struts文件上传例子

package com.upload.struts.filter; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; public class SetCharacterEncodingFilter implements Filter { /** * Logger for this class */ // ----------------------------------------------------- Instance Variables /** * The default character encoding to set for requests that pass through this * filter. */ protected String encoding = "UTF-8"; /** * The filter configuration object we are associated with. If this value is * null, this filter instance is not currently configured. */ protected FilterConfig filterConfig = null; /** * Should a character encoding specified by the client be ignored? */ protected boolean ignore = true; // --------------------------------------------------------- Public Methods /** * Take this filter out of service. */ public void destroy() { this.encoding = null; this.filterConfig = null; } /** * Select and set (if specified) the character encoding to be used to * interpret request parameters for this request. * * @param request * The servlet request we are processing * @param response * The servlet response we are creating * @param chain * The filter chain we are processing * @throws IOException * if an input/output error occurs * @throws ServletException * if a servlet error occurs */ public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { try { // Conditionally select and set the character encoding to be used if (ignore || (request.getCharacterEncoding() == null)) { String encoding = selectEncoding(request); if (encoding != null) request.setCharacterEncoding(encoding); } // Pass control on to the next filter chain.doFilter(request, response); } catch (IOException e) { throw e; } catch (ServletException e) { throw e; } } /** * Place this filter into service. * * @param filterConfig * The filter configuration object */ public void init(FilterConfig filterConfig) throws ServletException { this.filterConfig = filterConfig; this.encoding = filterConfig.getInitParameter("encoding"); String value = filterConfig.getInitParameter("ignore"); if (value == null) this.ignore = true; else if (value.equalsIgnoreCase("true")) this.ignore = true; else if (value.equalsIgnoreCase("yes")) this.ignore = true; else this.ignore = false; } // ------------------------------------------------------ Protected Methods /** * Select an appropriate character encoding to be used, based on the * characteristics of the current request and/or filter initialization * parameters. If no character encoding should be set, return * <code>null</code>. <p/> The default implementation unconditionally * returns the value configured by the <strong>encoding</strong> * initialization parameter for this filter. * * @param request * The servlet request we are processing */ protected String selectEncoding(ServletRequest request) { return (this.encoding); } }