Mybatis的增刪改查
阿新 • • 發佈:2020-09-06
一、準備
建立一個空的maven專案
匯入依賴包:
<dependencies> <!--資料庫驅動--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.9</version> </dependency> <!--mybatis--> <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.5</version> </dependency> <!--單元測試--> <!-- https://mvnrepository.com/artifact/junit/junit --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13</version> <scope>test</scope> </dependency> </dependencies>
maven專案過濾靜態檔案:
<build> <resources> <resource > <directory>src/main/resources</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> <resource > <directory>src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> </resources> </build> <!--設定字符集--> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties>
配置完pom.xml檔案之後,要記得點選右下角的Enable Auto-import,讓idea自動匯入jar包,過程可能有點慢。
二、建立資料庫表
建立名為userinfo的資料表:
CREATE TABLE userinfo( id INT(10) NOT NULL AUTO_INCREMENT COMMENT '使用者id', name VARCHAR(100) NOT NULL COMMENT '使用者名稱', password VARCHAR(20) NOT NULL COMMENT '密碼', KEY id (id) )ENGINE=INNODB DEFAULT CHARSET=utf8
向資料表新增資料:
INSERT INTO userinfo (id,name,password) VALUES
(1,'小明','123456'),
(2,'小藍','123456'),
(3,'小黃','123456'),
(4,'小綠','123456');
三、建立實體類
public class UserInfo {
private int id;
private String name;
private String password;
public UserInfo(int id, String name, String password) {
this.id = id;
this.name = name;
this.password = password;
}
public UserInfo() {
}
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 getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "UserInfo{" +
"id=" + id +
", name='" + name + '\'' +
", password='" + password + '\'' +
'}';
}
}
四、介面實現類和UserMapper.xml
介面類要與配置檔案放在同一個包下
UserMapper.java介面檔案:
public interface UserMapper {
List<UserInfo> getList(); //查詢所有的使用者資料
int addUser(UserInfo userInfo); //新增使用者
int deleteUser(int id); //刪除使用者
int updateUser(UserInfo userInfo); //修改使用者
UserInfo getUserById(int id); //根據id查詢使用者
}
UserMapper.xml配置檔案:
<?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.dao.UserMapper">
<!--
在mybatis-config.xml中設定的別名在這裡使用,resultType,userInfo
-->
<!--查詢所有使用者資訊-->
<select id="getList" resultType="userInfo">
select * from userinfo;
</select>
<!--根據id查詢使用者資訊-->
<select id="getUserById" parameterType="int" resultType="userInfo">
select * from userinfo where id = #{id};
</select>
<!--新增使用者-->
<insert id="addUser" parameterType="userInfo">
insert into userinfo(id,name,password)value(#{id},#{name},#{password});
</insert>
<!--刪除使用者-->
<delete id="deleteUser" parameterType="int">
delete from userinfo where id = #{id};
</delete>
<!--修改使用者-->
<update id="updateUser" parameterType="userInfo">
update userinfo set name=#{name},password=#{password} where id = #{id};
</update>
</mapper>
五、建立mybatis的配置檔案
首先建立一個mybatis-config.xml的配置檔案,其次建立一個db.properties的資料庫連線基本資訊檔案,db.properties的作用是放置資料庫引數,可以動態改變你需要用的資料庫,當你想換資料庫時無需改動mybatis-config.xml,只需要改動db.properties中的引數即可
mybatis-config.xml配置檔案:
<?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>
<!--引入連線資料庫的基本配置資訊-->
<properties resource="db.properties"></properties>
<!--別名-->
<typeAliases>
<!--根據包名下的類來起別名,一般用類的小寫來作為名字,大寫也可以用,也可以用註解的方式加上別名@Alias("")-->
<package name="com.pojo"/>
</typeAliases>
<!--連線資料庫的環境-->
<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 resource="com/dao/UserMapper.xml"/>
</mappers>
</configuration>
db.properties資料庫引數檔案:
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/text?userSSL=true&userUnicode=true&characterEncoding=UTF-8
username=root
password=123456
mybatis工具類:
public class MyBatisUtils {
private static SqlSessionFactory sqlSessionFactory;
static{
try {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSqlSession(){
//這個true是自動提交事務,當要對資料表進行操作時,就要提交事務,否則進行新增修改等操作資料表無變化
return sqlSessionFactory.openSession(true);
}
}
六、測試類
public class MyTest {
//顯示所有使用者資料
@Test
public void getAllUser(){
SqlSession sqlSession = MyBatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
List<UserInfo> list = mapper.getList();
for (UserInfo user : list) {
System.out.println(user);
}
sqlSession.close();
}
//根據使用者id查詢使用者資訊
@Test
public void getUserByid(){
SqlSession sqlSession = MyBatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
UserInfo userInfo = mapper.getUserById(1);//傳入使用者id
System.out.println(userInfo);
}
//新增使用者
@Test
public void addUser(){
SqlSession sqlSession = MyBatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
int i = mapper.addUser(new UserInfo(5,"小紅","77777777"));
if (i>0){
System.out.println("新增成功");
}
sqlSession.close();
}
//刪除使用者
@Test
public void deleteUser(){
SqlSession sqlSession = MyBatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
int i = mapper.deleteUser(5);
if (i>0){
System.out.println("刪除成功");
}
sqlSession.close();
}
//修改使用者
@Test
public void updateUser(){
SqlSession sqlSession = MyBatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
int i = mapper.updateUser(new UserInfo(1,"小花","444444"));
if (i>0){
System.out.println("修改成功");
}
sqlSession.close();
}
}