目录

1、简介

2、实例

1、简介

Apache FreeMarker 是一个模板引擎：一个基于模板和变化数据生成文本输出（HTML网页、电子邮件、配置文件、源代码等）的Java库。模板是用FreeMarker模板语言（FTL）编写的，它是一种简单的、专门的语言（不是像PHP那样的全面的编程语言）

2、实例

1）创建一个maven项目，我的相关类最终目录，就3个文件

2）创建模板文件hello.ftl，ftl 语法可简单网上了解下

package ${classPath};

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
* @author yourFather
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
public class ${className} {

<#list properties as property>
    /**
    * ${property.comment}
    */
    private ${property.type} ${property.name};
</#list>

    public static void main(String[] args) {
        System.out.println("${helloWorld}");
    }

}

3）创建生成功能类 GenerateFile，运行main方法后，即会发现生成了UserDemo类

pom文件引入的依赖：

<dependency>
  <groupId>org.freemarker</groupId>
  <artifactId>freemarker</artifactId>
  <version>2.3.30</version>
</dependency>

package com.future.docker.freemarker;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.*;

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

/**
 * @author yourFather
 */
public class GenerateFile {

    private static final String TEMPLATE_PATH = "src/main/java/com/future/docker/freemarker/template";
    private static final String CLASS_PATH = "src/main/java/com/future/docker/freemarker/output";

    public static void main(String[] args) {
        // step1 创建freeMarker配置实例，参数：版本实例（FreeMarker 2.3.23之前不带参数的Configuration方法被弃用）
        Configuration configuration = new Configuration(Configuration.VERSION_2_3_30);
        Writer out = null;
        try {
            // step2 获取模版路径
            configuration.setDirectoryForTemplateLoading(new File(TEMPLATE_PATH));
            // step3 创建数据模型
            Map<String, Object> dataMap = fillData("UserDemo","com.future.docker.freemarker.output");
            // step4 加载模版文件
            Template template = configuration.getTemplate("hello.ftl");
            // step5 生成数据
            File docFile = new File(CLASS_PATH + "\\" + "UserDemo.java");
            out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(docFile)));
            // step6 输出文件
            template.process(dataMap, out);
            System.out.println("UserDemo.java 文件创建成功 !");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != out) {
                    out.flush();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
    }

    public static Map<String, Object> fillData(String className,String classPath){
        String[] properties = {"name","sex","age"};
        String[] types = {"String","String","Integer"};
        String[] comments = {"姓名","性别","年龄"};
        List<Map> listMap = new ArrayList<>();
        for(int i =0; i<properties.length; i++){
            Map<String, Object> map = new HashMap<>();
            map.put("name",properties[i]);
            map.put("type",types[i]);
            map.put("comment",comments[i]);
            listMap.add(map);
        }
        Map<String, Object> dataMap = new HashMap<>();
        dataMap.put("properties", listMap);
        dataMap.put("classPath", classPath);
        dataMap.put("className", className);
        dataMap.put("helloWorld", "生成实体类");
        return dataMap;
    }
}

 4）生成的UserDemo如下

package com.future.docker.freemarker.output;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
* @author yourFather
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
public class UserDemo {

    /**
    * 姓名
    */
    private String name;
    /**
    * 性别
    */
    private String sex;
    /**
    * 年龄
    */
    private Integer age;

    public static void main(String[] args) {
        System.out.println("生成实体类");
    }

}