WebUtils Tutorial

This tutorial provides an overview of the WebUtils class, which is part of the lightweight-component/aj-util library. The WebUtils class provides utility methods for web-related operations in Java applications.

Introduction

The WebUtils class contains static methods for common web operations such as IP address retrieval and cookie handling.

Main Features

• Get local IP address
• Get client IP address from HTTP request
• Retrieve cookies from HTTP request

Methods

1. getLocalIp()

Retrieves the local IP address of the server.

• Returns: The local IP address as a String, or null if the address cannot be determined.

Example:

String ip = WebUtils.getLocalIp();

2. getClientIp(HttpServletRequest request)

Retrieves the client's IP address from an HTTP request, handling various proxy headers.

• Parameters:
  • request: The HttpServletRequest object
• Returns: The client IP address as a String

Example:

String clientIp = WebUtils.getClientIp(request);

3. getCookie(HttpServletRequest request, String cookieName)

Retrieves a cookie value by name from an HTTP request.

• Parameters:
  • request: The HttpServletRequest object
  • cookieName: The name of the cookie to retrieve
• Returns: The cookie value as a String, or null if the cookie doesn't exist

Example:

String sessionId = WebUtils.getCookie(request, "JSESSIONID");

Usage Example

Here's a complete example of using the WebUtils class:

import javax.servlet.http.HttpServletRequest;
import com.ajaxjs.util.WebUtils;

public class Example {
    public void processRequest(HttpServletRequest request) {
        // Get server IP
        String serverIp = WebUtils.getLocalIp();
        System.out.println("Server IP: " + serverIp);
        
        // Get client IP
        String clientIp = WebUtils.getClientIp(request);
        System.out.println("Client IP: " + clientIp);
        
        // Get session cookie
        String sessionId = WebUtils.getCookie(request, "JSESSIONID");
        System.out.println("Session ID: " + sessionId);
    }
}

Conclusion

The WebUtils class provides simple utility methods for common web operations, making it easier to handle IP addresses and cookies in Java web applications.