Web项目中使用Freemarker

89570691

2013-02-21

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FreeMarker是一款模板引擎：一种基于模板的、用来生成输出文本的通用工具。

Web项目中，有时用其作为视图层技术来生成响应的html，其实下载的freemarker压缩包中已经有很多例子介绍如何在项目中使用。如图，有jsp的、struts中使用的等等，很详细。

Web项目中使用Freemarker

下面还是就简单介绍一下如何使用，方便以后回忆：

准备：添加freemarker.jard到项目fmk

一、直接使用Freemarker模板替代jsp、html页面

1.web.xml配置

<!-- Freemarker模板servlect -->
  <servlet>
    <servlet-name>freemarker</servlet-name>
    <servlet-class>freemarker.ext.servlet.FreemarkerServlet</servlet-class>
    <init-param>
      <param-name>TemplatePath</param-name>
      <param-value>/</param-value>
    </init-param>
    <init-param>
      <param-name>NoCache</param-name>
      <param-value>true</param-value>
    </init-param>
    <init-param>
      <param-name>ContentType</param-name>
      <param-value>text/html</param-value>
    </init-param>
    <init-param>
      <param-name>template_update_delay</param-name>
      <param-value>0</param-value>
    </init-param>
    <init-param>
      <param-name>default_encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
      <param-name>locale</param-name>
      <param-value>en_US</param-value>
    </init-param>
    <init-param>
      <param-name>number_format</param-name>
      <param-value>0.##</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>freemarker</servlet-name>
    <url-pattern>*.ftl</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.ftl</welcome-file>
  </welcome-file-list>

2.freemarker的欢迎页index.ftl

<html>
	<head>
		<title>Freemarker练手</title>
	</head>
	<body>
		<#assign msg="你好，这是Freemarker发出的消息">
		<h1>Freemarker说：</h1>
		${msg}
	</body>
</html>

3.注意：

项目编码需要和web.xml中配置的freemarker编码一致，不然会出现乱码

4.访问：

下面就可以通过URL【http://localhost:8080/fmk/】来访问了

二、使用Servlet作为控制器

这里加入servlet作为控制器，给Freemarker模板传入数据。

1.新建servlet：SimpleMsgServlet.java

package com.kyj.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;

public class SimpleMsgServlet extends HttpServlet {
	private static Configuration cfg;

	@Override
	public void init() throws ServletException {
		if (cfg == null) {
			cfg = new Configuration();
			cfg.setServletContextForTemplateLoading(getServletContext(),"WEB-INF/template");
		}
	}

	@Override
	protected void service(HttpServletRequest req, HttpServletResponse res)throws ServletException, IOException {
		//传给模板用来存储数据的model
		Map<String, Object> model = new HashMap<String, Object>();
		//传给模板的list数据
		List<String> authors = Arrays.asList(new String[]{"James","Killer","King"});
		//传给模板的map数据
		Map<String, Object> viewLogs = new HashMap<String, Object>();
		viewLogs.put("ROOT", "2012-12-31 23:43:11");
		viewLogs.put("LOG_VIEWER", "2012-12-31 23:43:11");
		viewLogs.put("DATA_MANAGER", "2012-12-31 23:43:11");
		
		//添加到model中
		model.put("viewLogs", viewLogs);
		model.put("authors", authors);
		
		//加载模板输出
		Template t = cfg.getTemplate("SimpleMsg.ftl");
		res.setCharacterEncoding("UTF-8");
		t.setEncoding("UTF-8");
		PrintWriter out = res.getWriter();
		try {
			t.process(model, out);
		} catch (TemplateException e) {
			e.printStackTrace();
		}
	}
}

<servlet>
	<servlet-name>simpleMsg</servlet-name>
	<servlet-class>com.kyj.servlet.SimpleMsgServlet</servlet-class>
</servlet>
<servlet-mapping>
	<servlet-name>simpleMsg</servlet-name>
	<url-pattern>/simpleMsg</url-pattern>
</servlet-mapping>

2.WEB-INF/template下新建模板文件：SimpleMsg.ftl

<#ftl encoding="UTF-8">
<html>
	<head>
		<title>Freemarker简单Servlet消息</title>
	</head>
	<body>
		<h1>下面是Servlet传过来的信息</h1>
		<#-- list数据 -->
		<h4>作者列表</h4>
		<ul>
			<#list authors as author>
				<li>${author}</li>
			</#list>
		</ul>
		<#-- map数据 -->
		<h4>管理员最后登录时间列表</h4>
		<table cellpadding="1" border='1' cellspacing="1">
			<tr>
				<th width='120' align='center'>用户名</th>
				<th width='200' align='center'>最后登录时间</th>
			</tr>
			<#list viewLogs?keys as record>
				<tr>
					<td>${record}</td>
					<td align='center'>${viewLogs[record]}</td>
				</tr>
			</#list>
		</table>
	</body>
</html>

3.web.xml配置servlet

<servlet>
	<servlet-name>simpleMsg</servlet-name>
	<servlet-class>com.kyj.servlet.SimpleMsgServlet</servlet-class>
</servlet>
<servlet-mapping>
	<servlet-name>simpleMsg</servlet-name>
	<url-pattern>/simpleMsg</url-pattern>
</servlet-mapping>

4.访问servlet

http://localhost:8080/fmk/simpleMsg

三、与Struts框架整合

见freemarker提供的例子。

freemarker web技术 servlet