mybatis不能find mapper.xml以及全部代码。查询表中所有数据。
这个问题困扰了我很久。
这次总算是搞定了mybatis的配置。
SqlSession session = sqlSessionFactory.openSession();
这个代码一直报错，最后查到是mybitis.xml的配置文件mapper写错了。用/斜杠隔开是对的。
<mappers>
<mapper resource="com/dao/MyBookMapper.xml"/>
</mappers>
之前是
<mappers>
<mapper resource="com.dao.MyBookMapper.xml"/>
</mappers>
这个是错误的。
第二个困扰pom中必须加一下代码，运行程序会自动把
resources
properties
.xml文件自动添加入class的打包文件中。
<!--导入resource防止资源导出失败-->
<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>
下面是全部代码,按照这个可以直接实现功能。前提是数据的自己写，结构下面有。
1.实体类
package com.books;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@AllArgsConstructor
@NoArgsConstructor
@Data
public class Books {
private int BOOKID;
private String BOOKNAME;
private int BOOKCOUTS;
private String DETAIL;
2.接口就是相当于是以前的DAO
package com.dao;
import com.books.Books;
import java.util.List;
public interface MyBookMapper {
List<Books> selectBooks();
}
3.接口映射文件
<?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.MyBookMapper">
<select id="selectBooks" resultType="com.books.Books">
select * from BOOKS
</select>
</mapper>
4.mybatis的主配置文件
<?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>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
<property name="url" value="jdbc:oracle:thin:@localhost:1521:orcl"/>
<property name="username" value="s"/>
<property name="password" value="0"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/dao/MyBookMapper.xml"/>
</mappers>
</configuration>
5.工具类主要是减少重复代码。
package com.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 Utils {
private static SqlSessionFactory sqlSessionFactory ;
static {
String in = "mybatis.xml";
try {
InputStream inputStream = Resources.getResourceAsStream(in);
System.out.println("获取到了xml");
System.out.println("sqlSessionFactory的值是:"+sqlSessionFactory);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSession(){
System.out.println("sqlSessionFactory:"+ sqlSessionFactory);
SqlSession session = sqlSessionFactory.openSession();
System.out.println("已经获取到了SqlSessionFactory");
return session;
}
}
6.测试类
import com.books.Books;
import com.dao.MyBookMapper;
import com.utils.Utils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class MybatisTest {
@Test
public void test(){
SqlSession session = Utils.getSession();
MyBookMapper mapper = session.getMapper(MyBookMapper.class);
List<Books> list = mapper.selectBooks();
for(Books books:list){
System.out.println(books);
}
}
}
7.结果
已经获取到了SqlSessionFactory
Books(BOOKID=1, BOOKNAME=dddd, BOOKCOUTS=0, DETAIL=discribe)
Books(BOOKID=2, BOOKNAME=eeee, BOOKCOUTS=0, DETAIL=discribe)
Books(BOOKID=3, BOOKNAME=java, BOOKCOUTS=0, DETAIL=从入门到放弃)
Books(BOOKID=4, BOOKNAME=Oracle, BOOKCOUTS=0, DETAIL=从删库到跑路)
Books(BOOKID=5, BOOKNAME=Linux, BOOKCOUTS=0, DETAIL=从进门到进牢)
下面是数据库结构和pom。
BOOKID Integer,
,BOOKNAME varchar ,
BOOKCOUNT Integer ,
DETAIL varchar.
pom
<?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>
<groupId>org.example</groupId>
<artifactId>mybatis</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.5</version>
</dependency>
<dependency>
<groupId>com.oracle</groupId>
<artifactId>ojdbc6</artifactId>
<version>12.1.0.1-atlassian-hosted</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.16</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>
</dependencies>
<!--导入resource防止资源导出失败-->
<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>
</project>
