request.getServletPath()和request.getPathInfo()用法

本文转载于http://my.oschina.net/sub/blog/182408?fromerr=8xxvSrQt

在 Web 中，我们通常需要获取 URL 相对于 Webapp 的路径，主要是下面的几个方法：

request.getServletPath()
request.getPathInfo()
request.getContextPath()
request.getRequestURI()

其中 request.getRequestURI() 的返回值包含了 request.getContextPath()，所以是相对于网站的根目录的。

下面我们分析 request.getServletPath() 和 request.getPathInfo()

1. 如果我们的 servlet-mapping 如下配置：

< servlet-mapping >
  < servlet-name >jetbrick-template servlet-name >
  < url-pattern >*.jetx url-pattern >
servlet-mapping >

那么访问: /context/templates/index.jetx

request.getServletPath() == "/templates/index.jetx"
request.getPathInfo() == < null >

2. 如果我们的 servlet-mapping 如下配置：

< servlet-mapping >
  < servlet-name >jetbrick-template servlet-name >
  < url-pattern >/* url-pattern >
servlet-mapping >

那么访问: /context/templates/index.jetx

request.getServletPath() == ""
request.getPathInfo() == "/templates/index.jetx"

3. 如果我们的 servlet-mapping 如下配置：

< servlet-mapping >
  < servlet-name >jetbrick-template servlet-name >
  < url-pattern >/template/* url-pattern >
servlet-mapping >

那么访问: /context/templates/index.jetx

request.getServletPath() == "/templates"
request.getPathInfo() == "/index.jetx"

总结 ：

所以，我们要获取相对于 request.getContextPath() 的路径，我们可以使用如下的代码：

String uri = request.getServletPath();
String pathInfo = request.getPathInfo();
if (pathInfo != null && pathInfo.length() > 0 ) {
    uri = uri + pathInfo;
}

或者：

String uri = request.getRequestURI();
String contextPath = request.getContextPath();
if (contextPath != null && contextPath.length() > 0 ) {
    uri = uri.substring(contextPath.length());
}

===============================

2013-02-08 补上一个 Tomcat 自身的实现:

catalina.jar,  DefaultServlet.java

protected String getRelativePath(HttpServletRequest request)
{
  if (request.getAttribute( "javax.servlet.include.request_uri" ) != null )
  {
    String result = (String)request.getAttribute( "javax.servlet.include.path_info" );
    if (result == null ) {
      result = (String)request.getAttribute( "javax.servlet.include.servlet_path" );
    } else {
      result = (String)request.getAttribute( "javax.servlet.include.servlet_path" ) + result;
    }
    if ((result == null ) || (result.equals( "" ))) {
      result = "/" ;
    }
    return result;
  }
  String result = request.getPathInfo();
  if (result == null ) {
    result = request.getServletPath();
  } else {
    result = request.getServletPath() + result;
  }
  if ((result == null ) || (result.equals( "" ))) {
    result = "/" ;
  }
  return result;
}