之前已经讲过get或者post方法的中文乱码问题，之前都是在每个方法中编写设置编码。如果程序变大，就会很繁琐，使用filter可以避免这种繁琐。
1）写一个encodingFilter进行编码设置
public class encodingFilter implements Filter { @Override public void doFilter(ServletRequest req, ServletResponse res, FilterChain arg2) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); arg2.doFilter(new encodingRequestServlet(request), response); } @Override public void init(FilterConfig arg0) throws ServletException { // TODO Auto-generated method stub } @Override public void destroy() { // TODO Auto-generated method stub } }
2）在该方法中使用了一个继承自 HttpServletRequestWrapper 的类，该类可以覆盖HttpServletRequest 类中的方法
我们只需要重写 getParameter 方法即可。
public class encodingRequestServlet extends HttpServletRequestWrapper { private HttpServletRequest request; public encodingRequestServlet(HttpServletRequest request) { super(request); this.request = request; } @Override public String getParameter(String name) { String value = super.getParameter(name); if(value == null) return value; String method = request.getMethod(); if("get".equalsIgnoreCase(method)){ try { value = new String(value.getBytes("ISO8859-1"),"utf-8"); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } } return value; } }
原文：http://www.cnblogs.com/zhaopengcheng/p/6689443.html