码云链接 https://gitee.com/Chuangzw/JavaEE_Learn/tree/master/student-springmvc-maven
Springmvc整合mybatis，需要引入mybatis包，在pom.xml中添加以下依赖包：
<!--mybatis--> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.2</version> </dependency> <!--mybatis spring整合--> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> <version>2.0.3</version> </dependency>mybatis-generator插件
<plugins> <!--mybatis-generator插件--> <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>mybatis-generator自动生成的代码 不能自动添加外键 所以要自己添加
Mapper.xml中的代码 自动生成的 参数都是bjid 需要改成 bj.ij
一是直接在Controller中 建立会话
// BjDao bjDao=new BjDao(); // Reader reader; // { // try { // reader = Resources.getResourceAsReader("mybatis-config.xml"); // } catch (IOException e) { // e.printStackTrace(); // } // } // // SqlSessionFactory sessionFactory=new SqlSessionFactoryBuilder().build(reader); // SqlSession session = sessionFactory.openSession();二是建立SqlSessionFactoryUtil
package cn.oneseek.student.util; 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.InputStream; public class SqlSessionFactoryUtil { private static SqlSessionFactory sqlSessionFactory; private static SqlSessionFactory getSqlSessionFactory(){ if(sqlSessionFactory==null){ InputStream inputStream=null; try{ inputStream= Resources.getResourceAsStream("mybatis-config.xml"); sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream); }catch(Exception e){ e.printStackTrace(); } } return sqlSessionFactory; } public static SqlSession openSession(){ return getSqlSessionFactory().openSession(); } }然后在Controller中
private SqlSession session=SqlSessionFactoryUtil.openSession(); private BjMapper bjDao = session.getMapper(BjMapper.class);引入datasource数据源的包，引入了2种方式，但本次项目中，我们使用的是alibaba的Druid DataSource。
<!-- JDBC连接池 --> <dependency> <groupId>com.mchange</groupId> <artifactId>c3p0</artifactId> <version>0.9.5.2</version> </dependency> <!-- DruidDataSource，本工程的dataSource配置使用的Druid --> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.0.29</version> </dependency>pom.xml build添加
<resources> <!--表示把java目录下的有关xml文件,properties文件编译/打包的时候放在resource目录下--> <resource> <directory>${basedir}/src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> </resource> <resource> <directory>${basedir}/src/main/resources</directory> </resource> </resources>添加spring-jdbc
<!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>5.2.0.RELEASE</version> </dependency>出现异常
org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from class path resource [spring-mvc.xml]; nested exception is java.lang.NoSuchMethodError: org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.getEnvironment()Lorg/springframework/core/env/Environment;原因：忘记在mybatis-config.xml中配置
<typeAliases> <typeAlias alias="Bj" type="cn.oneseek.student.entity.Bj"/> <typeAlias alias="Student" type="cn.oneseek.student.entity.Student"/> </typeAliases> <mappers> <mapper resource="cn/oneseek/student/mapping/BjMapper.xml"/> <mapper resource="cn/oneseek/student/mapping/StudentMapper.xml"/> </mappers>一种是：
session.selectList("cn.oneseek.student.dao.BjMapper.queryAll");另一种
private SqlSession session=SqlSessionFactoryUtil.openSession(); private BjMapper bjDao = session.getMapper(BjMapper.class); List<Bj> bjList = bjDao.queryAll();原生的mybatis-generator中没有一对一和一对多的关联关系的配置，所以反向生成代码的时候不会产生关联关系
手动添加一对多关系如下：
package cn.oneseek.student.entity; import java.util.List; public class Bj { private Integer id; private String bjname; List<Student> students; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getBjname() { return bjname; } public void setBjname(String bjname) { this.bjname = bjname; } public List<Student> getStudents() { return students; } public void setStudents(List<Student> students) { this.students = students; } @Override public String toString() { return "Bj [id=" + id + ", bjname=" + bjname + "]"; } } package cn.oneseek.student.entity; public class Student { private Integer id; private String sno; private String sname; private String sex; // private Integer bjid; private Bj bj; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getSno() { return sno; } public void setSno(String sno) { this.sno = sno; } public String getSname() { return sname; } public void setSname(String sname) { this.sname = sname; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } // public Integer getBjid() { // return bjid; // } // // public void setBjid(Integer bjid) { // this.bjid = bjid; // } public Bj getBj() { return bj; } public void setBj(Bj bj) { this.bj = bj; } @Override public String toString() { return "Student [id=" + id + ", sno=" + sno + ", sname=" + sname + ", sex=" + sex + ", bj=" + bj + "]"; } }控制台乱码
VM options;
-Dfile.encoding=UTF-8出现原因：控制台打印发现bj=null
[Student [id=1, sno=001, sname=����, sex=��, bj=null]]未查询到班级
在Mapper里增加以下代码
<resultMap type="cn.oneseek.student.entity.Student" id="StudentWithBj"> <association property="bj" column="bjid" select="cn.oneseek.student.dao.BjMapper.selectByPrimaryKey"/></resultMap> <select id="queryAllWithBj" resultMap="StudentWithBj"> select * from student </select>原因:自动生成的entity没有bj.id属性
解决方法：
在StudentMapper.xml增加
<insert id="add" parameterType="Student" > insert into student values(null,#{sno},#{sname},#{sex},#{bj.id}) </insert>StudentMapping.java
void add(Student student);原因：
Student实体没有bjid
