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servlet与freeMark组合

ServletfreemarkerHTMLWebCache 
阅读更多

控制器由servlet实现，页由freeMark完成。

第一个例子：

test.ftl如下：

<html>
<head>
  <title>FreeMarker Example Web Application 1</title>
</head>
<body>
  ${message}
</body>
</html>

 servlet如下：

public class HelloServlet extends HttpServlet {
	private Configuration cfg;

	public void init() {
		cfg = new Configuration();
		cfg.setServletContextForTemplateLoading(getServletContext(),
				"templates");
	}

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		Map root = new HashMap();
		root.put("message", "Hello World!");
		Template t = cfg.getTemplate("test.ftl");
		System.out.println(t.getEncoding());//GBK编码
		response.setContentType("text/html; charset=" + t.getEncoding());
		Writer out = response.getWriter();
		try {
			t.process(root, out);
		} catch (TemplateException e) {
			throw new ServletException(
					"Error while processing FreeMarker template", e);
		}
	}
}

 

web.xml配置如下：

<servlet>
		<servlet-name>hello</servlet-name>
		<servlet-class>com.mengya.servlet.HelloServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello</url-pattern>
	</servlet-mapping>

 测试：

<body>
  		<a href="hello">FreeMark测试</a>
	</body>

 

第二个例子：(get,set方法省掉，辅助类)

public class Page {
    private String template;
    private String forward;
    private Map root = new HashMap();
}

共同的servlet如下：

public class ControllerServlet extends HttpServlet {
	private Configuration cfg;

	public void init() {
		cfg = new Configuration();
		//设置ftl文件加载的路径
		cfg.setServletContextForTemplateLoading(getServletContext(),
				"templates");
		//设置freeMark更新缓存的时间//0表示不用缓存
		cfg.setTemplateUpdateDelay(0);
		cfg.setTemplateExceptionHandler(TemplateExceptionHandler.HTML_DEBUG_HANDLER);
		//设置freeMark的包裹策略
		cfg.setObjectWrapper(ObjectWrapper.BEANS_WRAPPER);
		cfg.setDefaultEncoding("ISO-8859-1");
		cfg.setOutputEncoding("UTF-8");
		cfg.setLocale(Locale.US);
	}

	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		doGet(req, resp);
	}

	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		//URL：http://127.0.0.1:8080/FreeMarkStudy/templates/index.a
		//request.getServletPath：/templates/index.a
		String action = req.getServletPath();
		if (action == null)
			action = "index";
		if (action.startsWith("/"))
			//action = action.substring(1);
			action = action.substring(action.lastIndexOf("/")+1);//获得index
		if (action.lastIndexOf(".") != -1) {
			action = action.substring(0, action.lastIndexOf("."));
		}
		Method actionMethod;
		try {
			actionMethod = getClass().getMethod(action + "Action",
					new Class[] { HttpServletRequest.class, Page.class });
		} catch (NoSuchMethodException e) {
			throw new ServletException("Unknown action: " + action);
		}
		req.setCharacterEncoding(cfg.getOutputEncoding());
		Page page = new Page();
		try {
			actionMethod.invoke(this, new Object[] { req, page });
		} catch (IllegalAccessException e) {
			throw new ServletException(e);
		} catch (InvocationTargetException e) {
			throw new ServletException(e.getTargetException());
		}

		if (page.getTemplate() != null) {
			Template t = cfg.getTemplate(page.getTemplate());

			resp.setContentType("text/html; charset=" + cfg.getOutputEncoding());
			resp.setHeader("Cache-Control",
					"no-store, no-cache, must-revalidate, "
							+ "post-check=0, pre-check=0");
			resp.setHeader("Pragma", "no-cache");
			resp.setHeader("Expires", "Thu, 01 Dec 1994 00:00:00 GMT");
			Writer out = resp.getWriter();
			try {
				t.process(page.getRoot(), out);
			} catch (TemplateException e) {
				throw new ServletException(
						"Error while processing FreeMarker template", e);
			}
		} else if (page.getForward() != null) {
			RequestDispatcher rd = req.getRequestDispatcher(page.getForward());
			rd.forward(req, resp);
		} else {
			throw new ServletException("The action didn't specified a command.");
		}
	}
}

 实体Bean如下：(get,set方法省掉)

public class GuestbookEntry {
    private String name;
    private String email;
    private String message;
}

 servlet如下：

public class GuestbookServlet extends ControllerServlet {
	
    private ArrayList guestbook = new ArrayList();
    
    public void indexAction(HttpServletRequest req, Page p) {
        List snapShot;
        synchronized (guestbook) {
            snapShot = (List) guestbook.clone();
        }
        p.put("guestbook", snapShot);
        p.setTemplate("index.ftl");
    }

    public void formAction (HttpServletRequest req, Page p)
            throws IOException, ServletException {
        p.put("name", noNull(req.getParameter("name")));
        p.put("email", noNull(req.getParameter("email")));
        p.put("message", noNull(req.getParameter("message")));
        List errors = (List) req.getAttribute("errors");
        p.put("errors", errors == null ? new ArrayList() : errors);
        p.setTemplate("form.ftl");
    }

    public void addAction (HttpServletRequest req, Page p)
            throws IOException, ServletException {
        List errors = new ArrayList();
        String name = req.getParameter("name");
        String email = req.getParameter("email");
        String message = req.getParameter("message");
        if (isBlank(name)) {
            errors.add("You must give your name.");
        }
        if (isBlank(message)) {
            errors.add("You must give a message.");
        }
        if (errors.isEmpty()) {
            if (email == null) email = "";
            GuestbookEntry e = new GuestbookEntry(name.trim(), email.trim(), message);
            synchronized (guestbook) {
                guestbook.add(0, e);
            }
            p.put("entry", e);
            p.setTemplate("add.ftl");
        } else {
            req.setAttribute("errors", errors);
            p.setForward("form.a");
        }
    }

    public static String noNull(String s) {
        return s == null ? "" : s;
    }
    
    public static boolean isBlank(String s) {
        return s == null || s.trim().length() == 0; 
    }
}

 

web.xml配置如下：

<servlet>
		<servlet-name>guestbook</servlet-name>
		<servlet-class>com.mengya.servlet.GuestbookServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>guestbook</servlet-name>
		<url-pattern>*.a</url-pattern>
	</servlet-mapping>

 共同的ftl如下：

<#macro page title>
  <html>
  <head>
    <title>FreeMarker Example Web Application 2 - ${title?html}</title>
    <meta http-equiv="Content-type" content="text/html; charset=${.output_encoding}">
  </head>
  <body>
    <h1>${title?html}</h1>
    <hr>
    	<#nested>
    <hr>
    <table border="0" cellspacing=0 cellpadding=0 width="100%">
      <tr valign="middle">
        <td align="left">
          <i>FreeMarker Example 2</i>
        </td>
        <td align="right">
          <a href="http://freemarker.org"><img src="poweredby_ffffff.png" border=0></a>
        </td>
      </tr> 
    </table>
  </body>
  </html>
</#macro>

 

页面ftl文件一：index.ftl（做list用）

 

<#import "/common/common.ftl" as com>
<#escape x as x?html>

<@com.page title="Index">
  <a href="form.a">Add new message</a> | <a href="help.html">How this works?</a>
  
  <#if guestbook?size = 0>
    <p>No messages.
  <#else>
    <p>The messages are:
    <table border=0 cellspacing=2 cellpadding=2 width="100%">
      <tr align=center valign=top>
        <th bgcolor="#C0C0C0">Name</th>
        <th bgcolor="#C0C0C0">Message</td>
      </tr>
      <#list guestbook as e>
        <tr align=left valign=top>
          <td bgcolor="#E0E0E0">${e.name} <#if e.email?length != 0> (<a href="mailto:${e.email}">${e.email}</a>)</#if></td>
          <td bgcolor="#E0E0E0">${e.message}</td>
        </tr>
      </#list>
    </table>
  </#if>
</@com.page>

 

add.ftl如下：

<#import "/common/common.ftl" as com>
<#escape x as x?html>

<@com.page title="Entry added">
  <p>You have added the following entry to the guestbook:
  <p><b>Name:</b> ${entry.name}
  <#if entry.email?length != 0>
    <p><b>Email:</b> ${entry.email}
  </#if>
  <p><b>Message:</b> ${entry.message}
  <p><a href="index.a">Back to the index page...</a>
</@com.page>

</#escape>

 

from.ftl如下：

<#import "/common/common.ftl" as com>
<#escape x as x?html>

<@com.page title="Add Entry">
  <#if errors?size != 0>
    <p><font color=red>Please correct the following problems:</font>
    <ul>
      <#list errors as e>
        <li><font color=red>${e}</font>
      </#list>
    </ul>
  </#if>
  
  <form method="POST" action="add.a">
    <p>Your name:<br>
    <input type="text" name="name" value="${name}" size=60>
    <p>Your e-mail (optional):<br>
    <input type="text" name="email" value="${email}" size=60>
    <p>Message:<br>
    <textarea name="message" wrap="soft" rows=3 cols=60>${message}</textarea>
    <p><input type="submit" value="Submit">
  </form>
  <p><a href="index.a">Back to the index page</a>
</@com.page>

 

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| JSON实例应用
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1 楼 help112 2012-06-11  
？第二个案例看不懂
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