手把手教你开发代码生成器，学不会的来怼我！

<dependency>
    <groupId>org.freemarker</groupId>
    <artifactId>freemarker</artifactId>
    <version>2.3.23</version>
</dependency>

package ${package};

import java.io.Serializable;

/**
 * <p>
 * ${tableComment}
 * </p>
 *
 * @author ${author}
 * @since ${date}
 */
public class ${entityClass} implements Serializable {

 private static final long serialVersionUID = 1L;
 
 <#--属性遍历-->
 <#list columns as pro>

 /**
  * ${pro.comment}
  */
 private ${pro.propertyType} ${pro.propertyName};
 </#list>

 <#--属性get||set方法-->
 <#list columns as pro>
 public ${pro.propertyType} get${pro.propertyName?cap_first}() {
  return this.${pro.propertyName};
 }

 public ${entityClass} set${pro.propertyName?cap_first}(${pro.propertyType} ${pro.propertyName}) {
  this.${pro.propertyName} = ${pro.propertyName};
  return this;
 }
 </#list>
}

public class CodeGeneratorDemo {

    public static void main(String[] args) throws IOException, TemplateException {
        Map<String, Object> objectMap = new HashMap<>();
        //定义包路径
        objectMap.put("package", "com.example.test");
        //定义实体类
        objectMap.put("entityClass", "Student");

        //定义实体类属性
        List<Map<String, Object>> columns = new ArrayList<>();
        //姓名字段
        Map<String, Object> column1 = new HashMap<>();
        column1.put("propertyType", "String");
        column1.put("propertyName", "name");
        column1.put("comment", "姓名");
        columns.add(column1);
        //年龄字段
        Map<String, Object> column2 = new HashMap<>();
        column2.put("propertyType", "Integer");
        column2.put("propertyName", "age");
        column2.put("comment", "年龄");
        columns.add(column2);

        //定义类的属性
        objectMap.put("columns", columns);
        //定义作者
        objectMap.put("author", "张三");
        //定义创建时间
        objectMap.put("date", new SimpleDateFormat("yyyy-MM-dd").format(new Date()));
        //定义类描述
        objectMap.put("tableComment", "学生信息");

        //生产目标代码
        Configuration configuration = new Configuration(Configuration.VERSION_2_3_23);
        configuration.setDefaultEncoding(Charset.forName("UTF-8").name());
        configuration.setClassForTemplateLoading(CodeGeneratorDemo.class, "/");
        Template template = configuration.getTemplate("/templates/entity.java.ftl");
        FileOutputStream fileOutputStream = new FileOutputStream(new File("../src/main/java/com/example/generator/Student.java"));
        template.process(objectMap, new OutputStreamWriter(fileOutputStream, Charset.forName("UTF-8").name()));
        fileOutputStream.close();
        System.out.println("文件创建成功");

    }
}

package com.example.test;

import java.io.Serializable;

/**
 * <p>
 * 学生信息
 * </p>
 *
 * @author 张三
 * @since 2021-08-22
 */
public class Student implements Serializable {

 private static final long serialVersionUID = 1L;
 

 /**
  * 姓名
  */
 private String name;

 /**
  * 年龄
  */
 private Integer age;

 public String getName() {
  return this.name;
 }

 public Student setName(String name) {
  this.name = name;
  return this;
 }
 public Integer getAge() {
  return this.age;
 }

 public Student setAge(Integer age) {
  this.age = age;
  return this;
 }
}