集成技术开发指南

Beetl默认提供了WebRender用于帮助web集成开发，所有内置的集成均基于此方法。如果你认为Beetl内置的各个web框架集成功能不够，你可以继承此类，或者参考此类源码重新写，其代码如下

  1. package org.beetl.ext.web;
  3. import java.io.IOException;
  4. import java.io.OutputStream;
  5. import java.io.Writer;
  6. import java.util.Enumeration;
  8. import javax.servlet.http.HttpServletRequest;
  9. import javax.servlet.http.HttpServletResponse;
  11. import org.beetl.core.GroupTemplate;
  12. import org.beetl.core.Template;
  13. import org.beetl.core.exception.BeetlException;
  15. /**
  16.  *  通常web渲染的类，将request变量赋值给模板，同时赋值的还有session,request,ctxPath
  17.  *  其他框架可以继承此类做更多的定制
  18.  * @author joelli
  19.  *
  20.  */
  21. public class WebRender{
  22.         GroupTemplate gt = null;
  24.         public WebRender(GroupTemplate gt){
  25.                 this.gt = gt;
  26.         }
  28.         /**
  29.          * @param key 模板资源id
  30.          * @param request
  31.          * @param response
  32.          * @param args 其他参数，将会传给modifyTemplate方法
  33.          */
  34.         public void render(String key, HttpServletRequest request, HttpServletResponse response, Object... args){
  35.                 Writer writer = null;
  36.                 OutputStream os = null;
  37.                 try{
  38.                         //response.setContentType(contentType);
  39.                         Template template = gt.getTemplate(key);
  40.                         Enumeration<String> attrs = request.getAttributeNames();
  42.                         while (attrs.hasMoreElements()){
  43.                                 String attrName = attrs.nextElement();
  44.                                 template.binding(attrName, request.getAttribute(attrName));
  45.                         }
  46.                         WebVariable webVariable = new WebVariable();
  47.                         webVariable.setRequest(request);
  48.                         webVariable.setResponse(response);
  49.                         webVariable.setSession(request.getSession());
  51.                         template.binding("session", new SessionWrapper(webVariable.getSession()));
  53.                         template.binding("servlet", webVariable);
  54.                         template.binding("request", request);
  55.                         template.binding("ctxPath", request.getContextPath());
  57.                         modifyTemplate(template, key, request, response, args);
  59.                         String strWebAppExt = gt.getConf().getWebAppExt();
  60.                         if(strWebAppExt!=null){
  61.                                 WebRenderExt renderExt = this.getWebRenderExt(strWebAppExt);
  62.                                 renderExt.modify(template, gt, request, response);
  63.                         }
  64.                         if (gt.getConf().isDirectByteOutput()){
  65.                                 os = response.getOutputStream();
  66.                                 template.renderTo(os);
  67.                         }else{
  68.                                 writer = response.getWriter();
  69.                                 template.renderTo(writer);
  70.                         }
  72.                 } catch (IOException e){
  73.                         handleClientError(e);
  74.                 } catch (BeetlException e){
  75.                         handleBeetlException(e);
  76.                 } finally{
  77.                         try{
  78.                                 if (writer != null)
  79.                                         writer.flush();
  80.                                 if (os != null)
  81.                                         os.flush();
  82.                         } catch (IOException e){
  83.                                 handleClientError(e);
  84.                         }
  85.                 }
  86.         }
  88.         /**
  89.          * 可以添加更多的绑定
  90.          * @param template 模板
  91.          * @param key 模板的资源id
  92.          * @param request
  93.          * @param response
  94.          * @param args  调用render的时候传的参数
  95.          */
  96.         protected void modifyTemplate(Template template, String key, HttpServletRequest request,
  97.                 HttpServletResponse response, Object... args){
  98.         }
  100.         /**处理客户端抛出的IO异常
  101.          * @param ex
  102.          */
  103.         protected void handleClientError(IOException ex){
  104.                 //do nothing
  105.         }
  107.         /**处理客户端抛出的IO异常
  108.          * @param ex
  109.          */
  110.         protected void handleBeetlException(BeetlException ex){
  111.                 throw ex;
  112.         }
  113. }