在oracle中创建序列语句并执行:
create sequence user_seq start with 1 increment by 1;
create or replace trigger user_trigger before insert on tb_user for each row begin select user_seq.nextval into :new.id from dual; end ;
2.然后在mybatis的mapper配置文件中插入一条记录时就不用指定id
    <?xml version="1.0" encoding="UTF-8"?>    
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.cn.mapper.UserMapper">
        <insert id="save" parameterType="com.cn.domain.User" useGeneratedKeys="true">
            INSERT INTO TB_USER(name,sex,age) VALUES(#{name},#{sex},${age})
        </insert>
    </mapper>原文:http://wuxiaozhu.blog.51cto.com/7942143/1915692