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1.问题：mybatis一对一关联查询报错 org.apache.ibatis.builder.IncompleteElementException: Could not find result map，但是无轮建表，到sql查询均可以查询到，请问哪里出问题了？
SQL建表如下：
# 创建teacher 与 class 表
CREATE TABLE IF NOT EXISTS teacher(
t_id INT PRIMARY KEY AUTO_INCREMENT,
t_name VARCHAR(20)
);
CREATE TABLE IF NOT EXISTS class(
c_id INT PRIMARY KEY AUTO_INCREMENT,
c_name VARCHAR(20),
teacher_id INT
);
#建立一对一外键关系，这个需要学习了解
ALTER TABLE class ADD CONSTRAINT fk_teacher_id FOREIGN KEY (teacher_id) REFERENCES teacher(t_id);
#插入teacher数据
INSERT INTO teacher(t_name) VALUES('Mandy');
INSERT INTO teacher(t_name) VALUES('Chris');
#插入class数据
INSERT INTO class(c_name, teacher_id) VALUES('class_a', 1);
INSERT INTO class(c_name, teacher_id) VALUES('class_b', 2);
SELECT * FROM teacher;
SELECT * FROM class;
#级联查询表
select * from class c, teacher t where c.teacher_id=t.t_id and c.c_id=1;java项目中maven配置：（pom.xml）
<dependencies>
<!--log4j日志文件-->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
</dependency>
<!--mysql数据库连接-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.33</version>
</dependency>
<!--MyBatis框架-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
</dependencies>
<!-- mybatis idea插件 -->
<build>
<finalName>mybatis</finalName>
<plugins>
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<configuration>
<verbose>true</verbose>
<overwrite>true</overwrite>
</configuration>
</plugin>
</plugins>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<!-- 是否替换资源中的属性-->
<filtering>false</filtering>
</resource>
<resource>
<directory>src/main/resources</directory>
<!--
<includes> <include>**/*.properties</include>
<include>**/*.xml</include> </includes> <filtering>true</filtering>
-->
</resource>
</resources>
</build>mybatis配置文档：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!--重点1：引入db.properties文件 -->
<properties resource="db.properties" />
<typeAliases>
<typeAlias type="com.mybatis.oneToone.domain.Classes" alias="Classes" />
<typeAlias type="com.mybatis.oneToone.domain.Teacher" alias="Teacher" />
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<!--配置mysql数据库信息-->
<dataSource type="POOLED">
<property name="driver" value="${driver}" />
<property name="url" value="${url}" />
<property name="username" value="${name}" />
<property name="password" value="${password}" />
</dataSource>
</environment>
</environments>
<!-- 配置注册的userMapper-->
<mappers>
<mapper resource="com/mybatis/oneToone/mapping/ClassMapper.xml"/>
</mappers>
</configuration>两个domain类：
public class Classes {
private int id;//id===>c_id
private String name;//name===>c_name
private Teacher teacher;
public Classes(int id, String name, Teacher teacher) {
this.id = id;
this.name = name;
this.teacher = teacher;
}
public Classes() {
}
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 Teacher getTeacher() {
return teacher;
}
public void setTeacher(Teacher teacher) {
this.teacher = teacher;
}
@Override
public String toString() {
return "Classes {id="+id+" ,name="+name+" , teacher="+teacher+"}";
}
}
public class Teacher {
private int id; // id --> t_id
private String name; // name --> t_name
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;
}
@Override
public String toString() {
return "Teacher {id="+ id+" ,name="+ name +"}";
}
}ClassMapper.xml
<mapper namespace="com.mybatis.oneToone.mapping.ClassMapper">
<select id="getClass1" parameterType="int" resultMap="classResultMap">
select *
from class c,teacher t
where c.teacher_id =t.t_id
and c.c_id=#{id}
</select>
<!-- 使用resultMap映射实体类和字段之间的一一对应关系 -->
<resultMap id="classResultMap" type="Classes">
<id property="id" column="c_id" />
<result property="name" column="c_name" />
<!-- 一对一映射 使用的标签 -->
<association property="teacher" column="teacher_id" javaType="Teacher">
<id property="id" column="t_id" />
<result property="name" column="t_name" />
</association>
</resultMap>
</mapper> 运行代码时候：
public class App
{
public static void main( String[] args )
{
SqlSession session = MyBatisUtil.getSqlSession();
String strId = "com.mybatis.oneToone.mapping.ClassMapper.getClass1";
Classes clazz = session.selectOne(strId,1);
System.out.println(clazz);
}
}显示如下错误：
Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException:
Error querying database. Cause: org.apache.ibatis.builder.IncompleteElementException: Could not find result map com.mybatis.oneToone.domain.Teacher
Cause: org.apache.ibatis.builder.IncompleteElementException: Could not find result map com.mybatis.oneToone.domain.Teacher
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:23)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:104)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:95)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:59)
at com.mybatis.oneToone.App.main(App.java:17)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)Caused by: org.apache.ibatis.builder.IncompleteElementException: Could not find result map com.mybatis.oneToone.domain.Teacher
at org.apache.ibatis.builder.MapperBuilderAssistant.setStatementResultMap(MapperBuilderAssistant.java:354)
at org.apache.ibatis.builder.MapperBuilderAssistant.addMappedStatement(MapperBuilderAssistant.java:292)
at org.apache.ibatis.builder.xml.XMLStatementBuilder.parseStatementNode(XMLStatementBuilder.java:113)
at org.apache.ibatis.session.Configuration.buildAllStatements(Configuration.java:579)
at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:505)
at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:500)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:100)
... 8 moreCaused by: java.lang.IllegalArgumentException: Result Maps collection does not contain value for com.mybatis.oneToone.domain.Teacher
at org.apache.ibatis.session.Configuration$StrictMap.get(Configuration.java:672)
at org.apache.ibatis.session.Configuration.getResultMap(Configuration.java:434)
at org.apache.ibatis.builder.MapperBuilderAssistant.setStatementResultMap(MapperBuilderAssistant.java:352)
... 14 more
希望好心人帮忙一下，我已经尽力排查我自己能够知道的错误，但是真的不米昂白为何还是报错。
java
mysql
这个问题，我已经找到方法了，首先mybatis我现在用的版本是有一对一映射，使用association标签。这里需要这样修改：