## 3.2 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 ```java package org.beetl.ext.web; import java.io.IOException; import java.io.OutputStream; import java.io.Writer; import java.util.Enumeration; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.beetl.core.GroupTemplate; import org.beetl.core.Template; import org.beetl.core.exception.BeetlException; /** * 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 * 其他框架可以继承此类做更多的定制 * @author joelli * */ public class WebRender{ GroupTemplate gt = null; public WebRender(GroupTemplate gt){ this.gt = gt; } /** * @param key 模板资源id * @param request * @param response * @param args 其他参数，将会传给modifyTemplate方法 */ public void render(String key, HttpServletRequest request, HttpServletResponse response, Object... args){ Writer writer = null; OutputStream os = null; try{ //response.setContentType(contentType); Template template = gt.getTemplate(key); Enumeration<String> attrs = request.getAttributeNames(); while (attrs.hasMoreElements()){ String attrName = attrs.nextElement(); template.binding(attrName, request.getAttribute(attrName)); } WebVariable webVariable = new WebVariable(); webVariable.setRequest(request); webVariable.setResponse(response); webVariable.setSession(request.getSession()); template.binding("session", new SessionWrapper(webVariable.getSession())); template.binding("servlet", webVariable); template.binding("request", request); template.binding("ctxPath", request.getContextPath()); modifyTemplate(template, key, request, response, args); String strWebAppExt = gt.getConf().getWebAppExt(); if(strWebAppExt!=null){ WebRenderExt renderExt = this.getWebRenderExt(strWebAppExt); renderExt.modify(template, gt, request, response); } if (gt.getConf().isDirectByteOutput()){ os = response.getOutputStream(); template.renderTo(os); }else{ writer = response.getWriter(); template.renderTo(writer); } } catch (IOException e){ handleClientError(e); } catch (BeetlException e){ handleBeetlException(e); } finally{ try{ if (writer != null) writer.flush(); if (os != null) os.flush(); } catch (IOException e){ handleClientError(e); } } } /** * 可以添加更多的绑定 * @param template 模板 * @param key 模板的资源id * @param request * @param response * @param args 调用render的时候传的参数 */ protected void modifyTemplate(Template template, String key, HttpServletRequest request, HttpServletResponse response, Object... args){ } /**处理客户端抛出的IO异常 * @param ex */ protected void handleClientError(IOException ex){ //do nothing } /**处理客户端抛出的IO异常 * @param ex */ protected void handleBeetlException(BeetlException ex){ throw ex; } } ```