import java.io.IOException;  import java.util.Map;    import javax.servlet.http.HttpServletRequest;  import javax.servlet.http.HttpServletResponse;  import javax.servlet.http.HttpSession;    import org.apache.commons.lang.StringUtils;  import org.apache.struts2.ServletActionContext;  import org.json.JSONObject;  import org.slf4j.Logger;  import org.slf4j.LoggerFactory;    /**   * Struts2 Utils类.   *    * 实现获取Request/Response/Session与绕过jsp/freemaker直接输出文本的简化函数.   *    */  public class Struts2Utils {            //header 常量定义          private static final String ENCODING_PREFIX = "encoding:";          private static final String NOCACHE_PREFIX = "no-cache:";          private static final String ENCODING_DEFAULT = "UTF-8";          private static final boolean NOCACHE_DEFAULT = true;            private static Logger logger = LoggerFactory.getLogger(Struts2Utils.class);            private Struts2Utils() {          }            // 取得Request/Response/Session的简化函数 //            /**           * 取得HttpSession的简化方法.           */          public static HttpSession getSession() {                  return ServletActionContext.getRequest().getSession();          }            /**           * 取得HttpRequest的简化方法.           */          public static HttpServletRequest getRequest() {                  return ServletActionContext.getRequest();          }            /**           * 取得HttpResponse的简化方法.           */          public static HttpServletResponse getResponse() {                  return ServletActionContext.getResponse();          }            /**           * 取得Request Parameter的简化方法.           */          public static String getParameter(String name) {                  return getRequest().getParameter(name);          }            // 绕过jsp/freemaker直接输出文本的函数 //            /**           * 直接输出内容的简便函数.                       * eg.           * render("text/plain", "hello", "encoding:GBK");           * render("text/plain", "hello", "no-cache:false");           * render("text/plain", "hello", "encoding:GBK", "no-cache:false");           *            * @param headers 可变的header数组，目前接受的值为"encoding:"或"no-cache:",默认值分别为UTF-8和true.                            */          public static void render(final String contentType, final String content, final String... headers) {                  try {                          //分析headers参数                          String encoding = ENCODING_DEFAULT;                          boolean noCache = NOCACHE_DEFAULT;                          for (String header : headers) {                                  String headerName = StringUtils.substringBefore(header, ":");                                  String headerValue = StringUtils.substringAfter(header, ":");                                    if (StringUtils.equalsIgnoreCase(headerName, ENCODING_PREFIX)) {                                          encoding = headerValue;                                  } else if (StringUtils.equalsIgnoreCase(headerName, NOCACHE_PREFIX)) {                                          noCache = Boolean.parseBoolean(headerValue);                                  } else                                          throw new IllegalArgumentException(headerName + "不是一个合法的header类型");                          }                            HttpServletResponse response = ServletActionContext.getResponse();                            //设置headers参数                          String fullContentType = contentType + ";charset=" + encoding;                          response.setContentType(fullContentType);                          if (noCache) {                                  response.setHeader("Pragma", "No-cache");                                  response.setHeader("Cache-Control", "no-cache");                                  response.setDateHeader("Expires", 0);                          }                            response.getWriter().write(content);                    } catch (IOException e) {                          logger.error(e.getMessage(), e);                  }          }            /**           * 直接输出文本.           */          public static void renderText(final String text, final String... headers) {                  render("text/plain", text, headers);          }            /**           * 直接输出HTML.           */          public static void renderHtml(final String html, final String... headers) {                  render("text/html", html, headers);          }            /**           * 直接输出XML.           */          public static void renderXml(final String xml, final String... headers) {                  render("text/xml", xml, headers);          }            /**           * 直接输出JSON.           *            * @param string json字符串.           */          public static void renderJson(final String string, final String... headers) {                  render("application/json", string, headers);          }            /**           * 直接输出JSON.           *            * @param map Map对象,将被转化为json字符串.           */          @SuppressWarnings("unchecked")          public static void renderJson(final Map map, final String... headers) {                  String jsonString = new JSONObject(map).toString();                  renderJson(jsonString, headers);          }            /**           * 直接输出JSON.           *            * @param object Java对象,将被转化为json字符串.           */          public static void renderJson(final Object object, final String... headers) {                  String jsonString = new JSONObject(object).toString();                  renderJson(jsonString, headers);          }  }