mybatis之dao开发

1、相关jar包

   

只需要mybatis\mybatis-generator-core\mysql-connection

   

Junit \log4j 系列都是辅助使用，可有可无

   

Mybatis-spring.jar 是spring是整合mybatis所需要的jar

   

   

2、配置

   

• <?xml version="1.0" encoding="UTF-8" ?>
• <!DOCTYPE configuration
•   PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
•   "http://mybatis.org/dtd/mybatis-3-config.dtd">
• <configuration>
•     <!-- 取别名 -->
•     <typeAliases>
•            <package name="cn.tri.sm.pojo"/>    
•            <package name="cn.tri.sm.dao"/>
•            <package name="cn.tri.sm.daoImpl"/>
•     </typeAliases>
• <!--配置数据库信息-->
•   <environments default="development">
•     <environment id="development">
•       <transactionManager type="JDBC"/>
•       <dataSource type="POOLED">
•         <property name="driver" value="com.mysql.jdbc.Driver"/>
•         <property name="url" value="jdbc:mysql://localhost:3306/project"/>
•         <property name="username" value="root"/>
•         <property name="password" value="admin"/>
•       </dataSource>
•     </environment>
•   </environments>
•   <!-- 扫描映射文件路径 -->
•   <mappers>
•     <mapper resource="cn\tri\sm\mapper\UserDao.xml"/>
•   </mappers>
• </configuration>

   

userMapper.xml文件中

Namespace="命名空间" 可以随便取，但是最好独一无二，与XXDao类似。

   

1. <?xml version="1.0" encoding="UTF-8" ?>
2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
3. <mapper namespace="UserDao">
4.     <select id="getId" parameterType="int" resultType="User">
5.         select * from user where id=#{id}
6.     </select>
7. </mapper>

   

   

3.demo

目录结构

   

   

//user、必须要有无参的构造方法

   

• 
  public class User {
•     private int id ;
•     private String name ;
•     private String pwd ;
•     public int getId() {
•         return id;
•     }
•     public void setId(int id) {
•         this.id = id;
•     }
•     public String getName() {
•         return name;
•     }
•     public void setName(String name) {
•         this.name = name;
•     }
•     public String getPwd() {
•         return pwd;
•     }
•     public void setPwd(String pwd) {
•         this.pwd = pwd;
•     }
•     public User(int id, String name, String pwd) {
•         super();
•         this.id = id;
•         this.name = name;
•         this.pwd = pwd;
•     }
•     public User() {
•         super();
•     }
•     @Override
•     public String toString() {
•         return "User [id=" + id + ", name=" + name + ", pwd=" + pwd + "]";
•     }
• }

   

//userDao

   

• public interface UserDao {
•     public User getId(int id);
• }
• //userDaoImpl、此处必须拿到sqlsessionFactory
  
  public class UserDaoImpl implements UserDao{
•     private SqlSessionFactory factory;
•     // 带 sqlsessionFactory参数的构造函数
  
      public UserDaoImpl(SqlSessionFactory factory){
•         this.factory = factory;
•     }
•     public User getId(int id) {
•         SqlSession sqlSession = factory.openSession();
•         User user = sqlSession.selectOne("UserDao.getId",id);
•         sqlSession.close();
•         return user;
•     }
• }

   

//测试

   

• public static void main(String[] args) {
•             String resource = "mybaties-config.xml";
•             InputStream is = null;
•             try {
•                 is = Resources.getResourceAsStream(resource);
•             } catch (IOException e) {
•                 e.printStackTrace();
•             }
•             SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
•             UserDaoImpl userDao = new UserDaoImpl(factory);
•             User user = userDao.getId(8);
•             System.out.println(user);
•         
•     }

   

   

   

1. <!--idea的maven项目中，java程序不会读取非resources里的xml文件，需加入提示他要读取在指定路径的xml-->
2. <resources>
3.     <resource>
4.         <directory>src/main/java</directory>
5.         <includes>
6.             <include>**/*.xml</include>
7.         </includes>
8.     </resource>
9. </resources>