在jsp中作HTTP认证的方法

最近研究了jsp中作HTTP认证的问题，它的工作方式如下：

1、server发送一个要求认证代码401和一个头信息WWW-authenticate，激发browser弹出一个认证窗口

2、server取得browser送来的认证头"Authorization",它是加密的了，要用Base64方法解密，取得明文的用户名和密码

3、检查用户名和密码，根据结果传送不同的页面

以下是jsp的片断，你也可以把它做成include文件。和Base64的加解密的class源码。
如有兴趣可与我联系： [email protected]

1<jsp:usebean class="Base64" id="base64" scope="page"></jsp:usebean>

 1   
 2if(request.getHeader("Authorization")==null){   
 3response.setStatus(401);   
 4response.setHeader("WWW-authenticate","Basic realm=\"unixboy.com\"");   
 5}else{   
 6String encoded=(request.getHeader("Authorization"));   
 7String tmp=encoded.substring(6);   
 8String up=Base64.decode(tmp);   
 9String user="";   
10String password="";   
11if(up!=null){   
12user=up.substring(0,up.indexOf(":"));   
13password=up.substring(up.indexOf(":")+1);   
14}   
15if(user.equals("unixboy")&&password.equals("123456")){   
16//认证成功   
17}else{   
18//认证失败   
19}   
20}

//消息加解密class
public class Base64
{
/** decode a Base 64 encoded String.
*

1<p><h4>String to byte conversion</h4>   
2* This method uses a naive String to byte interpretation, it simply gets each   
3* char of the String and calls it a byte.</p>

1<p>Since we should be dealing with Base64 encoded Strings that is a reasonable   
2* assumption.</p>

1<p><h4>End of data</h4>   
2* We don''t try to stop the converion when we find the"="end of data padding char.   
3* We simply add zero bytes to the unencode buffer.</p>

*/
public static String decode(String encoded)
{
StringBuffer sb=new StringBuffer();
int maxturns;
//work out how long to loop for.
if(encoded.length()%3==0)
maxturns=encoded.length();
else
maxturns=encoded.length()+(3-(encoded.length()%3));
//tells us whether to include the char in the unencode
boolean skip;
//the unencode buffer
byte[] unenc=new byte[4];
byte b;
for(int i=0,j=0;i

  1<maxturns;i++) ''="" ''+''="" 0="" and="" b="0;" byte="" capital="" convert="" digits="" else="" first="" get="" if(b="" if(i<encoded.length())="" letters,="" lowercase,="" or="" skip="false;" test="" the="" then="" to="" {="">=65&amp;&amp;b&lt;91)   
  2unenc[j]=(byte)(b-65);   
  3else if(b&gt;=97&amp;&amp;b&lt;123)   
  4unenc[j]=(byte)(b-71);   
  5else if(b&gt;=48&amp;&amp;b&lt;58)   
  6unenc[j]=(byte)(b+4);   
  7else if(b==''+'')   
  8unenc[j]=62;   
  9else if(b==''/'')   
 10unenc[j]=63;   
 11//if we find"="then data has finished, we''re not really dealing with this now   
 12else if(b==''='')   
 13unenc[j]=0;   
 14else   
 15{   
 16char c=(char)b;   
 17if(c==''\n'' || c==''\r'' || c=='' '' || c==''\t'')   
 18skip=true;   
 19else   
 20//could throw an exception here? it''s input we don''t understand.   
 21;   
 22}   
 23//once the array has boiled convert the bytes back into chars   
 24if(!skip&amp;&amp;++j==4)   
 25{   
 26//shift the 6 bit bytes into a single 4 octet word   
 27int res=(unenc[0]&lt;&lt;18)+(unenc[1]&lt;&lt;12)+(unenc[2]&lt;&lt;6)+unenc[3];   
 28byte c;   
 29int k=16;   
 30//shift each octet down to read it as char and add to StringBuffer   
 31while(k&gt;=0)   
 32{   
 33c=(byte)(res&gt;&gt;k);   
 34if ( c&gt;0 )   
 35sb.append((char)c);   
 36k-=8;   
 37}   
 38//reset j and the unencode buffer   
 39j=0;   
 40unenc[0]=0;unenc[1]=0;unenc[2]=0;unenc[3]=0;   
 41}   
 42}   
 43return sb.toString();   
 44}   
 45  
 46/** encode plaintext data to a base 64 string   
 47* @param plain the text to convert. If plain is longer than 76 characters this method   
 48* returns null (see RFC2045).   
 49* @return the encoded text (or null if string was longer than 76 chars).   
 50*/   
 51public static String encode(String plain)   
 52{   
 53if(plain.length()&gt;76)   
 54return null;   
 55int maxturns;   
 56StringBuffer sb=new StringBuffer();   
 57//the encode buffer   
 58byte[] enc=new byte[3];   
 59boolean end=false;   
 60for(int i=0,j=0;!end;i++)   
 61{   
 62char _ch=plain.charAt(i);   
 63if(i==plain.length()-1)   
 64end=true;   
 65enc[j++]=(byte)plain.charAt(i);   
 66if(j==3 || end)   
 67{   
 68int res;   
 69//this is a bit inefficient at the end point   
 70//worth it for the small decrease in code size?   
 71res=(enc[0]&lt;&lt;16)+(enc[1]&lt;&lt;8)+enc[2];   
 72int b;   
 73int lowestbit=18-(j*6);   
 74for(int toshift=18;toshift&gt;=lowestbit;toshift-=6)   
 75{   
 76b=res&gt;&gt;&gt;toshift;   
 77b&amp;=63;   
 78if(b&gt;=0&amp;&amp;b&lt;26)   
 79sb.append((char)(b+65));   
 80if(b&gt;=26&amp;&amp;b&lt;52)   
 81sb.append((char)(b+71));   
 82if(b&gt;=52&amp;&amp;b&lt;62)   
 83sb.append((char)(b-4));   
 84if(b==62)   
 85sb.append(''+'');   
 86if(b==63)   
 87sb.append(''/'');   
 88if(sb.length()%76==0)   
 89sb.append(''\n'');   
 90}   
 91//now set the end chars to be pad character if there   
 92//was less than integral input (ie: less than 24 bits)   
 93if(end)   
 94{   
 95if(j==1)   
 96sb.append("==");   
 97if(j==2)   
 98sb.append(''='');   
 99}   
100enc[0]=0;enc[1]=0;enc[2]=0;   
101j=0;   
102}   
103}   
104return sb.toString();   
105}   
106}</maxturns;i++)>