在Java中，您可以通過HttpServletRequest對象來獲取瀏覽器的IP地址。以下是一個簡單的方法：

import javax.servlet.http.HttpServletRequest;

public String getClientIpAddress(HttpServletRequest request) {
    String ipAddress = request.getHeader("X-Forwarded-For");
    
    if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
        ipAddress = request.getHeader("Proxy-Client-IP");
    }
    
    if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
        ipAddress = request.getHeader("WL-Proxy-Client-IP");
    }
    
    if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
        ipAddress = request.getHeader("HTTP_CLIENT_IP");
    }
    
    if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
        ipAddress = request.getHeader("HTTP_X_FORWARDED_FOR");
    }
    
    if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
        ipAddress = request.getRemoteAddr();
    }
    
    return ipAddress;
}

這個方法首先檢查請求頭中的"X-Forwarded-For"字段，因為在經過代理服務器時，客戶端的真實IP地址可能會被放在這個字段中。如果沒有找到有效的IP地址，它會繼續檢查其他可能包含IP地址的請求頭字段。最后，如果所有這些字段都沒有找到有效的IP地址，它會使用HttpServletRequest的getRemoteAddr()方法來獲取IP地址。