源代码片断：
作用是把 URL 中的 %2F 等解码为十进制数格式
public static byte[] decode(byte[] url) throws IllegalArgumentException {
if (url.length == 0) {
return new byte[0];
}
// Create a new byte array with the same length to ensure capacity
byte[] tempData = new byte[url.length];
int tempCount = 0;
for (int i = 0; i < url.length; i++) {
byte b = url[i];
if (b == '%') {
if (url.length - i > 2) {
b = (byte) (parseHex(url[i + 1]) * 16
+ parseHex(url[i + 2]));
i += 2;
} else {
throw new IllegalArgumentException("Invalid format");
}
}
tempData[tempCount++] = b;
}
byte[] retData = new byte[tempCount];
System.arraycopy(tempData, 0, retData, 0, tempCount);
return retData;
}
private static int parseHex(byte b) {
if (b >= '0' && b <= '9') return (b - '0');
if (b >= 'A' && b <= 'F') return (b - 'A' + 10);
if (b >= 'a' && b <= 'f') return (b - 'a' + 10);
throw new IllegalArgumentException("Invalid hex char '" + b + "'");
}
