Struts2工具类[实现获取Request/Response/Session与绕过jsp/freemaker直接输出文本的简化函数]

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 package org.eline.web.struts2;

 import java.io.IOException;
 import java.util.Map;

 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;

 import net.sf.json.JSONObject;

 import org.apache.commons.lang.StringUtils;
 import org.apache.struts2.ServletActionContext;
 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();
     }

     // 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:",见示例代码.
      *            不设置时默认值分别为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.
      *
      * @see #render(String, String, String...)
      */
     public static void renderText(final String text, final String... headers)
     {
         render("text/plain", text, headers);
     }

     /**
      * 直接输出HTML.
      *
      * @see #render(String, String, String...)
      */
     public static void renderHtml(final String html, final String... headers)
     {
         render("text/html", html, headers);
     }

     /**
      * 直接输出XML.
      *
      * @see #render(String, String, String...)
      */
     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.
      * @see #render(String, String, String...)
      */
     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.
      * @see #render(String, String, String...)
      */
     @SuppressWarnings("unchecked")
     public static void renderJson(final Map map, final String... headers)
     {
         String jsonString = new JSONObject().toString();
         renderJson(jsonString, headers);
     }

     /**
      * 直接输出JSON.???
      *
      * @param object
      *            Java对象,将被转化为json字符串.
      * @see #render(String, String, String...)
      */
     public static void renderJson(final Object object, final String... headers)
     {
         String jsonString = new JSONObject().toString();
         renderJson(jsonString, headers);
     }
 }