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mybatis项目CRUD步骤实例详解

Java开发
2023-06-02

这篇文章主要介绍了mybatis项目CRUD步骤,包括pom.xml引入相应的依赖，在resources目录下写配置文件，本文结合实例代码给大家介绍的非常详细，需要的朋友可以参考下

mybatis项目CRUD步骤

1.pom.xml引入相应的依赖

  <?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>
  <!--父工程-->
      <groupId>org.example</groupId>
      <artifactId>demo1</artifactId>
      <packaging>pom</packaging>
      <version>1.0-SNAPSHOT</version>
      <modules>
          <module>demo01</module>
          <module>demo02</module>
          <module>demo03</module>
          <module>demo04</module>
      </modules>
      <!--    导入依赖-->
       <dependencies>
           <dependency>
               <groupId>mysql</groupId>
               <artifactId>mysql-connector-java</artifactId>
               <version>8.0.28</version>
           </dependency>
  <!--         导入lombok依赖-->
           <dependency>
               <groupId>org.projectlombok</groupId>
               <artifactId>lombok</artifactId>
               <version>1.18.22</version>
           </dependency>
           <dependency>
               <groupId>org.mybatis</groupId>
               <artifactId>mybatis</artifactId>
               <version>3.5.9</version>
           </dependency>
           <dependency>
               <groupId>junit</groupId>
               <artifactId>junit</artifactId>
               <version>4.13</version>
               <scope>test</scope>
           </dependency>
           <dependency>
               <groupId>org.mybatis.caches</groupId>
               <artifactId>mybatis-ehcache</artifactId>
               <version>1.2.1</version>
           </dependency>
       </dependencies>
  <!--maven资源导出，约定大于配置-->
      <build>
          <resources>
              <resource>
                  <directory>src/main/resources</directory>
                  <includes>
                      <include>**/*.properties
                      </include>
                      <include>**/*.xml</include>
                  </includes>
                  <filtering>false</filtering>
              </resource>
              <resource>
                  <directory>src/main/java</directory>
                  <includes>
                      <include>**/*.properties
                      </include>
                      <include>**/*.xml</include>
                  </includes>
                  <filtering>false</filtering>
              </resource>
          </resources>
      </build>
  
  
  </project>

2. 在resources目录下写配置文件

  • 数据库连接配置
  • db.properties
  driver=com.mysql.cj.jdbc.Driver
  url=jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=UTF-8
  username=root
  password=123456
  • mybatis配置
  • 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核心配置文件-->
  <configuration>
  <!--    引入外部配置文件-->
      <properties resource="db.properties">
  
      </properties>
  
      <settings>
          <!--    开启日志-->
          <setting name="logImpl" value="STDOUT_LOGGING"/>
          <!--显示的开启缓存-->
          <setting name="cacheEnabled" value="true"/>
      </settings>
  <!--    类型别名:可以给实体类起别名-->
      <typeAliases>
  <!--        固定别名-->
  <!--        <typeAlias type="com.wyc.pojo.User" alias="User"></typeAlias>-->
  
  <!--        扫描包:扫描实体类的包，它的默认别名就为这个类的类名，首字母小写！-->
          <package name="com.wyc.pojo"/>
      </typeAliases>
  
      <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>
  <!--    注册mapper-->
      <mappers>
          <mapper class="com.wyc.dao.UserMapper"/>
      </mappers>
  </configuration>
  • 自定义缓存配置
  • ehcache.xml
  <?xml version="1.0" encoding="UTF-8"?>
  <ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd"
           updateCheck="false">
  
      <diskStore path="./tmpdir/Tmp_EhCache"/>
  
      <defaultCache
              eternal="false"
              maxElementsInMemory="10000"
              overflowToDisk="false"
              diskPersistent="false"
              timeToIdleSeconds="1800"
              timeToLiveSeconds="259200"
              memoryStoreEvictionPolicy="LRU"/>
  
      <cache
              name="cloud_user"
              eternal="false"
              maxElementsInMemory="5000"
              overflowToDisk="false"
              diskPersistent="false"
              timeToIdleSeconds="1800"
              timeToLiveSeconds="1800"
              memoryStoreEvictionPolicy="LRU"/>
  </ehcache>

3. 创建相应的包

各个层的含义

4. 在utils层

获取获取sqlSessionFactory对象

  package com.wyc.utils;
  
  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;
  
  //sqlSessionFactory -->sqlSession
  public class MybayisUtils {
      private static SqlSessionFactory sqlSessionFactory;
      static {
          try{
              //使用mybatis第一步: 获取sqlSessionFactory对象
                  String resource = "mybatis-config.xml";
                  InputStream inputStream = Resources.getResourceAsStream(resource);
                  sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
              } catch (IOException e) {
                  e.printStackTrace();
              }
      }
      public static SqlSession getSqlSession(){
          return sqlSessionFactory.openSession(true);
  
  
      }
  }

5. 在pojo层创建实体类，类名与数据库表一致

  package com.wyc.pojo;
  
  import lombok.Data;
  
  @Data   //自动生成get set 等方法，详细点击 右边的Structure
  public class User {
      private int id;
      private String name;
      private String pwd;
  }

6.在dao层编写Mapper接口，和Mapper.xml sql语法

UserMapper

  package com.wyc.utils;
  
  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;
  
  //sqlSessionFactory -->sqlSession
  public class MybayisUtils {
      private static SqlSessionFactory sqlSessionFactory;
      static {
          try{
              //使用mybatis第一步: 获取sqlSessionFactory对象
                  String resource = "mybatis-config.xml";
                  InputStream inputStream = Resources.getResourceAsStream(resource);
                  sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
              } catch (IOException e) {
                  e.printStackTrace();
              }
      }
      public static SqlSession getSqlSession(){
          return sqlSessionFactory.openSession(true);
  
  
      }
  }

UserMapper.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="com.wyc.dao.UserMapper">
      <insert id="add">
  
      </insert>
      <insert id="addUser" parameterType="com.wyc.pojo.User">
      insert into mybatis.user (id,name,pwd) value (#{id},#{name},#{pwd})
      </insert>
      <insert id="addUser2" parameterType="map">
      insert into mybatis.user (id,name,pwd) value (#{userid},#{username},#{userpwd})
      </insert>
      <update id="update" parameterType="com.wyc.pojo.User">
      update mybatis.user set name =#{name},pwd=#{pwd} where id = #{id} ;
      </update>
      <delete id="deleteUser">
          delete from mybatis.user where id = #{id}
      </delete>
      <select id="getUserList" resultType="com.wyc.pojo.User">
      select * from mybatis.user
    </select>
      <select id="getUserById" resultType="com.wyc.pojo.User" parameterType="int">
      select * from mybatis.user where id = #{id}
      </select>
      <select id="getUserById2" resultType="com.wyc.pojo.User" parameterType="map">
      select * from mybatis.user where id = #{id} and name = #{name};
      </select>
      <select id="getUserLike" resultType="com.wyc.pojo.User">
      select * from mybatis.user where name like "%"#{value}"%"
  
      </select>
          
          
  <!--    在当前mapper.xml中开启二级缓存-->
      <cache eviction="FIFO"
             flushInterval="60000"
             size="512"
             readOnly="true"
      ></cache>
  
  <!--自定义缓存-->
  <cache type="org.mybatis.caches.ehcache.EhcacheCache"/>
  <!--useCache="true":使用开启缓存-->
      <select id="queryUserById" parameterType="int" resultType="user" useCache="true">
          select * from mybatis.user where id = #{id}
      </select>
  </mapper>

BlogMapper

BlogMapper.xml

  <?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE mapper
          PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
          "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  <mapper namespace="com.wyc.dao.BlogMapper">
      <insert id="addBlog" parameterType="blog">
          insert into mybatis.blog (id,title,author,create_time,views)
          value (#{id},#{title},#{author},#{createTime},#{views});
      </insert>
      <sql id="if-title-author">                     //if语句
          <if test="title != null">
              and title = #{title}
          </if>
          <if test="author != null">
              and author = #{author}
          </if>
      </sql>
      <select id="queryBlogIf" parameterType="map" resultType="blog">
      select * from mybatis.blog where 1=1
      <where>
          <include refid="if-title-author"></include>
      </where>
      </select>
  
  
  
      <select id="queryBlogChoose" parameterType="map" resultType="blog">   //choose语句
      select * from mybatis.blog
      <where>
          <choose>
              <when test="title != null">
                   title = #{title}
              </when>
              <when test="title != null">
                   and author = #{author}
              </when>
              <otherwise>
                  and views = #{views}
              </otherwise>
          </choose>
      </where>
      </select>
  <!--我们现在传入一个万能的map，这个map可以存一个集合
            select * from mybatis.blog where 1=1 and (id=1 or id=2 or id=3)
  -->
      <select id="queryBlogForeach" parameterType="map" resultType="blog">   //foreach语句
      select * from mybatis.blog
       <where>
              <foreach collection="ids" item="id" open="and (" close=")" separator="or">  separator  拼接sql
                  id = #{id}
              </foreach>
       </where>
      </select>
  
  
      <update id="updateBlog" parameterType="map">
       update mybatis.blog
       <set>
           <if test="title != null">
               title = #{title},
           </if>
           <if test="author != null">
               author = #{author}
           </if>
       </set>
       where id = #{id}
      </update>
  </mapper>

7.编写测试类test，进行测试

1. UserTest

  package com.wyc.dao;
  
  import com.wyc.pojo.User;
  import com.wyc.utils.MybayisUtils;
  import org.apache.ibatis.session.SqlSession;
  import org.junit.Test;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  public class UserDaoTest {
      @Test
      //查询所有用户
      public void test(){
          //第一步：获得SqlSession对象
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          //执行sql  方式一：getMapper
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          List<User> userList = mapper.getUserList();
          for (User user : userList) {
              System.out.println(user);
  
          }
  
      }
      @Test
      public void testlike(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          List<User> userLike = mapper.getUserLike("zhang%");  //%最好在sql中拼接
          for (User user : userLike) {
              System.out.println("______________________");
              System.out.println(user);
          }
      }
      @Test
      //根据id查询
      public void test1(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
              UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          User userById = mapper.getUserById(1);
          System.out.println(userById);
  
      }
      @Test
      //添加用户 增删改查需要提交事物
      public void test2(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          int addUser = mapper.addUser(new User(5,"HH","123"));
          sqlSession.commit();
  
      }
      @Test
      public void add(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          Map<String, Object> map = new HashMap<String, Object>();
          map.put("userid",7);
          map.put("username","zhangsan");
          mapper.addUser2(map);
          sqlSession.commit();
  
      }
      @Test
      //修改用户
      public void test3(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          int update = mapper.update(new User(3, "rr", "1234"));
          sqlSession.commit();
      }
      @Test
      //删除用户
      public void test4(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          int user = mapper.deleteUser(2);
          sqlSession.commit();
  
      }
  }

2. BlogTest

  import com.wyc.dao.BlogMapper;
  import com.wyc.dao.UserMapper;
  import com.wyc.pojo.Blog;
  import com.wyc.pojo.User;
  import com.wyc.utils.IDutils;
  import com.wyc.utils.MybayisUtils;
  import org.apache.ibatis.session.SqlSession;
  import org.junit.Test;
  
  import java.util.ArrayList;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.List;
  
  public class MyTest {
      @Test
      public void test(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
          Blog blog = new Blog();
          blog.setId(IDutils.getId());
          blog.setTitle("mybatis如此简单");
          blog.setAuthor("狂神说");
          blog.setCreateTime(new Date());
          blog.setViews(9999);
          mapper.addBlog(blog);
  
          blog.setId(IDutils.getId());
          blog.setTitle("java如此简单");
          mapper.addBlog(blog);
  
          blog.setId(IDutils.getId());
          blog.setTitle("spring如此简单");
          mapper.addBlog(blog);
  
          blog.setId(IDutils.getId());
          blog.setTitle("微服务如此简单");
          mapper.addBlog(blog);
  
          sqlSession.commit();
  
      }
      @Test
      public void test2(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
          HashMap map = new HashMap();
          map.put("author","狂神说");
          List<Blog> blogs = mapper.queryBlogIf(map);
          for (Blog blog : blogs) {
              System.out.println(blog);
          }
  
      }
      @Test
      public void test3(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
          HashMap map = new HashMap();
          map.put("views",9999);
          List<Blog> blogs = mapper.queryBlogChoose(map);
          for (Blog blog : blogs) {
              System.out.println(blog);
          }
  
      }
      @Test
      public void test4(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
          HashMap map = new HashMap();
  //        map.put("views",9999);
          map.put("id","aaee3fee53d041ef93f51ff42d432d");
          map.put("author","超哥说");
          map.put("title","编程如此简单");
          mapper.updateBlog(map);
          sqlSession.commit();
  
      }
      @Test
      public void test5(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
          HashMap map = new HashMap();
          ArrayList<Integer> ids = new ArrayList<Integer>();
          ids.add(1);
          map.put("ids",ids);
          List<Blog> blogs = mapper.queryBlogForeach(map);
          for (Blog blog : blogs) {
              System.out.println(blog);
          }
          sqlSession.commit();
  
      }
      @Test
      public void queryUserById(){
          SqlSession sqlSession = MybayisUtils.getSqlSession();
          SqlSession sqlSession2 = MybayisUtils.getSqlSession();
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          User user = mapper.queryUserById(1);
          System.out.println(user);
          sqlSession.close();
          UserMapper mapper2 = sqlSession2.getMapper(UserMapper.class);
          User user2 = mapper2.queryUserById(1);
          System.out.println(user2);
      }
  }

到此这篇关于mybatis项目CRUD步骤的文章就介绍到这了,更多相关mybatis CRUD步骤内容请搜索编程学习网以前的文章希望大家以后多多支持编程学习网！

本文标题为：mybatis项目CRUD步骤实例详解

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