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 }