直接给出代码,有3个需要注意的点:

• toArray方法要实现类型转换需要使用 toArray(T[] .. )方法,不可以直接类型转换
• BufferedReader内需要使用一个转换流来保证不出现乱码
• String[] 和 Map<String,String[]>不可以改变,需要重新创建新的作为返回值
  

[Java] 纯文本查看 复制代码

@WebFilter("/*")
public class SensitiveWordsFilter implements Filter {
    private List<String> list = new ArrayList<>();

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        //1.获取文件的真实路径
        ServletContext context = filterConfig.getServletContext();
        String realPath = context.getRealPath("/WEB-INF/classes/敏感词汇.txt");
        //2.读取realPath中的敏感词汇
        try (FileInputStream fis = new FileInputStream(realPath);
             BufferedReader br = new BufferedReader(new InputStreamReader(fis, "utf-8"));) {
            //3.使用br读取敏感词汇
            String line;
            while ((line = br.readLine()) != null) {
                list.add(line);
            }
            System.out.println(list);
            //4.不用释放资源了,fis和br的作用域仅在这个try中
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
        //0.强制转型
        HttpServletRequest request = (HttpServletRequest) req;
        //1.创建proxy_req对象
        HttpServletRequest proxy_req = (HttpServletRequest) Proxy.newProxyInstance(request.getClass().getClassLoader(), request.getClass().getInterfaces(), new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                String methodName = method.getName();
                //2.1 判断方法是否为getParameter对象
                if (methodName.equals("getParameter")) {
                    String value = (String) method.invoke(request, args);
                    if (value != null) {
                        for (String str : list) {
                            value = value.replaceAll(str, "***");
                        }
                    }
                    return value;
                }
                //2.2判断方法是否为getParameterValues
                if (methodName.equals("getParameterValues")) {
                    String[] values = (String[]) method.invoke(request, args);
                    List<String> sb = new ArrayList<>();
                    if (values != null) {
                        for (String value : values) {
                            for (String str : list) {
                                value = value.replaceAll(str, "***");
                            }
                            sb.add(value);
                        }
                    }
                    String[] sBuffer = new String[values.length];
                    String[] sb_string = sb.toArray(sBuffer);
                    return sb_string;
                }
                //2.3判断方法是否为getParameterMap
                if (methodName.equals("getParameterMap")) {
                    Map<String, String[]> map = (Map<String, String[]>) method.invoke(request, args);
                    Set<String> keys = map.keySet();
                    Map<String, Object> newMap = new HashMap<>();
                    for (String key : keys) {
                        String[] values = map.get(key);
                        List<String> sb = new ArrayList<>();
                        for (String value : values) {
                            for (String str : list) {
                                value = value.replaceAll(str, "***");
                            }
                            sb.add(value);
                        }
                        String[] sBuffer = new String[values.length];
                        String[] sb_string = sb.toArray(sBuffer);
                        newMap.put(key, sb_string);
                    }
                    return newMap;
                }
                return method.invoke(request, args);
            }
        });
        //3.放行
        chain.doFilter(proxy_req, resp);
    }

    @Override
    public void destroy() {

    }
}

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