CRLF escape

最近需要对用户输入的CRLF即（\r\n）做escape,参考了一下jackson的处理方式，大概就是把字符串转换成char数组，循环判断每个字符的ascii编码是否等于需要做escape。code如下：

    String str = "fuck\r\nlala";
        char[] cs = str.toCharArray();
        for (char c : cs) {
            if ((int) c == 13) {
                System.out.println('\\');
                System.out.println((char) 114);
            } else if ((int) c == 10) {
                System.out.println('\\');
                System.out.println((char) 110);
            } else {
                System.out.println(c);
            }
        }

重构之后的代码

        StringBuilder sb = new StringBuilder();
        HashMap<Integer, Integer> escCodes = new HashMap<Integer, Integer>();
        escCodes.put(13, 114); // \r
        escCodes.put(10, 110); // \n

        String str = "fuck\r\nlala";
        char[] cs = str.toCharArray();
        for (char c : cs) {
            int charCode = (int) c;
            if (charCode < 24 && escCodes.containsKey(charCode)) { // need escape
                sb.append('\\');
                int escCode = escCodes.get(charCode);
                sb.append((char) escCode);
            }else{
              sb.append(c);  
            }
        }
        System.out.println(sb.toString());

 jackson的测试代码

     ObjectMapper mapper = new ObjectMapper();
        Map param = new HashMap();
        String str = "中文fuck\r\nlala";
         param.put("test", str);
         String value = mapper.writeValueAsString(param);
         System.out.println(value);

 jackson的调用堆栈：

1. StdSerializerProvider.serializeValue()
2. StdSerializerProvider._serializeValue()
3. MapSerializer.serialize(Map value,JsonGenerator jgen, SerializerProvider provider)
4. MapSerializer.serializeFields(Map value,JsonGenerator jgen, SerializerProvider provider)
5. JsonGenerator.writeString(String text)
6. WriterBasedGenerator._writeString(String text)
7. WriterBasedGenerator._writeString2(final int len)