Java Filter实现对敏感词的过滤

淡淡的烟草味﹌ 2022-02-15 10:11 370阅读 0赞

**一、需求：敏感词汇 过滤  
二、技术点：过滤器（Filter），代理增强（Proxy）  
三、代码：**  
1、测试工程目录  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70]  
2、src下创建敏感词文件 敏感词.txt  
![在这里插入图片描述][20190424114936768.png]  
3、新建敏感词过滤器 SensitiveWordsFilter.java

package com.mollen.filter;
    package com.mollen.filter.filter;
    
    import javax.servlet.*;
    import javax.servlet.annotation.WebFilter;
    import java.io.BufferedReader;
    import java.io.FileReader;
    import java.io.IOException;
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.lang.reflect.Proxy;
    import java.util.ArrayList;
    import java.util.List;
    
    /**
     * @ClassName:  SensitiveWordsFilter
     * @Auther:     Mollen
     * @CreateTime: 2018-10-09  21:04:35
     * @Description:
     *              敏感词过滤
     */
    @WebFilter("/testServlet")
    public class SensitiveWordsFilter implements Filter {
        // 1.创建敏感词汇集合
        private List<String> list = new ArrayList<>();
    
        // 2.加载敏感词汇文件
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
           
            try {
                //ServletContext是servlet全局对象
                ServletContext servletContext = filterConfig.getServletContext();
                String path = servletContext.getRealPath("/WEB-INF/classes/敏感词.txt");
                BufferedReader br = new BufferedReader(new FileReader(path));
                
                String line = null;
                while ((line = br.readLine()) != null) {
                    list.add(line);
                }
                br.close();
    
                System.out.println(list);
    
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        
        //3.创建代理对象，增强getParameter方法
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        
            ServletRequest proxy_request = (ServletRequest) Proxy.newProxyInstance(servletRequest.getClass().getClassLoader(), servletRequest.getClass().getInterfaces(), new InvocationHandler() {
    
                @Override
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                    //判断是否是getParameter方法
                    if (method.getName().equals("getParameter")) {
                        //增强返回值，获取返回值
                        String value = (String) method.invoke(servletRequest, args);
                        if (value != null) {
                            for (String str : list) {
                                if (value.contains(str)) {
                                    value = value.replaceAll(str, "***");
                                }
                            }
                        }
                        return value;
                    }
                    return method.invoke(servletRequest, args);
                }
            });
            //过滤器放行
            filterChain.doFilter(proxy_request, servletResponse);
        }
    
        @Override
        public void destroy() {
        }
    }

4、新建测试 TestServlet.java

package com.mollen.servlet;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/testServlet")
    public class TestServlet extends HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doGet(request, response);
       }
    
       protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           //1.乱码处理
           request.setCharacterEncoding("utf-8");
           response.setContentType("text/html;charset=utf-8");
    
           //2.获取前台数据
           String id = request.getParameter("id");
    
           //3.控制台打印一下
           System.out.println(id);
    
           //4.页面再打印一下
           response.getWriter().write("提交的数据是："+id);
       }
    }

## 实现效果如下： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70 1]  
原文：[https://blog.csdn.net/mollen/article/details/82989303][https_blog.csdn.net_mollen_article_details_82989303]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70]: /images/20220215/efb0ec480aaa41db896b5f4e603a7cd2.png
[20190424114936768.png]: /images/20220215/6d9ba8f156974de6b17a5c854c516d84.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70 1]: /images/20220215/d3c176cce0114fb38a1691c6b806f1da.png
[https_blog.csdn.net_mollen_article_details_82989303]: https://blog.csdn.net/mollen/article/details/82989303