How to solve the problem that Tomcat cannot display the page? Tips and experiences shared!

What should I do if Tomcat cannot display the page? Solution sharing!
Tomcat is a commonly used Java web server. When we encounter the problem that Tomcat cannot display the page during the development process, it may be confusing. However, this problem usually has several possible causes and solutions. This article will introduce some common causes and provide corresponding solutions, along with specific code examples.

1. Port conflict
   The HTTP port used by Tomcat by default is 8080. If this port is occupied by other programs, Tomcat will not start normally. The solution is to modify Tomcat's HTTP port number. We can find the following configuration in Tomcat's server.xml file:

<Connector port="8080" protocol="HTTP/1.1"
           connectionTimeout="20000"
           redirectPort="8443" />

can be modified to:

<Connector port="8888" protocol="HTTP/1.1"
           connectionTimeout="20000"
           redirectPort="8443" />

and then restart Tomcat.

2. Project deployment error
   If the project is not deployed correctly to Tomcat's webapps directory, or the project's directory structure is incorrect, Tomcat will not be able to display the page. The solution is to check whether the project's deployment path and directory structure are correct. Make sure that the entire project folder is placed correctly under Tomcat's webapps directory.
3. Code Error
   Sometimes Tomcat cannot display the page because there are errors in the code, such as NullPointerException or other Java exceptions. The solution is to carefully check the code for errors and fix it accordingly.

The following is a sample code that demonstrates a simple Java Servlet for handling client requests:

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HelloWorldServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        response.getWriter().println("<h1>Hello, world!</h1>");
    }

}

In this example, we create a called HelloWorldServlet Java Servlet, which displays "Hello, world!" in the browser. Make sure that the Servlet mapping is configured in the correct web.xml file with the correct file path.

4. Configuration file error
   There are many parameters and options in Tomcat's configuration file. If these configuration errors are incorrect, Tomcat may not be able to display the page. The solution is to check Tomcat's configuration file and make sure all parameters and options are configured correctly.

To sum up, when Tomcat cannot display the page, we need to investigate the possible reasons one by one and take corresponding solutions. This article describes some common causes and provides solutions and specific code examples. I hope this article can help readers successfully solve the problem that Tomcat cannot display the page.

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