Servlet + Freemarker 入门练习
建立web项目，拷贝freemarker的jar文件到类路径，其他步骤略。
首先配置web.xml，添加freemarker解析的Servlet配置，内容如下
?<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;charset=UTF-8</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>number_format</param-name> <param-value>0.##########</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>freemarker</servlet-name> <url-pattern>*.ftl</url-pattern> </servlet-mapping>
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添加一个测试用的Servlet，代码如下：
package test.servlet;import java.io.IOException;import java.util.ArrayList;import java.util.Date;import java.util.HashMap;import java.util.HashSet;import java.util.List;import java.util.Map;import java.util.Set;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class TestFreemarker extends HttpServlet {private static final long serialVersionUID = 1L;@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {String strValue = "this is String";Date myDate = new Date();Object[] objectArray = new Object[]{1,"str",1.2};Set<Object> setData = new HashSet<Object>();setData.add("dataValue1");setData.add("dataValue2");setData.add("dataValue3");List<String> strList = new ArrayList<String>();strList.add("字符串1");strList.add("字符串2");strList.add("字符串3");Map<String,Object> map = new HashMap<String, Object>();map.put("key1", "value1");map.put("key2", "value2");map.put("key3", "value3");req.setAttribute("strValue", strValue);req.setAttribute("objectArray", objectArray);req.setAttribute("strList", strList);req.setAttribute("map", map);req.setAttribute("myDate", myDate);req.setAttribute("setData", setData);req.getRequestDispatcher("/WEB-INF/view/freemarker/test.ftl").forward(req, resp);}}?
配置此Servlet到web.xml中，增加如下内容到web.xml文件中：
<servlet> <servlet-name>test</servlet-name> <servlet-class>test.servlet.TestFreemarker</servlet-class> </servlet> <servlet-mapping> <servlet-name>test</servlet-name> <url-pattern>/test</url-pattern> </servlet-mapping>
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在/WEB-INF/view/freemarker目录下建立文件test.ftl，内容如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh-CN" dir="ltr"><head> <title>test!</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/></head><body><div>直接显示字符串<br />String:${strValue}<br/><hr/></div><div>显示日期date:${myDate?date}<br/><hr/>显示时间time:${myDate?time}<br/><hr/>显示时间戳datetime:${myDate?datetime}<br/><hr/></div><div>访问对象数组ObjectArray:${objectArray[0]},${objectArray[1]},${objectArray[2]}<br /><hr/></div><div>遍历Set中的元素SetData:<br /><#list setData as value>${value}</#list><hr/></div><div>遍历List中的元素strList:<br/><#list strList as strValue ><#if strValue_index == 0>${strValue} is first element<#elseif !strValue_has_next>${strValue} is last element<#else>${strValue}</#if><br /></#list><hr/></div><div>获取map中的值<br/>map:key1=${map.key1},key2=${map.key2},key3=${map.key3}<hr/></div><#include "foot.html"></body> </html> ?
模板中包含的foot.html，在和test.ftl相同的目录下，文件内容如下
<div style="margin-top: 50px;text-align: center;font-size: 12px"><hr />this is foot</div>
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运行此项目访问/test路径，输出内容如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh-CN" dir="ltr"><head> <title>test!</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/></head><body><div>直接显示字符串<br />String:this is String<br/><hr/></div><div>显示日期date:2011-3-18<br/><hr/>显示时间time:17:21:44<br/><hr/>显示时间戳datetime:2011-3-18 17:21:44<br/><hr/></div><div>访问对象数组ObjectArray:1,str,1.2<br /><hr/></div><div>遍历Set中的元素SetData:<br />dataValue2dataValue1dataValue3<hr/></div><div>遍历List中的元素strList:<br/>字符串1 is first element<br />字符串2<br />字符串3 is last element<br /><hr/></div><div>获取map中的值<br/>map:key1=value1,key2=value2,key3=value3<hr/></div><div style="margin-top: 50px;text-align: center;font-size: 12px"><hr />this is foot</div></body> </html>
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freemarker的list指令，不能遍历如Object[]类型的对象数组。但可以遍历List和Set
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