Java操作FreeMarker模板引擎的基本用法示例小结
程序员文章站
2024-02-26 09:44:13
freemarker 是一个采用 java 开发的模版引擎，是一个基于模版生成文本的通用工具。 它被设计用来生成 html web 页面，特别是基于 mvc 模式的应用程序...
freemarker 是一个采用 java 开发的模版引擎，是一个基于模版生成文本的通用工具。 它被设计用来生成 html web 页面，特别是基于 mvc 模式的应用程序。虽然使用freemarker需要具有一些编程的能力，但通常由 java 程序准备要显示的数据，由 freemarker 生成页面，并通过模板显示准备的数据。
http://freemarker.org/
public void process(string template, map<string, ?> data) throws exception {
configuration cfg = new configuration();
cfg.setdirectoryfortemplateloading(new file("ftl"));
cfg.setobjectwrapper(new defaultobjectwrapper());
//设置字符集
cfg.setdefaultencoding("utf-8");
//设置尖括号语法和方括号语法,默认是自动检测语法
// 自动 auto_detect_tag_syntax
// 尖括号 angle_bracket_tag_syntax
// 方括号 square_bracket_tag_syntax
cfg.settagsyntax(configuration.auto_detect_tag_syntax);
writer out = new outputstreamwriter(new fileoutputstream(file_dir + template + ".txt"),"utf-8");
template temp = cfg.gettemplate(template);
temp.process(data, out);
out.flush();
}
0、使用freemarker制作helloword web页面
新建一个web工程，并导入freemarker.jar，在web-inf下新建文件夹templates用于存放模版文件，在templates下新建test.ftl，这是示例模版文件。内容就是html内容，里面带有一个标记符，用于将来进行变量替换，内容如下：
<html>
<head>
<title>freemarker测试</title>
</head>
<body>
<h1>${message},${name}</h1>
</body>
</html>
新建一个servlet，用于请求设置变量，并处理模版的输出：
package com.test.servlet;
import java.io.ioexception;
import java.io.writer;
import java.util.hashmap;
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;
@suppresswarnings("serial")
public class hellofreemarkerservlet extends httpservlet {
// 负责管理freemarker模板的configuration实例
private configuration cfg = null;
public void init() throws servletexception {
// 创建一个freemarker实例
cfg = new configuration();
// 指定freemarker模板文件的位置
cfg.setservletcontextfortemplateloading(getservletcontext(),
"/web-inf/templates");
}
@suppresswarnings("unchecked")
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
// 建立数据模型
map root = new hashmap();
root.put("message", "hello world");
root.put("name", "java小强");
// 获取模板文件
template t = cfg.gettemplate("test.ftl");
// 使用模板文件的charset作为本页面的charset
// 使用text/html mime-type
response.setcontenttype("text/html; charset=" + t.getencoding());
writer out = response.getwriter();
// 合并数据模型和模板，并将结果输出到out中
try {
t.process(root, out); // 往模板里写数据
} catch (templateexception e) {
e.printstacktrace();
}
}
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
dopost(request, response);
}
public void destroy() {
super.destroy();
}
}
注意要在你的web.xml中配置该servlet：
<?xml version="1.0" encoding="utf-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>hello</servlet-name>
<servlet-class>
com.test.servlet.hellofreemarkerservlet
</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>hello</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
为了方便测试，访问工程直接跳转到servlet，对主页index.jsp做一个简单修改：
<%@ page language="java" import="java.util.*" pageencoding="utf-8"%> <% string path = request.getcontextpath(); string basepath = request.getscheme()+"://"+request.getservername() +":"+request.getserverport()+path+"/"; %> <html> <body> <% string mypath = "hello"; response.sendredirect(basepath + mypath); %> </body> </html>
部署工程到tomcat，启动并访问http://localhost:8080/f ，这里我建立的工程名称就是 f 。
1、计算式
<#-- 1、算术运算 -->[br]
${3 + 4}
<#-- 2、内建函数 -->[br]
${"rensanning"?upper_case}
2、输出一个值
hashmap t2root = new hashmap<string, string>();
t2root.put("user", "rensanning");
${user}, welcome!
3、输出一个列表
map<string, object> t3root = new hashmap<string, object>();
list<food> menu = new arraylist<food>();
menu.add(new food("itext in action", 98));
menu.add(new food("ibatis in action", 118));
menu.add(new food("lucene in action", 69));
t3root.put("menu", menu);
<#list menu as food>
${food.name} ${food.price?string.currency}
</#list>
4、逻辑判断（if,switch)
map<string, object> t4root = new hashmap<string, object>();
t4root.put("x", 2);
t4root.put("y", "medium");
<1>if, else, elseif:
<#if x == 1>
x is 1
<#elseif x == 2>
x is 2
<#elseif x == 3>
x is 3
<#elseif x == 4>
x is 4
<#else>
x is not 1 nor 2 nor 3 nor 4
</#if>
<2>switch, case, default, break:
<#switch y>
<#case "small">
this will be processed if it is small
<#break>
<#case "medium">
this will be processed if it is medium
<#break>
<#case "large">
this will be processed if it is large
<#break>
<#default>
this will be processed if it is neither
</#switch>
<3>list, break:
<#assign seq = ["winter", "spring", "summer", "autumn"]>
<#list seq as x>
${x_index + 1}. ${x}<#if x_has_next>,</#if>
</#list>
5、自定义函数
<#function fact n>
<#if n == 0>
<#return 1 />
<#else>
<#return fact(n - 1) * n />
</#if>
</#function>
<#list 0..10 as i>
${i}! => ${fact(i)}
</#list>
6、定义变量
<#-- 1、本地变量 -->[br]
<#function partg n lst>
<#local ans = []>
<#list lst as x>
<#if (x >= n)>
<#local ans = ans + [x]>
</#if>
</#list>
<#return ans>
</#function>
<#assign ls = [10, 2, 4, 5, 8, 1, 3]>
<#list partg(4, ls) as x>${x} </#list>
<#-- 2、变量域测试 -->[br]
<#macro test>
03. ${x}
<#global x = "global2">
04. ${x}
<#assign x = "assign2">
05. ${x}
<#local x = "local1">
06. ${x}
<#list ["循环1"] as x>
07. ${x}
<#local x = "local2">
08. ${x}
<#assign x = "assign3">
09. ${x}
</#list>
10. ${x}
</#macro>
<#global x = "global1" />
01. ${x}
<#assign x = "assign1" />
02. ${x}
<@test />
11. ${x}
7、定义宏macro
<#-- 1、无参数 -->[br]
<#macro greet>
welcome!
</#macro>
<@greet />
<#-- 2、有参数 -->[br]
<#macro greet user>
${user}, welcome!
</#macro>
<@greet user="rensanning"/>
<#-- 3、有多个参数 -->[br]
<#macro table cols rows>
<table>
<#list 1..rows as row>
<tr>
<#list 1..cols as col>
<td>${row}, ${col}</td>
</#list>
</tr>
</#list>
</table>
</#macro>
<@table cols=3 rows=2 />
<#-- 4、中间跳出 -->[br]
<#macro out>
显示文字
<#return>
不显示文字
</#macro>
<@out />
<#-- 5、嵌套 -->[br]
<#macro lprint lst>
<#list lst as item>
・${item}<#nested item />
</#list>
</#macro>
<@lprint 1..3; x>^2 = ${x * x}</@lprint>
<@lprint 1..3; x>^3 = ${x * x * x}</@lprint>
<@lprint ["let's go", "to the", "land of medetai"] />
8、include
<#include "t108include.ftl">
${url}
<@greet name="rensanning" />
t108include.ftl
<#macro greet name>
${name}, welcome!
</#macro>
<#assign url="http://www.baidu.com/">
9、名字空间
<#import "t109include.ftl" as my>
<#assign url="http://www.google.com/">
${my.url}
<@my.greet name="rensanning" />
${url}
t109include.ftl
<#macro greet name>
${name}, welcome!
</#macro>
<#assign url="http://www.baidu.com/">
10、自定义指令directive
public class systemdatedirective implements templatedirectivemodel {
public void execute(environment env, map params, templatemodel[] loopvars,
templatedirectivebody body) throws templateexception, ioexception {
calendar cal = calendar.getinstance();
simpledateformat sdf = new simpledateformat("yyyy/mm/dd hh:mm:ss");
env.getout().append(sdf.format(cal.gettime()));
}
}
public class textcutdirective implements templatedirectivemodel {
public static final string param_s = "s";
public static final string param_len = "len";
public static final string param_append = "append";
@suppresswarnings("unchecked")
public void execute(environment env, map params, templatemodel[] loopvars,
templatedirectivebody body) throws templateexception, ioexception {
string s = getstring(param_s, params);
integer len = getint(param_len, params);
string append = getstring(param_append, params);
if (s != null) {
writer out = env.getout();
if (len != null) {
out.append(textcut(s, len, append));
} else {
out.append(s);
}
}
}
....
map<string, object> t10root = new hashmap<string, object>();
t10root.put("systemdate", new systemdatedirective());
t10root.put("text_cut", new textcutdirective());
上一篇： php利用GD库生成缩略图示例