Mybatis入門
介紹
官方文檔 http://www.mybatis.org/mybatis-3/getting-started.html
Mybatis結構
實操
jar包
別忘了build Path
Maven項目舉例
pom文件引包(注意xml名稱可能不一樣)
<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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.0.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<groupId>init.wuji</groupId>
<artifactId>mavenMybatis</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.4</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.62</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.6</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.21</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.4</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jsp-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
然後便是config配置
文件名:/mavenMybatis/src/main/resources/config/mybatis/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>
<properties resource="config/mybatis/DB.properties">
</properties>
<environments default="development">
<environment id="development">
<!-- 事務管理器,JDBC類型的事務管理器 -->
<transactionManager type="JDBC" />
<!-- 數據源,池類型的數據源 -->
<dataSource type="POOLED">
<property name="driver" value="${mysql_driver}" /> <!-- 配置了properties,所以可以直接引用 -->
<property name="url" value="${mysql_url}" />
<property name="username" value="${mysql_username}" />
<property name="password" value="${mysql_passwd}" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="init/wuji/mybatis/mapper/dao/StuCardMapper.xml" />
</mappers>
</configuration>
注意第7行你自己的DB配置文件位置
還有各value的值與DB文件對應
另外23的mapper.xml文件可先不寫,稍後編輯
附上DB配置文件吧,名稱:/mavenMybatis/src/main/resources/config/mybatis/DB.properties
代碼:
mysql_driver=com.mysql.cj.jdbc.Driver
mysql_url=jdbc:mysql://localhost:3306/xthotel?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai
mysql_username=root
mysql_passwd=root
ok至此環境搭建完成,我們用一個學生卡數據庫舉例子
涉及的相關文件
entity就不說了就是stucard的基本類
接下來是mapper的代理接口
文件名:/mavenMybatis/src/main/java/init/wuji/mybatis/mapper/dao/StuCardMapper.java
代碼
注意只寫方法名,不寫具體方法(因爲是代理)
package init.wuji.mybatis.mapper.dao;
import init.wuji.mybatis.mapper.entity.StuCard;
public interface StuCardMapper {
public StuCard getStuCardByStuNo(String cardNo);
}
接下來是mapper.xml文件,文件位置行業各有不同有的放在了config裏面,有的和代理結構放一起,個人建議方法2,因爲它雖然是xml文件但是並不是配置文件,而且下面的namespace的路徑直接複製上面的java類名路徑即可,很方便
文件名稱:/mavenMybatis/src/main/java/init/wuji/mybatis/mapper/dao/StuCardMapper.xml
代碼
<?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:根標籤,namespace:命名空間,隨便寫,一般保證命名空間唯一 -->
<mapper namespace="init.wuji.mybatis.mapper.dao.StuCardMapper">
<!-- statement,內容:sql語句。id:唯一標識,隨便寫,在同一個命名空間下保持唯一
resultType:sql語句查詢結果集的封裝類型,tb_user即爲數據庫中的表
-->
<select id="getStuCardByStuNo" parameterType="String" resultType="init.wuji.mybatis.mapper.entity.StuCard">
select card_no cardNo,money from stu_card where card_no = #{value}
</select>
</mapper>
注意select標籤裏的屬性值,和namesapce的路徑以及文件名稱,當然還有sql語句
重點
將剛纔的mapper.xml文件路徑配置到一開始的config.xml的mapper標籤中去,纔可以使用。
最後一步,運行頁面
文件名稱:/mavenMybatis/src/main/java/init/wuji/mybatis/mapper/dao/MapperTest.java
代碼:
package init.wuji.mybatis.mapper.dao;
import java.io.IOException;
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 org.junit.Before;
import org.junit.Test;
public class MapperTest {
private SqlSession session;
@Before
public void mybatisInit() throws IOException{
SqlSessionFactory ssf =new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("config/mybatis/mybatis-config.xml"));
session = ssf.openSession();
}
@Test
public void queryEmpByEmpNo() {
StuCardMapper cardMapper = session.getMapper(StuCardMapper.class);
System.out.println("----->"+cardMapper.getStuCardByStuNo("111"));
}
}
注意19行的mybits-config.xml的路徑位置,以及29的操作代碼。(我用了JUnit的註解)
運行成功截圖