mybatis笔记-04【MyBatis基于XML的详细使用——高级结果映射】

emp.java

1 package cn.tulingxueyuan.pojo; 
2
3 import java.time.LocalDate; 
4
5  
9 public class Emp { 
10 private Integer id; 
11 private String username; 
12 private LocalDate createDate; 
13 private deptId deptId; 
14
15
16 public Integer getId() { 
17 return id; 
18 } 
19
20 public void setId(Integer id) { 
21 this.id = id; 
22 }
23
24 public String getUsername() { 
25 return username; 
26 } 
27
28 public void setUsername(String username) { 
29 this.username = username; 
30 } 
31
32 public LocalDate getCreateDate() { 
33 return createDate; 
34 } 
35
36 public void setCreateDate(LocalDate createDate) { 
37 this.createDate = createDate; 
38 } 
39
40 public Integer getDeptId() { 
41 return dept; 
42 } 
43
44 public void setDeptId(Integer deptId) { 
45 this.dept = dept; 
46 } 
47
48 @Override 
49 public String toString() { 
50 return "Emp{" + 
51 "id=" + id + 
52 ", username='" + username + ''' + 
53 ", createDate=" + createDate + 
54 ", deptId=" + deptId+ 
55 '}'; 
56 } 
57
58 }

EmpMapper.xml

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3 
4  
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7  
8
9  
10 select t1.id as e_id,t1.user_name,t2.id as d_id,t2.dept_name from emp t 
1
11 INNER JOIN dept t2 on t1.dept_id=t2.id 
12 where t1.id=#{id} 
13  
14
15
16
17
18  
19  
20  
21  
22  
23  
24  
25
26  
27 select t1.id as e_id,t1.user_name,t2.id as d_id,t2.dept_name from emp t 
1
28 INNER JOIN dept t2 on t1.dept_id=t2.id 
29 where t1.id=#{id} 
30  
 
QueryEmpDTO
 
1 package cn.tulingxueyuan.pojo; 
2
3  
7 public class QueryEmpDTO { 
8
9 private String deptName; 
10 private Integer deptId; 
11 private Integer id;
12 private String username; 
13
14 public String getDeptName() { 
15 return deptName; 
16 } 
17
18 public void setDeptName(String deptName) { 
19 this.deptName = deptName; 
20 } 
21
22 public Integer getDeptId() { 
23 return deptId; 
24 } 
25
26 public void setDeptId(Integer deptId) { 
27 this.deptId = deptId; 
28 } 
29
30 public Integer getId() { 
31 return id; 
32 } 
33
34 public void setId(Integer id) { 
35 this.id = id; 
36 } 
37
38 public String getUsername() { 
39 return username; 
40 } 
41
42 public void setUsername(String username) { 
43 this.username = username; 
44 } 
45
46 @Override 
47 public String toString() { 
48 return "QueryEmpDTO{" + 
49 "deptName='" + deptName + ''' + 
50 ", deptId=" + deptId + 
51 ", id=" + id + 
52 ", username='" + username + ''' +
53 '}'; 
54 } 
55 } 
 
Test
 
1  
4 @Test 
5 public void test01() { 
6 try(SqlSession sqlSession = sqlSessionFactory.openSession()){ 
7 // Mybatis在getMapper就会给我们创建jdk动态代理 
8 EmpMapper mapper = sqlSession.getMapper(EmpMapper.class); 
9 QueryEmpDTO dto = mapper.QueryEmp(4); 
10 System.out.println(dto); 
11 } 
12 } 
 
2、嵌套结果 
2.1多对一 
EmpMapper.xml
 
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2  
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15
16  
17 select t1.id as e_id,t1.user_name,t2.id as d_id,t2.dept_name from emp t 
1
18 INNER JOIN dept t2 on t1.dept_id=t2.id 
19 where t1.id=#{id}
20  
21

1  
2  
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16
17  
18 select t1.id as d_id,t1.dept_name,t2.id e_id,t2.user_name,t2.create_dat 
e from dept t1 
19 LEFT JOIN emp t2 on t1.id=t2.dept_id 
20 where t1.id=#{id} 
21 

Emp.java

1 package cn.tulingxueyuan.pojo; 
2
3 import java.time.LocalDate; 
4
5  
9 public class Emp { 
10 private Integer id; 
11 private String username; 
12 private LocalDate createDate; 
13 private Dept dept; 
14
15
16 public Integer getId() { 
17 return id; 
18 } 
19
20 public void setId(Integer id) { 
21 this.id = id; 
22 } 
23
24 public String getUsername() { 
25 return username; 
26 } 
27
28 public void setUsername(String username) { 
29 this.username = username; 
30 } 
31
32 public LocalDate getCreateDate() { 
33 return createDate; 
34 } 
35
36 public void setCreateDate(LocalDate createDate) { 
37 this.createDate = createDate; 
38 } 
39
40 public Dept getDept() { 
41 return dept; 
42 } 
43
44 public void setDept(Dept dept) { 
45 this.dept = dept; 
46 } 
47
48 @Override 
49 public String toString() { 
50 return "Emp{" + 
51 "id=" + id + 
52 ", username='" + username + ''' + 
53 ", createDate=" + createDate + 
54 ", dept=" + dept + 
55 '}';
56 } 
57
58 }

Dept.java:

1 package cn.tulingxueyuan.pojo; 
2
3 import java.util.List; 
4
5  
9 public class Dept { 
10 private Integer id; 
11 private String deptName; 
12 private List emps; 
13
14 public Integer getId() { 
15 return id; 
16 } 
17
18 public void setId(Integer id) { 
19 this.id = id; 
20 } 
21
22 public String getDeptName() { 
23 return deptName; 
24 } 
25
26 public void setDeptName(String deptName) { 
27 this.deptName = deptName; 
28 } 
29
30 public List getEmps() { 
31 return emps; 
32 } 
33
34 public void setEmps(List emps) { 
35 this.emps = emps; 
36 } 
37
38
39 @Override 
40 public String toString() { 
41 return "Dept{" + 
42 "id=" + id + 
43 ", deptName='" + deptName + ''' + 
44 ", emps=" + emps + 
45 '}'; 
46 } 
47 } 

EmpMapper.java:

1 package cn.tulingxueyuan.mapper; 
2
3
4 import cn.tulingxueyuan.pojo.Emp; 
5 import cn.tulingxueyuan.pojo.QueryEmpDTO; 
6
7 import java.util.Map; 
8
9  
13 public interface EmpMapper { 
14
15  
16 QueryEmpDTO QueryEmp(Integer id); 
17
18  
19 Emp QueryEmp2(Integer id); 
20
21
22  
23 Emp QueryEmp3(Integer id); 
24 } 

DeptMapper.java:

1 package cn.tulingxueyuan.mapper; 
2
3
4 import cn.tulingxueyuan.pojo.Dept;5
6  
10 public interface DeptMapper { 
11 //嵌套查询： 一对多 使用部门id查询员工 
12 Dept SelectDeptAndEmps(Integer id); 
13
14 // 嵌套查询（异步查询）： 一对多 查询部门及所有员工 
15 Dept SelectDeptAndEmps2(Integer id); 
16 } 

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