mybatis之注解式开发之关联查询

 1 package com.bjsxt.mapper;
 2 
 3 import org.apache.ibatis.annotations.Select;
 4 
 5 import com.bjsxt.pojo.Clazz;
 6 
 7 public interface ClazzMapper {
 8 
 9     @Select("select * from t_class where id=#{0}")
10     Clazz selById(int id);
11 }

 1 package com.bjsxt.mapper;
 2 
 3 import java.util.List;
 4 
 5 import org.apache.ibatis.annotations.One;
 6 import org.apache.ibatis.annotations.Result;
 7 import org.apache.ibatis.annotations.Results;
 8 import org.apache.ibatis.annotations.Select;
 9 
10 import com.bjsxt.pojo.Student;
11 
12 public interface StudentMapper {
13 
14     @Select("select * from t_student")
15     @Results(value = {
16         @Result(column="id", property="id", id=true),
17         @Result(column="name", property="name"),
18         @Result(column="age", property="age"),
19         @Result(column="gender", property="gender"),
20         @Result(column="cid", property="cid"),
21         @Result(property="clazz", one=@One(select="com.bjsxt.mapper.ClazzMapper.selById"), column="cid")
22     })
23     List<Student> sel();
24 }

 1 package com.bjsxt.pojo;
 2 
 3 import java.io.Serializable;
 4 
 5 public class Clazz implements Serializable {
 6 
 7     private int id;
 8     private String name;
 9     private String room;
10 
11     public Clazz() {
12         super();
13     }
14 
15     public int getId() {
16         return id;
17     }
18 
19     public void setId(int id) {
20         this.id = id;
21     }
22 
23     public String getName() {
24         return name;
25     }
26 
27     public void setName(String name) {
28         this.name = name;
29     }
30 
31     public String getRoom() {
32         return room;
33     }
34 
35     public void setRoom(String room) {
36         this.room = room;
37     }
38 
39     @Override
40     public int hashCode() {
41         final int prime = 31;
42         int result = 1;
43         result = prime * result + id;
44         result = prime * result + ((name == null) ? 0 : name.hashCode());
45         result = prime * result + ((room == null) ? 0 : room.hashCode());
46         return result;
47     }
48 
49     @Override
50     public boolean equals(Object obj) {
51         if (this == obj)
52             return true;
53         if (obj == null)
54             return false;
55         if (getClass() != obj.getClass())
56             return false;
57         Clazz other = (Clazz) obj;
58         if (id != other.id)
59             return false;
60         if (name == null) {
61             if (other.name != null)
62                 return false;
63         } else if (!name.equals(other.name))
64             return false;
65         if (room == null) {
66             if (other.room != null)
67                 return false;
68         } else if (!room.equals(other.room))
69             return false;
70         return true;
71     }
72 
73     @Override
74     public String toString() {
75         return "Clazz [id=" + id + ", name=" + name + ", room=" + room + "]";
76     }
77 }

  1 package com.bjsxt.pojo;
  2 
  3 import java.io.Serializable;
  4 
  5 public class Student implements Serializable {
  6 
  7     private int id;
  8     private String name;
  9     private int age;
 10     private String gender;
 11     private int cid;
 12     private Clazz clazz;
 13 
 14     public Student() {
 15         super();
 16     }
 17 
 18     public int getId() {
 19         return id;
 20     }
 21 
 22     public void setId(int id) {
 23         this.id = id;
 24     }
 25 
 26     public String getName() {
 27         return name;
 28     }
 29 
 30     public void setName(String name) {
 31         this.name = name;
 32     }
 33 
 34     public int getAge() {
 35         return age;
 36     }
 37 
 38     public void setAge(int age) {
 39         this.age = age;
 40     }
 41 
 42     public String getGender() {
 43         return gender;
 44     }
 45 
 46     public void setGender(String gender) {
 47         this.gender = gender;
 48     }
 49 
 50     public int getCid() {
 51         return cid;
 52     }
 53 
 54     public void setCid(int cid) {
 55         this.cid = cid;
 56     }
 57 
 58     public Clazz getClazz() {
 59         return clazz;
 60     }
 61 
 62     public void setClazz(Clazz clazz) {
 63         this.clazz = clazz;
 64     }
 65 
 66     @Override
 67     public int hashCode() {
 68         final int prime = 31;
 69         int result = 1;
 70         result = prime * result + age;
 71         result = prime * result + cid;
 72         result = prime * result + ((clazz == null) ? 0 : clazz.hashCode());
 73         result = prime * result + ((gender == null) ? 0 : gender.hashCode());
 74         result = prime * result + id;
 75         result = prime * result + ((name == null) ? 0 : name.hashCode());
 76         return result;
 77     }
 78 
 79     @Override
 80     public boolean equals(Object obj) {
 81         if (this == obj)
 82             return true;
 83         if (obj == null)
 84             return false;
 85         if (getClass() != obj.getClass())
 86             return false;
 87         Student other = (Student) obj;
 88         if (age != other.age)
 89             return false;
 90         if (cid != other.cid)
 91             return false;
 92         if (clazz == null) {
 93             if (other.clazz != null)
 94                 return false;
 95         } else if (!clazz.equals(other.clazz))
 96             return false;
 97         if (gender == null) {
 98             if (other.gender != null)
 99                 return false;
100         } else if (!gender.equals(other.gender))
101             return false;
102         if (id != other.id)
103             return false;
104         if (name == null) {
105             if (other.name != null)
106                 return false;
107         } else if (!name.equals(other.name))
108             return false;
109         return true;
110     }
111 
112     @Override
113     public String toString() {
114         return "Student [id=" + id + ", name=" + name + ", age=" + age + ", gender=" + gender + ", cid=" + cid
115                 + ", clazz=" + clazz + "]";
116     }
117 }

 1 package com.bjsxt.test;
 2 
 3 import java.util.List;
 4 
 5 import org.apache.ibatis.session.SqlSession;
 6 
 7 import com.bjsxt.mapper.StudentMapper;
 8 import com.bjsxt.pojo.Student;
 9 import com.bjsxt.util.MyBatisUtil;
10 
11 public class TestStu {
12 
13     public static void main(String[] args) {
14         SqlSession session = MyBatisUtil.getSession();
15 
16         StudentMapper mapper = session.getMapper(StudentMapper.class);
17 
18         List<Student> sel = mapper.sel();
19         for (Student student : sel) {
20             System.out.println(student);
21         }
22 
23         session.close();
24     }
25 
26 }

 1 package com.bjsxt.util;
 2 
 3 import java.io.IOException;
 4 import java.io.InputStream;
 5 
 6 import org.apache.ibatis.io.Resources;
 7 import org.apache.ibatis.session.SqlSession;
 8 import org.apache.ibatis.session.SqlSessionFactory;
 9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
10 
11 public class MyBatisUtil {
12 
13     private static SqlSessionFactory factory = null;
14 
15     static {
16         try {
17             InputStream is = Resources.getResourceAsStream("mybatis-cfg.xml");
18             factory = new SqlSessionFactoryBuilder().build(is);
19         } catch (IOException e) {
20             e.printStackTrace();
21         }
22     }
23 
24     public static SqlSession getSession() {
25         SqlSession session = null;
26         if (factory != null) {
27             // true表示开启自动提交
28             // session = factory.openSession(true);
29             session = factory.openSession();
30         }
31         return session;
32     }
33 }

1 jdbc.driver=com.mysql.jdbc.Driver
2 jdbc.url=jdbc:mysql://localhost:3306/java505
3 jdbc.username=root
4 jdbc.password=root

# Set root category priority to INFO and its only appender to CONSOLE.
log4j.rootCategory=ERROR, CONSOLE
# log4j.rootCategory=DEBUG, CONSOLE, LOGFILE

# 单独设置SQL语句的输出级别为DEBUG级别
log4j.logger.com.bjsxt.mapper=DEBUG

# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=- %m%n

# LOGFILE is set to be a File appender using a PatternLayout.
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=d:/test.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=- %m %l%n

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE configuration
 3   PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4   "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 <configuration>
 6     <!-- properties加载外部文件 -->
 7     <properties resource="db.properties" />
 8     <!-- settings标签 -->
 9     <settings>
10         <!-- 设置MyBatis使用log4j日志支持 -->
11         <setting name="logImpl" value="LOG4J"/>
12     </settings>
13     <!-- typeAliases给类型起别名 -->
14     <typeAliases>
15         <package name="com.bjsxt.pojo" />
16     </typeAliases>
17     <environments default="dev">
18         <environment id="dev">
19             <transactionManager type="JDBC" />
20             <dataSource type="POOLED">
21                 <property name="driver" value="${jdbc.driver}"/>
22                 <property name="url" value="${jdbc.url}"/>
23                 <property name="username" value="${jdbc.username}"/>
24                 <property name="password" value="${jdbc.password}"/>
25             </dataSource>
26         </environment>
27     </environments>
28     <mappers>
29         <package name="com.bjsxt.mapper" />
30     </mappers>
31 </configuration>