Filter解决乱码问题

引用接口

public class filter implements Filter {
    
    
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    
    
        servletRequest.setCharacterEncoding("UTF-8");
        servletResponse.setCharacterEncoding("UTF-8");
        servletResponse.setContentType("text/html; Charset =utf-8");
        filterChain.doFilter(servletRequest,servletResponse);
    }
}

这里接口不用完全实现，只需要实现一个doFilter。因为在接口里有defalut修饰

public interface Filter {
    
    
    default void init(javax.servlet.FilterConfig filterConfig) throws javax.servlet.ServletException {
    
     /* compiled code */ }

    void doFilter(javax.servlet.ServletRequest servletRequest, javax.servlet.ServletResponse servletResponse, javax.servlet.FilterChain filterChain) throws java.io.IOException, javax.servlet.ServletException;

    default void destroy() {
    
     /* compiled code */ }
}

在xml里面配置

<filter>
      <filter-name>character</filter-name>
      <filter-class>com.yim.Servlet.filter</filter-class>
   </filter>
   <filter-mapping>
      <filter-name>character</filter-name>
      <url-pattern>/test2</url-pattern>
   </filter-mapping>

这里就完成了控制台和输出到页面都没有乱码问题，也不用每个类都去修改一次乱码问题

注：writer乱码问题

FileReader读取中文字符乱码问题，注意UTF-8

        InputStream inputStream= req.getInputStream();
        Reader reader=new InputStreamReader(inputStream, "UTF-8");
        BufferedReader bufferedReader=new BufferedReader(reader);

屏蔽敏感词

@WebFilter("/test")
public class WordFilter implements Filter {
    
    
 @Override
 public void doFilter(ServletRequest servletRequest, ServletResponse
servletResponse, FilterChain filterChain) throws IOException, ServletException
{
    
    
 servletRequest.setCharacterEncoding("UTF-8");
 //将"敏感词"替换成"***"
 String name = servletRequest.getParameter("name");
 name = name.replaceAll("敏感词","***");
 servletRequest.setAttribute("name",name);
 filterChain.doFilter(servletRequest,servletResponse);
 }
}

控制页面的访问权限。

假如用户无登陆状态直接打开下载链接，是不会跳转到下载页面而是跳转到登陆页面。
主要利用session和webfilter过滤器

@WebFilter("/download.jsp")
public class DownloadFilter implements Filter {
    
    
 @Override
 public void doFilter(ServletRequest servletRequest, ServletResponse
servletResponse, FilterChain filterChain) throws IOException, ServletException
{
    
    
 HttpServletRequest request = (HttpServletRequest) servletRequest;
 HttpServletResponse response = (HttpServletResponse) servletResponse;
 HttpSession session = request.getSession();
 String name = (String) session.getAttribute("name");
 if(name == null){
    
    
 //不是登录状态
 response.sendRedirect("/login.jsp");
 }else{
    
    
 filterChain.doFilter(servletRequest,servletResponse);
 }
 }
}