iBATIS的多对多映射配置方法和多对一映射配置方法差不多，不同的是，多对多映射，数据库设计上需要一个记录两个类关系的中间表，本文以学生-老师为例，在iBATIS的sqlmap中配置多对多关系。
iBATIS的多对多映射配置1，建表。数据库中三个表，分别为：
1 CREATE TABLE [student] ( 2 [id] [int] IDENTITY (1, 1) NOT NULL , 3 [name] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL , 4 [birthday] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL , 5 CONSTRAINT [PK_student] PRIMARY KEY CLUSTERED 6 ( 7 [id] 8 ) ON [PRIMARY] 9 ) ON [PRIMARY] 10 GO 11 -------------------------------------------------- 12 CREATE TABLE [teacher] ( 13 [id] [int] IDENTITY (1, 1) NOT NULL , 14 [name] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL , 15 [subject] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NOT NULL , 16 CONSTRAINT [PK_teacher] PRIMARY KEY CLUSTERED 17 ( 18 [id] 19 ) ON [PRIMARY] 20 ) ON [PRIMARY] 21 GO 22 --------------------------------------------------- 23 CREATE TABLE [student_teacher] ( 24 [studentid] [int] NOT NULL , 25 [teacherid] [int] NOT NULL , 26 CONSTRAINT [PK_student_teacher] PRIMARY KEY CLUSTERED 27 ( 28 [studentid], 29 [teacherid] 30 ) ON [PRIMARY] 31 ) ON [PRIMARY] 32 GO
iBATIS的多对多映射配置2，准备数据
1 insert into student(name,birthday) values(‘张三‘,‘1982-01-01‘) 2 insert into student(name,birthday) values(‘李四‘,‘1983-02-02‘) 3 insert into student(name,birthday) values(‘王五‘,‘1984-03-03‘) 4 5 insert into student(name,birthday) values(‘赵六‘,‘1985-04-04‘) 6 insert into teacher(name,subject) values(‘Jerry‘,‘语文‘) 7 insert into teacher(name,subject) values(‘Tom‘,‘数学‘) 8 9 insert into teacher(name,subject) values(‘Steven‘,‘英语‘) 10 insert into student_teacher(studentid,teacherid) values(1,1) 11 insert into student_teacher(studentid,teacherid) values(1,2) 12 insert into student_teacher(studentid,teacherid) values(2,1) 13 insert into student_teacher(studentid,teacherid) values(3,2)
iBATIS的多对多映射配置3，properties文件内容如下：
1 driver=com.microsoft.jdbc.sqlserver.SQLServerDriver 2 url=jdbc:microsoft:sqlserver://localhost:1433;SelectMethod=cursor;DatabaseName=ibatistest 3 username=sa 4 password=000
iBATIS的多对多映射配置4，总配置文件SqlMapConfig.xml内容如下：
﹤?xml version="1.0" encoding="UTF-8" ?﹥
﹤!DOCTYPE sqlMapConfig PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 2.0//EN"
"http://ibatis.apache.org/dtd/sql-map-config-2.dtd"﹥
﹤sqlMapConfig﹥
﹤properties resource="com/lsm/cfg/jdbc.properties" /﹥
﹤transactionManager type="JDBC"﹥
﹤dataSource type="SIMPLE"﹥
﹤property value="${driver}" name="JDBC.Driver" /﹥
﹤property value="${url}" name="JDBC.ConnectionURL" /﹥
﹤property value="${username}" name="JDBC.Username" /﹥
﹤property value="${password}" name="JDBC.Password" /﹥
﹤/dataSource﹥
﹤/transactionManager﹥
﹤sqlMap resource="com/lsm/domain/Student.xml" /﹥
﹤sqlMap resource="com/lsm/domain/Teacher.xml" /﹥
﹤/sqlMapConfig﹥
iBATIS的多对多映射配置5，domain对象两个，Student 和 Teacher，如下：
Teacher.java
package com.lsm.domain;
import java.util.List;
public class Teacher
{
private int id;
private String name;
private String subject;
private List students; //注意这里有个List类型的students，表示一个老师对应多个学生
public List getStudents()
{
return students;
}
public void setStudents(List students)
{
this.students = students;
}
//省略掉其他的getter and setter
}
//Student.java
package com.lsm.domain;
import java.util.List;
public class Student
{
private int id;
private String name;
private String birthday;
private List teachers; //这里有一个list类型的teachers，表示一个学生有多个老师
public List getTeachers()
{
return teachers;
}
public void setTeachers(List teachers)
{
this.teachers = teachers;
}
//省略掉其他的getter and setter
}
iBATIS的多对多映射配置6，sqlmap配置文件
Teacher.xml
1 ﹤?xml version="1.0" encoding="UTF-8" ?﹥
2 !DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
3 "http://ibatis.apache.org/dtd/sql-map-2.dtd"﹥
4
5 ﹤sqlMap namespace="teacher"﹥
6 ﹤typeAlias alias="Teacher" type="com.lsm.domain.Teacher" /﹥
7 ﹤typeAlias alias="Student" type="com.lsm.domain.Student" /﹥
8
9 ﹤resultMap class="Teacher" id="teacherBasicResultMap"﹥
10 ﹤result property="id" column="id"/﹥
11 ﹤result property="name" column="name"/﹥
12 ﹤result property="subject" column="subject"/﹥
13 ﹤/resultMap﹥
14 ﹤!-- 下面这个resultMap中有个students属性，这个结果映射继承自上面的结果映射
15 由于有了继承，结果映射可以任意扩展--﹥
16 ﹤resultMap class="Teacher" id="teacherWithTeacherResultMap" extends="teacherBasicResultMap"﹥
17 ﹤result property="students" column="id" select="getStudentsByTeacherId"/﹥
18 ﹤/resultMap﹥
19 ﹤!-- 这个查询中使用到了上面定义的结果映射，从而决定了查询出来的Teacher中关联出相关的students，在student.xml中配置相似，不再注释。--﹥
20 ﹤select id="getTeachers" resultMap="teacherWithTeacherResultMap"﹥
21 ﹤!--[CDATA[
22 select * from teacher
23 ]]﹥
24 ﹤/select﹥
25
26 ﹤select id="getStudentsByTeacherId" resultClass="Student"﹥
27 ﹤![CDATA[
28 select s.* from student s,student_teacher st where s.id=st.studentid and st.teacherid=#value# ]]--﹥
29 ﹤/select﹥
30
31 ﹤/sqlMap﹥
32
33 tudent.xml
34
35 ﹤?xml version="1.0" encoding="UTF-8" ?﹥
36 !DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
37 "http://ibatis.apache.org/dtd/sql-map-2.dtd"﹥
38
39 ﹤sqlMap namespace="student"﹥
40 ﹤typeAlias alias="Student" type="com.lsm.domain.Student" /﹥
41 ﹤typeAlias alias="Teacher" type="com.lsm.domain.Teacher" /﹥
42
43 ﹤resultMap class="Student" id="studentBasicResultMap"﹥
44 ﹤result property="id" column="id"/﹥
45 ﹤result property="name" column="name"/﹥
46 ﹤result property="birthday" column="birthday"/﹥
47 ﹤/resultMap﹥
48
49 ﹤resultMap class="Student" id="studentWithTeacherResultMap" extends="studentBasicResultMap"﹥
50 ﹤result property="teachers" column="id" select="getTeachersByStudentId"/﹥
51 ﹤/resultMap﹥
52
53 ﹤select id="getStudents" resultMap="studentWithTeacherResultMap"﹥
54 ﹤!--[CDATA[
55 select * from student
56 ]]﹥
57 ﹤/select﹥
58
59 ﹤select id="getTeachersByStudentId" resultClass="Teacher"﹥
60 ﹤![CDATA[
61 select t.* from teacher t,student_teacher st where t.id=st.teacherid and st.studentid=#value# ]]--﹥
62 ﹤/select﹥
63
64 ﹤/sqlMap﹥
65
66 iBATIS的多对多映射配置7，测试
67
68 package com.lsm.test;
69
70 import java.io.Reader;
71 import java.sql.SQLException;
72 import java.util.List;
73 import com.ibatis.common.resources.Resources;
74 import com.ibatis.sqlmap.client.SqlMapClient;
75 import com.ibatis.sqlmap.client.SqlMapClientBuilder;
76 import com.lsm.domain.Student;
77 import com.lsm.domain.Teacher;
78
79 public class Many2Many
80 {
81
82 private static SqlMapClient sqlMapClient = null;
83 static
84 {
85 try
86 {
87 Reader reader = Resources.getResourceAsReader("com/lsm/cfg/SqlMapConfig.xml");
88 sqlMapClient = SqlMapClientBuilder.buildSqlMapClient(reader);
89 }
90 catch(Exception e)
91 {
92 e.printStackTrace();
93 }
94 }
95 /**
96 * @param args
97 */
98 public static void main(String[] args)
99 {
100 Many2Many m2m = new Many2Many();
101 List studentlist = null;
102 studentlist = m2m.getStudentInfo();
103 for(int i=0;i﹤studentlist.size();i++)
104 {
105 Student s = new Student();
106 s = (Student) studentlist.get(i);
107 System.out.println("name:"+s.getName() + "\t" + "birthday:"+s.getBirthday());
108 List tlist = s.getTeachers();
109 if(tlist!=null)
110 {
111 System.out.println("his teachers as follows:");
112 {
113 for(int ti=0;ti﹤tlist.size();ti++)
114 {
115 Teacher t = new Teacher();
116 t = (Teacher) tlist.get(ti);
117 System.out.println("teacher name:" + t.getName());
118 }
119 }
120 }
121 }
122
123 List teacherlist = null;
124 teacherlist = m2m.getTeacherInfo();
125 for(int i=0;i﹤teacherlist.size();i++)
126 {
127 Teacher t = new Teacher();
128 t = (Teacher) teacherlist.get(i);
129 System.out.println("name:"+t.getName() + "\t" + "subject:" + t.getSubject());
130 List slist = t.getStudents();
131 if(slist!=null)
132 {
133 System.out.println("his students as follows:");
134 for(int si=0;si﹤slist.size();si++)
135 {
136 Student s = new Student();
137 s = (Student) slist.get(si);
138 System.out.println("student name:"+s.getName());
139 }
140 }
141 }
142 }
143
144 // 获取学生信息
145 public List getStudentInfo()
146 {
147 List studentList = null;
148 try
149 {
150 System.out.println("学生信息如下：");
151 studentList = sqlMapClient.queryForList("getStudents");
152 }
153 catch (SQLException e)
154 {
155 e.printStackTrace();
156 }
157 return studentList;
158 }
159
160 // 获取老师信息
161 // 获取学生信息
162 public List getTeacherInfo()
163 {
164 List studentList = null;
165 try
166 {
167 System.out.println("老师信息如下：");
168 studentList = sqlMapClient.queryForList("getTeachers");
169 }
170 catch (SQLException e)
171 {
172 e.printStackTrace();
173 }
174 return studentList;
175 }
176
177 }
178
8，输出
- 学生信息如下：
- name:张三 birthday:1982-01-01
- his teachers as follows:
- teacher name:Jerry
- teacher name:Tom
- name:李四 birthday:1983-02-02
- his teachers as follows:
- teacher name:Jerry
- name:王五 birthday:1984-03-03
- his teachers as follows:
- teacher name:Tom
- name:赵六 birthday:1985-04-04
- his teachers as follows:
- 老师信息如下：
- name:Jerry subject:语文
- his students as follows:
- student name:张三
- student name:李四
- name:Tom subject:数学
- his students as follows:
- student name:张三
- student name:王五
- name:Steven subject:英语
- his students as follows:
查询学生时带出老师信息，查询老师时带出学生信息，说明多对多映射成功。
iBATIS的多对多映射配置的情况就向你介绍到这里，希望对你有所帮助。
时间： 2024-11-04 09:03:44