Poi工具类快速生成Ecxel

先导入POI需要的依赖

    <dependencies>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>4.1.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>4.1.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml-schemas</artifactId>
            <version>4.1.2</version>
        </dependency>
    </dependencies>

上代码，后面再做解释

package top.hjie;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

/**
 * @ClassName: PoiUtils
 * @Description: TODO
 * @author 何杰
 * @date 2020年5月20日
 */
public class PoiUtil {

    public static void main(String[] args) throws Exception {
        String a = "student.xx";
        System.out.println(a.substring(0, a.lastIndexOf(".")));
        String[] title = { "id", "标题", "名称", "重量" ,"学生"};
        String[] property = { "id", "title", "name", "weight" ,"student.xx"};
        List<Object> list = new ArrayList<Object>();
        for (int i = 0; i < 100; i++) {
            Person person = new Person();
            person.setId(i + 1);
            person.setName("名称" + (i + 1));
            person.setTitle("标题" + (i + 1));
            person.setWeight(new Random().nextInt(100000) + "g");
            Student s = new Student();
            s.setXx("222");
            person.setStudent(s);
            list.add(person);
        }
        Student student = new Student();
        student.setXx("6666");
        createEcxelByGroups(title, property, list, PoiType.XLSX);
        typeDict(a);
    }

    /**
     * @Title: createEcxel
     * @Description: 通过属性组创建Excel，序号自动生成
     * @param title
     *            标题
     * @param property
     *            对象的属性名
     * @param coll
     *            需要生成表格的对象
     * @param suffix
     *            后缀名 xls || xlsx
     * @throws SecurityException
     * @throws NoSuchFieldException
     * @throws IllegalAccessException
     * @throws IllegalArgumentException
     * @throws IOException
     */
    public static void createEcxelByGroups(String[] title, String[] property,
            List<Object> coll, PoiType suffix) throws NoSuchFieldException,
            SecurityException, IllegalArgumentException, IllegalAccessException {
        if (suffix == null) {
            throw new RuntimeException("请选择文件后缀名");
        }
        Workbook wb = null;
        if (suffix == PoiType.XLS) {
            wb = new HSSFWorkbook();
        } else {
            wb = new XSSFWorkbook();
        }
        Sheet st = wb.createSheet();
        // 创建第一行
        Row rowone = st.createRow(0);
        // 设置标题
        for (int i = 0; i <= title.length; i++) {
            Cell cell = rowone.createCell(i);
            if (i == 0) {
                cell.setCellValue("序号");
                continue;
            }
            cell.setCellValue(title[i - 1]);
        }

        // 填充值
        for (int i = 0; i < coll.size(); i++) {
            Class<? extends Object> clazz = coll.get(i).getClass();

            Row row = st.createRow(i + 1);
            for (int j = 0; j <= property.length; j++) {
                // 创建j++列
                Cell cell = row.createCell(j);
                if (j == 0) {
                    cell.setCellValue(i + 1);
                    continue;
                }
                // 判断要获取的属性名是否包含.
                if(property[j - 1].indexOf(".") == -1){
                    // 不包含
                    Field field = coll.get(i).getClass()
                            .getDeclaredField(property[j - 1]);
                    // 设置对象的访问权限，保证对private的属性的访问
                    field.setAccessible(true);
                    Object o = field.get(coll.get(i));
                    cell.setCellValue(o + "");
                }else{
                    // 包含
                    Field field = coll.get(i).getClass()
                            .getDeclaredField(property[j - 1].substring(0, property[j - 1].lastIndexOf(".")));
                    // 设置对象的访问权限，保证对private的属性的访问
                    field.setAccessible(true);
                    Object o = field.get(coll.get(i));
                    // 判断是否属于基本数据类型，或是否包含.
                    if(!typeDict(o) && property[j - 1].indexOf(".") != -1){
                        String value = getFieldValue(o, property[j - 1]);
                        cell.setCellValue(value + "");
                        continue;
                    }
                    cell.setCellValue(o + "");
                }
            }
        }
        OutputStream fileOut = null;
        try {
            fileOut = new FileOutputStream("D:\测试."
                    + suffix.toString().toLowerCase());
            wb.write(fileOut);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fileOut != null) {
                try {
                    wb.close();
                    fileOut.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            if (wb != null) {
                try {
                    wb.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
    
    /**
     * 
     * @Description: 获取字段值
     * @param @param obj 对象
     * @param @param field 获取的字段名
     * @param @return
     * @return String
     * @throws
     */
    public static String getFieldValue(Object obj, String field){
        // 截取字段名，只支持一级，obj -> obj， 
        try {
            String fname = field.substring(field.lastIndexOf(".") + 1,field.length());
            // 创建j++列
            Field d = obj.getClass().getDeclaredField(fname);
            // 设置对象的访问权限，保证对private的属性的访问
            d.setAccessible(true);
            Object o = d.get(obj);
            return o + "";
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static boolean typeDict(Object obj){
        Class<?>[] clazzs = {int.class,short.class,double.class,
                float.class,byte.class,long.class,char.class,boolean.class,
                String.class,Double.class,Float.class,Integer.class,Long.class,
                Short.class,Boolean.class,Character.class,Byte.class,BigDecimal.class};
        
        for (Class<?> c : clazzs) {
            if(obj.getClass().isAssignableFrom(c)){
                return true;
            }
        }
        return false;
    }

}

enum PoiType {
    XLS, XLSX;
}

class Person {

    private int id;
    private String title;
    private String name;
    private String weight;
    private Student student;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getWeight() {
        return weight;
    }

    public void setWeight(String weight) {
        this.weight = weight;
    }

    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }

}

class Student {
    private String xx;

    public String getXx() {
        return xx;
    }

    public void setXx(String xx) {
        this.xx = xx;
    }
}

解释：

　　自动生成序号，title为标题，property为改标题下需要显示的对象属性名与对象属性名一一对应,只支持嵌套一级对象，对象->对象，由于是直接根据属性名获取值所以存在在get里写逻辑无效的问题，后期更改！