1 package example;
2
3 import java.io;
4 import java.util;
5 import java.lang.reflect;
6 import javax.servlet;
7 import javax.servlet.http;
8 import freemarker.template;
9
10 /**
11 * <p>This is very very primitive MVC Controller servlet base class, based
12 * on example 1. The application specific controller servlet should extend
13 * this class.
14 */
15 public class ControllerServlet extends HttpServlet {
16 private Configuration cfg;
17
18 public void init() {
19 // Initialize the FreeMarker configuration;
20 // - Create a configuration instance
21 cfg = new Configuration();
22 // - Templates are stoted in the WEB-INF/templates directory of the Web app.
23 cfg.setServletContextForTemplateLoading(
24 getServletContext(), "WEB-INF/templates");
25 // - Set update dealy to 0 for now, to ease debugging and testing.
26 // Higher value should be used in production environment.
27 cfg.setTemplateUpdateDelay(0);
28 // - Set an error handler that prints errors so they are readable with
29 // a HTML browser.
30 cfg.setTemplateExceptionHandler(
31 TemplateExceptionHandler.HTML_DEBUG_HANDLER);
32 // - Use beans wrapper (recommmended for most applications)
33 cfg.setObjectWrapper(ObjectWrapper.BEANS_WRAPPER);
34 // - Set the default charset of the template files
35 cfg.setDefaultEncoding("ISO-8859-1");
36 // - Set the charset of the output. This is actually just a hint, that
37 // templates may require for URL encoding and for generating META element
38 // that uses http-equiv="Content-type".
39 cfg.setOutputEncoding("UTF-8");
40 // - Set the default locale
41 cfg.setLocale(Locale.US);
42 }
43
44 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
45 throws ServletException, IOException {
46 doGet(req, resp);
47 }
48
49 protected void doGet(HttpServletRequest req, HttpServletResponse resp)
50 throws ServletException, IOException {
51
52 // Choose action method
53 String action = req.getServletPath();
54 if (action == null) action = "index";
55 if (action.startsWith("/")) action = action.substring(1);
56 if (action.lastIndexOf(".") != -1) {
57 action = action.substring(0, action.lastIndexOf("."));
58 }
59 Method actionMethod;
60 try {
61 actionMethod =
62 getClass().getMethod(action + "Action",
63 new Class[]{HttpServletRequest.class, Page.class});
64 } catch (NoSuchMethodException e) {
65 throw new ServletException("Unknown action: " + action);
66 }
67
68 // Set the request charset to the same as the output charset,
69 // because HTML forms normally send parameters encoded with that.
70 req.setCharacterEncoding(cfg.getOutputEncoding());
71
72 // Call the action method
73 Page page = new Page();
74 try {
75 actionMethod.invoke(this, new Object[]{req, page});
76 } catch (IllegalAccessException e) {
77 throw new ServletException(e);
78 } catch (InvocationTargetException e) {
79 throw new ServletException(e.getTargetException());
80 }
81
82 if (page.getTemplate() != null) { // show a page with a template
83 // Get the template object
84 Template t = cfg.getTemplate(page.getTemplate());
85
86 // Prepare the HTTP response:
87 // - Set the MIME-type and the charset of the output.
88 // Note that the charset should be in sync with the output_encoding setting.
89 resp.setContentType("text/html; charset=" + cfg.getOutputEncoding());
90 // - Prevent browser or proxy caching the page.
91 // Note that you should use it only for development and for interactive
92 // pages, as it significantly slows down the Web site.
93 resp.setHeader("Cache-Control", "no-store, no-cache, must-revalidate, "
94 + "post-check=0, pre-check=0");
95 resp.setHeader("Pragma", "no-cache");
96 resp.setHeader("Expires", "Thu, 01 Dec 1994 00:00:00 GMT");
97 Writer out = resp.getWriter();
98
99 // Merge the data-model and the template
100 try {
101 t.process(page.getRoot(), out);
102 } catch (TemplateException e) {
103 throw new ServletException(
104 "Error while processing FreeMarker template", e);
105 }
106 } else if (page.getForward() != null) { // forward request
107 RequestDispatcher rd = req.getRequestDispatcher(page.getForward());
108 rd.forward(req, resp);
109 } else {
110 throw new ServletException("The action didn't specified a command.");
111 }
112 }
113 }
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