使用easyexcel导出入excel

• 使用easyexcel导出excel
• • easyexcel简介
  • 使用easyexcel
  • • 1.导入依赖
    • 2.工具类
    • • ①FileUtils：作为文件处理
      • ②字符串工具类StringUtils
      • ③数据转换类（防止数据过大失真）ExcelBigNumberConvert
    • 3.ExcelUtils
    • 4.创建（修改）导出对象模板类
    • 测试
• 使用easyexcel导入excel

Java解析、生成Excel比较有名的框架有Apache poi、jxl。但他们都存在一个严重的问题就是非常的耗内存，poi有一套SAX模式的API可以一定程度的解决一些内存溢出的问题，但POI还是有一些缺陷，比如07版Excel解压缩以及解压后存储都是在内存中完成的，内存消耗依然很大。easyexcel重写了poi对07版Excel的解析，一个3M的excel用POI sax解析依然需要100M左右内存，改用easyexcel可以降低到几M，并且再大的excel也不会出现内存溢出；03版依赖POI的sax模式，在上层做了模型转换的封装，让使用者更加简单方便

        
            cn.hutool
            hutool-all
            5.7.14
        
				//easyexcel主要依赖
        
            com.alibaba
            easyexcel
            3.0.5
        
        
        
            org.projectlombok
            lombok
            true
       

import cn.hutool.core.io.FileUtil;
import lombok.AccessLevel;
import lombok.NoArgsConstructor;

import javax.servlet.http.HttpServletResponse;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;


@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class FileUtils extends FileUtil {

    
    public static void setAttachmentResponseHeader(HttpServletResponse response, String realFileName) throws UnsupportedEncodingException {
        String percentEncodedFileName = percentEncode(realFileName);

        StringBuilder contentDispositionValue = new StringBuilder();
        contentDispositionValue.append("attachment; filename=")
            .append(percentEncodedFileName)
            .append(";")
            .append("filename*=")
            .append("utf-8''")
            .append(percentEncodedFileName);

        response.addHeader("Access-Control-Allow-Origin", "*");
        response.addHeader("Access-Control-Expose-Headers", "Content-Disposition,download-filename");
        response.setHeader("Content-disposition", contentDispositionValue.toString());
        response.setHeader("download-filename", percentEncodedFileName);
    }

    
    public static String percentEncode(String s) throws UnsupportedEncodingException {
        String encode = URLEncoder.encode(s, StandardCharsets.UTF_8.toString());
        return encode.replaceAll("\+", "%20");
    }
}

import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.lang.Validator;
import cn.hutool.core.util.StrUtil;
import lombok.AccessLevel;
import lombok.NoArgsConstructor;
import org.springframework.util.AntPathMatcher;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;


@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class StringUtils extends org.apache.commons.lang3.StringUtils {

	
	public static String blankToDefault(String str, String defaultValue) {
		return StrUtil.blankToDefault(str, defaultValue);
	}

	
	public static boolean isEmpty(String str) {
		return StrUtil.isEmpty(str);
	}

	
	public static boolean isNotEmpty(String str) {
		return !isEmpty(str);
	}

	
	public static String trim(String str) {
		return StrUtil.trim(str);
	}

	
	public static String substring(final String str, int start) {
		return substring(str, start, str.length());
	}

	
	public static String substring(final String str, int start, int end) {
		return StrUtil.sub(str, start, end);
	}

	
	public static String format(String template, Object... params) {
		return StrUtil.format(template, params);
	}

	
	public static boolean ishttp(String link) {
		return Validator.isUrl(link);
	}

	
	public static Set str2Set(String str, String sep) {
		return new HashSet<>(str2List(str, sep, true, false));
	}

	
	public static List str2List(String str, String sep, boolean filterBlank, boolean trim) {
		List list = new ArrayList<>();
		if (isEmpty(str)) {
			return list;
		}

		// 过滤空白字符串
		if (filterBlank && isBlank(str)) {
			return list;
		}
		String[] split = str.split(sep);
		for (String string : split) {
			if (filterBlank && isBlank(string)) {
				continue;
			}
			if (trim) {
				string = trim(string);
			}
			list.add(string);
		}

		return list;
	}

	
	public static boolean containsAnyIgnoreCase(CharSequence cs, CharSequence... searchCharSequences) {
		return StrUtil.containsAnyIgnoreCase(cs, searchCharSequences);
	}

	
	public static String toUnderScoreCase(String str) {
		return StrUtil.toUnderlineCase(str);
	}

	
	public static boolean inStringIgnoreCase(String str, String... strs) {
		return StrUtil.equalsAnyIgnoreCase(str, strs);
	}

	
	public static String convertToCamelCase(String name) {
		return StrUtil.upperFirst(StrUtil.toCamelCase(name));
	}

	
	public static String toCamelCase(String s) {
		return StrUtil.toCamelCase(s);
	}

	
	public static boolean matches(String str, List strs) {
		if (isEmpty(str) || CollUtil.isEmpty(strs)) {
			return false;
		}
		for (String pattern : strs) {
			if (isMatch(pattern, str)) {
				return true;
			}
		}
		return false;
	}

	
	public static boolean isMatch(String pattern, String url) {
		AntPathMatcher matcher = new AntPathMatcher();
		return matcher.match(pattern, url);
	}

	@SuppressWarnings("unchecked")
	public static  T cast(Object obj) {
		return (T) obj;
	}
}

import cn.hutool.core.convert.Convert;
import cn.hutool.core.util.ObjectUtil;
import com.alibaba.excel.converters.Converter;
import com.alibaba.excel.enums.CellDataTypeEnum;
import com.alibaba.excel.metadata.GlobalConfiguration;
import com.alibaba.excel.metadata.property.ExcelContentProperty;
import lombok.extern.slf4j.Slf4j;
import com.alibaba.excel.metadata.data.ReadCellData;
import com.alibaba.excel.metadata.data.WriteCellData;
import java.math.BigDecimal;


@Slf4j
public class ExcelBigNumberConvert implements Converter {

    @Override
    public Class supportJavaTypeKey() {
        return Long.class;
    }

    @Override
    public CellDataTypeEnum supportExcelTypeKey() {
        return CellDataTypeEnum.STRING;
    }

    @Override
    public Long convertToJavaData(ReadCellData cellData, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) {
        return Convert.toLong(cellData.getData());
    }

    @Override
    public WriteCellData