在 servlet 中,我们可以使用 requestdispatcher,它将从一个 servlet 转发到同一项目中具有相同 session 的另一个 servlet。但是如果我使用不同的项目,getRequestDispatcher 将不起作用。它给出 404 错误。因为它在网址。如何在同一服务器的不同项目中实现 getRequestDispatcher?
RequestDispatcher rd = request.getRequestDispatcher("/v1/status1/toreply1");
rd.forward(request, response);
在同一项目中,getRequestDispatcher 工作正常。但在不同的项目中它不起作用?谁能解释为什么会发生..?
最佳答案
您可以在同一台服务器上的不同项目中实现getRequestDispatcher。
查看 https://stackoverflow.com/a/19273223/1428052
它通过使用在不同项目的同一服务器上工作 getServletContext().getContext() 方法。
您可以按照以下步骤进行详细实现。
首先你需要修改下面的文件
(Windows) C:\Program Files\Apache Software Foundation\Tomcat 7.0\conf\context.xml 将 crossContext 的值设置为 true。
context.xml
<Context crossContext="true">
<!-- Default set of monitored resources -->
<WatchedResource>WEB-INF/web.xml</WatchedResource>
<!-- Uncomment this to disable session persistence across Tomcat restarts -->
<!--
<Manager pathname="" />
-->
<!-- Uncomment this to enable Comet connection tacking (provides events
on session expiration as well as webapp lifecycle) -->
<!--
<Valve className="org.apache.catalina.valves.CometConnectionManagerValve" />
-->
</Context>
请注意crossContext="true"。
假设您有两个名为 InterServletComm1 和 InterServletComm2 的 Web 应用程序 在每个 Web 应用程序中分别具有 servlet Servlet1 和 Servlet1。然后每个 servlet 中的代码如下:
Servlet1.java
package interServletComm1;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Servlet1
*/
@WebServlet("/Servlet1")
public class Servlet1 extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public Servlet1() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
request.setAttribute("name", "WebApp1");
ServletContext context = getServletContext().getContext("/InterServletComm2");
RequestDispatcher rd = context.getRequestDispatcher("/Servlet2");
rd.forward(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}
Servlet2.java
package interServletComm2;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Servlet2
*/
@WebServlet("/Servlet2")
public class Servlet2 extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public Servlet2() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
String name = (String) request.getAttribute("name");
pw.println("This is web application 2.");
pw.println("<br>The value received from web application one is: " + name);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}
以上代码从 InterServletComm1 发送属性 name 并在 InterServletComm2 中接收。 如果这个答案不清楚,请告诉我。
关于java - getRequestDispatcher 如何在同一服务器的不同项目中为 servlet 工作?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20139414/