android解析JSON数据

2019-12-10 18:41:46王旭

四、 nextValue方法比较关键,它流转解析的大部分工作!在nextValue中有一个readLiteral方法,针对一些类型做处理,得到解析之后的结果:

private Object readLiteral() throws JSONException {
  String literal = nextToInternal("{}[]/:,=;# tf");

  if (literal.length() == 0) {
    throw syntaxError("Expected literal value");
  } else if ("null".equalsIgnoreCase(literal)) {
    return JSONObject.NULL;
  } else if ("true".equalsIgnoreCase(literal)) {
    return Boolean.TRUE;
  } else if ("false".equalsIgnoreCase(literal)) {
    return Boolean.FALSE;
  }

  /* try to parse as an integral type... */
  if (literal.indexOf('.') == -1) {
    int base = 10;
    String number = literal;
    if (number.startsWith("0x") || number.startsWith("0X")) {
      number = number.substring(2);
      base = 16;
    } else if (number.startsWith("0") && number.length() > 1) {
      number = number.substring(1);
      base = 8;
    }
    try {
      long longValue = Long.parseLong(number, base);
      if (longValue <= Integer.MAX_VALUE && longValue >= Integer.MIN_VALUE) {
        return (int) longValue;
      } else {
        return longValue;
      }
    } catch (NumberFormatException e) {
      /*
       * This only happens for integral numbers greater than
       * Long.MAX_VALUE, numbers in exponential form (5e-10) and
       * unquoted strings. Fall through to try floating point.
       */
    }
  }

  /* ...next try to parse as a floating point... */
  try {
    return Double.valueOf(literal);
  } catch (NumberFormatException ignored) {
  }

  /* ... finally give up. We have an unquoted string */
  return new String(literal); // a new string avoids leaking memory
}

五、至于JSONArray的解析与JsonObject的解析过程是一样的,它里面维护的是一个List:

private final List<Object> values;
public JSONArray(JSONTokener readFrom) throws JSONException {
  Object object = readFrom.nextValue();
  if (object instanceof JSONArray) {
    values = ((JSONArray) object).values;
  } else {
    throw JSON.typeMismatch(object, "JSONArray");
  }
}