javaWeb+freemarker的使用

导入pom坐标

<?xml version="1.0" encoding="UTF-8"?>

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.xst</groupId>
  <artifactId>freemarker</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>freemarker Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.freemarker</groupId>
      <artifactId>freemarker</artifactId>
      <version>2.3.23</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.0.1</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
   <plugins>
     <plugin>
       <groupId>org.eclipse.jetty</groupId>
       <artifactId>jetty-maven-plugin</artifactId>
       <version>9.2.1.v20140609</version>
     </plugin>
   </plugins>
  </build>
</project>

配置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 Application</display-name>

  <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>default_encoding</param-name>
      <param-value>utf-8</param-value>
    </init-param>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>freemarker</servlet-name>
    <url-pattern>*.ftl</url-pattern>
  </servlet-mapping>
</web-app>

freemarker简单的使用

Freemarker基础数据类型

package com.sxt.controller;

import com.sxt.controller.vo.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.*;

/**
 * @Author panghl
 * @Date 2021/1/16 9:40
 * @Description TODO
 **/
@WebServlet(urlPatterns = "/f01")
public class F01 extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /**
         * 准备Model数据
         * 转发页面(指定模板文件)
         */
        req.setAttribute("msg","hello freemarker");

        req.setAttribute("flag",true);
        req.setAttribute("createTime",new Date());
        req.setAttribute("age",20);
        req.setAttribute("salary",6666);
        req.setAttribute("test",0.57);
        req.setAttribute("msg02","freemarker is so essay");

        String[] strs = new String[] {"admin","super-admin","test"};
        req.setAttribute("strs",strs);

        Integer[] ids = new Integer[] {1,23,4,5};
        req.setAttribute("ids",ids);

        List<User> users = Arrays.asList(new User(10,"heloUser","浙江杭州",40),new User(20,"李彦宏","北京百度",35));
        req.setAttribute("users",users);


        Map<String,String> map = new HashMap<>();
        map.put("admin","码云");
        map.put("test","李彦宏");
        req.setAttribute("map",map);

        req.setAttribute("userName",null);
        // ftl 文件浏览器不能直接访问
        req.getRequestDispatcher("/templates/f01.ftl").forward(req,resp);
    }

}

f01.ftl

<#--
    html标签
    js
    css
-->

<h1>Freemarker基础数据类型</h1>

你好啊!
<h2>${msg}</h2>

<#-- boolean 类型不能直接输出， 如果输出，需要转换为字符串-->
<#--${flag} 源码不可见-->
?string: ${flag?string} || ?c:${flag?c}
<br/>
<#if flag>
    flag 为true
    <#else>
    flag 为false
</#if>
<br/>
<#--
    日期类型 不能直接输出，需要转换为字符串输出
-->
<#--${createTime}-->
date: ${createTime?date} || string :${createTime?string("yyyy-MM-dd")} || datetime: ${createTime?datetime} || time: ${createTime?time}
<br/>

<#--
    数值输出
-->
${age} || ${salary} ||非格式化输出: ${salary?c}|| 货币: ${test?string.currency} || 百分比: ${test?string.percent}

<br/>

<#--
    字符串输出
-->
${msg02} || 大写: ${msg02?upper_case} || 首字母大写: ${msg02?cap_first} || 每个单词首字母大写: ${msg02?capitalize}
<br/>
字符串切割:
<br/>
start..end : 索引2-3: ${msg02[2..3]} || ${msg02[2..<4]}
<br/>
start..小于end+1 和start ..end相同: ${msg02[2..<4]}
<br/>
限制长度的值域 (start..*length): ${msg02[2..*4]}
<br/>
无右边界值域 (start..) : ${msg02[2..]}
<br/>

<br/>

<#--
    序列类型：
        数组  list  set
-->
<#list strs as str>
    <li>${str}</li>
</#list>
<hr/>
<#list ids as id>
    <li>${id}</li>
</#list>
<hr/>
<#list users as user>
    <li>${user.id} || ${user.userName} || ${user.addr} </li>
</#list>
<hr/>
排序
<#list ids?sort as id>
    <li>${id_index} - ${id}</li>
</#list>
<#list users?sort_by("age") as user>
    <li>${user.id} || ${user.userName} || ${user.addr} || ${user.age}</li>
</#list>

<hr/> hash
<#list map?keys as key>
    ${key} || ${map[key]}<br/>
</#list>

<#--
值为null 时的处理：
    1.使用默认值 !"默认值"
    2.判断变量值是否存在 输出内容
-->
<br/>值为null 时的处理： ||
使用默认值： ${userName!"admin"}
<br/>
判断变量值是否存在：
<#if userName??>
    ${userName}
    <#else>
    userName不存在
</#if>

FreeMarker常见指令

package com.sxt.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;

/**
 * @Author panghl
 * @Date 2021/1/16 10:56
 * @Description TODO
 **/
@WebServlet(urlPatterns = "/f02")
public class F02 extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String action = req.getParameter("action");
//        if (action.equals("")){
//
//        }else if (){
//
//        }else if (){
//
//        }else{}

        req.getRequestDispatcher("/templates/f02.ftl").forward(req,resp);
    }
}

f02.ftl


<h1>FreeMarker常见指令</h1>
<#--
    常用指令 -assign   变量的定义
-->
<#assign str="freemarker">
<H2>${str}</H2>
<hr/>
<#assign ids = [10, 20, 30]>
${ids?join(" - ")}
<br/>
<#assign x=0>
${x+1}
<br/>
<#assign userName = "admin",userPwd = "123456", str=["test","user"]>
${userName} || ${userPwd} ||  ${str?join(",")}
<br/>

<#--
    常用指令02-if elseif else
-->
<#assign action="main">
<#if action =="index">
    首页。。。
    <#elseif action=="main">
    主页。。。
    <#else>
    404。。。
</#if>
<br/>
<#--
    常用指令03-list
-->
<#assign users=["admin"]>
<#list users as user>
    ${user}
<#else>
    暂无用户
</#list>
<br/>
<#if users?? && users?size gt 0 >
    <#list users as user>
        ${user}
    </#list>
    <#else>
    暂无数据
</#if>
<br/>
<#list users>
<ul>
    <#items as user>
        <li>${user}</li>
    </#items>
</ul>
</#list>

<br/>
<#--
    常用指令04-macro
-->

<#--
    1.定义宏test01
-->
<#macro test01>
    hello macro
</#macro>
<#--
    2.使用宏test01
-->
<@test01></@test01>
<br/>
<@test01></@test01>
<br/>
<@test01></@test01>
<br/>
<@test01></@test01>
<br/>

<hr/>

<#macro test02 userName>
    hello ${userName}
</#macro>

<@test02 userName="admin"></@test02>

<hr/>
<#macro test03 userName users>
    hello ${userName}
    <br/>
    <#list users as user>
        ${user}
        <#else>
        暂无数据
    </#list>
</#macro>
<@test03 "auper-panghl" users></@test03>

<br>
<#--
    常用指令05-import
-->
<#import "f03.ftl" as f03>
<@f03.test04 userName="admin"></@f03.test04>
<hr>
<@f03.cfb n=9></@f03.cfb>


<#--
    常用指令05-include
-->
<hr>
<#include "index.html">
<#include "f04.ftl">


<hr>
<#function avg x y>
    <#return (x + y)/2>
</#function>
${avg(10,20)}

f03.ftl

<#macro test04 userName>
    我是f03.ftl hello ${userName}
</#macro>

<#--
9*9乘法表
-->
<#macro cfb n>
    <#list 1..n as i>
        <#list 1..i as j>
            <#if i*j lt 10>
                ${j}*${i}= &nbsp;${i*j}
                <#else>
                ${j}*${i}=${i*j}
            </#if>
        </#list>
        <br/>
    </#list>
</#macro>

f04.ftl

testtest
testtest
testtest
test

test
vtest

将网页静态化案例

package com.sxt.controller;

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

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.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 * @Author panghl
 * @Date 2021/1/16 12:27
 * @Description TODO
 **/
@WebServlet(urlPatterns = "/f03")
public class F03 extends HttpServlet {


    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.创建FreeMarker的配置类
        Configuration cfg = new Configuration();
        cfg.setDefaultEncoding("utf-8");
        cfg.setServletContextForTemplateLoading(getServletContext(),"/");
        //2.指定模块加载器：将模板存入缓存中
       // cfg.setTemplateLoader(new FileTemplateLoader(new File("templates")));
        //3. 根据模板文件获取模板对象
        Template template = cfg.getTemplate("templates/news.ftl");
        //4.构造数据模型
        Map<String,Object> map = new HashMap<>();
        map.put("title","开业五年 习近平推动这家银行点石成金");
        map.put("source","新闻社");
        map.put("createTime",new Date());
        map.put("content","对一切为亚洲和平与发展贡献正能量的意愿和行动，我们都持积极态度”“倡议成立亚投行，就是中国承担更多国际责任、推动完善现有国际经济体系、提供国际公共产品的建设性举动，有利于促进各方实现互利共赢”“亚投行应该成为促进成员共同发展、推动构建人类命运共同体的新平台”……");
        String basePath = req.getSession().getServletContext().getRealPath("/");
        File html = new File(basePath+"/html");
        if (!(html.exists())){
            //创建目录 用于存放.html文件
            html.mkdir();
        }
        String fileName = System.currentTimeMillis()+".html";
        //5.文件输出
        try {
            template.process(map,new FileWriter(new File(html,fileName)));
        } catch (TemplateException e) {
            e.printStackTrace();
        }


    }

}

news.ftl

<h1>${title}</h1>
<br/>
发布时间:${createTime?string("yyyy-MM-dd HH:mm:ss")}
来源:${source}
<br/>
${content}

springboot项目中application.properties配置

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#freemarker config
spring.freemarker.cache=false
spring.freemarker.check-template-location=true
spring.freemarker.content-type=text/html
spring.freemarker.suffix=.html
spring.freemarker.template-loader-path=classpath:/templates/

javaWeb+freemarker的使用

Freemarker基础数据类型

FreeMarker常见指令

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