freemarker学习
一、Freemarker引入
二、环境搭建和测试
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0modelVersion>
<groupId>com.itheimagroupId>
<artifactId>FMDemo01artifactId>
<packaging>warpackaging>
<version>1.0-SNAPSHOTversion>
<name>FMDemo01 Maven Webappname>
<url>http://maven.apache.orgurl>
<dependencies>
<dependency>
<groupId>org.freemarkergroupId>
<artifactId>freemarkerartifactId>
<version>2.3.23version>
dependency>
<dependency>
<groupId>javax.servletgroupId>
<artifactId>javax.servlet-apiartifactId>
<version>4.0.1version>
dependency>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>3.8.1version>
<scope>testscope>
dependency>
dependencies>
<build>
<finalName>FMDemo01finalName>
build>
project>
web.xml
DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
<display-name>Archetype Created Web Applicationdisplay-name>
<servlet>
<servlet-name>freemarkerservlet-name>
<servlet-class>freemarker.ext.servlet.FreemarkerServletservlet-class>
<init-param>
<param-name>TemplatePathparam-name>
<param-value>/param-value>
init-param>
<init-param>
<param-name>default_encodingparam-name>
<param-value>UTF-8param-value>
init-param>
servlet>
<servlet-mapping>
<servlet-name>freemarkerservlet-name>
<url-pattern>*.ftlurl-pattern>
servlet-mapping>
web-app>
freemarker
<#--freemarker注释，隐式注释，浏览器中看不到-->
${msg}
controller
package com.itheima.controller;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* Description:
* date: 2023/7/12 20:51
*
* @since JDK 11
*/
@WebServlet("/fm01")
public class FMServlet01 extends HttpServlet {
public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setAttribute("msg","hello world!");
request.getRequestDispatcher("f01.ftl").forward(request,response);
}
}
三、数据类型
1、布尔型
controller
package com.itheima.controller;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm02")
public class FMServlet02 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setAttribute("bool",true);
req.getRequestDispatcher("f02.ftl").forward(req,resp);
}
}
f02.ftl
<#--是错误的，freemarker中不允许输出布尔类型的值，会报错
> ${bool}h2>-->
<h1>布尔类型的转换h1>
<#--方式一：?c-->
<h2>${bool?c}h2>
<#--方式二：?string 弃用-->
<h2>${bool?string}h2>
<#--${bool?string("bool为true时返回这个","bool为false时返回这个")-->
<h2>${bool?string("yes","false")}h2>
<#--方式三：?then("true时返回这个","false时返回这个")-->
<h2>${bool?then("then_true","then_false")}h2>
2、日期型
controller
package com.itheima.controller;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Date;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm02")
public class FMServlet02 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//布尔类型
req.setAttribute("bool",true);
//日期类型
req.setAttribute("date",new Date());
req.getRequestDispatcher("f02.ftl").forward(req,resp);
}
}
f02.ftl
<#--freemarker注释，隐式注释，浏览器中看不到-->
<#--是错误的，freemarker中不允许输出布尔类型的值，会报错
> ${bool}h2>-->
<h1>布尔类型的转换h1>
<#--方式一：?c-->
<h2>${bool?c}h2>
<#--方式二：?string 弃用-->
<h2>${bool?string}h2>
<#--${bool?string("bool为true时返回这个","bool为false时返回这个")-->
<h2>${bool?string("yes","false")}h2>
<#--方式三：?then("true时返回这个","false时返回这个")-->
<h2>${bool?then("then_true","then_false")}h2>
<hr><br/>
<h1>日期类型h1>
<#--在freemarker中，日期类型也不支持直接输出如果要输出，先转换成日期型或字符串-->
<h3>${date?date}h3>
<h3>${date?time}h3>
<h3>${date?datetime}h3>
<h3>${date?string("yyyy-MM-dd,HH:mm:ss")}h3>
3、数值类型
package com.itheima.controller;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Date;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm02")
public class FMServlet02 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//布尔类型
req.setAttribute("bool",true);
//日期类型
req.setAttribute("date",new Date());
// 数值类型
req.setAttribute("age",18);
req.setAttribute("salary",16800);
req.setAttribute("double",0.5485);
// 请求转发到模版2
req.getRequestDispatcher("f02.ftl").forward(req,resp);
}
}
<#--freemarker注释，隐式注释，浏览器中看不到-->
<#--是错误的，freemarker中不允许输出布尔类型的值，会报错
> ${bool}h2>-->
<h1>布尔类型的转换h1>
<#--方式一：?c-->
<h2>${bool?c}h2>
<#--方式二：?string 弃用-->
<h2>${bool?string}h2>
<#--${bool?string("bool为true时返回这个","bool为false时返回这个")-->
<h2>${bool?string("yes","false")}h2>
<#--方式三：?then("true时返回这个","false时返回这个")-->
<h2>${bool?then("then_true","then_false")}h2>
<hr><br/>
<h1>日期类型h1>
<#--在freemarker中，日期类型也不支持直接输出如果要输出，先转换成日期型或字符串-->
<h3>${date?date}h3>
<h3>${date?time}h3>
<h3>${date?datetime}h3>
<h3>${date?string("yyyy-MM-dd,HH:mm:ss")}h3>
<hr><br/>
<h1>数值类型，可以直接表示h1>
${age?c}<br>
${salary?string.currency}<br>
${double?string.percent}，自动四舍五入<br>
${double?string["0.##"]}，自动四舍五入<br>
4、字符串类型
<h1>字符串类型的展示h1>
<h4>${str1?substring(1,3)}截取字符串，左闭右开h4>
<h4>${str1?uncap_first}首字符小写h4>
<h4>${str1?cap_first}首字符大写h4>
<h4>${str1?lower_case}全部小写h4>
<h4>${str1?substring(1,3)}h4>
<h4>${str1?upper_case}全部大写h4>
package com.itheima.controller;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Date;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm02")
public class FMServlet02 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//布尔类型
req.setAttribute("bool",true);
//日期类型
req.setAttribute("date",new Date());
// 数值类型
req.setAttribute("age",18);
req.setAttribute("salary",16800);
req.setAttribute("double",0.5485);
// 字符串类型的展示
req.setAttribute("str1","WWW.ee");
// 请求转发到模版2
req.getRequestDispatcher("f02.ftl").forward(req,resp);
}
}
5、字符串空值类型的处理
package com.itheima.controller;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Date;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm02")
public class FMServlet02 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 空字符串的处理
req.setAttribute("a",null);
req.setAttribute("b","");
// 请求转发到模版2
req.getRequestDispatcher("f02.ftl").forward(req,resp);
}
}
<#--freemarker注释，隐式注释，浏览器中看不到-->
<#--是错误的，freemarker中不允许输出布尔类型的值，会报错
> ${bool}h2>-->
<h1>布尔类型的转换h1>
<#--方式一：?c-->
<h2>${bool?c}h2>
<#--方式二：?string 弃用-->
<h2>${bool?string}h2>
<#--${bool?string("bool为true时返回这个","bool为false时返回这个")-->
<h2>${bool?string("yes","false")}h2>
<#--方式三：?then("true时返回这个","false时返回这个")-->
<h2>${bool?then("then_true","then_false")}h2>
<hr><br/>
<h1>日期类型h1>
<#--在freemarker中，日期类型也不支持直接输出如果要输出，先转换成日期型或字符串-->
<h3>${date?date}h3>
<h3>${date?time}h3>
<h3>${date?datetime}h3>
<h3>${date?string("yyyy-MM-dd,HH:mm:ss")}h3>
<hr><br/>
<h1>数值类型，可以直接表示h1>
${age?c}<br>
${salary?string.currency}<br>
${double?string.percent}，自动四舍五入<br>
${double?string["0.##"]}，自动四舍五入<br>
<hr><br/>
<h1>字符串类型的展示h1>
<h4>${str1?substring(1,3)}截取字符串，左闭右开h4>
<h4>${str1?uncap_first}首字符小写h4>
<h4>${str1?cap_first}首字符大写h4>
<h4>${str1?lower_case}全部小写h4>
<h4>${str1?substring(1,3)}h4>
<h4>${str1?upper_case}全部大写h4>
<hr><br/>
<h1>空值情况的处理：h1>
<h2>freemarker中对null和未定义的变量输出时都会报错，但是对空字符串不会报错h2>
${a!}<br>
${b}<br>
${c!}<br>
${c???c} ?c转为字符串类型
6、序列类型
package com.itheima.controller;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Date;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm02")
public class FMServlet02 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 存储数组在request作用域中
String[] arr = new String[]{"alili","clili","blili","dlili"};
req.setAttribute("arr",arr);
// 请求转发到模版2
req.getRequestDispatcher("f02.ftl").forward(req,resp);
}
}
存储集合
package com.itheima.controller;
import com.itheima.pojo.User;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm02")
public class FMServlet02 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 存储数组在request作用域中
String[] arr = new String[]{"alili","clili","blili","dlili"};
req.setAttribute("arr",arr);
// 存储map在request作用域中
User user1 = new User("xx1",18);
User user2 = new User("xx2",20);
User user3 = new User("xx3",22);
List<User> list = Arrays.asList(user1,user2,user3);
req.setAttribute("list",list);
// 请求转发到模版2
req.getRequestDispatcher("f02.ftl").forward(req,resp);
}
}
<hr><br>
<h1>序列类型h1>
<#list arr as el>
${el}----${el?index}<br>
#list>
<hr>
获取数组的大小：${arr?size}<br/><hr>
获取数组的第一个元素：${arr?first}<br/><hr>
获取数组的最后一个元素：${arr?last}<br/><hr>
使数组反转输出<br>
<#list arr?reverse as el>
${el}----${el?index}<br>
#list>
<hr>
使数组升序输出<br>
<#list arr?sort as el>
${el}----${el?index}<br/>
#list>
<hr>
使数组降序输出<br>
<#list arr?sort?reverse as el>
${el}----${el?index}<br/>
#list>
<hr><br>
<h1>存储集合h1>
<#list list as el>
${el.name} and ${el.age}<br>
#list>
7、***hash类型->map重点
package com.itheima.controller;
import com.itheima.pojo.User;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.*;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm02")
public class FMServlet02 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 存储map在request作用域中
Map<String,String> city = new HashMap<String, String>();
city.put("beijing","北京");
city.put("shanghai","上海");
city.put("jinan","济南");
req.setAttribute("city",city);
// 请求转发到模版2
req.getRequestDispatcher("f02.ftl").forward(req,resp);
}
}
<hr><br/>
<h1>maph1>
<h2>map循环h2>
<#list city?keys as key>
${key}----${city[key]}----${key_index}--
<#--key_index返回索引坐标-->
<#--key_has_next 返回布尔值，判断是否还有下一个元素-->
<#if key_has_next>
还有下一个---hello
#if>
<br>
#list>
<hr>
<#list city?values as v>
${v}<br/>
#list>
<h2>可以直接对map进行value的输出h2>
${city["beijing"]!"xx"}<br>
${city["jinan"]!"xx"}<br>
${city["1234"]!"xx"}<br>
四、freemarker常见指令
1、定义变量
<#--定义变量-->
<#assign name="xxx" age=12 array=[1,"xxx"]>
${name} and ${age}<br>
${array[0]}<br>
${array[1]}<br>
<h2>对array进行拼接h2>
${array?join("___")}
package com.itheima.controller;
import com.itheima.pojo.User;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.*;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/fm03")
public class FMServlet03 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//定义变量
req.getRequestDispatcher("f03.ftl").forward(req,resp);
}
}
2、***ifelse
3、list指令
五、模版复用
后端
package com.itheima.controller;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
/**
* Description:
* date: 2023/7/12 21:08
*
* @since JDK 11
*/
@WebServlet("/index1")
public class FMServlet04 extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Map<String,String> city = new HashMap<String, String>();
city.put("0","北京");
city.put("1","上海");
city.put("2","济南");
req.setAttribute("map",city);
req.getRequestDispatcher("index.ftl").forward(req,resp);
}
}
前端
1、共用select、option
index.ftl
<#import "optionmodel.ftl" as op>
<@op.optionfun map>@op.optionfun>
optionmodel.ftl
<#macro optionfun map>
<select>
<#list map?keys as key>
<option value="${key}">${map[key]}option>
#list>
select>
#macro>
