URLDecoder对参数进行解码时候,代码如:
URLDecoder.decode(param,"utf-8");
有时候会出现类似如下的错误:
URLDecoder异常Illegal hex characters in escape (%)
这是因为传参有一些特殊字符,比如%号或者说+号,导致不能解析,报错
解决方法是:
public static String replacer(StringBuffer outBuffer) {
String data = outBuffer.toString();
try {
data = data.replaceAll("%(?![0-9a-fA-F]{2})", "%25");
data = data.replaceAll("\\+", "%2B");
data = URLDecoder.decode(data, "utf-8");
} catch (Exception e) {
e.printStackTrace();
}
return data;
}
URLDecoder源码:
public static String decode(String s, String enc)
throws UnsupportedEncodingException{
boolean needToChange = false;
int numChars = s.length();
StringBuffer sb = new StringBuffer(numChars > 500 ? numChars / 2 : numChars);
int i = 0;
if (enc.length() == 0) {
throw new UnsupportedEncodingException ("URLDecoder: empty string enc parameter");
}
char c;
byte[] bytes = null;
while (i < numChars) {
c = s.charAt(i);
switch (c) {
case '+':
sb.append(' ');
i++;
needToChange = true;
break;
case '%':
/*
* Starting with this instance of %, process all
* consecutive substrings of the form %xy. Each
* substring %xy will yield a byte. Convert all
* consecutive bytes obtained this way to whatever
* character(s) they represent in the provided
* encoding.
*/
try {
// (numChars-i)/3 is an upper bound for the number
// of remaining bytes
if (bytes == null)
bytes = new byte[(numChars-i)/3];
int pos = 0;
while ( ((i+2) < numChars) &&
(c=='%')) {
int v = Integer.parseInt(s.substring(i+1,i+3),16);
if (v < 0)
throw new IllegalArgumentException("URLDecoder: Illegal hex characters in escape (%) pattern - negative value");
bytes[pos++] = (byte) v;
i+= 3;
if (i < numChars)
c = s.charAt(i);
}
// A trailing, incomplete byte encoding such as
// "%x" will cause an exception to be thrown
if ((i < numChars) && (c=='%'))
throw new IllegalArgumentException(
"URLDecoder: Incomplete trailing escape (%) pattern");
sb.append(new String(bytes, 0, pos, enc));
} catch (NumberFormatException e) {
throw new IllegalArgumentException(
"URLDecoder: Illegal hex characters in escape (%) pattern - "
+ e.getMessage());
}
needToChange = true;
break;
default:
sb.append(c);
i++;
break;
}
}
return (needToChange? sb.toString() : s);
}