文章目录
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
- java各个层的含义链接
- java各个层的含义详解
- java各个层的含义链接
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. UserTestpackage 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. BlogTestimport 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); } }
本文转载自: https://blog.csdn.net/qq_45903007/article/details/126685597
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版权归原作者 super-broo 所有， 如有侵权，请联系我们删除。