如何解析url参数

tomcat中servlet的实现：

  1     public void processParameters( byte bytes[], int start, int len,
  2                                    String enc ) {
  3         int end=start+len;
  4         int pos=start;
  5 
  6         if(log.isDebugEnabled()) {
  7             try {
  8                 log.debug("Bytes: " +
  9                         new String(bytes, start, len, DEFAULT_ENCODING));
 10             } catch (UnsupportedEncodingException e) {
 11                 // Should never happen...
 12                  log.error("Unable to convert bytes", e);
 13             }
 14         }
 15 
 16         do {
 17             boolean noEq=false;
 18             int valStart=-1;
 19             int valEnd=-1;
 20 
 21             int nameStart=pos;
 22             int nameEnd=ByteChunk.indexOf(bytes, nameStart, end, '=' );
 23             // Workaround for a&b&c encoding
 24             int nameEnd2=ByteChunk.indexOf(bytes, nameStart, end, '&' );
 25             if( (nameEnd2!=-1 ) &&
 26                 ( nameEnd==-1 || nameEnd > nameEnd2) ) {
 27                 nameEnd=nameEnd2;
 28                 noEq=true;
 29                 valStart=nameEnd;
 30                 valEnd=nameEnd;
 31                 if(log.isDebugEnabled()) {
 32                     try {
 33                         log.debug("no equal " + nameStart + " " + nameEnd + " " +
 34                                 new String(bytes, nameStart, nameEnd-nameStart,
 35                                         DEFAULT_ENCODING) );
 36                     } catch (UnsupportedEncodingException e) {
 37                         // Should never happen...
 38                         log.error("Unable to convert bytes", e);
 39                     }
 40                 }
 41             }
 42             if( nameEnd== -1 )
 43                 nameEnd=end;
 44 
 45             if( ! noEq ) {
 46                 valStart= (nameEnd < end) ? nameEnd+1 : end;
 47                 valEnd=ByteChunk.indexOf(bytes, valStart, end, '&');
 48                 if( valEnd== -1 ) valEnd = (valStart < end) ? end : valStart;
 49             }
 50 
 51             pos=valEnd+1;
 52 
 53             if( nameEnd<=nameStart ) {
 54                 StringBuilder msg = new StringBuilder("Parameters: Invalid chunk ");
 55                 // No name eg ...&=xx&... will trigger this
 56                 if (valEnd >= nameStart) {
 57                     msg.append('\'');
 58                     try {
 59                         msg.append(new String(bytes, nameStart,
 60                                 valEnd - nameStart, DEFAULT_ENCODING));
 61                     } catch (UnsupportedEncodingException e) {
 62                         // Should never happen...
 63                         log.error("Unable to convert bytes", e);
 64                     }
 65                     msg.append("' ");
 66                 }
 67                 msg.append("ignored.");
 68                 log.warn(msg);
 69                 continue;
 70                 // invalid chunk - it's better to ignore
 71             }
 72             tmpName.setBytes( bytes, nameStart, nameEnd-nameStart );
 73             tmpValue.setBytes( bytes, valStart, valEnd-valStart );
 74 
 75             // Take copies as if anything goes wrong originals will be
 76             // corrupted. This means original values can be logged.
 77             // For performance - only done for debug
 78             if (log.isDebugEnabled()) {
 79                 try {
 80                     origName.append(bytes, nameStart, nameEnd-nameStart);
 81                     origValue.append(bytes, valStart, valEnd-valStart);
 82                 } catch (IOException ioe) {
 83                     // Should never happen...
 84                     log.error("Error copying parameters", ioe);
 85                 }
 86             }
 87 
 88             try {
 89                 addParam( urlDecode(tmpName, enc), urlDecode(tmpValue, enc) );
 90             } catch (IOException e) {
 91                 StringBuilder msg =
 92                     new StringBuilder("Parameters: Character decoding failed.");
 93                 msg.append(" Parameter '");
 94                 if (log.isDebugEnabled()) {
 95                     msg.append(origName.toString());
 96                     msg.append("' with value '");
 97                     msg.append(origValue.toString());
 98                     msg.append("' has been ignored.");
 99                     log.debug(msg, e);
100                 } else {
101                     msg.append(tmpName.toString());
102                     msg.append("' with value '");
103                     msg.append(tmpValue.toString());
104                     msg.append("' has been ignored. Note that the name and ");
105                     msg.append("value quoted here may be corrupted due to ");
106                     msg.append("the failed decoding. Use debug level logging ");
107                     msg.append("to see the original, non-corrupted values.");
108                     log.warn(msg);
109                 }
110             }
111 
112             tmpName.recycle();
113             tmpValue.recycle();
114             // Only recycle copies if we used them
115             if (log.isDebugEnabled()) {
116                 origName.recycle();
117                 origValue.recycle();
118             }
119         } while( pos<end );
120     }
121

逻辑很简单，以下是个简易的MFC改写：

 1 void process_parameters( CString str, int start, CMapStringToString &parameters )
 2 {
 3     int pos = start;
 4     int end = start + str.GetLength();
 5     CString tmpName;
 6     CString tmpValue;
 7     while (pos < end)
 8     {
 9         boolean noEq=false;
10         int valStart = -1;
11         int valEnd = -1;
12         int nameStart = pos;
13         int nameEnd = str.Find('=', nameStart);
14 
15         // Workaround for a&b&c encoding
16         int nameEnd2 = str.Find('&', nameStart);
17         if( (nameEnd2!=-1 ) && ( nameEnd==-1 || nameEnd > nameEnd2) )
18         {
19             noEq = true;
20             nameEnd = nameEnd2;
21             valStart = nameEnd;
22             valEnd = nameEnd;
23         }
24         if (nameEnd == -1)
25         {
26             nameEnd = end;
27         }
28 
29         if (!noEq)
30         {
31             valStart= (nameEnd < end) ? nameEnd+1 : end;
32             valEnd=str.Find('&', valStart);
33             if( valEnd== -1 ) 
34                 valEnd = (valStart < end) ? end : valStart;
35         }
36 
37         pos = valEnd + 1;
38         tmpName = str.Mid( nameStart, nameEnd-nameStart );
39         tmpValue = str.Mid( valStart, valEnd-valStart );
40         parameters.SetAt(tmpName, tmpValue);
41     }
42 }

参考：http://www.google.com/codesearch/p?hl=en#RP9-mFsAT-A/trunk/java/org/apache/tomcat/util/http/Parameters.java&q=getParameter&exact_package=http://svn.apache.org/repos/asf/tomcat/&sa=N&cd=4&ct=rc

posted on 2010-10-29 17:46 lbsx 阅读(3216) 评论(0) 收藏举报