基础

首先这次学习mybatis，得先下载idea软件。maven在idea上好操作点，破解方案自行百度。这里暂不详细介绍。
image.png
这是最初的练习，可能注释有问题，但是后面的代码就纠正过来了。
image.png
为了更好的xml分离，就创建了一个文件夹，然后转成编译包，在再下面创建相同的mapper包。
image.png
下面是代码

  1. <dependencies>
  3.   <dependency>
  4.     <groupId>mysql</groupId>
  5.     <artifactId>mysql-connector-java</artifactId>
  6.     <version>8.0.28</version>
  7.   </dependency>
  8.   <dependency>
  9.     <groupId>org.mybatis</groupId>
  10.     <artifactId>mybatis</artifactId>
  11.     <version>3.5.9</version>
  12.   </dependency>
  13. </dependencies>

数据库DAO层

  1. package org.lisonglin.entity;
  3. public class Student {
  4.     private int id;
  5.     private String name;
  6.     private int age;
  8.     public int getId() {
  9.         return id;
  10.     }
  12.     public void setId(int id) {
  13.         this.id = id;
  14.     }
  16.     public String getName() {
  17.         return name;
  18.     }
  20.     public void setName(String name) {
  21.         this.name = name;
  22.     }
  24.     public int getAge() {
  25.         return age;
  26.     }
  28.     public void setAge(int age) {
  29.         this.age = age;
  30.     }
  32.     public Student(int id, String name, int age) {
  33.         this.id = id;
  34.         this.name = name;
  35.         this.age = age;
  36.     }
  38.     public Student(String name, int age) {
  39.         this.name = name;
  40.         this.age = age;
  41.     }
  43.     public Student() {
  44.     }
  46.     @Override
  47.     public String toString() {
  48.         return "Student{" +
  49.                 "id=" + id +
  50.                 ", name='" + name + '\'' +
  51.                 ", age=" + age +
  52.                 '}';
  53.     }
  54. }
  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3.         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-config.dtd">
  5. <configuration>
  6.     <settings>
  7.         <!-- 对数据库与属性不一致，自动转换 -->
  8.         <setting name="mapUnderscoreToCamelCase" value="true"/>
  9.     </settings>
  10.         <environments default="development">
  11.         <environment id="development">
  12.             <transactionManager type="JDBC"/>
  13.             <dataSource type="POOLED">
  14.                 <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
  15.                 <property name="url" value="jdbc:mysql://localhost:3306/stus?createDatabaseIfNotExist=true&amp;useSSL=false"/>
  16.                 <property name="username" value="root"/>
  17.                 <property name="password" value="123"/>
  18.             </dataSource>
  19.         </environment>
  20.     </environments>
  21.     <mappers>
  22.         <!-- 调用dao层 -->
  23.         <mapper resource="org/lisonglin/mapper/StudentMapper.xml"/>
  24.     </mappers>
  25. </configuration>
  1. package org.lisonglin.mapper;
  3. import org.apache.ibatis.annotations.Param;
  4. import org.lisonglin.entity.Student;
  6. public interface StudentMapper {
  7.     Student get(int id);
  8.     void insert(Student stu);
  9.     void insertInfo(@Param("name") String name, @Param("age") int age);
  10. }
  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <mapper namespace="org.lisonglin.mapper.StudentMapper">
  6.     <select id="get" resultType="org.lisonglin.entity.Student">
  7.         select * from student where id=#{id}
  8.     </select>
  9.     <insert id="insert">
  10.         insert into student values(null,#{name},#{age})
  11.     </insert>
  12.     <insert id="insertInfo">
  13.         insert into student values(null,#{name},#{age})
  14.     </insert>
  15. </mapper>

测试

  1. package org.lisonglin.test;
  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. import org.junit.Test;
  8. import org.lisonglin.entity.Student;
  9. import org.lisonglin.mapper.StudentMapper;
  11. import java.io.IOException;
  12. import java.io.InputStream;
  15. public class TestMyBatis {
  17.     @Test
  18.     public void test(){
  19.         InputStream is=null;
  20.         try {
  21.             //获取src下全局配置文件的输入流
  22.             is = Resources.getResourceAsStream("mybatis-config.xml");
  23.             //获取SqlSessionFactory对象
  24.             SqlSessionFactory factory =new SqlSessionFactoryBuilder().build(is);
  25.             SqlSession sqlSession = factory.openSession();
  26.             StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
  27. //            Student student = mapper.get(1);
  28. //            System.out.print(student);
  29. //            Student s=new Student();
  30. //            s.setName("bb");
  31. //            s.setAge(12);
  32. //            mapper.insert(s);
  33.             mapper.insertInfo("cc",13);
  34.             //手动提交
  35.             sqlSession.commit();
  36.         } catch (IOException e) {
  37.             e.printStackTrace();
  38.         }
  40.     }
  42. }

image.png
新增成功~

进阶

  1.     <dependencies>
  2.         <dependency>
  3.             <groupId>mysql</groupId>
  4.             <artifactId>mysql-connector-java</artifactId>
  5.             <version>8.0.28</version>
  6.         </dependency>
  7.         <dependency>
  8.             <groupId>org.mybatis</groupId>
  9.             <artifactId>mybatis</artifactId>
  10.             <version>3.5.9</version>
  11.         </dependency>
  12.         <dependency>
  13.             <groupId>junit</groupId>
  14.             <artifactId>junit</artifactId>
  15.             <version>4.13.2</version>
  16.         </dependency>
  17.     </dependencies>
  1. package org.lisonglin.entity;
  3. public class Student {
  4.     private int id;
  5.     private String sName;
  6.     private int age;
  7.     public final static String MYBATIS_CONFIG_FILE="mybatis-config2.xml";
  9.     public int getId() {
  10.         return id;
  11.     }
  13.     public void setId(int id) {
  14.         this.id = id;
  15.     }
  17.     public String getsName() {
  18.         return sName;
  19.     }
  21.     public void setsName(String sName) {
  22.         this.sName = sName;
  23.     }
  25.     public int getAge() {
  26.         return age;
  27.     }
  29.     public void setAge(int age) {
  30.         this.age = age;
  31.     }
  33.     @Override
  34.     public String toString() {
  35.         return "Student{" +
  36.                 "id=" + id +
  37.                 ", sName='" + sName + '\'' +
  38.                 ", age=" + age +
  39.                 '}';
  40.     }
  42.     public Student(int id, String sName, int age) {
  43.         this.id = id;
  44.         this.sName = sName;
  45.         this.age = age;
  46.     }
  49.     public Student() {
  50.     }
  51. }
  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3.         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-config.dtd">
  5. <configuration>
  6.     <!-- 读取配置文件信息 -->
  7.     <properties resource="jdbc.properties"></properties>
  8.     <settings>
  9.         <!--把数据中的下划线改为驼峰命名法-->
  10.         <setting name="mapUnderscoreToCamelCase" value="true"/>
  11.     </settings>
  12.     <typeAliases>
  13.         <!-- 别名 -->
  14.         <!--<typeAlias type="org.lisonglin.entity.Student" alias="Student"></typeAlias>-->
  15.         <!-- 直接导包 -->
  16.         <package name="org.lisonglin.entity"></package>
  17.     </typeAliases>
  18.     <!-- 配置坏境变量，可以配置多个，默认值与id一致 -->
  19.    <environments default="development">
  20.        <environment id="development">
  21.            <transactionManager type="JDBC"></transactionManager><!--事务-->
  22.            <dataSource type="POOLED"><!-- 数据源  连接池POOLED -->
  23.                <property name="driver" value="${jdbc.driver}"/>
  24.                <property name="url" value="${jdbc.url}"/>
  25.                <property name="username" value="${jdbc.username}"/>
  26.                <property name="password" value="${jdbc.password}"/>
  27.            </dataSource>
  28.        </environment>
  29.    </environments>
  30.     <!--配置映射文件-->
  31.     <mappers>
  32.         <!--基于XML配置文件-->
  33.         <!--<mapper resource="org/lisonglin/mapper/StudentMapper.xml"/>-->
  34.         <package name="org.lisonglin.mapper"></package>
  35.     </mappers>
  36. </configuration>
  1. package org.lisonglin.mapper;
  3. import org.apache.ibatis.annotations.Param;
  4. import org.apache.ibatis.annotations.Select;
  5. import org.lisonglin.entity.Student;
  7. import java.util.List;
  9. public interface StudentMapper {
  10.     /**
  11.     * XML配置方式
  12.     * @param id
  13.     * @return
  14.     */
  15.     Student get(int id);
  16.     void insert(Student stu);
  17.     void insertInfo(@Param("name") String name, @Param("age") int age);
  18.     List<Student> getAll();
  19.     int insertStudentCacheId(Student stu);
  20.     List<Student> getByName(@Param("key") String key);
  21.     List<Student> getByIds(@Param("ids") int ... ids);
  22.     List<Student> getStudents(Student stu);
  23.     /**
  24.     * 注解方式（代码耦合性不高，不推荐）
  25.     * @param stu
  26.     * @return
  27.     */
  28.     @Select("insert into stu(id,s_name,age) values(null,#{name},#{age})")
  29.     public int add(Student stu);
  30. }
  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3.         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5. <mapper namespace="org.lisonglin.mapper.StudentMapper">
  6.     <!-- 通用sql -->
  7.     <sql id="selectInfo">
  8.         select * from stu
  9.     </sql>
  10.     <select id="getById" resultType="Student" parameterType="int">
  11.         <!-- 引入通用sql -->
  12.        <include refid="selectInfo"></include>
  13.        where id=#{id}
  14.     </select>
  15.     <select id="getStudents" resultType="Student">
  16.         <include refid="selectInfo"></include>
  17.         <!-- 条件查询，如果没有符合条件，那么sql中的and会自动去掉 -->
  18.         <where>
  19.             <!-- 判断中属性是bean中的命名 -->
  20.             <if test="sName != null">
  21.                 and s_name = #{sName}
  22.             </if>
  23.             <if test="age!=0">
  24.                 and age = #{age}
  25.             </if>
  26.         </where>
  27.     </select>
  28.     <select id="getByIds" resultType="Student">
  29.         <include refid="selectInfo"></include>
  30.         <where>
  31.             <!--<foreach collection="ids" open="id in (" close=")" separator="," item="id">-->
  32.                 <!--id=#{id}-->
  33.             <!--</foreach>-->
  34.             <foreach collection="ids" item="id" separator="or">
  35.                 id=#{id}
  36.             </foreach>
  37.         </where>
  38.     </select>
  39.     <select id="get" resultType="Student" parameterType="int">
  40.         select * from stu where id=#{id}
  41.     </select>
  42.     <insert id="insert">
  43.         insert into stu values(null,#{name},#{age})
  44.     </insert>
  45.     <insert id="insertInfo">
  46.         insert into stu values(null,#{name},#{age})
  47.     </insert>
  48.     <select id="getAll" resultType="Student">
  49.         select * from stu
  50.     </select>
  51.     <!-- 查询出增加的主键(方法一) -->
  52.     <insert id="insertStudentCacheId" keyColumn="id" keyProperty="id" useGeneratedKeys="true">
  53.         insert into stu values(null,#{sName},#{age})
  54.     </insert>
  55.     <!-- 方法二 -->
  56.     <insert id="insertStudentId">
  57.           <selectKey keyProperty="id" keyColumn="id" order="AFTER" resultType="int">
  58.               <!-- 查询自增id （方法一） -->
  59.               select last_insert_id()
  60.               <!--方法二-->
  61.               <!--select @@identity-->
  62.           </selectKey>
  63.          insert into stu values(null,#{sName},#{age})
  64.     </insert>
  65.     <select id="getByName" resultType="Student">
  66.         <!-- ${} 拼接sql #{}  占位符 -->
  67.         <!-- 推荐使用这种 -->
  68.         <!-- select * from stu where s_name like '%' #{key} '%' -->
  69.         <bind name="new_key" value="'%'+key+'%'"></bind>
  70.         <include refid="selectInfo"></include>
  71.         where s_name like #{new_key}
  72.         <!-- select * from stu where s_name like concat('%',#{key},'%') -->
  73.         <!-- 这种不建议使用，这种使用statement查询方式，有sql注入风险 -->
  74.         <!-- select * from stu where s_name like '%${key}%' -->
  75.     </select>
  77. </mapper>
  1. package org.lisonglin.servlet;
  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. import org.lisonglin.entity.Student;
  8. import org.lisonglin.mapper.StudentMapper;
  10. import java.io.IOException;
  11. import java.io.InputStream;
  13. public class DataUtil {
  14.     private static SqlSessionFactory sqlSessionFactory;
  16.     public static StudentMapper getStudentMapper(){
  17.         InputStream is=null;
  18.         try {
  19.             is = Resources.getResourceAsStream("mybatis-config.xml");
  20.             SqlSessionFactory build = new SqlSessionFactoryBuilder().build(is);
  21.             SqlSession sqlSession = build.openSession();
  22.             StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
  23.             return  mapper;
  24.         } catch (IOException e) {
  25.             e.printStackTrace();
  26.         }
  27.         return  null;
  28.     }
  30.     public static SqlSessionFactory getSqlSessionFactory(){
  31.         InputStream is=DataUtil.class.getClassLoader().getResourceAsStream(Student.MYBATIS_CONFIG_FILE);
  32.         return new SqlSessionFactoryBuilder().build(is);
  33.     }
  35.     /**
  36.      * @param autoCommit
  37.      *      true：表示创建的SqlSession对象在执行完SQL之后自动提交事务
  38.      *      false:表示创建的SqlSession对象在执行完SQL之后不会自动提交事务，这时就需要我们手动调用SqlSession.commit()提交事务
  39.      * @return
  40.      */
  41.     public static SqlSession getSqlSession(boolean autoCommit){
  42.         return getSqlSessionFactory().openSession(autoCommit);
  43.     }
  45.     public static SqlSession getSqlSession(){
  46.         return getSqlSessionFactory().openSession();
  47.     }
  49. }
  1. package org.lisonglin.test;
  3. import org.apache.ibatis.io.Resources;
  4. import org.apache.ibatis.session.SqlSessionFactory;
  5. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
  6. import org.junit.Test;
  7. import org.lisonglin.dao.StudentImpl;
  8. import org.lisonglin.entity.Student;
  9. import org.lisonglin.mapper.StudentMapper;
  10. import org.lisonglin.servlet.DataUtil;
  12. import java.io.IOException;
  13. import java.io.Reader;
  14. import java.util.List;
  16. public class MyTest {
  17.     private SqlSessionFactory sqlSessionFactory;
  19.     @Test
  20.     public void getStudentByAgeOrNames(){
  21.         StudentMapper studentMapper = DataUtil.getStudentMapper();
  22.         Student student=new Student();
  23.         student.setAge(20);
  24.         System.out.println(student.toString());
  25.         List<Student> studentByAgeOrName = studentMapper.getStudents(student);
  26.         System.out.println(studentByAgeOrName);
  27.     }
  29.     @Test
  30.     public void getByIdsStudent(){
  31.         StudentMapper studentMapper = DataUtil.getStudentMapper();
  32.         List<Student> byIds = studentMapper.getByIds(1, 2, 3);
  33.         System.out.println(byIds);
  34.     }
  36.     @Test
  37.     public void getByNameStu(){
  38.         StudentMapper studentMapper = DataUtil.getStudentMapper();
  39.         List<Student> a = studentMapper.getByName("a");
  40.         System.out.println(a);
  41.     }
  43.     @Test
  44.     public void getMapperAll(){
  45.         StudentMapper sqlSession = DataUtil.getStudentMapper();
  46.         List<Student> all = sqlSession.getAll();
  47.         System.out.print(all.toString());
  48.     }
  50.     /**
  51.      * mybatis代理模式
  52.      */
  53.     @Test
  54.     public void getMapperMybatis(){
  55.         StudentMapper sqlSession = DataUtil.getStudentMapper();
  56.         Student student = sqlSession.get(1);
  57.         System.out.print(student);
  58.     }
  60.     @Test
  61.     public void insertGetId(){
  62.         StudentMapper studentMapper = DataUtil.getStudentMapper();
  63.         Student stu=new Student();
  64.         stu.setAge(12);
  65.         stu.setsName("aaa");
  66.         int i = studentMapper.insertStudentCacheId(stu);
  67.         System.out.println(i);
  68.         System.out.println(stu.getId());
  69.     }
  71.     /**
  72.      * 原生Dao开发
  73.      */
  74.     @Test
  75.     public void getDaoMyBatis(){
  76.         String resource = "mybatis-config.xml";
  77.         Reader reader = null;
  78.         try {
  79.             reader = Resources.getResourceAsReader(resource);
  80.         } catch (IOException e) {
  81.             e.printStackTrace();
  82.         }
  83.         sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
  84.         StudentMapper studentMapper=new StudentImpl(sqlSessionFactory);
  85.         Student student = studentMapper.get(2);
  86.         System.out.print(student);
  87.     }
  88. }