mybatis 嵌套查询一对一 贴代码的来,感谢 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 检查下看mybatis的扫描路径是否正确. author类package com.geyao.mybatis.pojo;public class Author { private Integer id; private String username; private String password; private String email; private String bio; private String favouriteSection; private String nickname; private String realname; public Author() { super(); } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getBio() { return bio; } public void setBio(String bio) { this.bio = bio; } public String getFavouriteSection() { return favouriteSection; } public void setFavouriteSection(String favouriteSection) { this.favouriteSection = favouriteSection; } public String getNickname() { return nickname; } public void setNickname(String nickname) { this.nickname = nickname; } public String getRealname() { return realname; } public void setRealname(String realname) { this.realname = realname; } public Author(Integer id, String username, String password, String email, String bio, String favouriteSection, String nickname, String realname) { super(); this.id = id; this.username = username; this.password = password; this.email = email; this.bio = bio; this.favouriteSection = favouriteSection; this.nickname = nickname; this.realname = realname; } } blog类package com.geyao.mybatis.pojo;import java.io.Serializable;public class Blog implements Serializable { private static final long serialVersionUID = 1L; private Integer id; private String title; private Author author; private String state; private boolean featured; private String style; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public Author getAuthor() { return author; } public void setAuthor(Author author) { this.author = author; } public String getState() { return state; } public void setState(String state) { this.state = state; } public boolean isFeatured() { return featured; } public void setFeatured(boolean featured) { this.featured = featured; } public String getStyle() { return style; } public void setStyle(String style) { this.style = style; } public static long getSerialversionuid() { return serialVersionUID; } } authormap。xml<?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"><!-- 为这个mapper指定一个唯一的namespace,namespace的值习惯上设置成包名+sql映射文件名,这样就能够保证namespace的值是唯一的例如namespace="me.gacl.mapping.userMapper"就是me.gacl.mapping(包名)+userMapper(userMapper.xml文件去除后缀) --><mapper namespace="com.geyao.mybatis.mapper.AuthorMapper"> <resultMap type="Author" id="authorResultMap"> <id column="id" property="id" jdbcType="INTEGER"></id> </resultMap> <select id="selectAuthorById" parameterType="int" resultMap="authorResultMap"> select * from author where id=#{id} </select></mapper>blogmapper。xml<?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.geyao.mybatis.mapper.BlogMapper"> <resultMap type="Blog" id="blogResultMap"> <id column="id" property="id" jdbcType="INTEGER"></id> <association property="author" column="author" javaType="Author" select="com.geyao.mybatis.mapper.AuthorMapper.selectAuthorById"> </association> </resultMap> <select id="selectAuthorById" parameterType="int" resultMap="blogResultMap"> select * from Blog where id=#{id} </select></mapper> 测试类package com.geyao.mybatis.mapper;import org.apache.ibatis.session.SqlSession;import org.junit.Test;import com.geyao.mybatis.pojo.Author;import com.geyao.mybatis.pojo.Blog;import com.geyao.mybatis.util.MyBatisUtil;public class BlogMapperTest { @Test public void testSelectBlog() { SqlSession session =MyBatisUtil.getSqlSession(); BlogMapper blogMapper =session.getMapper(BlogMapper.class); Blog blog = blogMapper.selectBlogById(1); session.close(); System.out.println(blog); } } mybatis-config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><settings> <setting name="useGeneratedKeys" value="true"/></settings><typeAliases> <typeAlias type="com.geyao.mybatis.pojo.Blog" alias="Blog"/> <typeAlias type="com.geyao.mybatis.pojo.Author" alias="Author"/></typeAliases> <environments default="development"> <environment id="development"> <transactionManager type="JDBC" /> <!-- 配置数据库连接信息 --> <dataSource type="POOLED"> <property name="driver" value="com.mysql.cj.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/blog_gp1701?serverTimezone=GMT%2B8" /> <property name="username" value="root" /> <property name="password" value="123" /> </dataSource> </environment> </environments> <mappers> <!-- 注册userMapper.xml文件, userMapper.xml位于me.gacl.mapping这个包下,所以resource写成me/gacl/mapping/userMapper.xml--> <mapper resource="com/geyao/mybatis/mapper/BlogMapper.xml"/> <mapper resource="com/geyao/mybatis/mapper/AuthorMapper.xml"/> </mappers></configuration> 大家一般在做页面原型花多久时间啊? 关于项目部署问题! 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package com.geyao.mybatis.pojo;public class Author {
private Integer id;
private String username;
private String password;
private String email;
private String bio;
private String favouriteSection;
private String nickname;
private String realname;
public Author() {
super();
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getBio() {
return bio;
}
public void setBio(String bio) {
this.bio = bio;
}
public String getFavouriteSection() {
return favouriteSection;
}
public void setFavouriteSection(String favouriteSection) {
this.favouriteSection = favouriteSection;
}
public String getNickname() {
return nickname;
}
public void setNickname(String nickname) {
this.nickname = nickname;
}
public String getRealname() {
return realname;
}
public void setRealname(String realname) {
this.realname = realname;
}
public Author(Integer id, String username, String password, String email, String bio, String favouriteSection,
String nickname, String realname) {
super();
this.id = id;
this.username = username;
this.password = password;
this.email = email;
this.bio = bio;
this.favouriteSection = favouriteSection;
this.nickname = nickname;
this.realname = realname;
}
}
package com.geyao.mybatis.pojo;import java.io.Serializable;public class Blog implements Serializable { private static final long serialVersionUID = 1L;
private Integer id;
private String title;
private Author author;
private String state;
private boolean featured;
private String style;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public Author getAuthor() {
return author;
}
public void setAuthor(Author author) {
this.author = author;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public boolean isFeatured() {
return featured;
}
public void setFeatured(boolean featured) {
this.featured = featured;
}
public String getStyle() {
return style;
}
public void setStyle(String style) {
this.style = style;
}
public static long getSerialversionuid() {
return serialVersionUID;
}
}
<?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">
<!-- 为这个mapper指定一个唯一的namespace,namespace的值习惯上设置成包名+sql映射文件名,这样就能够保证namespace的值是唯一的
例如namespace="me.gacl.mapping.userMapper"就是me.gacl.mapping(包名)+userMapper(userMapper.xml文件去除后缀)
-->
<mapper namespace="com.geyao.mybatis.mapper.AuthorMapper">
<resultMap type="Author" id="authorResultMap">
<id column="id" property="id" jdbcType="INTEGER"></id>
</resultMap>
<select id="selectAuthorById" parameterType="int" resultMap="authorResultMap">
select * from author where id=#{id}
</select>
</mapper>
blogmapper。xml
<?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.geyao.mybatis.mapper.BlogMapper">
<resultMap type="Blog" id="blogResultMap">
<id column="id" property="id" jdbcType="INTEGER"></id>
<association property="author" column="author" javaType="Author"
select="com.geyao.mybatis.mapper.AuthorMapper.selectAuthorById">
</association>
</resultMap>
<select id="selectAuthorById" parameterType="int" resultMap="blogResultMap">
select * from Blog where id=#{id}
</select>
</mapper>
package com.geyao.mybatis.mapper;import org.apache.ibatis.session.SqlSession;
import org.junit.Test;import com.geyao.mybatis.pojo.Author;
import com.geyao.mybatis.pojo.Blog;
import com.geyao.mybatis.util.MyBatisUtil;public class BlogMapperTest {
@Test
public void testSelectBlog() {
SqlSession session =MyBatisUtil.getSqlSession();
BlogMapper blogMapper =session.getMapper(BlogMapper.class);
Blog blog = blogMapper.selectBlogById(1);
session.close();
System.out.println(blog);
}
}
<?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>
<settings>
<setting name="useGeneratedKeys" value="true"/>
</settings>
<typeAliases>
<typeAlias type="com.geyao.mybatis.pojo.Blog" alias="Blog"/>
<typeAlias type="com.geyao.mybatis.pojo.Author" alias="Author"/>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<!-- 配置数据库连接信息 -->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/blog_gp1701?serverTimezone=GMT%2B8" />
<property name="username" value="root" />
<property name="password" value="123" />
</dataSource>
</environment>
</environments>
<mappers>
<!-- 注册userMapper.xml文件,
userMapper.xml位于me.gacl.mapping这个包下,所以resource写成me/gacl/mapping/userMapper.xml-->
<mapper resource="com/geyao/mybatis/mapper/BlogMapper.xml"/>
<mapper resource="com/geyao/mybatis/mapper/AuthorMapper.xml"/>
</mappers>
</configuration>