javajohn — Tue, 06 Jun 2006 01:01:00 GMT

Dwr 通过用户配置文�g dwr.xml ��?/span> java �c�L��成一�?/span> javascript 对象�Q�从实现手法上看�?/span> java 里的数据映射很相伹{��?/span> dwr 是将 JAVA 的对象映��到�?/span> js 里，由客��L(f��ng)��?/span> JS 提供�l�用户各�c�d��玎ͼ��?/span> java 代码完全在后台运行�?/span>

DWR 函数调用里涉及到�?/span> JS 代码�Q?/span> engine.js

DWR 函数调用里涉及到的类有：(x��) AbstractDWRServlet �?/span> DefaultProcessor

用户在提�?/span> request 以后的操作步骤请参见�?/span> blog 里的�Q��?/span> dwr 源码学习(f��n)�Q�一�Q�》， JAVA 代码生成的映��?/span> JS 代码其实只是一�?/span> javascript 接口�Q�它调用�?/span> DWREngine._execute �q�个函数�Q�而这个函数大体只是执行了一些解析的工作�Q�在它结��֤�调用�?/span> DWREngine.endBatch() �Q�然后又执行�?/span> DWREngine._sendData(batch) �Q�这时我们会(x��)发现有这样一句：(x��) �?/span> batch.req.open("GET", batch.path + "/exec/" + statsInfo + "?" + query, batch.async); ”很熟�?zh��n)�吧�?/span>

下一步就��C��真正的实�?/span> js 调用 java 代码里方法的时候了�Q�兴奋吧。其实实��C��是很��单的。通过 servlet �q�里实现了对各类�?/span> request 参数的不同的匚w��Q�还是看 AbstractDWRServlet .getPost() �q�个�Ҏ(gu��)��Q?br />

1     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException
2     {
3         try
4         {
5             builder.set(req, resp, getServletConfig(), getServletContext(), container);
6             ServletLoggingOutput.setExecutionContext(this);
7
8             processor.handle(req, resp);
9         }
10         finally
11         {
12             builder.unset();
13             ServletLoggingOutput.unsetExecutionContext();
14         }
15 }
16 注意processor.handle(req, resp);
17     public void handle(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException
18     {
19         String pathInfo = req.getPathInfo();
20         String servletPath = req.getServletPath();
21
22         if (nullPathInfoWorkaround && pathInfo == null)
23         {
24             pathInfo = req.getServletPath();
25             servletPath = HtmlConstants.PATH_ROOT;
26             log.debug("Default servlet suspected. pathInfo=" + pathInfo + "; contextPath=" + req.getContextPath() + "; servletPath=" + servletPath); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
27         }
28
29         if (pathInfo == null ||
30             pathInfo.length() == 0 ||
31             pathInfo.equals(HtmlConstants.PATH_ROOT))
32         {
33             resp.sendRedirect(req.getContextPath() + servletPath + HtmlConstants.FILE_INDEX);
34         }
35         else if (pathInfo.startsWith(HtmlConstants.FILE_INDEX))
36         {
37             index.handle(req, resp);
38         }
39         else if (pathInfo.startsWith(HtmlConstants.PATH_TEST))
40         {
41             test.handle(req, resp);
42         }
43         else if (pathInfo.startsWith(HtmlConstants.PATH_INTERFACE))
44         {
45             iface.handle(req, resp);
46         }
47         else if (pathInfo.startsWith(HtmlConstants.PATH_EXEC))
48         {
49             exec.handle(req, resp);
50         }
51         else if (pathInfo.equalsIgnoreCase(HtmlConstants.FILE_ENGINE))
52         {
53             file.doFile(req, resp, HtmlConstants.FILE_ENGINE, HtmlConstants.MIME_JS);
54         }
55         else if (pathInfo.equalsIgnoreCase(HtmlConstants.FILE_UTIL))
56         {
57             file.doFile(req, resp, HtmlConstants.FILE_UTIL, HtmlConstants.MIME_JS);
58         }
59         else if (pathInfo.equalsIgnoreCase(HtmlConstants.FILE_DEPRECATED))
60         {
61             file.doFile(req, resp, HtmlConstants.FILE_DEPRECATED, HtmlConstants.MIME_JS);
62         }
63         else
64         {
65             log.warn("Page not found (" + pathInfo + "). In debug/test mode try viewing /[WEB-APP]/dwr/"); //$NON-NLS-1$ //$NON-NLS-2$
66             resp.sendError(HttpServletResponse.SC_NOT_FOUND);
67         }
68     }
69

也就只有�q�几�U�类型的��h��Q�还记得 DWREngine._sendData 吗？里面有这么一句：(x��)�?/span> batch.req.open("GET", batch.path + "/exec/" + statsInfo + "?" + query, batch.async); ”看��C��的请求�\径是 exec �Q�对应在 processor.handle(req, resp); �q�个�Ҏ(gu��)��里就�?/span> exec �Q�在刚才�?/span> JAVA 代码里我们已�l�看到过了是括号内的代码�Q?/span> else if (pathInfo.startsWith(HtmlConstants. PATH_EXEC )) �Q�，�?/span> exec 早已�?/span> servlet 初始化的时候就已经讄��?/span> DefaultExecProcessor �Q�它的函�?/span> hadle() ��是具体�?/span> js 调用 java �c�L��法的实现了�?/span>

DWR 是一个小型的 AJAX 框架�Q�它的实现思�\��单，其实有很多�h在开发中一定也有过�c�M��的想法。它之所以现在才出现我想大概�q�是要归功于异步 javascript 消息发送这��L(f��ng)��技术成为现实。所以我又想 AJAX �Q�从技术上说只能是 javascript 有了一个飞跃性的�q�步�Q��?/span> AJAX 的最�l�成功却要靠软�g工程�?/span>

javajohn 2006-06-06 09:01 发表评论

javajohn — Sat, 27 May 2006 11:23:00 GMT

摘要: DWR一个外国�h实现的很有前途的AJAX框架。多余的话就不说了，��L(f��ng)��DWR的例子程序：(x��)web.xml 1 2阅读全文

javajohn 2006-05-27 19:23 发表评论

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