java基础之URLDecoder异常解决方法

URLDecoder对参数进行解码时候，代码如：

URLDecoder.decode(param,"utf-8");

  

 

  
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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; }

  

 

  
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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); }

  

 

  
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文章来源: smilenicky.blog.csdn.net，作者：smileNicky，版权归原作者所有，如需转载，请联系作者。

原文链接：smilenicky.blog.csdn.net/article/details/100606102