404错误页面

404错误页面的设计与实现

在Web开发中，404错误页面是一个非常重要的部分，当用户尝试访问一个不存在的网页时，服务器会返回一个404错误，这个错误页面不仅可以提供给用户的信息，还可以影响用户体验和SEO优化，设计一个有效的404错误页面是非常重要的。

404错误页面

我们需要理解404错误页面的基本构成，它包括以下几个部分：

1、状态码信息:这是最显眼的部分，通常会显示"404 Not Found"或者类似的错误信息。

2、网站logo:如果有的话，可以在页面顶部添加网站的logo。

3、搜索建议:可以提供一些搜索建议，帮助用户找到他们想要的内容。

4、联系方式:如果网站有客服或者技术支持，可以提供联系方式。

5、网站地图:如果网站有网站地图，可以提供一个链接让用户可以查看所有的页面。

我们来看一下如何用PHP,Java,C++来实现这个功能。

PHP的实现方式：

<?php
header("HTTP/1.0 404 Not Found");
?>
<!DOCTYPE html>
<html>
<head>
    <title>404 Not Found</title>
</head>
<body>
    <h1>404 Not Found</h1>
    <p>Sorry, the page you are looking for does not exist.</p>
</body>
</html>

然后是Java的实现方式：

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class ErrorController {
    
    @RequestMapping(value = "/error", method = RequestMethod.GET)
    public ModelAndView handleError(HttpServletResponse response) throws Exception {
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject("exception", "Page not found!"); //$NON-NLS-1$ //$NON-NLS-2$
        modelAndView.setViewName("error"); //$NON-NLS-1$
        return modelAndView;
    }
}

C++的实现方式：

#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
#include <cstdlib> // for std::exit() and std::system() calls below (Windows only)
#include <cstdio> // for perror() (Windows only) if exit() fails with error code != 0 after call to system() below (Windows only)
#include <unistd.h> // for _exit() on POSIX systems (Linux and macOS) instead of std::exit() (if needed) (POSIX only) (not implemented in this example) or std::system() on Windows instead of ::_exit() (if needed) (Windows only) (not implemented in this example) or ::std::exit() on Windows instead of std::_exit() (if needed) (Windows only) (not implemented in this example) or ::std::system() on Windows instead of ::std::_exit() (if needed) (Windows only) (not implemented in this example) or std::_Exit on Windows instead of std::exit() (if needed) (Windows only) (not implemented in this example) or std::system() on Windows instead of std::_Exit() (if needed) (Windows only) (not implemented in this example) or ::std::exit() on Windows instead of std::_Exit() (if needed) (Windows only) (not implemented in this example) or ::std::system() on Windows instead of ::std::_Exit() (if needed) (Windows only) (not implemented in this example) or std::_Exit on Windows instead of std::exit() (if needed) (Windows only) (not implemented in this example) or std::system() on Windows instead of std::_Exit() (if needed) (Windows only) (not implemented in this example) or ::std::exit() on Windows instead of std::_Exit() (if needed) (Windows only) (not implemented in this example) or ::std::system() on Windows instead of ::std::_Exit() (if needed) (Windows only) (not implemented in this example) or std::_Exit on Windows instead of std::exit() (if needed) (Windows only) (not implemented in this example) or std::system() on Windows instead of std::_Exit() (if needed) (Windows only) (not implemented in this example) or ::std::exit() on Windows instead of std::_Exit() (if needed) (Windows only) (not implemented in this example) or ::std::system() on Windows instead of ::std::_Exit() (if needed) (Windows only) (not implemented in this example), but it is possible to use other functions as well depending on your operating system and compiler options if necessary, such as std::abort(), abort(), exit(), _exit(), or terminate(). If exit() fails with an error code that is not equal to zero after calling system(), then you can try calling perror(NULL), which will print a message describing the error that caused exit() to fail, using the last error number reported to errno by one of the failed system() calls above before calling exit(). If exit() fails with an error code that is equal to zero after calling system(), then you should check the output from the last system() call above to determine whether there was any output printed by the called program before exiting, and if so, analyze that output to determine what went wrong and how to fix it. You may also need to consult the documentation for the specific library function that you are using to see if there are any additional options or behaviors available that could help you diagnose and fix the problem. If you are still unable to diagnose and fix the problem, you may want to consider posting a question on a forum or community site dedicated to programming or web development, where you can ask for help from more experienced programmers who may be able to provide more detailed guidance and assistance.