Use the comment @WebFilter

filter filters, SpringBoot @WebFilter in a class can be used to filter the annotations in the tomcat servlet packages from servlet3.0 version began to support this annotated.

　This note contains the following parameters can be set:

 

Property name	Types of	Explanation	other
description	String	The description of annotations
displayName	String	Filters were equivalent with <display-name>
initParams	WebInitParam[]	Used for setting the initialization parameters of the filter type, equivalent to <init-param>	如：initParams = {@WebInitParam(name = "ignoredUrl", value = ".css#.js#.jpg#.png#.gif#.ico")
filterName	String	Filter Name, equivalent to <filter-name>
servletNames	String[]	String type array that specifies filtering servlet. The value is the value of the name attribute @WebServlet, or in web.xml <servlet-name> values.
value，urlPatterns	String[]	URL pattern matching filter. It is equivalent to <url-pattern> tag.	Such as: urlPatterns = { "/ *"} block all, only need to pay attention value and URLPATTERN is selected from a recommended URLPATTERN is, look better
dispatcherTypes	DispatcherType[]	Forwarding mode filter. Specific values ​​include: ASYNC, ERROR, FORWARD, INCLUDE, REQUEST.	Has a default value, see above, is the default request
asyncSupported	boolean	Filter support asynchronous mode of operation, equivalent to <async-supported> tag.	默认为false

 

 

 还有就是，被@WebFilter注解的类，会在容器启动时被加载，并进行属性配置。即项目一启动容器自动加载init方法。

可以看到，项目启动后进入到filter的init方法里面了

 

 

 先看一下filterconfig：

 

 

 

 

 

 可以看到在filterDef中有我们之前提到的注解里面的所有内容。

当filter的init方法执行完毕后就注册完毕了，进入类：org.apache.catalina.core.ApplicationFilterConfig，方法：initFilter。

@WebFilter(filterName = "LogCostFilter", urlPatterns = {"/*"},
        initParams = {@WebInitParam(name = "ignoredUrl", value = ".css#.js#.jpg#.png#.gif#.ico"),
                      @WebInitParam(name = "filterPath",
                              value = "/user/login#/user/registerUser")})
public class LogCostFilter implements Filter {

    private static final String FILTER_PATH = "filterPath";
    private static final String IGNORED_PATH = "ignoredUrl";

    private static final List<String> ignoredList = new ArrayList<>();
    private String[] allowUrls;
    private String[] ignoredUrls;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        String filterPath = filterConfig.getInitParameter(FILTER_PATH);
        if (!StringUtils.isEmpty(filterPath)) {
            allowUrls = filterPath.contains("#") ? filterPath.split("#") : new String[]{filterPath};
        }

        String ignoredPath = filterConfig.getInitParameter(IGNORED_PATH);
        if (!StringUtils.isEmpty(ignoredPath)) {
            ignoredUrls = ignoredPath.contains("#") ? ignoredPath.split("#") : new String[]{ignoredPath};
            for (String ignoredUrl : ignoredUrls) {
                ignoredList.add(ignoredUrl);
            }
        }
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException {
        HttpServletRequest servletRequest = (HttpServletRequest) request;
        HttpServletResponse servletResponse = (HttpServletResponse) response;
        String requestUrl = servletRequest.getRequestURI();
        //具体，比如：处理若用户未登录，则跳转到登录页
        Object userInfo = servletRequest.getSession().getAttribute("user");
        if(userInfo!=null) { //如果已登录，不阻止
            chain.doFilter(request, response);
            return;
        }
        if (requestUrl != null && (requestUrl.contains("/login.html") || requestUrl.contains("/register.html"))) {
            chain.doFilter(request, response);
            return;
        }
        if (verify(ignoredList, requestUrl)) {
            chain.doFilter(servletRequest, response);
            return;
        }
        if (null != allowUrls && allowUrls.length > 0) {
            for (String url : allowUrls) {
                if (requestUrl.startsWith(url)) {
                    chain.doFilter(request, response);
                    return;
                }
            }
        }
        servletResponse.sendRedirect("/login.html");
    }

    private static String regexPrefix = "^.*";
    private static String regexSuffix = ".*$";

    private static boolean verify(List<String> ignoredList, String url) {
        for (String regex : ignoredList) {
            Pattern pattern = Pattern.compile(regexPrefix + regex + regexSuffix);
            Matcher matcher = pattern.matcher(url);
            if (matcher.matches()) {
                return true;
            }
        }
        return false;
    }
    @Override
    public void destroy() {

    }
}

　　

urlPatterns