旨在: 判断用户发送的评论是否包含一些非法词汇，替换成*号, 屏蔽词库由配置文件提供.
1.解决中文乱码的filter
@WebFilter("/*")
public class CharEncodingFilter implements Filter {
@Override
public void destroy() {
}
@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
//统一设置请求的编码方式为UTF-8
req.setCharacterEncoding("UTF-8");
//统一设置响应的编码方式(如果设置了这种解决响应乱码的代码，那么就不能做下载)
resp.setContentType("text/html;charset=UTF-8");
chain.doFilter(req, resp);
}
@Override
public void init(FilterConfig config) throws ServletException {
}
}
2.过滤非法字符的filter
(这里的 过滤词库.txt，每一行为一个关键词，当作配置文件放到properties文件夹下)
@WebFilter("/*")
public class IllegalCharFilter implements Filter {
private List<String> strList = new ArrayList<>();
@Override
public void destroy() {
}
@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
//放行之前，使用动态代理技术，增强req对象的方法
//将req强转成HttpServletRequest
HttpServletRequest request = (HttpServletRequest) req;
//类加载器
ClassLoader classLoader = req.getClass().getClassLoader();
//被代理的接口: HttpServletRequest
HttpServletRequest requestProxy = (HttpServletRequest) Proxy.newProxyInstance(classLoader, new Class[]{
HttpServletRequest.class}, new InvocationHandler() {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
//增强getParameter()方法，其它方法还是调用被代理者原本的方法
if (method.getName().equals("getParameter")) {
//要增强getParameter()方法，其实就是将请求参数值中的非法字符替换成*
//1. 获取请求参数值
String value = (String) method.invoke(request, args);
//2. 判断请求参数值中是否包含非法字符
for (String str : strList) {
if (value.contains(str)) {
//2.1 包含非法字符，就要将value中的非法字符替换成*
String start = "";
for (int i=0;i<str.length();i++){
start += "*";
}
value = value.replace(str,start);
}
}
return value;
}
//不用增强的方法，要调用被代理者原本的方法
return method.invoke(request,args);
}
});
//最后肯定要放行
chain.doFilter(requestProxy, resp);
}
@Override
public void init(FilterConfig config) throws ServletException {
//读取IllegalWords.txt里面的数据
//1. 将IllegalWords.txt转换成字节输入流
InputStream is = IllegalCharFilter.class.getClassLoader().getResourceAsStream("IllegalWords.txt");
//2. 将字节输入流，包装成BufferReader
try {
BufferedReader bfr = new BufferedReader(new InputStreamReader(is,"UTF-8"));
String str = null;
while (( str = bfr.readLine()) != null) {
//每读到一个字符串，就将它存储到strList中
strList.add(str);
}
} catch (Exception e) {
e.printStackTrace();
}finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
3.servlet
@WebServlet("/comment")
public class CommentServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String content = request.getParameter("content");
response.getWriter().write("评论成功,评论内容为:"+content);
}
}