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package
my.view;
import
java.io.*;
import
java.util.*;
import
javax.servlet.*;
import
javax.servlet.http.*;
import
org.apache.commons.lang.StringUtils;
import
org.apache.commons.logging.Log;
import
org.apache.commons.logging.LogFactory;
/**
*
用于URL地址的转换
*
http://www.oschina.net/news/list/1/3 -> {base}/news/list.vm?p1=1&p2=3
*
@author liudong
*/
public
final
class
URLMappingServlet extends
HttpServlet {
private
final
static
Log log = LogFactory.getLog(URLMappingServlet.class);
public
final
static
String CURRENT_URI = "current_uri";
//{index}
public
final
static
String REQUEST_URI = "request_uri";
//{/index}
private
final
static
String DEFAULT_INDEX_PAGE = "index.vm";
private
final
static
String PAGE_EXTENSION = ".vm";
private
final
static
char
URL_SEPERATOR = ‘/‘;
private
String default_base;
private
HashMap<String, String> other_base = new
HashMap<String, String>();
private
String rootDomain = "oschina.net";
@Override
@SuppressWarnings("unchecked")
public
void
init() throws
ServletException {
Enumeration<String>
names = getInitParameterNames();
while(names.hasMoreElements()){
String
name = names.nextElement();
String
v = getInitParameter(name);
if("default".equalsIgnoreCase(name)){
default_base
= v;
continue;
}
for(String
n : StringUtils.split(name, ‘,‘)){
other_base.put(n,
v);
}
}
}
private
String _GetTemplateBase(HttpServletRequest req) {
String
base = null;
String
prefix = req.getServerName().toLowerCase();
base
= other_base.get(prefix);
if(base
!= null)
return
base;
int
idx = prefix.indexOf(rootDomain);
if(idx
> 0){
prefix
= prefix.substring(0,
idx - 1);
base
= other_base.get(prefix);
}
return
(base==null)?default_base:base;
}
/**
*
执行页面映射过程
*
@param req
*
@param res
*
@throws ServletException
*
@throws IOException
*/
protected
void
perform(HttpServletRequest req, HttpServletResponse res)
throws
ServletException, IOException {
StringBuilder
show_page = new
StringBuilder(_GetTemplateBase(req));
String
prefix = req.getServletPath().substring(1);
String
spath = req.getRequestURI();
req.setAttribute(REQUEST_URI,
spath);
req.setAttribute(CURRENT_URI,
prefix);
//解析URL地址
String[]
s_result = spath.substring(1).split(String.valueOf(URL_SEPERATOR));
if(s_result.length==1){
show_page.append(prefix);
show_page.append(URL_SEPERATOR);
show_page.append(DEFAULT_INDEX_PAGE);
}
else{
show_page.append(prefix);
show_page.append(URL_SEPERATOR);
//
Ex: http://www.oschina.net/admin/login/ld
StringBuilder
testPath = new
StringBuilder(show_page);
testPath.append(s_result[1]);
testPath.append(PAGE_EXTENSION);
boolean
isVM = _IsVmExist(testPath.toString());
int
param_idx = 1;
if(isVM){
show_page.append(s_result[1]);
show_page.append(PAGE_EXTENSION);
param_idx
= 2;
}
else{
show_page.append(DEFAULT_INDEX_PAGE);
}
for(int
i=param_idx;i<s_result.length;i++){
if(i==param_idx)
show_page.append(‘?‘);
else
show_page.append(‘&‘);
show_page.append(‘p‘);
show_page.append((i-param_idx+1));
show_page.append(‘=‘);
show_page.append(s_result[i]);
}
testPath.setLength(0);
testPath
= null;
}
if(log.isDebugEnabled())
log.debug("request_uri="+spath+",servlet_path="+
req.getServletPath()+",vm="+show_page);
//执行真实的页面
RequestDispatcher
rd = getServletContext().getRequestDispatcher(show_page.toString());
rd.forward(req,
res);
}
private
final
static
List<String> vm_cache = new
Vector<String>();
/**
*
判断某个页面是否存在，如果存在则缓存此结果
*
@param path
*
@return
*/
private
boolean
_IsVmExist(String path){
if(vm_cache.contains(path))
return
true;
File
testFile = new
File(getServletContext().getRealPath(path));
boolean
isVM = testFile.exists() && testFile.isFile();
if(isVM)
vm_cache.add(path);
return
isVM;
}
@Override
protected
void
doGet(HttpServletRequest req, HttpServletResponse resp)
throws
ServletException, IOException {
perform(req,
resp);
}
@Override
protected
void
doPost(HttpServletRequest req, HttpServletResponse resp)
throws
ServletException, IOException {
perform(req,
resp);
}
}
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