通用mapper根据条件修改，查询Example的实例函数以及例子

条件：

Example  example =new Example(User.class);
Criteria criteria = example.createCriteria();

注意：
criteria.andEqualTo(property,value);
property 对应的是实体类中的属性字段
1，根据条件查询

/**
*根据名称，id,ntype 等获取其对应节点总数
*用于判断名称是否重复
*/
public int getCountByNameAndUId(String name,Long id, Long userId){
     Example  example  =new Example(User.class);
     Criteria criteria =example.createCriteria();
     criteria.andEqualTo("name",name);
     criteria.andNotEqualTo("id",id);
      criteria.andEqualTo("userId",uid);
int count =categoryMapper.selectCountByExample(example);



}

等效于：

select count(0) from user where name =#{name} and id != #{id} and uid !=#{uid}

2, and or 查询

   public Example test(list<Long>ids ,String name, String des){
      Example example =new Example(User.getClass());
//where 条件
   Criteria  criteria =example.createCriteria();
     Criteria  criteria1 =example.createCriteria();
   criteria.andIn("id",ids);
criteria1.orLike("des", "%"+des+"%");
critera1.orLike("name","%" +name+"%");
 example.and(criteria1);
return example;


}

等效于

where id in (#{ids}) and (name like concat( '%', #{name}, '%' ) or des like concat('%', #{des}, '%'))

3,根据条件修改

       Example example =new Example(User.getClass());
         //where 条件
  Criteria criteria =example.createCriteria();
       criteria.andEqualTo("name",name);
 userMapper.updateByExampleSelective(user,example);

等效于:

Update user set ... where name =#{name}

参照：
MyBatis的Mapper接口以及Example的实例函数及详解(http://blog.csdn.net/biandous/article/details/65630783)
通用mapper