Struts2工具類

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類.

實現獲取Request/Response/Session與繞過jsp/freemaker直接輸出文本的簡化函數.
*/
public class Struts2Utils {

 //header 常量定義
 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的簡化函數 //

 /**
  * 取得HttpSession的簡化方法.
  */
 public static HttpSession getSession() {
         return ServletActionContext.getRequest().getSession();
 }

 /**
  * 取得HttpRequest的簡化方法.
  */
 public static HttpServletRequest getRequest() {
         return ServletActionContext.getRequest();
 }

 /**
  * 取得HttpResponse的簡化方法.
  */
 public static HttpServletResponse getResponse() {
         return ServletActionContext.getResponse();
 }

 /**
  * 取得Request Parameter的簡化方法.
  */
 public static String getParameter(String name) {
         return getRequest().getParameter(name);
 }

 // 繞過jsp/freemaker直接輸出文本的函數 //

 /**
  * 直接輸出內容的簡便函數.

  * 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 可變的header數組，目前接受的值為"encoding:"或"no-cache:",默認值分別為UTF-8和true.                 
  */
 public static void render(final String contentType, final String content, final String... headers) {
         try {
                 //分析headers參數
                 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 + "不是一個合法的header類型");
                 }

                 HttpServletResponse response = ServletActionContext.getResponse();

                 //設置headers參數
                 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);
         }
 }

 /**
  * 直接輸出文本.
  */
 public static void renderText(final String text, final String... headers) {
         render("text/plain", text, headers);
 }

 /**
  * 直接輸出HTML.
  */
 public static void renderHtml(final String html, final String... headers) {
         render("text/html", html, headers);
 }

 /**
  * 直接輸出XML.
  */
 public static void renderXml(final String xml, final String... headers) {
         render("text/xml", xml, headers);
 }

 /**
  * 直接輸出JSON.
  * 
  * @param string json字符串.
  */
 public static void renderJson(final String string, final String... headers) {
         render("application/json", string, headers);
 }

 /**
  * 直接輸出JSON.
  * 
  * @param map Map對象,將被轉化為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);
 }

 /**
  * 直接輸出JSON.
  * 
  * @param object Java對象,將被轉化為json字符串.
  */
 public static void renderJson(final Object object, final String... headers) {
         String jsonString = new JSONObject(object).toString();
         renderJson(jsonString, headers);
 }

}</pre>