String srcString = "{ITEM_LT=AA, ITEM_DESC=BB, REQ_ITEM_CD=, ITEM_EN_NM=  000.0}";
Map paramMap = new Map();

Pattern pattern = Pattern.compile("(([^\\{,\\s]+)=([^,\\}]*))");
Matcher matcher = pattern.matcher(srcString);

out.println(matcher.matches());   // 전체문장에 대해한 match 여부이다.
out.println("<br/>");
out.println(matcher.groupCount());  // 괄호로 묶은 그룹 갯수이다. 여기서는 3개이다.
out.println("<br/>");

while (matcher.find())
{
           // match된 전체 문장
 out.println(String.format("%d %d %s", matcher.start(), matcher.end(),  matcher.group()));
 out.println("<br/>");
 
 for (int i = 0; i <= matcher.groupCount(); i++)
 {
                     // match된 개별 문장
  out.println(String.format("%d : [%s]", i, matcher.group(i)));
  out.println("<br/>");
 }
}

false 
3 
1 11 ITEM_LT=AA 
0 : [ITEM_LT=AA] 
1 : [ITEM_LT=AA] 
2 : [ITEM_LT] 
3 : [AA] 
13 25 ITEM_DESC=BB 
0 : [ITEM_DESC=BB] 
1 : [ITEM_DESC=BB] 
2 : [ITEM_DESC] 
3 : [BB] 
27 39 REQ_ITEM_CD= 
0 : [REQ_ITEM_CD=] 
1 : [REQ_ITEM_CD=] 
2 : [REQ_ITEM_CD] 
3 : [] 
41 59 ITEM_EN_NM= 000.0 
0 : [ITEM_EN_NM= 000.0] 
1 : [ITEM_EN_NM= 000.0] 
2 : [ITEM_EN_NM] 
3 : [ 000.0] 

* 메소드 

    /*
     *  Map형 literal 문자 -> Map으로 변환
     *  문자열 형태 "{ITEM_LT=AA, ITEM_DESC=BB, REQ_ITEM_CD=java,test, ITEM_EN_NM=  000.0}" -> Map
     */
    public static Map literalToMap(String literal)
    {
     Map rtnMap = new Map();
     
     if (literal != null)
     {
      Pattern pattern = Pattern.compile("([^\\{,\\s]+)=([^=]*(?=, .+=|\\}))");
      Matcher matcher = pattern.matcher(literal);
 
      while (matcher.find())
      {
       rtnMap.put(matcher.group(1), matcher.group(2));
      }
     }

     return rtnMap;
    }
        
    /*
     *  List형 literal 문자 -> List으로 변환
     *  문자열 형태 "[{ITEM_LT=AA, ITEM_DESC=BB, REQ_ITEM_CD=, ITEM_EN_NM=  000.0}, {ITEM_LT=AA, ITEM_DESC=BB, REQ_ITEM_CD=, ITEM_EN_NM=  000.0}]" -> List<Map>
     */
    public static List<Map> literalToList(String literal)
    {
     List<Map> rtnList = new List<Map>();
     
     if (literal != null)
     {
         Pattern pattern = Pattern.compile("^\\[\\s*\\{.+\\}\\s*\\]$");
         Matcher matcher = pattern.matcher(literal);

         if (matcher.matches())
         {
          pattern = Pattern.compile("(\\{[^\\}]*\\})");
          matcher = pattern.matcher(literal);
          
          while (matcher.find())
          {
           rtnList.add(literalToMap(matcher.group(1)));
          }
         } 
     }
     
     return rtnList;
    }