mybatis注解方式动态sql

1匿名内部类
class chatDaoProvider {
public String modifyGroup(String roomName, String roomPic, String roomDesc,int id){
return new SQL(){{
UPDATE(“chat”);
if(roomName!=null){
SET(“roomName=#{roomName}”);
}
if(roomPic!=null){
SET(“roomPic=#{roomPic}”);
}
if(roomDesc!=null){
SET(“roomDesc=#{roomDesc}”);
}
WHERE(“id=#{id}”);
//从这个toString可以看出，其内部使用高效的StringBuilder实现SQL拼接
}}.toString();
}