小峰mybatis（4）mybatis使用注解配置sql映射器
一、基本映射语句：
@Inert
@Update
@Delete
@Select
二、结果集映射语句
项目结够：
Student.java model实体类：
package com.cy.model;
public class Student{
private Integer id;
private String name;
private Integer age;
public Student(){
}
public Student(String name, Integer age){
this.name = name;
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
}
}
mybatis-config.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>
<properties resource="jdbc.properties"/>
<!-- 别名 -->
<typeAliases>
<package name="com.cy.model"/>
</typeAliases> <environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driverClassName}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
</dataSource>
</environment>
<environment id="test">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driverClassName}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
</dataSource>
</environment>
</environments> <mappers>
<package name="com.cy.mapper"/>
</mappers>
</configuration>
StudentMapper.java 接口：
package com.cy.mapper; import java.util.List; import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Update;
import org.apache.ibatis.annotations.Select; import com.cy.model.Student; public interface StudentMapper { //插入
@Insert("insert into t_student values(null, #{name}, #{age})")
public int inertStudent(Student student); //更新
@Update("update t_student set name=#{name}, age=#{age} where id = #{id}")
public int updateStudent(Student stu); //删除
@Delete("delete from t_student where id=#{id}")
public int deleteStudent(int id); //根据id查找学生
@Select("select * from t_student where id=#{id}")
public Student getStudentById(Integer id); //查询所有学生 结果集映射 id主键列
@Select("select * from t_student")
@Results(
{
@Result(id=true,column="id",property="id"),
@Result(column="name",property="name"),
@Result(column="age",property="age")
}
)
public List<Student> findStudents(); }
测试代码StudentTest.java:
package com.cy.service; import java.util.List; import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.After;
import org.junit.Before;
import org.junit.Test; import com.cy.mapper.StudentMapper;
import com.cy.model.Student;
import com.cy.util.SqlSessionFactoryUtil; public class StudentTest {
private static Logger logger = Logger.getLogger(StudentTest.class); private SqlSession sqlSession=null;
private StudentMapper studentMapper=null; @Before
public void setUp() throws Exception {
sqlSession=SqlSessionFactoryUtil.openSession();
studentMapper=sqlSession.getMapper(StudentMapper.class);
} @After
public void tearDown() throws Exception {
sqlSession.close();
} @Test
public void testInsertStudent() {
logger.info("测试insertStudent");
Student stu = new Student("cpp", 12);
int count = studentMapper.inertStudent(stu);
sqlSession.commit();
} @Test
public void testUpdateStudent() {
logger.info("测试updateStudent");
Student stu = new Student("cppp", 13);
stu.setId(14);
int count = studentMapper.updateStudent(stu);
sqlSession.commit();
} @Test
public void testDeleteStudent() {
logger.info("测试删除学生");
int count = studentMapper.deleteStudent(14);
sqlSession.commit();
} @Test
public void testGetById(){
logger.info("根据id查找学生");
Student stu = studentMapper.getStudentById(1);
System.out.println(stu);
} @Test
public void testFindStudent() {
logger.info("测试查询所有学生");
List<Student> students = studentMapper.findStudents();
for(Student student : students){
System.out.println(student);
}
}
}
三、使用注解 一对一映射：
package com.cy.model;
public class Student{
private Integer id;
private String name;
private Integer age;
private Address address;
public Student(){
}
public Student(String name, Integer age){
this.name = name;
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
@Override
public String toString() {
return "Student [id=" + id + ", name=" + name + ", age=" + age
+ ", address=" + address + "]";
}
}
Address.java 实体：
package com.cy.model;
public class Address {
private Integer id;
private String sheng;
private String shi;
private String qu;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getSheng() {
return sheng;
}
public void setSheng(String sheng) {
this.sheng = sheng;
}
public String getShi() {
return shi;
}
public void setShi(String shi) {
this.shi = shi;
}
public String getQu() {
return qu;
}
public void setQu(String qu) {
this.qu = qu;
}
@Override
public String toString() {
return "Address [id=" + id + ", sheng=" + sheng + ", shi=" + shi
+ ", qu=" + qu + "]";
}
}
StudentMapper.java接口：
//查询学生，带地址
@Select("select * from t_student where id=#{id}")
@Results(
{
@Result(id=true,column="id",property="id"),
@Result(column="name",property="name"),
@Result(column="age",property="age"),
@Result(column="addressId",property="address",one=@One(select="com.cy.mapper.AddressMapper.findById"))
}
)
public Student findStudentWithAddress(int id);
AddressMapper.java接口：
public interface AddressMapper {
@Select("select * from t_address where id=#{id}")
public Address findById(Integer id);
}
mybatis的实现是：在查找学生的时候，将addressId,传到AddressMapper.findById方法，根据这个addressId查找address；
测试代码：
@Test
public void testFindStudentWithAddress() {
logger.info("测试学生,带地址");
Student student = studentMapper.findStudentWithAddress(15);
System.out.println(student);
}
console打印：
四、使用注解，一对多映射
package com.cy.model;
public class Student{
private Integer id;
private String name;
private Integer age;
private Address address;
private Grade grade;
public Student(){
}
public Student(String name, Integer age){
this.name = name;
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public Grade getGrade() {
return grade;
}
public void setGrade(Grade grade) {
this.grade = grade;
}
@Override
public String toString() {
return "Student [id=" + id + ", name=" + name + ", age=" + age
+ ", address=" + address + ", grade=" + grade + "]";
}
}
Grade.java:
package com.cy.model;
import java.util.List;
public class Grade {
private Integer id;
private String gradeName;
private List<Student> students;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getGradeName() {
return gradeName;
}
public void setGradeName(String gradeName) {
this.gradeName = gradeName;
}
public List<Student> getStudents() {
return students;
}
public void setStudents(List<Student> students) {
this.students = students;
}
@Override
public String toString() {
return "Grade [id=" + id + ", gradeName=" + gradeName +"]";
}
}
数据库中表，t_student:
t_grade:
1)根据id查找年级，将年级下的学生也查出来：
GradeMapper.java:
public interface GradeMapper {
//根据id查找年级，将年级下的学生也查出来
@Select("select * from t_grade where id = #{id}")
@Results(
{
@Result(id=true,column="id",property="id"),
@Result(column="gradeName",property="gradeName"),
@Result(column="id",property="students",many=@Many(select="com.cy.mapper.StudentMapper.findStudentByGradeId"))
}
)
public Grade findById(Integer id);
}
StudentMapper.java:
//根据年级查找学生
@Select("select * from t_student where gradeId=#{gradeId}")
@Results(
{
@Result(id=true,column="id",property="id"),
@Result(column="name",property="name"),
@Result(column="age",property="age"),
@Result(column="addressId",property="address",one=@One(select="com.cy.mapper.AddressMapper.findById"))
}
)
public Student findStudentByGradeId(int gradeId);
测试代码：
//根据id查找年级，将年级下的学生也查出来
@Test
public void testFindGradeWithStudents() {
logger.info("根据id查询年级(带学生)");
Grade grade=gradeMapper.findById(1);
System.out.println(grade);
List<Student> studentList=grade.getStudents();
for(Student student:studentList){
System.out.println(student);
}
}
结果：
2）根据id查询学生，将年级信息也查出来：
StudentMapper.java:
//根据id查询学生带地址 和 年级
@Select("select * from t_student where id=#{id}")
@Results(
{
@Result(id=true,column="id",property="id"),
@Result(column="name",property="name"),
@Result(column="age",property="age"),
@Result(column="addressId",property="address",one=@One(select="com.cy.mapper.AddressMapper.findById")),
@Result(column="gradeId",property="grade",one=@One(select="com.cy.mapper.GradeMapper.findById"))
}
)
public Student findStudentWithAddressAndGrade(int id);
GradeMapper.java中的findById和上面1）中一样；
测试代码：
//根据id查询学生，带地址和年级
@Test
public void testSelectStudentWithAddressAndGrade() {
logger.info("根据id查询学生(带地址、年级)");
Student student=studentMapper.findStudentWithAddressAndGrade(1);
System.out.println(student);
}
打印结果：
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