02.Mybatis的动态代理方式实现增删改查

动态代理的方式实现增删改查:

通过约定的方式定位sql语句

约定 > 配置文件 > 硬编码

约定的目标是省略掉通过硬编码的方式定位sql的代码，通过接口直接定位出sql语句,以下代码为通过硬编码的方法定位sql:

 1 　　　　　//读取conf.xml 配置文件
 2         Reader reader = Resources.getResourceAsReader("conf.xml");
 3         //创建sqlSessionFactory
 4         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
 5         //创建session---> connection
 6         SqlSession session = sessionFactory.openSession();
 7         //statement ---> statement
 8         String sql = "com.offcn.entity.personMapper." + "selectPersonById";
 9         //查询一条数据
10         Person person = session.selectOne(sql,1);
11         //提交事务
12         session.commit();
13         System.out.println(person);
14         //关闭连接
15         session.close();

通过约定的方式定位sql:

 1  Reader reader = Resources.getResourceAsReader("conf.xml");
 2 //创建一个sqlSessionFactory
 3 SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
 4 //创建一个sqlSession
 5 SqlSession session = sessionFactory.openSession();
 6 //用sqlSession定位sql
 7 PersonMapper personMapper = session.getMapper(PersonMapper.class);
 8 //通过接口中的方法找到sql语句并执行
 9 Person person = personMapper.queryPersonById(3);
10 //提交事务
11 session.commit();
12 System.out.println(person);
13 //关闭连接
14 session.close();

接口定义的规则:

1.方法名和mapper.xml文件中标签的id值相同

2.方法的输入参数类型和mapper.xml文件中标签的parameterType类型一致

3.方法的返回值和mapper.xml文件中标签的resultType类型一致

定义接口的代码如下:

 1 package com.offcn.mapper;
 2 
 3 
 4 import java.util.List;
 5 
 6 import com.offcn.entity.Person;
 7 
 8 public interface PersonMapper {
 9     Person queryPersonById(int id);
10     List<Person> queryAllPersons();
11     void insertPerson(Person person);
12     void deletePersonById(int id);
13     void updatePersonById(Person person);
14 }

接口和映射文件的对应关系图示:

匹配过程;(约定的过程)

1.根据接口名找到mapper.xml文件(根据的是namespace=接口的全类名)

2.根据接口的方法名找到mapper.xml文件中的sql标签(方法名=sql标签中的id值)

以上两点可以保证当调用接口中的方法时，程序能自动定位到某一个Mapper.xml文件中的sql标签

习惯:sql映射文件（mapper.xml）和接口放在同一个包中

具体实现:

1.实体类代码:

 1 package com.offcn.entity;
 2 
 3 import java.util.Date;
 4 
 5 public class Person {
 6     private int id;
 7     private String name;
 8     private Date dir;
 9     private String address;
10     public Person() {
11         super();
12         // TODO Auto-generated constructor stub
13     }public Person( String name, Date dir, String address) {
14         this.name = name;
15         this.dir = dir;
16         this.address = address;
17     }
18     public Person(int id, String name, Date dir, String address) {
19         super();
20         this.id = id;
21         this.name = name;
22         this.dir = dir;
23         this.address = address;
24     }
25     public int getId() {
26         return id;
27     }
28     public void setId(int id) {
29         this.id = id;
30     }
31     public String getName() {
32         return name;
33     }
34     public void setName(String name) {
35         this.name = name;
36     }
37     public Date getDir() {
38         return dir;
39     }
40     public void setDir(Date dir) {
41         this.dir = dir;
42     }
43     public String getAddress() {
44         return address;
45     }
46     public void setAddress(String address) {
47         this.address = address;
48     }
49     @Override
50     public String toString() {
51         return "Person [id=" + id + ", name=" + name + ", dir=" + dir + ", address=" + address + "]";
52     }
53     
54 }

2.映射文件mapper.xml代码:

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE mapper
 3   PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4   "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 <mapper namespace="com.offcn.mapper.PersonMapper">
 6     <!-- 根据id查询 -->
 7   <select id="queryPersonById" parameterType="int" resultType="com.offcn.entity.Person">
 8     select * from person where id = #{id}
 9   </select>
10   <!-- 查询所有 -->
11   <select id="queryAllPersons"  resultType="com.offcn.entity.Person">
12     select * from person
13   </select>
14   <!-- 增加 -->
15   <insert id="insertPerson" parameterType="com.offcn.entity.Person">
16       insert into person (name,bir,address) value (#{name},#{dir},#{address})
17   </insert>
18   <!-- 删除 -->
19   <delete id="deletePersonById" parameterType="int">
20       delete from person where id = #{id}
21   </delete>
22   <!-- 修改 -->
23   <update id="updatePersonById" parameterType="com.offcn.entity.Person">
24       update person set name = #{name},bir = #{dir},address = #{address} where id = #{id}
25   </update>
26 </mapper>

3.接口代码:

 1 package com.offcn.mapper;
 2 import java.util.List;
 3 import com.offcn.entity.Person;
 4 public interface PersonMapper {
 5     Person queryPersonById(int id);
 6     List<Person> queryAllPersons();
 7     void insertPerson(Person person);
 8     void deletePersonById(int id);
 9     void updatePersonById(Person person);
10 }

4.全局配置文件conf.xml：

 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   <environments default="development">
 7     <environment id="development">
 8       <transactionManager type="JDBC"/>
 9       <dataSource type="POOLED">
10         <property name="driver" value="com.mysql.jdbc.Driver"/>
11         <property name="url" value="jdbc:mysql://localhost:3306/person?serverTimezone=UTC"/>
12         <property name="username" value="root"/>
13         <property name="password" value="root"/>
14       </dataSource>
15     </environment>
16   </environments>
17   <mappers>
18     <mapper resource="com/offcn/mapper/personMapper.xml"/>
19   </mappers>
20 </configuration>

5.测试类代码:

  1 package com.offcn.test;
  2 
  3 import java.io.IOException;
  4 import java.io.Reader;
  5 import java.util.Date;
  6 import java.util.List;
  7 
  8 import org.apache.ibatis.io.Resources;
  9 import org.apache.ibatis.session.SqlSession;
 10 import org.apache.ibatis.session.SqlSessionFactory;
 11 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 12 
 13 import com.offcn.entity.Person;
 14 import com.offcn.mapper.PersonMapper;
 15 
 16 public class Test {
 17     public static void main(String[] args) throws IOException {
 18         //queryPersonById();
 19         //insertPerson();
 20         //deletePerson();
 21         updatePerosnById();
 22         queryAllPersons();
 23     }
 24     //根据id查询
 25     public static void queryPersonById() throws IOException {
 26         //读取conf.xml文件
 27         Reader reader = Resources.getResourceAsReader("conf.xml");
 28         //创建一个sqlSessionFactory
 29         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
 30         //创建一个sqlSession
 31         SqlSession session = sessionFactory.openSession();
 32         //用sqlSession定位sql
 33         PersonMapper personMapper = session.getMapper(PersonMapper.class);
 34         //通过接口中的方法找到sql语句并执行
 35         Person person = personMapper.queryPersonById(3);
 36         //提交事务
 37         session.commit();
 38         System.out.println(person);
 39         //关闭连接
 40         session.close();
 41     }
 42     //查询所有的方法
 43     public static void queryAllPersons() throws IOException {
 44         //读取conf.xml文件
 45         Reader reader = Resources.getResourceAsReader("conf.xml");
 46         //创建sqlSessionFactory
 47         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
 48         //创建一个sqlSession
 49         SqlSession session = sessionFactory.openSession();
 50         //通过session定位映射文件
 51         PersonMapper personMapper = session.getMapper(PersonMapper.class);
 52         //通过接口中的方法定位sql语句并执行
 53         List<Person> persons = personMapper.queryAllPersons();
 54         //提交事务
 55         session.commit();
 56         for (Person person : persons) {
 57             System.out.println(person);
 58         }
 59         //关闭连接
 60         session.close();
 61     }
 62     //增加的方法
 63     public static void insertPerson() throws IOException {
 64         //读取conf.xml文件
 65         Reader reader = Resources.getResourceAsReader("conf.xml");
 66         //创建sqlSessionFactory
 67         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
 68         //创建sqlSession
 69         SqlSession session = sessionFactory.openSession();
 70         //通过sqlSession定位映射文件
 71         PersonMapper personMapper = session.getMapper(PersonMapper.class);
 72         //通过接口中的方法定位sql语句
 73         Person person = new Person("王大拿",new Date(),"天津");
 74         personMapper.insertPerson(person);
 75         //提交事务
 76         session.commit();
 77         System.out.println("增加成功");
 78         //关闭连接
 79         session.close();
 80     }
 81     //删除的方法
 82     public static void deletePerson() throws IOException {
 83         //读取conf.xml
 84         Reader reader = Resources.getResourceAsReader("conf.xml");
 85         //创建一个sqlSessionFactory
 86         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
 87         //创建一个sqlSession
 88         SqlSession session = sessionFactory.openSession();
 89         //通过session定位映射文件
 90         PersonMapper personMapper = session.getMapper(PersonMapper.class);
 91         //通过接口中的方法定位sql语句
 92         personMapper.deletePersonById(1);
 93         //提交事务
 94         session.commit();
 95         System.out.println("删除成功");
 96         //关闭连接
 97         session.close();
 98     }
 99     //修改的方法
100     public static void updatePerosnById() throws IOException {
101         //读取conf.xml
102         Reader reader = Resources.getResourceAsReader("conf.xml");
103         //创建sqlSessionFactory
104         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
105         //创建一个sqlSession
106         SqlSession session = sessionFactory.openSession();
107         //通过sqlSession定位樱色号文件
108         PersonMapper personMapper = session.getMapper(PersonMapper.class);
109         //通过接口中的方法定位sql
110         Person person = new Person(3,"张三",new Date(),"江苏");
111         personMapper.updatePersonById(person);
112         //提交事务
113         session.commit();
114         System.out.println("修改成功");
115         session.close();
116     }
117 }