避免ibatisN+1查询的方法
如果您在实体类工作的时候想要避免ibatisN+1查询，您可以参考如下代码。
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Java代码避免ibatisN+1查询
多方：
public class Employ {
private int id;
private String enployName;
private int salary;
private Department department;
public Employ() {
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getEnployName() {
return enployName;
}
public void setEnployName(String enployName) {
this.enployName = enployName;
}
public int getSalary() {
return salary;
}
public void setSalary(int salary) {
this.salary = salary;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
}
一方：
public class Department {
private int did;
private String departmentName;
private List employees;
public int getDid() {
return did;
}
public void setDid(int did) {
this.did = did;
}
public String getDepartmentName() {
return departmentName;
}
public void setDepartmentName(String departmentName) {
this.departmentName = departmentName;
}
public List getEmployees() {
return employees;
}
public void setEmployees(List employees) {
this.employees = employees;
}
}
多方：
public class Employ {
private int id;
private String enployName;
private int salary;
private Department department;
public Employ() {
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getEnployName() {
return enployName;
}
public void setEnployName(String enployName) {
this.enployName = enployName;
}
public int getSalary() {
return salary;
}
public void setSalary(int salary) {
this.salary = salary;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
}
一方：
public class Department {
private int did;
private String departmentName;
private List employees;
public int getDid() {
return did;
}
public void setDid(int did) {
this.did = did;
}
public String getDepartmentName() {
return departmentName;
}
public void setDepartmentName(String departmentName) {
this.departmentName = departmentName;
}
public List getEmployees() {
return employees;
}
public void setEmployees(List employees) {
this.employees = employees;
}
}
如果您在映射文件的工作中想要避免ibatisN+1查询，您可以参考如下代码。
Xml代码避免ibatisN+1查询
多方：
1. ＜?xml version="1.0" encoding="UTF-8" ?＞
2.
3. ＜!DOCTYPE sqlMap
4. PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
5. "http://ibatis.apache.org/dtd/sql-map-2.dtd"＞
6.
7. ＜sqlMap namespace="Employ"＞
8.
9. ＜!-- Use type aliases to avoid typing the full classname every time. --＞
10. ＜typeAlias alias="Employ" type="com.test.domain.Employ"/＞
11.
12. ＜!-- Result maps describe the mapping between the columns returned
13. from a query, and the class properties. A result map isn't
14. necessary if the columns (or aliases) match to the properties
15. exactly. --＞
16. ＜resultMap id="EmployResult" class="Employ"＞
17. ＜result property="id" column="id"/＞
18. ＜result property="enployName" column="employ_name"/＞
19. ＜result property="salary" column="salary"/＞
20. ＜result property="department.did" column="did"/＞
21. ＜result property="department.departmentName" column="department_name"/＞
22. ＜/resultMap＞
23.
24. ＜!-- Select with no parameters using the result map for Account class. --＞
25. ＜select id="selectAllEmploy" resultMap="EmployResult"＞
26. ＜![CDATA[
27. select * from employees e, departments d where e.departmentid = d.did
28. ]]＞
29. ＜/select＞
30. ＜!-- A simpler select example without the result map. Note the
31. aliases to match the properties of the target result class. --＞
32.
33. ＜!-- Insert example, using the Account parameter class --＞
34. ＜insert id="insertEmploy" parameterClass="Employ"＞
35. ＜![CDATA[
36. insert into employees (employ_name, salary, departmentid) values(#enployName#, #salary#, #department.did#)
37. ]]＞
38. ＜/insert＞
39.
40. ＜!-- Update example, using the Account parameter class --＞
41.
42. ＜!-- Delete example, using an integer as the parameter class --＞
43. ＜/sqlMap＞
一方：
1. ＜?xml version="1.0" encoding="UTF-8" ?＞
2.
3. ＜!DOCTYPE sqlMap
4. PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
5. "http://ibatis.apache.org/dtd/sql-map-2.dtd"＞
6.
7. ＜sqlMap namespace="Department"＞
8.
9. ＜!-- Use type aliases to avoid typing the full classname every time. --＞
10. ＜typeAlias alias="Department" type="com.test.domain.Department"/＞
11.
12. ＜!-- Result maps describe the mapping between the columns returned
13. from a query, and the class properties. A result map isn't
14. necessary if the columns (or aliases) match to the properties
15. exactly. --＞
16. ＜resultMap id="DepartmentResult" class="Department"＞
17. ＜result property="did" column="did"/＞
18. ＜result property="departmentName" column="department_name"/＞
19. ＜/resultMap＞
20.
21. ＜!-- Select with no parameters using the result map for Account class. --＞
22. ＜select id="selectDepartmentById" parameterClass="int" resultMap="DepartmentResult"＞
23. ＜![CDATA[
24. select * from departments where did = #did#
25. ]]＞
26. ＜/select＞
27. ＜!-- A simpler select example without the result map. Note the
28. aliases to match the properties of the target result class. --＞
29.
30. ＜!-- Insert example, using the Account parameter class --＞
31. ＜insert id="insertDepartment" parameterClass="Department"＞
32. ＜![CDATA[
33. insert into departments (department_name) values(#departmentName#)
34. ]]＞
35. ＜/insert＞
36.
37. ＜!-- Update example, using the Account parameter class --＞
38.
39. ＜!-- Delete example, using an integer as the parameter class --＞
40. ＜/sqlMap＞
通过以上的代码，您可以有效地避免ibatisN+1查询，相信能够为您的工作起到相关的帮助。
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