SpringMVC 中无缓存的BasicController的设计

最新推荐文章于 2021-08-22 11:39:05 发布

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最新推荐文章于 2021-08-22 11:39:05 发布

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分类专栏： SpringMVC框架

本文链接：https://blog.youkuaiyun.com/chenpeng19910926/article/details/51198130

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BaseController是一个基础控制器，用于无缓存响应处理。它包含各种方法如输出文本、HTML、XML和JSON内容，同时也支持设置下载文件头和禁止缓存的HTTP头。方法initResponseHeader分析并设置contentType与headers，setNoCacheHeader则用于确保客户端不缓存响应。

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public class BaseController {

   // header 常量定义
   private static final String DEFAULT_ENCODING = "UTF-8";
   private static final boolean DEFAULT_NOCACHE = true;
   // Content Type 常量定义
   public static final String TEXT_TYPE = "text/plain";
   public static final String JSON_TYPE = "application/json";
   public static final String XML_TYPE = "text/xml";
   public static final String HTML_TYPE = "text/html";
   public static final String JS_TYPE = "text/javascript";
   public static final String EXCEL_TYPE = "application/vnd.ms-excel";
   public static int PAGE_NUMERIC = 20;



   /**
   * 直接输出内容的简便函数.
   */
   protected void render(final String contentType, final String content,
           final HttpServletResponse response) {
       HttpServletResponse resp = initResponseHeader(contentType, response);
       try {
           resp.getWriter().write(content);
           resp.getWriter().flush();
       } catch (Exception e) {
           e.printStackTrace();
       }
   }

   /**
   * 直接输出文本.
   */
   protected void outText(final String text, final HttpServletResponse response) {
       render(TEXT_TYPE, text, response);
   }

   /**
   * 直接输出HTML.
   */
   protected void outHtml(final String html, final HttpServletResponse response) {
       render(HTML_TYPE, html, response);
   }

   /**
   * 直接输出XML.
   */
   protected void outXml(final String xml, final HttpServletResponse response) {
       render(XML_TYPE, xml, response);
   }

   /**
   * 输出JSON,可以接收参数如： [{'name':'www'},{'name':'www'}],['a','b'],new
   * String[]{'a','b'},合并如下：jsonString = "{TOTALCOUNT:" + totalCount + ",
   * ROOT:" + jsonString + "}";
   *
   * @param jsonString
   *            json字符串.
   *
   */
   protected void outJson(final String json, final HttpServletResponse response) {
       render(JSON_TYPE, json, response);
   }

   /**
   * 设置让浏览器弹出下载对话框的Header.
   *
   * @param fileName
   *            下载后的文件名.
   */
   protected void setFileDownloadHeader(HttpServletResponse response,
           String fileName) {
       try {
           // 中文文件名支持
           String encodedfileName = new String(fileName.getBytes(),
                   "ISO8859-1");
           response.setHeader("Content-Disposition", "attachment; filename=\""
                   + encodedfileName + "\"");
       } catch (Exception e) {
           e.printStackTrace();
       }
   }

   /**
   * 分析并设置contentType与headers.
   */
   protected HttpServletResponse initResponseHeader(final String contentType,
           final HttpServletResponse response) {
       // 分析headers参数
       String encoding = DEFAULT_ENCODING;
       boolean noCache = DEFAULT_NOCACHE;
       // 设置headers参数
       String fullContentType = contentType + ";charset=" + encoding;
       response.setContentType(fullContentType);
       if (noCache) {
           setNoCacheHeader(response);
       }

       return response;
   }

   /**
   * 设置客户端无缓存Header.
   */
   protected void setNoCacheHeader(HttpServletResponse response) {
       // Http 1.0 header
       response.setDateHeader("Expires", 0);
       response.addHeader("Pragma", "no-cache");
       // Http 1.1 header
       response.setHeader("Cache-Control", "no-cache");
   }
}