Root URl of the servlet

问题

I want to get the root url of my web application from one of the servlet.

If I deploy my application in "www.mydomain.com" I want to get the root url like "http://www.mydomain.com".

Same thing if I deploy it in local tomcat server with 8080 port it should give http://localhost:8080/myapp

Can anyone tell me how to get the root URL of my web application from servlet?

public class MyServlet extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String rootURL="";
        //Code to get the URL where this servlet is deployed

    }
}

回答1:

You do realize that the URL client sees (and/or types into his browser) and the URL served by the container your servlet is deployed on can be very different?

In order to get the latter, though, you have a few methods available on HttpServletRequest:

You can either call getScheme(), getServerName(), getServerPort() and getContextPath() and combine them using appropriate separators
OR you can call getRequestURL() and remove getServletPath() and getPathInfo() from it.

回答2:

This function helps you to get your base URL from a HttpServletRequest:

  public static String getBaseUrl(HttpServletRequest request) {
    String scheme = request.getScheme() + "://";
    String serverName = request.getServerName();
    String serverPort = (request.getServerPort() == 80) ? "" : ":" + request.getServerPort();
    String contextPath = request.getContextPath();
    return scheme + serverName + serverPort + contextPath;
  }

回答3:

Generally, you can't obtain the URL; but, there are workarounds for specific cases. See Finding your application’s URL with only a ServletContext

回答4:

Write a scriptlet in the welcome file to capture the root path. I assume index.jsp is the default file. So put the following code in that

<% RootContextUtil rootCtx = RootContextUtil.getInstance(); if( rootCtx.getRootURL()==null ){ String url = request.getRequestURL().toString(); String uri = request.getRequestURI(); String root = url.substring( 0, url.indexOf(uri) ); rootCtx.setRootURL( root ); } %>
Use this variable wherever needed within the application directly by calling the value as

String rootUrl = RootContextUtil.getInstance().getRootURL();

NOTE: No need to worry about protocols/ports/etc.. Hope this helps every one

回答5:

public static String getBaseUrl(HttpServletRequest request) {
    String scheme = request.getScheme();
    String host = request.getServerName();
    int port = request.getServerPort();
    String contextPath = request.getContextPath();

    String baseUrl = scheme + "://" + host + ((("http".equals(scheme) && port == 80) || ("https".equals(scheme) && port == 443)) ? "" : ":" + port) + contextPath;
    return baseUrl;
}

来源：https://stackoverflow.com/questions/1629102/root-url-of-the-servlet

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java

java-ee