '男', '七彩祥云1号楼');
    36. INSERT INTO `user` VALUES (42, '茶几上的', '2022-11-08', '男', '七彩祥云2号楼');
    37. INSERT INTO `user` VALUES (43, '所开发的', '2022-11-08', '男', '七彩祥云3号楼');
    38. INSERT INTO `user` VALUES (44, '哦怕', '2022-11-08', '男', '七彩祥云4号楼');
    39. INSERT INTO `user` VALUES (45, '说的', '2022-11-08', '男', '七彩祥云5号楼');
    40. INSERT INTO `user` VALUES (47, '梦鸽', '2022-11-08', '女', NULL);
    41.  
    42. SET FOREIGN_KEY_CHECKS = 1;

    9 项目结构 

    10 将数据库配置从mybatis中抽离出来 

    在resources中新建一个db.properties配置文件

     里面粘贴上如下代码

    1. jdbc.driveClassName=com.mysql.cj.jdbc.Driver
    2. jdbc.url=jdbc:mysql://localhost:3306/mybatis
    3. jdbc.username=root
    4. jdbc.password=abc123123123

    然后替换原来的mybatis文件

    注意两个地方

    第1个是propeties标签的位置应该在environment标签之上

    第2个地方是替换数据库驱动中的那些value的内容，使用美元加大括号的方式

    1. "1.0" encoding="UTF-8" ?>
    2.  
    4. configuration
    5.         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    6.         "http://mybatis.org/dtd/mybatis-3-config.dtd">
    8. <configuration>
    9.  
    10.     <properties resource="db.properties">
    11.  
    12.     properties>
    13.  
    15.     <environments default="development">
    16.         <environment id="development">
    20.             <transactionManager type="JDBC"/>
    22.             <dataSource type="POOLED">
    24.                 <property name="driver" value="${jdbc.driveClassName}"/>
    25.                 <property name="url" value="${jdbc.url}"/>
    26.                 <property name="username" value="${jdbc.username}"/>
    27.                 <property name="password" value="${jdbc.password}"/>
    28.             dataSource>
    29.         environment>
    30.     environments>
    31.  
    32.     <mappers>
    35.         <package name="com.learn.mapper"/>
    36.     mappers>
    37. configuration>

    11 关系（一对一，一对多，多对多）

    UserMapperTwo.xml

    1. "1.0" encoding="UTF-8"?>
    2. mapper
    3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    5. <mapper namespace="com.learn.mapper.UserMapperTwo">
    6.     
    7.     <resultMap id="selectCartAndUserMap" type="com.learn.entity.Cart">
    8.         <id column="cartId" property="cartId">id>
    9.         <result column="userId" property="userId">result>
    10.         <result column="totalnum" property="totalnum">result>
    11.         <result column="totalmoney" property="totalmoney">result>
    12.         
    13.         <collection property="cartItem" ofType="com.learn.entity.CartItem">
    14.             <id column="cartItemId" property="cartItemId">id>
    15.             <result column="cartId" property="cartId">result>
    16.             <result column="pid" property="pid">result>
    17.             <result column="pnum" property="pnum">result>
    18.             <result column="pmoney" property="pmoney">result>
    19.         collection>
    20.  
    21.     resultMap>
    22.  
    23.     <select id="selectCartAndUser" resultMap="selectCartAndUserMap">
    24.         select *
    25.         from cart c,
    26.              cartItem ci
    27.         where c.cartId = ci.cartId
    28.     select>
    29.  
    31.     <resultMap id="selectCartAndUserMap2" type="com.learn.entity.User">
    32.         <id column="id" property="id">id>
    33.         <result column="username" property="username">result>
    34.         <result column="sex" property="sex">result>
    35.         <result column="birthday" property="birthday">result>
    36.         <result column="address" property="address">result>
    37.  
    38.         <association property="cart" javaType="com.learn.entity.Cart">
    39.             <id column="cartId" property="cartId">id>
    40.             <result column="userId" property="userId">result>
    41.             <result column="totalnum" property="totalnum">result>
    42.             <result column="totalmoney" property="totalmoney">result>
    43.         association>
    44.     resultMap>
    45.  
    46.     <select id="selectCartAndUser2" resultMap="selectCartAndUserMap2">
    47.         select * from user u,cart c where u.id=c.cartId
    48.     select>
    49. mapper>

    UserMapperTwo.java

    1. package com.learn.mapper;
    2. import com.learn.entity.User;
    3. import java.util.List;
    4.  
    5. public interface UserMapperTwo {
    6.     List selectCartAndUser();
    7.  
    8.     List selectCartAndUser2();
    9. }

    UserMapperTwoTest.java

    1. package com.learn.mapper;
    2.  
    3. import com.learn.entity.User;
    4. import com.learn.utils.SqlSessionUtils;
    5. import org.apache.ibatis.session.SqlSession;
    6. import org.junit.AfterClass;
    7. import org.junit.BeforeClass;
    8. import org.junit.Test;
    9.  
    10. import java.util.List;
    11.  
    12. import static org.junit.Assert.*;
    13.  
    14. public class UserMapperTwoTest {
    15.     static SqlSession session ;
    16.     //在所有测试方法执行之前执行（只执行一次）
    17.     @BeforeClass
    18.     public static void init() {
    19.         System.out.println("初始化完成！");
    20.         session= SqlSessionUtils.getSqlSes();
    21.     }
    22.     //在所有测试方法执行完成之后执行（只执行一次）
    23.     @AfterClass
    24.     public static void end()
    25.     {
    26.         SqlSessionUtils.closeSqlSes(session);
    27.     }
    28.     @Test
    29.     public void selectCartAndUser()
    30.     {
    31.         UserMapperTwo userMapper = session.getMapper(UserMapperTwo.class);
    32.         List users = userMapper.selectCartAndUser();
    33.         System.out.println("1对多");
    34.         for (int i = 0; i < users.size(); i++) {
    35.             System.out.println(users.get(i));
    36.         }
    37.  
    38.     }
    39.  
    40.     @Test
    41.     public void selectSelectCartAndUser2() {
    42.         UserMapperTwo userMapper = session.getMapper(UserMapperTwo.class);
    43.         List users = userMapper.selectCartAndUser2();
    44.         System.out.println("1对1");
    45.         for (int i = 0; i < users.size(); i++) {
    46.             System.out.println(users.get(i));
    47.         }
    48.  
    49.     }
    50. }

     

    12 注解开发 

    UserMapperNotXml .java

    1. package com.learn.mapper;
    2. import com.learn.entity.User;
    3. import org.apache.ibatis.annotations.Select;
    4.  
    5. public interface UserMapperNotXml {
    6.     @Select("select * from user where id=#{id}")
    7.     User selectUserById(int userId);
    8.     
    9. }

    测试

    1. package com.learn.mapper;
    2.  
    3. import com.learn.entity.User;
    4. import com.learn.utils.SqlSessionUtils;
    5. import org.apache.ibatis.session.SqlSession;
    6. import org.junit.AfterClass;
    7. import org.junit.BeforeClass;
    8. import org.junit.Test;
    9.  
    10. import java.util.List;
    11.  
    12. import static org.junit.Assert.*;
    13.  
    14. public class UserMapperNotXmlTest {
    15.     static SqlSession session ;
    16.     //在所有测试方法执行之前执行（只执行一次）
    17.     @BeforeClass
    18.     public static void init() {
    19.         System.out.println("初始化完成！");
    20.         session= SqlSessionUtils.getSqlSes();
    21.     }
    22.     //在所有测试方法执行完成之后执行（只执行一次）
    23.     @AfterClass
    24.     public static void end()
    25.     {
    26.         SqlSessionUtils.closeSqlSes(session);
    27.     }
    28.  
    29.     @Test
    30.     public void TestselectUserById()
    31.     {
    32.         UserMapperNotXml userMapper = session.getMapper(UserMapperNotXml.class);
    33.         User users = userMapper.selectUserById(10);
    34.         System.out.println(users);
    35.     }
    36. }

     

    13 一级二级缓存

    一级

    默认情况下，MyBatis 只开启一级缓存。

    是sqlSession级别的缓存 缓存的结构是个Map集合

    注意  由于 SqlSession 是相互隔离的，所以如果你使用不同的 SqlSession 对象，即使调用相同的 Mapper、参数和方法，MyBatis 还是会再次发送 SQL 到数据库执行，返回结果。

    二级

    二级缓存是全局缓存，作用域超出 session 范围之外，可以被所有同一个namespace内的 SqlSession 共享。

    打开二级缓存

    在mybatis.xml中配置

    1.  
    3.  
    4.     "db.properties">
    5.  
    6.     
    8.     
    9.         "cacheEnabled" value="true" />
    10.     
    12.     default="development">

    使用

    1 在对应的maper里增加

     2 修改实体类

    3 测试

    略

    4 补充

    局部不2级缓存 

    刷新2级缓存

     

     

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  • 原文地址：https://blog.csdn.net/qq_53679247/article/details/127758192