MyBatis的纯注解开发

MyBatis的纯注解方式：
不用写实体类的配置文件，直接在接口里面写

实体类中：User.xml

public class User {
	private Integer uid;
	private String uname;
	private String pass;
	//get,set方法,tostring方法和构造方法
}

然后就不需要配置文件，在接口中写
UserMapper

public interface UserMapper {
	//查询全部的方法，直接Select("SQL语句")
	@Select("select * from user")
	public List<User> findAllUser();

	//新增  Insert("新增的SQL语句")
	@Insert("insert into user values(null,#{uname},#{pass})")
	public int addUser(User user);

	//删除 Delete("删除的SQL语句")
	@Delete("delete from user where uid=#{uid}")
	public int deleteUserById(int uid);
	
	//修改 Update("修改的SQL语句")
	@Update("update user set uname=#{uname},pass=#{pass} where uid=#{uid}")
	public int updateUserById(User user);



}

MyBatis的配置文件

<?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>
    <!--给包取别名-->
    <typeAliases>
        <package name="com.ywy.entity"/>
    </typeAliases>
    <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/test?characterEncoding=utf-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    
    <!--接口的注册-->
    <!--之前是配置实体类的映射文件，现在没有了，直接配置接口-->
    <mappers>
        <package name="com.ywy.mapper"/>
    </mappers>
</configuration>

测试类

UserMapper umapper=session.getMapper(UserMapper.class);
//直接调用接口的方法
 //查询全部
 List<User> list = umapper.findAllUser();
 for (User user : list) {
     System.out.println(user);
 }


//新增
 int i = umapper.addUser(new User("小明", "12345678"));
 System.out.println(i);

//删除
int i2 = umapper.deleteUserById(2);
System.out.println(i2);

//修改
User u=new User("xxxxx","1111111");
u.setUid(3);
int i = umapper.updateUserById(u);
System.out.println(i);