DBMS_XMLGEN+UTL_FILE+DBMS_LOB生成xml数据文件

CREATE OR REPLACE FUNCTION F_EXPORT2XML RETURN INTEGER IS
  RESULT     INTEGER := 0;
  XMLSTRING  CLOB := NULL;
  AMOUNT     INTEGER := 32767;
  POSITION   INTEGER := 1;
  CHARSTRING VARCHAR2(32767) := '';

  IDX_CHR10   INTEGER;
  LEN         INTEGER;
  WRITESTRING VARCHAR2(32767);
  FILEHANDLE  UTL_FILE.FILE_TYPE;

  XMLHDL DBMS_XMLGEN.CTXTYPE;

  SQLERRTEXT VARCHAR2(32767);

BEGIN

  XMLHDL := DBMS_XMLGEN.NEWCONTEXT('SELECT * FROM XXXXl');
 
  --open the file in "write" mode 
  FILEHANDLE := UTL_FILE.FOPEN('EXPDIR', 'XML_XXXX.XML', 'w');

  XMLSTRING := DBMS_XMLGEN.GETXML(XMLHDL);

  --Now open the lob data..  
  DBMS_LOB.OPEN(XMLSTRING, DBMS_LOB.LOB_READONLY);
  LOOP
    -- read the lob data  
    DBMS_LOB.READ(XMLSTRING, AMOUNT, POSITION, CHARSTRING);
    IDX_CHR10 := INSTR(CHARSTRING, CHR(10), -1);
    LEN       := LENGTH(CHARSTRING);
    IF (IDX_CHR10 < LEN AND IDX_CHR10 > 0) THEN
      WRITESTRING := SUBSTR(CHARSTRING, 1, IDX_CHR10 - 1);
    ELSE
      WRITESTRING := SUBSTR(CHARSTRING, 1, LEN - 1);
    END IF;
    UTL_FILE.PUT_LINE(FILEHANDLE, WRITESTRING);
    POSITION := POSITION + IDX_CHR10;
  END LOOP;
  RESULT := 1;
  RETURN(RESULT);
EXCEPTION
  WHEN NO_DATA_FOUND THEN
    -- end of fetch, free the lob  
    DBMS_LOB.CLOSE(XMLSTRING);
    DBMS_LOB.FREETEMPORARY(XMLSTRING);
    IF UTL_FILE.IS_OPEN(FILEHANDLE) THEN
      UTL_FILE.FCLOSE(FILEHANDLE);
    END IF;
    RETURN(RESULT);
  WHEN OTHERS THEN
    SQLERRTEXT := SQLERRM;
    IF UTL_FILE.IS_OPEN(FILEHANDLE) THEN
      UTL_FILE.FCLOSE(FILEHANDLE);
    END IF;
    RETURN(RESULT);
END F_EXPORT2XML;

 

经测试，效率比我写的上一个版本至少提供1倍，可能在某些特殊情况下，还是会出现异常，不过不影响大局了。