Solve the common problem of inaccessibility after Tomcat deploys war package

How to solve the problem that Tomcat cannot be accessed normally after deploying the war package

Introduction:
Tomcat is a commonly used Java Web application server that can provide powerful Web service support. However, when using Tomcat to deploy the war package, sometimes you may encounter a situation where you cannot access it normally. This article explains how to solve this problem and provides specific code examples.

1. Check the Tomcat log
When you cannot access it normally, you first need to check the Tomcat log file to understand the specific error information. Tomcat's log files are usually located in the logs folder under the Tomcat installation directory. There are two main files: catalina.out and localhost.log. Open both files and look for error messages. Common errors include 404 Not Found, 500 Internal Server Error, etc.

2. Check whether the war package is deployed correctly
1. Confirm whether the war package has been correctly deployed to Tomcat's webapps directory. You can view the war package folder in the webapps directory to ensure that the war package has been correctly decompressed and the corresponding files have been generated.

2. Check whether the name of the war package is correct. Tomcat uses the name of the war package as the Context path by default. If the name of the war package does not meet the requirements, you can try to change it to the correct name. For example, if test.war is renamed to mytest.war, the access path should be http://localhost:8080/mytest.

3. Check the web.xml configuration of the war package
1. Open the decompressed folder of the war package and find the web.xml file in the WEB-INF directory. web.xml is the deployment description file of the Web application, which defines the configuration of Servlet, Filter and other components.

2. Find whether there are errors or incomplete configurations in web.xml. Common errors include missing Servlet or Filter configuration, incorrect configuration path, etc. For example, if the accessed Servlet is not configured in web.xml, normal access will result.

3. Make sure that the servlet-mapping and welcome-file-list in web.xml are configured correctly. servlet-mapping specifies the path mapping relationship of the Servlet, and welcome-file-list specifies the file name of the welcome page.

4. Check the port and address configuration
1. Confirm whether Tomcat has been started and listening to the correct port. By default, Tomcat uses port 8080 for listening. You can verify whether Tomcat starts normally by visiting http://localhost:8080.

2. If Tomcat does not use the default port 8080, make sure you use the correct port number when accessing. For example, if Tomcat is configured to use port 8081, the accessed address should be http://localhost:8081.

5. Check the firewall and security group configuration
1. Check whether there is a firewall or security group configuration that prevents Tomcat from normal access. If you are using a firewall or security group, you can try turning them off temporarily and access Tomcat again.

2. Check the network configuration of the server to ensure that the server where Tomcat is located can access the Internet normally. If the server cannot access the Internet normally, you can try to configure a proxy server or set a network proxy.

Conclusion:
Through the above steps, in most cases, the problem of Tomcat being unable to access normally after deploying the war package can be solved. Of course, there are some special situations that need to be investigated based on specific error messages. I hope the methods and code examples provided in this article will help you solve your problem.

Code example:

1. Check the Tomcat startup port configuration

In the conf directory under the Tomcat installation directory, find the server.xml file. Open the file with a text editor and look for the following configuration:

       connectionTimeout="20000"
       redirectPort="8443" />

Make sure the port number is 8080, change the port if needed No., you can modify the port attribute.

2. Check web.xml configuration

The sample code is as follows:

<servlet>
    <servlet-name>HelloWorld</servlet-name>
    <servlet-class>com.example.HelloWorldServlet</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>HelloWorld</servlet-name>
    <url-pattern>/hello</url-pattern>
</servlet-mapping>

Make sure that servlet-name and servlet-class are configured correctly, and servlet-mapping The url-pattern configuration is consistent with the path when accessed.

3. Check the war package deployment example

Create a folder named myapp in Tomcat's webapps directory and put the war package into the folder. Then visit http://localhost:8080/myapp. If you can access it normally, the war package is deployed successfully.

The above are only some common solutions and code examples. Specific problems will be analyzed in detail. Please investigate and solve them according to the actual situation.

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