做网站建设还有钱赚吗,小程序模板教程,深圳快速网站制作哪里好,wordpress菜单的作用一、前言 最近项目中需要实现这样一个功能#xff0c;就是从本地读取CSV文件#xff0c;并以指定行作为标题行#xff0c;指定行开始作为数据读取行#xff0c;读取数据并返回给前端#xff0c;下面具体说下是如何通过java实现。
二、如何实现#xff1f; 1.引入相关mav…一、前言 最近项目中需要实现这样一个功能就是从本地读取CSV文件并以指定行作为标题行指定行开始作为数据读取行读取数据并返回给前端下面具体说下是如何通过java实现。
二、如何实现 1.引入相关maven依赖
dependencygroupIdcn.hutool/groupIdartifactIdhutool-all/artifactId
/dependency2.定义一个工具类CsvUtils。
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.collection.CollectionUtil;
import cn.hutool.core.collection.IterUtil;
import cn.hutool.core.text.csv.CsvData;
import cn.hutool.core.text.csv.CsvReader;
import cn.hutool.core.text.csv.CsvRow;
import cn.hutool.core.text.csv.CsvUtil;import cn.hutool.core.util.ReUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import java.io.*;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
public class CsvUtils {public static final String FIELD_NAMEcolumn;public static ListMapString, Object getCsvFileContent(InputStream in, Long readLine, int headerRowIndex, int readCount,String splitChar) throws IOException {InputStreamReader is null;CsvReader reader null;InputStream bufferedInputStreamOne null;InputStream bufferedInputStreamTwo null;ByteArrayOutputStream baos null;try {if (in null) {throw new FileStorageRuntimeException(文件读取失败文件不存在);}if (readLine null){readLine 2l;}ListMapString, Object resList new ArrayList();reader CsvUtil.getReader();baos new ByteArrayOutputStream();byte[] buffer new byte[1024*10];int len;while ((len in.read(buffer)) -1 ) {baos.write(buffer, 0, len);}baos.flush();bufferedInputStreamOnenew ByteArrayInputStream(baos.toByteArray());bufferedInputStreamTwonew ByteArrayInputStream(baos.toByteArray());boolean isUtf8checkUTF8(bufferedInputStreamOne);//从文件中读取CSV数据is new InputStreamReader(bufferedInputStreamTwo,Charset.forName(isUtf8 ? UTF-8:GBK));reader.setFieldSeparator(splitChar.charAt(0));reader.setSkipEmptyRows(false);CsvData data reader.read(is);ListCsvRow rows data.getRows();//空表格if (rows.isEmpty()) {return null;}ListString headRowList new ArrayList();if (headerRowIndex 0 rows.size()headerRowIndex - 1){//获取表头headRowList rows.get(headerRowIndex - 1).getRawList();}else {if (CollectionUtil.isNotEmpty(rows)){ListString rowListrows.get(0).getRawList();for(int i1;irowList.size();i) {headRowList.add(FIELD_NAMEi);}}}ListString headListnew ArrayList();for (int i0;iheadRowList.size();i) {String fieldName headRowList.get(i);if (StrUtil.isBlank(fieldName )) {headList.add(FIELD_NAME(i1));}else {headList.add(fieldName);}}if (CollUtil.isNotEmpty(rows)){CsvRow currCsvRow rows.get(0);if (headList.size() ! currCsvRow.getRawList().size()) {throw new FileStorageRuntimeException(列数量与数据数量不一致);}}if (readLine1) {//加上一行ListString addRawListNew headRowList.stream().map(s - StrUtil.trim(s)).collect(Collectors.toList());Map map IterUtil.toMap(headList, (Iterable) addRawListNew,true);resList.add(map);}//遍历行for (int i (int)((long)readLine)-1; i rows.size(); i) {CsvRow csvRow rows.get(i);//getRawList返回一个List列表列表的每一项为CSV中的一个单元格既逗号分隔部分ListString rawList csvRow.getRawList();ListString rawListNew rawList.stream().map(s - StrUtil.trim(s)).collect(Collectors.toList());Map map IterUtil.toMap(headList, (Iterable) rawListNew,true);resList.add(map);if(readCount0 ireadCount){break;}}return resList;} catch (Exception e) {e.printStackTrace();throw new RuntimeException(get inputStreamReader failed);} finally {if (in!null){in.close();}if (is!null){is.close();}if (reader!null){reader.close();}if(bufferedInputStreamTwo !null){bufferedInputStreamTwo.close();}if(bufferedInputStreamOne !null){bufferedInputStreamOne.close();}if (baos!null){baos.close();}}}/*** 判断文件内容是否为 UTF-8 编码* author*/public static boolean checkUTF8(InputStream fis) {//请注意fis是流是不能复用的try {while (true) {int curr fis.read();if (curr -1) {return true;}if (curr 0x80) {// (10000000): 值小于0x80的为ASCII字符} else if (curr (0xC0)) { // (11000000): 值介于0x80与0xC0之间的为无效UTF-8字符return false;} else if (curr (0xE0)) { // (11100000): 此范围内为2字节UTF-8字符if ((fis.read() (0xC0)) ! 0x80) {return false;}return true;} else if (curr (0xF0)) { // (11110000): 此范围内为3字节UTF-8字符if ((fis.read() (0xC0)) ! 0x80 || (fis.read() (0xC0)) ! 0x80) {return false;}return true;} else {return false;}}} catch (IOException e) {return true;}}}接着通过main方法调用下。 public static void main(String[] args) throws IOException {FileInputStream inputStream new FileInputStream(new File(D:\\111.csv));ListMapString, Object listgetCsvFileContent(inputStream,2l,1,50,,);System.err.println(list);}结果如下 其中readCount表示返回的数据数量。
