使用Mybatiss實現對數據庫的增刪改查

文件目錄

1.導入jar包，這里使用maven

<dependencies><!--mybatis依賴--><!-- org.mybatis " mybatis --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.2</version></dependency><!-- 連接數據庫 --><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.47</version></dependency><!--單元測試--><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version></dependency></dependencies><!-- 可以將文件正確導出 --><build><resources><resource><directory>src/main/resources</directory><excludes><exclude>**/*.properties</exclude><exclude>**/*.xml</exclude></excludes><filtering>false</filtering></resource><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>false</filtering></resource></resources></build>

2.編寫實體類

package com.qin.pojo;public class User {private int id;private String name;private String pwd;public User() {}public User(int id, String name, String pwd) {this.id = id;this.name = name;this.pwd = pwd;}@Overridepublic String toString() {return "User{" +"id=" + id +", name='" + name + ''' +", pwd='" + pwd + ''' +'}';}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getPwd() {return pwd;}public void setPwd(String pwd) {this.pwd = pwd;} }

3.編寫工具類

package com.qin.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;public class MybatisUtils {public static SqlSessionFactory sqlSessionFactory;//使用靜態方法，是為了能夠在類加載時，跟著一起啟動static{try {String resource = "mybatis-config.xml";InputStream inputStream = null;inputStream = Resources.getResourceAsStream(resource);sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);} catch (IOException e) {e.printStackTrace();}}//以后想要使用sqlSession，只需要調用這個類的這個方法即可public SqlSession getSqlSession(){SqlSession sqlSession = sqlSessionFactory.openSession();return sqlSession;}}

4.編寫mybatis核心配置文件(mybatis-config.xml)

<?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> <!----><properties resource="db.properties"></properties><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> <!----><mappers><mapper class="com.qin.mapper.UserMapper"/></mappers></configuration>

5.編寫db.properties

driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/mybatis?useSSL=true&characterEncoding=UTF-8&useUnicode=true username=root password=981216

6.編寫UserMapper接口（重點）增刪改查就是這里修改的，前面5點都基本上固定的，真正修改的就是這里

package com.qin.mapper;import com.qin.pojo.User; import org.apache.ibatis.annotations.Param;import java.util.List;public interface UserMapper {//查詢所有用戶List<User> queryAllUser();//根據id查詢一個用戶User queryUserById(@Param("id") int id);//根據名字查詢一個用戶User queryUserByName(@Param("name") String name);//增加一個用戶int addUser(User user);//修改一個用戶，根據idint updateUserById(User user);//根據id刪除一個用戶int deleteUserById(@Param("id") int id);}

7.編寫UserMapper對應的xml文件（重點）

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><!----> <mapper namespace="com.qin.mapper.UserMapper"><!-- 查詢所有用戶 --><select id="queryAllUser" resultType="com.qin.pojo.User">select * from mybatis.user;</select><!-- 根據id查詢用戶 --><select id="queryUserById" resultType="com.qin.pojo.User">select * from mybatis.userwhere id = #{id} ;</select><!-- 根據名字查詢用戶 --><select id="queryUserByName" resultType="com.qin.pojo.User">select * from mybatis.userwhere name = #{name} ;</select><!-- 增加一個用戶 --><insert id="addUser" parameterType="com.qin.pojo.User">insert into mybatis.user (id,name,pwd)values (#{id},#{name},#{pwd});</insert><!-- 修改一個用戶 --><update id="updateUserById" parameterType="com.qin.pojo.User">update mybatis.user set name=#{name},pwd=#{pwd} where id=#{id};</update><!-- 刪除一個用戶 --><delete id="deleteUserById" >delete from mybatis.userwhere id = #{id};</delete></mapper>

8.編寫測試文件（重點）

package com.qin.mapper;import com.qin.pojo.User; import com.qin.utils.MybatisUtils; import org.apache.ibatis.session.SqlSession; import org.junit.Test;import java.util.List;public class UserMapperTest {//查詢所有用戶@Testpublic void queryAllUseTest(){SqlSession sqlSession = new MybatisUtils().getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<User> userList = mapper.queryAllUser();for (User user : userList) {System.out.println(user);}sqlSession.close();}//根據id查詢用戶@Testpublic void queryUserByIdTest(){SqlSession sqlSession = new MybatisUtils().getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user = mapper.queryUserById(1);System.out.println(user);sqlSession.close();}//根據用戶名查詢用戶@Testpublic void queryUserByNameTest(){SqlSession sqlSession = new MybatisUtils().getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user = mapper.queryUserByName("狂小狗");System.out.println(user);sqlSession.close();}//增加一個用戶@Testpublic void addUserTest(){SqlSession sqlSession = new MybatisUtils().getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);int i = mapper.addUser(new User(2, "狂小狗", "99999"));if (i>0){System.out.println("添加成功");}//提交事務sqlSession.commit();sqlSession.close();}//根據id修改一個用戶@Testpublic void updateUserByIdTest(){SqlSession sqlSession = new MybatisUtils().getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);int i = mapper.updateUserById(new User(5, "廠長", "987654"));if (i>0){System.out.println("修改成功");}sqlSession.commit();sqlSession.close();}//根據id刪除一個用戶@Testpublic void deleteUserByIdTest(){SqlSession sqlSession = new MybatisUtils().getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);int i = mapper.deleteUserById(7);if (i>0){System.out.println("刪除成功");}else {System.out.println("刪除失敗，沒有這個用戶");}sqlSession.commit();sqlSession.close();}}

9.小結

• 如果需要添加不一樣的需求，真正需要修改的就是后3點，前面5點不需要修改

總結

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