mybatis02--增删改查

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1.修改StudentDao

public interface StudentDao {
/**
* 新增学生信息
*/
void addStudent(Student student); // 新增完毕之后有ID
void addStudentCacheId(Student student); // 删除学生信息
void deleteStudent(Integer id); // 修改
void updateStudent(Student student); // 查询所有
List<Student> selectAllStudents(); // 查询出来的是一个map集合
Map<String, Object> selectAllStudentsMap(); // 查询指定的
Student selectById(Integer id); // 根据姓名模糊查询
List<Student> selectByName(String name);
}

2.修改StudentMapper

<?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="student">

<insert id="addStudent" parameterType="Student">
insert into
student(age,name) values(#{age},#{name})
</insert>
<insert id="addStudentCacheId" parameterType="Student">
insert into
student(age,name) values(#{age},#{name})
<selectKey resultType="int" keyProperty="id" order="AFTER">
select
@@identity
</selectKey>
</insert> 
<delete id="deleteStudent">

delete from student where id=#{sa}
</delete>

<update id="updateStudent">

update student set name=#{name},age=#{age},id=#{id}
where id=#{id}
</update> 
<select id="selectAllStudents" resultType="Student">
select id,name,age
from student
</select>

<select id="selectById" resultType="Student">
select * from student where
id=#{xxx}
</select> 
<select id="selectByName" resultType="Student">




</select>
</mapper>

3.修改StudentDaoImpl

public class StudentDaoImpl implements StudentDao {
SqlSession session = null; /**
* 新增学生信息
*/
public void addStudent(Student student) {
try {
// 通过工具类获取session
session = SessionUtil.getSession();
/**
* "addStudent" 要和mapper.xml文件中的id一致
* 增删改操作底层执行的都是update方法
*/
session.insert("addStudent", student);
// 必须手动让session提交底层默认就提交了事务
session.commit();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close(); // 关闭session
}
}
} public void addStudentCacheId(Student student) {
try {
// 通过工具类获取session
session = SessionUtil.getSession();
session.insert("addStudentCacheId", student);
// 必须手动让session提交底层默认就提交了事务
session.commit();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close(); // 关闭session
}
} } // 删除
public void deleteStudent(Integer id) {
try {
// 通过工具类获取session
session = SessionUtil.getSession();
session.delete("deleteStudent", id);
// 必须手动让session提交底层默认就提交了事务
session.commit();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close(); // 关闭session
}
} } // 修改学生信息
public void updateStudent(Student student) {
try {
// 通过工具类获取session
session = SessionUtil.getSession();
session.update("updateStudent", student);
// 必须手动让session提交底层默认就提交了事务
session.commit();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close(); // 关闭session
}
} } // 查询返回list集合
public List<Student> selectAllStudents() {
List<Student> students = new ArrayList<Student>();
try {
// 通过工具类获取session
session = SessionUtil.getSession();
students = session.selectList("selectAllStudents");
// 查询就不需要提交事务了
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close(); // 关闭session
}
}
return students;
} // 返回map集合
public Map<String, Object> selectAllStudentsMap() {
Map<String, Object> students = new HashMap<String, Object>();
try {
// 通过工具类获取session
session = SessionUtil.getSession();
// 还是之前list的方法但是 key放什么？ key必须是查询出来实体类的属性值
students = session.selectMap("selectAllStudents", "name");
// 查询就不需要提交事务了
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close(); // 关闭session
}
}
return students;
} // 根据id查询指定的学生信息
public Student selectById(Integer id) {
Student students = null;
try {
// 通过工具类获取session
session = SessionUtil.getSession();
// 还是之前list的方法但是 key放什么？ key必须是查询出来实体类的属性值
students = session.selectOne("selectById", id);
// 查询就不需要提交事务了
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close(); // 关闭session
}
}
return students;
} // 根据name模糊查询返回list集合
public List<Student> selectByName(String name) {
List<Student> students = new ArrayList<Student>();
try {
// 通过工具类获取session
session = SessionUtil.getSession();
students = session.selectList("selectByName", name);
// 查询就不需要提交事务了
} catch (Exception e) {
e.printStackTrace();
} finally {
if (session != null) {
session.close(); // 关闭session
}
}
return students;
}
}

4.修改测试类

public class StudentTest {
StudentDao dao; @Before
public void before() {
dao = new StudentDaoImpl();
} @Test
public void test() {
/**
* 之前和之后都是显示我们赋予的id值，
* 但因为数据库中我们设置了主键的自增，所以我们的id相当于没有从数据库中查询到
*/ Student student = new Student("小黑333", 10);
System.out.println("方法之前==" + student);
dao.addStudent(student);
System.out.println("方法之后==" + student);
} @Test
public void addStudentCacheId() {
Student student = new Student("小黑33", 10);
// 方法之前因为没有insert语句所以也是没有ID的
System.out.println("方法之前==" + student);
dao.addStudentCacheId(student);
// 产生了数据库中的id
System.out.println("方法之后==" + student);
} // 删除
@Test
public void delete() {
dao.deleteStudent(17);
} // 修改
@Test
public void update() {
Student student = new Student(19, "小黑3111", 10);
student.setId(17);
dao.updateStudent(student);
} // 返回list
@Test
public void selectList() {
List<Student> allStudents = dao.selectAllStudents();
for (Student student : allStudents) {
System.out.println(student);
}
} // 返回map
@Test
public void selectMap() {
Map<String, Object> students = dao.selectAllStudentsMap();
/**
* 因为以name属性作为了key
* map集合key不允许出现重复的数据
* 所以后一个会覆盖前一个
*/
System.out.println(students.get("小黑122"));
} // 返回指定的一个学生信息
@Test
public void selectOne() {
Student students = dao.selectById(1);
System.out.println(students);
} // 模糊查询学生信息
@Test
public void selectByName() {
List<Student> students = dao.selectByName("1");
for (Student student : students) {
System.out.println(student);
}
}
}