Oracle截取JSON字符串内容的方法

CREATE OR REPLACE FUNCTION PLATFROM.parsejsonstr(p_jsonstr varchar2,startkey varchar2,endkey varchar2) RETURN VARCHAR2
 IS
  rtnVal VARCHAR2(1000);
  FindIdxS NUMBER(2);
  FindIdxE NUMBER(2);
 BEGIN
 if endkey='}' then
   rtnVal:=substr(p_jsonstr,(instr(p_jsonstr,startkey)+length(startkey) +2)
     ,(instr(p_jsonstr,endkey,instr(p_jsonstr,startkey))-instr(p_jsonstr,startkey)-length(startkey)-2));
 else
   rtnVal:=substr(p_jsonstr,(instr(p_jsonstr,startkey)+length(startkey) +2)
     ,(instr(p_jsonstr,endkey,instr(p_jsonstr,startkey))-instr(p_jsonstr,startkey)-length(startkey)-4));
 end if;
  RETURN rtnVal;
 END parsejsonstr;
 /