Mybatis的SQL語句傳回結果有兩種
resultType
查詢出的字段在相應的POJO中必須有和它相同的字段對應，或者基本資料類型
适合簡單查詢
resultMap
需要自定義字段，或者多表查詢，一對多等關系，比resultType更強大
适合複雜查詢
項目結構
pom.xml
4.0.0
net.cyb
cyb-mybatis
1.0-SNAPSHOT
org.mybatis
mybatis
3.5.4
mysql
mysql-connector-java
8.0.20
org.slf4j
slf4j-log4j12
1.7.30
mybatis-config.xml
/p>
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
db.properties
db.driver=com.mysql.cj.jdbc.Driver
db.url=jdbc:mysql://127.0.0.1:3306/cybclass
db.username=root
db.password=root
log4j.properties
#dev env [debug] product env [info]
log4j.rootLogger=ERROR, stdout
# Console output...
# 細化到列印某個mapper
# log4j.logger.包名.方法名=TRACE
log4j.logger.net.cybclass.online=TRACE
#log4j.logger.net.cybclass.online.dao.VideoMapper.selectById=TRACE
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
VideoMapper.xml
/p>
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
id,title title2,summary
selectfrom video where id=#{id}
VideoMapper.java
packagenet.cybclass.online.dao;importnet.cybclass.online.domain.Video;importorg.apache.ibatis.annotations.Param;importorg.apache.ibatis.annotations.Select;importjava.util.List;importjava.util.Map;public interfaceVideoMapper {
Video selectBaseFieldByIdWithResultMap(intid);
}
Video.java
packagenet.cybclass.online.domain;importjava.util.Date;
public classVideo {//内碼
private intid;//視訊标題
privateString title;//視訊詳情
privateString summary;//視訊封面
privateString coverImg;//加個
private intprice;private intc_id;//評分
private doublepoint;//建立日期
privateDate create_time;public intgetId() {returnid;
}public void setId(intid) {this.id =id;
}publicString getTitle() {returntitle;
}public voidsetTitle(String title) {this.title =title;
}publicString getSummary() {returnsummary;
}public voidsetSummary(String summary) {this.summary =summary;
}publicString getCoverImg() {returncoverImg;
}public voidsetCoverImg(String coverImg) {this.coverImg =coverImg;
}public intgetPrice() {returnprice;
}public void setPrice(intprice) {this.price =price;
}public intgetC_id() {returnc_id;
}public void setC_id(intc_id) {this.c_id =c_id;
}public doublegetPoint() {returnpoint;
}public void setPoint(doublepoint) {this.point =point;
}publicDate getCreate_time() {returncreate_time;
}public voidsetCreate_time(Date create_time) {this.create_time =create_time;
}
@OverridepublicString toString() {return "Video{" +
"id=" + id +
", title=‘" + title + ‘\‘‘ +
", summary=‘" + summary + ‘\‘‘ +
", coverImg=‘" + coverImg + ‘\‘‘ +
", price=" + price +
", c_id=" + c_id +
", point=" + point +
", create_time=" + create_time +
‘}‘;
}
}
SqlSessionDemo.java
packagenet.cybclass.online;importnet.cybclass.online.dao.VideoMapper;importnet.cybclass.online.domain.Video;importorg.apache.ibatis.io.Resources;importorg.apache.ibatis.session.SqlSession;importorg.apache.ibatis.session.SqlSessionFactory;importorg.apache.ibatis.session.SqlSessionFactoryBuilder;importjava.io.IOException;importjava.io.InputStream;import java.util.*;public classSqlSessionDemo {public static void main(String[] args) throwsIOException {
String resouce="config/mybatis-config.xml";
InputStream resourceAsStream=Resources.getResourceAsStream(resouce);
SqlSessionFactory build= newSqlSessionFactoryBuilder().build(resourceAsStream);try(SqlSession session=build.openSession()){
VideoMapper mapper= session.getMapper(VideoMapper.class);
Video video= mapper.selectBaseFieldByIdWithResultMap(52);
System.out.println(video.toString());
}catch(Exception e){
e.printStackTrace();
}
}
}