spring,mybatis整合时出现的一个小问题
整合步骤：
1.spring-mybatis.xml
</pre><pre name="code" class="html"><?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd"
default-autowire="byName" default-lazy-init="false"
>
<!-- 开启自动注入 -->
<context:annotation-config/>
<!-- 开启自动扫描，在指定的路径及子路径下扫描，将扫描到的bean注册到spring -->
<context:component-scan base-package="org.hnust.cn"/>
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/test"/>
<property name="username" value="root"/>
<property name="password" value="0128"/>
</bean>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 指定要用到的连接池 -->
<property name="dataSource" ref="dataSource"/>
<!-- 指定mybatis的核心配置文件 -->
<property name="configLocation" value="configuration.xml"/>
</bean>
<bean id="studentMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
<span style="color:#ff0000;"> <property name="mapperInterface" value="org.hnust.cn.dao.IStudentDao"/></span>
<!-- 注入sqlSessionFactory实例 -->
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>
</beans>
2.configuration.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> <!-- 表明重用预编译的sql语句 --> <settings> <setting name="defaultExecutorType" value="REUSE"/> </settings> <typeAliases> <!-- 学生类型别名定义 --> <typeAlias alias="Student" type="org.hnust.cn.pojo.Student"/> <!-- 老师类型别名定义 --> <typeAlias alias="Teacher" type="org.hnust.cn.pojo.Teacher"/> </typeAliases> <!-- 配置数据库连接环境，default指创建sqlSessionFactory时，若没有明确指定要用哪一个environment，则使用此属性指定的 --> <!-- 与spring整合之后，这一段就不需要 --> <!-- <environments default="development"> <environment id="development"> <transactionManager type="jdbc"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/test"/> <property name="username" value="root"/> <property name="password" value="0128"/> </dataSource> </environment> </environments> --> <mappers> <mapper resource="org/hnust/cn/mapping/StudentMapper.xml"/> </mappers> </configuration>3.IStudentDao
package org.hnust.cn.dao;
import org.hnust.cn.pojo.Student;
public interface IStudentDao {
/****
* 根据学生Id查询学生
* @return
*/
public Student getById(int id);
/**
* 增加学生信息
* @param student
*/
public void add(Student student);
/***
* 更新学生信息
* @param student
*/
public void update(Student student);
/***
* 删除
* @param id
*/
public void delete(int id);
}
4.StudentMapper.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">
<!-- nameSpace 指定接口名 -->
<mapper namespace="org.hnust.cn.dao.IStudentDao">
<!-- 数据库表和属性一一对应 -->
<resultMap id="studentResultMap" type="Student">
<id property="id" column="id"/>
<result property="username" column="username"/>
<result property="gender" column="gender"/>
<result property="major" column="major"/>
<result property="grade" column="grade"/>
<!-- javaType属性是必须的 -->
<association property="supervisor" javaType="Teacher">
<id property="id" column="id"/>
<result property="name" column="name"/>
<result property="gender" column="gender"/>
<result property="researchArea" column="reseachArea"/>
<result property="title" column="title"/>
</association>
</resultMap>
<!-- 查找 -->
<select id="getById" parameterType="int" resultMap="studentResultMap">
<!-- select * from student_tab where id=#{id}-->
select st.id,st.username,st.major,st.grade,t.id,t.name,t.gender,t.title,t.research_area from student_tab st,teacher_tab t
where st.supervisor_id=t.id and st.id=#{id}
</select>
<!-- 增加 -->
<!-- useGeneratedKeys="true" 获得数据库自动生成的主键 keyProperty="id" 指定把获得主键注入到Student的id属性中-->
<insert id="add" parameterType="Student" useGeneratedKeys="true" keyProperty="id">
insert into student_tab(username,major,grade,gender) values (#{username},#{major},#{grade},#{gender})
</insert>
<!-- 修改学生信息 -->
<update id="update" parameterType="Student">
update student_tab set username=#{username},
gender=#{gender},major=#{major},grade=#{grade}
where id=#{id}
</update>
<!-- 删除信息 -->
<delete id="delete" parameterType="int">
delete from student_tab where id=#{id}
</delete>
</mapper>
5.Student,Teacher
package org.hnust.cn.pojo;
public class Student {
private int id;
private String username;
private String gender;
private String major;
private String grade;
private Teacher supervisor;
public Teacher getSupervisor() {
return supervisor;
}
public void setSupervisor(Teacher supervisor) {
this.supervisor = supervisor;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getMajor() {
return major;
}
public void setMajor(String major) {
this.major = major;
}
public String getGrade() {
return grade;
}
public void setGrade(String grade) {
this.grade = grade;
}
}
package org.hnust.cn.pojo;
public class Teacher {
private int id;
private String name;
private String gender;
private String researchArea; //研究方向
private String title;//职称
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 String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getResearchArea() {
return researchArea;
}
public void setResearchArea(String researchArea) {
this.researchArea = researchArea;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
}
测试：
package org.hnust.cn.test;
import org.apache.ibatis.session.SqlSessionFactory;
import org.hnust.cn.dao.IStudentDao;
import org.hnust.cn.pojo.Student;
import org.hnust.cn.util.SqlSessionFactoryGen;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestMybatis2 {
// private static SqlSessionFactory factory=SqlSessionFactoryGen.getSqlSessionFactory(); 已经被spring注入
private static ApplicationContext ctx;
static{
ctx=new ClassPathXmlApplicationContext("spring-mybatis.xml");
}
public static void main(String[] args) {
IStudentDao studentDao=(IStudentDao) ctx.getBean("studentMapper");
Student student=studentDao.getById(2);
StringBuilder sb=new StringBuilder("学生信息：\n");
sb.append("姓名：");
sb.append(student.getUsername());
sb.append("专业:");
sb.append(student.getMajor()+"\n");
sb.append("指导教师:\n");
sb.append(student.getSupervisor().getName());
System.out.println(sb.toString());
}
}
中间出现的问题是：
最开始spring-mybatis.xml中我有一段是这样写的：
<bean id="studentMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
<property name="studentDao" value="org.hnust.cn.dao.IStudentDao"/>
<!-- 注入sqlSessionFactory实例 -->
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>
最终测试的时候始终报错，无法生成接口的实例，后来通过查看MapperfactoryBean的源码，发现这么一段：
private Class<T> mapperInterface;
private boolean addToConfig = true;
/**
* Sets the mapper interface of the MyBatis mapper
*
* @param mapperInterface class of the interface
*/
public void setMapperInterface(Class<T> mapperInterface) {
this.mapperInterface = mapperInterface;
}
MapperfactoryBean依赖注入的名字是mapperInterface,所以需要把名字改为一致。同理，网上有很多说把sqlSessionFactory改为sqlSessionfactoryBeanName.，，是一样的道理 只是很多人没有写明白原因