SpringBoot接口返回null则响应404

Hello，I’m Shendi

当我的接口遭到恶意访问时，我想返回404，达到让其以为此接口不存在的目的

实现思路

因为使用的 SpringBoot，所以第一时间想搜寻是否提供了某种方法来让我实现，然并卵

后来想到使用过滤器，过滤器可以在接口执行完毕后继续执行一些操作

因我要获取接口是否响应了数据，所以需要代理响应

允许扫描Servlet注解

因使用的SpringBoot，要扫描Servlet注解需要在启动类（Application）上加上 @ServletComponentScan注解

@ServletComponentScan
public class Application {}

编写过滤器

/**
 * 默认过滤器,统一编码,以及响应体为null则返回404错误.
 * @author Shendi <a href='tencent://AddContact/?fromId=45&fromSubId=1&subcmd=all&uin=1711680493'>QQ</a>
 * @version 1.0
 */
@WebFilter("/*")
public class DefaultFilter extends HttpFilter {
	private static final long serialVersionUID = 3455876099526058476L;
	
	public static final String ENCODING = "UTF-8";
	
	@Override
	protected void doFilter(HttpServletRequest req, HttpServletResponse resp, FilterChain chain) throws IOException, ServletException {
		req.setCharacterEncoding(ENCODING);
		resp.setCharacterEncoding(ENCODING);
		
		// 代理响应
		MyResponse mr = new MyResponse(resp);
		
		chain.doFilter(req, mr);
		
		if (mr.nullResp) resp.setStatus(404);
	}
	
	class MyResponse extends HttpServletResponseWrapper {
		
		/** 响应是否为空 */
		public boolean nullResp = true;
		
		public MyResponse(HttpServletResponse response) {
			super(response);
		}
		
		@Override
		public ServletOutputStream getOutputStream() throws IOException {
			// 当接口return null或者无返回值时,则不会触发此函数
			nullResp = false;
			return super.getOutputStream();
		}
		
	}
	
}

后续补充

大意了，当项目前后端分离，跨域请求，有时浏览器会自行的发送一个options请求，如果不响应200状态，浏览器则会报错

Access to XMLHttpRequest at 'xxx' from origin 'xxx' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.

因为是浏览器自行发起的请求，所以与我们写的无关，在过滤器中判断是否为 options 请求，是则直接放行即可

/**
 * 默认过滤器,统一编码,以及响应体为null则返回404错误.
 * @author Shendi <a href='tencent://AddContact/?fromId=45&fromSubId=1&subcmd=all&uin=1711680493'>QQ</a>
 * @version 1.0
 */
@WebFilter("/*")
public class DefaultFilter extends HttpFilter {
	private static final long serialVersionUID = 3455876099526058476L;
	
	public static final String ENCODING = "UTF-8";
	
	@Override
	protected void doFilter(HttpServletRequest req, HttpServletResponse resp, FilterChain chain) throws IOException, ServletException {
		req.setCharacterEncoding(ENCODING);
		resp.setCharacterEncoding(ENCODING);
		
		// 如果是 option 请求则直接放行
		if ("OPTIONS".equals(req.getMethod())) {
			chain.doFilter(req, resp);
			return;
		}
		
		// 代理响应
		MyResponse mr = new MyResponse(resp);
		
		chain.doFilter(req, mr);
		
		if (mr.nullResp) resp.setStatus(404);
	}
	
	class MyResponse extends HttpServletResponseWrapper {
		
		/** 响应是否为空 */
		public boolean nullResp = true;
		
		public MyResponse(HttpServletResponse response) {
			super(response);
		}
		
		@Override
		public ServletOutputStream getOutputStream() throws IOException {
			// 当接口return null或者无返回值时,则不会触发此函数
			nullResp = false;
			return super.getOutputStream();
		}
		
	}
	
}