序言
有一个新的需求，前端提供下载的入口，后端能将指定了全路径的各种文件格式的文件下载到浏览器。
对于压缩的zip文件格式需要解析后写入到txt文件格式的文件中，其他的写入原本的文件格式的文件中。
1、连接ftp
<!-- jsch-sftp连接 -->
<dependency>
<groupId>com.jcraft</groupId>
<artifactId>jsch</artifactId>
<version>0.1.54</version>
</dependency>
@Slf4j
public class SftpUtil {
public static ChannelSftp login(String userName, String host, String port, String password) throws JSchException {
Session session;
Channel channel;
JSch jSch = new JSch();
try {
session = jSch.getSession(userName, host, Integer.parseInt(port));
session.setPassword(password);
// 配置链接的属性
Properties properties = new Properties();
properties.setProperty("StrictHostKeyChecking", "no");
session.setConfig(properties);
//设置超时时间：3分钟
session.setTimeout(180000);
// 进行sftp链接
session.connect();
// 获取通信通道
channel = session.openChannel("sftp");
channel.connect();
log.info("连接ftp成功，ftp信息为:userName:{}, host:{}, port:{}", userName, host, port);
} catch (JSchException e) {
log.error("连接ftp异常，异常信息：{}", e.getMessage());
return null;
}
return (ChannelSftp) channel;
}
}
2、设置不同文件格式的格式名和导出的文件格式的枚举类
import lombok.Getter;
/**
* @version 1.0
* @date 2024年08月22日 11:55
*/
@Getter
public enum FileFormatEnum {
XLSX(1001, "xlsx","xlsx"),
XLS(1002, "xls","xls"),
CSV(1003, "csv","csv"),
ZIP(1004, "zip","txt"),
TXT(1005, "txt","txt"),
NO_FORMAT(1007, "",""),
;
private final Integer code;
private final String value;
/**
* 解压或解密后的文件格式
**/
private final String parseFormat;
FileFormatEnum(Integer code, String value, String desc) {
this.code = code;
this.value = value;
this.parseFormat = desc;
}
}
3、读取各种类型的文件数据
3.1 通过监听器来读取大数据量的xls文件：
import com.google.common.collect.Lists;
import org.apache.poi.hssf.eventusermodel.*;
import org.apache.poi.hssf.eventusermodel.dummyrecord.LastCellOfRowDummyRecord;
import org.apache.poi.hssf.eventusermodel.dummyrecord.MissingCellDummyRecord;
import org.apache.poi.hssf.model.HSSFFormulaParser;
import org.apache.poi.hssf.record.*;
import org.apache.poi.hssf.record.Record;
import org.apache.poi.hssf.usermodel.HSSFDataFormatter;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
public class MyHSSFListener implements HSSFListener {
public MyHSSFListener(Integer readRowNum) {
this.readRowNum = readRowNum;
}
/**
* 当前行
*/
private final Integer readRowNum;
/**
* 是否输出formula，还是它对应的值
*/
private final boolean outputFormulaValues = true;
/**
* 用于转换formulas
*/
private EventWorkbookBuilder.SheetRecordCollectingListener workbookBuildingListener;
//excel2003工作簿
private HSSFWorkbook stubWorkbook;
private SSTRecord sstRecord;
private FormatTrackingHSSFListener formatListener;
private final HSSFDataFormatter formatter = new HSSFDataFormatter();
private BoundSheetRecord[] orderedBSRs;
private final List<BoundSheetRecord> boundSheetRecords = new ArrayList<>();
private boolean outputNextStringRecord;
//存储一行记录所有单元格的容器
private final List<String> cellList = Lists.newLinkedList();
/**
* 判断整行是否为空行的标记
*/
private boolean flag = false;
/**
* 遍历excel下所有的sheet
*/
public void process(InputStream inputStream) throws Exception {
POIFSFileSystem fs = new POIFSFileSystem(inputStream);
MissingRecordAwareHSSFListener listener = new MissingRecordAwareHSSFListener(this);
formatListener = new FormatTrackingHSSFListener(listener);
HSSFEventFactory factory = new HSSFEventFactory();
HSSFRequest request = new HSSFRequest();
if (outputFormulaValues) {
request.addListenerForAllRecords(formatListener);
} else {
workbookBuildingListener = new EventWorkbookBuilder.SheetRecordCollectingListener(formatListener);
request.addListenerForAllRecords(workbookBuildingListener);
}
factory.processWorkbookEvents(request, fs);
}
/**
* HSSFListener 监听方法，处理Record
* 处理每个单元格
* @param record 文件内容
*/
@Override
public void processRecord(Record record) {
int thisColumn;
String thisStr = null;
String value;
//当前行
switch (record.getSid()) {
case BoundSheetRecord.sid:
boundSheetRecords.add((BoundSheetRecord) record);
break;
case BOFRecord.sid: //开始处理每个sheet
BOFRecord br = (BOFRecord) record;
if (br.getType() == BOFRecord.TYPE_WORKSHEET) {
//如果有需要，则建立子工作簿
if (workbookBuildingListener != null && stubWorkbook == null) {
stubWorkbook = workbookBuildingListener.getStubHSSFWorkbook();
}
if (orderedBSRs == null) {
orderedBSRs = BoundSheetRecord.orderByBofPosition(boundSheetRecords);
}
}
break;
case SSTRecord.sid:
sstRecord = (SSTRecord) record;
break;
case BlankRecord.sid: //单元格为空白
BlankRecord brec = (BlankRecord) record;
thisColumn = brec.getColumn();
cellList.add(thisColumn, "");
break;
case BoolErrRecord.sid: //单元格为布尔类型
BoolErrRecord berec = (BoolErrRecord) record;
thisColumn = berec.getColumn();
thisStr = berec.getBooleanValue() + "";
cellList.add(thisColumn, thisStr);
checkRowIsNull(thisStr); //如果里面某个单元格含有值，则标识该行不为空行
break;
case FormulaRecord.sid://单元格为公式类型
FormulaRecord frec = (FormulaRecord) record;
thisColumn = frec.getColumn();
if (outputFormulaValues) {
if (Double.isNaN(frec.getValue())) {
outputNextStringRecord = true;
} else {
thisStr = '"' + HSSFFormulaParser.toFormulaString(stubWorkbook, frec.getParsedExpression()) + '"';
}
} else {
thisStr = '"' + HSSFFormulaParser.toFormulaString(stubWorkbook, frec.getParsedExpression()) + '"';
}
cellList.add(thisColumn, thisStr);
checkRowIsNull(thisStr); //如果里面某个单元格含有值，则标识该行不为空行
break;
case StringRecord.sid: //单元格中公式的字符串
if (outputNextStringRecord) {
outputNextStringRecord = false;
}
break;
case LabelRecord.sid:
LabelRecord lrec = (LabelRecord) record;
thisColumn = lrec.getColumn();
value = lrec.getValue().trim();
value = value.equals("") ? "" : value;
cellList.add(thisColumn, value);
checkRowIsNull(value); //如果里面某个单元格含有值，则标识该行不为空行
break;
case LabelSSTRecord.sid: //单元格为字符串类型
LabelSSTRecord lsrec = (LabelSSTRecord) record;
thisColumn = lsrec.getColumn();
if (sstRecord == null) {
cellList.add(thisColumn, "");
} else {
value = sstRecord.getString(lsrec.getSSTIndex()).toString().trim();
value = value.equals("") ? "" : value;
cellList.add(thisColumn, value);
checkRowIsNull(value); //如果里面某个单元格含有值，则标识该行不为空行
}
break;
case NumberRecord.sid: //单元格为数字类型
NumberRecord numrec = (NumberRecord) record;
thisColumn = numrec.getColumn();
//参照formatNumberDateCell里面的实现方法编写
double valueDouble = numrec.getValue();
String formatString = formatListener.getFormatString(numrec);
if (formatString.contains("m/d/yy")){
formatString="yyyy-MM-dd hh:mm:ss";
}
int formatIndex = formatListener.getFormatIndex(numrec);
value = formatter.formatRawCellContents(valueDouble, formatIndex, formatString).trim();
value = value.equals("") ? "" : value;
//向容器加入列值
cellList.add(thisColumn, value);
checkRowIsNull(value); //如果里面某个单元格含有值，则标识该行不为空行
break;
default:
break;
}
//空值的操作
if (record instanceof MissingCellDummyRecord) {
MissingCellDummyRecord mc = (MissingCellDummyRecord) record;
thisColumn = mc.getColumn();
cellList.add(thisColumn, "");
}
//行结束时的操作
if (record instanceof LastCellOfRowDummyRecord) {
int rowNum = ((LastCellOfRowDummyRecord) record).getRow();
//有些地方只需要读取前10行，根据MyHSSFListener构造中传过来的readRowNum来判断是否继续把读到的数据放到集合中
if (rowNum >= 0 && Objects.nonNull(readRowNum) && rowNum >= readRowNum) {
return;
}
if (flag) {
ExcelForXlsRowListUtil.sendRows(cellList);
}
//清空容器
cellList.clear();
flag = false;
}
}
/**
* 如果里面某个单元格含有值，则标识该行不为空行
* @param value 数据值
*/
public void checkRowIsNull(String value){
if (value != null && !"".equals(value)) {
flag = true;
}
}
}
3.2 将监听类读取到的每行数据放到新的集合中：
public class ExcelForXlsRowListUtil {
public static List<List<String>> rowList = new ArrayList<>();
public static void sendRows(List<String> cellList) {
rowList.add(new ArrayList<>(cellList));
}
public static List<List<String>> getRowList() {
return rowList;
}
}
3.3 读取xlsx，xls以及csv文件格式的工具类：
@Slf4j
public class ExcelReadUtil {
/**
* <p>
* 通过输入流创建workbook，单独调用记得关闭流（上面通过try()的方式会自动关闭流，因为他们实现了AutoCloseble）
* </p>
* @param inputStream excel文件流
* @return Workbook对象
*/
public static Workbook getWorkbookByInputStream(InputStream inputStream) {
try {
return StreamingReader.builder()
.rowCacheSize(5000) //缓存到内存中的行数，默认是10
.bufferSize(4096) //读取资源时，缓存到内存的字节大小，默认是1024
.open(inputStream);//打开资源，必须，可以是InputStream或者是File，注意：只能打开XLSX格式的文件
} catch (Exception e) {
log.error("通过输入流创建workbook异常，异常信息为:{}", e.getMessage());
}
return null;
}
/**
* 读取xlsx文件流的数据后并写入新的workbook中
* @param inputStream 文件流
* @date 2024/8/22 15:34
* @return Workbook
**/
public static Workbook getWorkbookForXlsx(InputStream inputStream) {
Workbook workbook = getWorkbookByInputStream(inputStream);
if (Objects.isNull(workbook)) {
log.error("读取xlsx文件流为空");
return null;
}
Workbook newWorkbook = null;
try {
newWorkbook = new XSSFWorkbook();
Sheet newSheet = newWorkbook.createSheet("Sheet1");
Sheet sheet = workbook.getSheetAt(0);
int i = 0;
for (Row row : sheet) {
Row newRow = newSheet.createRow(i);
int j = 0;
for (Cell cell : row) {
CellType cellType = cell.getCellType();
String cellValue = getCellValue(cellType, cell);
Cell newCell = newRow.createCell(j);
newCell.setCellValue(cellValue);
j++;
}
i++;
}
} catch (Exception e) {
log.error("读取xlsx文件异常，异常信息为:{}", e.getMessage());
}
return newWorkbook;
}
/**
* 读取xls文件流的数据
* @param inputStream 文件流
* @date 2024/8/22 11:30
* @return Workbook
**/
public static Workbook getWorkbookForXls(InputStream inputStream) {
MyHSSFListener excelXls = new MyHSSFListener(null);
Workbook workbook;
try {
excelXls.process(inputStream);
List<List<String>> rowList = ExcelForXlsRowListUtil.getRowList();
workbook = new HSSFWorkbook();
Sheet sheet = workbook.createSheet("Sheet1");
for (int i = 0; i < rowList.size(); i++) {
Row row = sheet.createRow(i);
List<String> cellDataList = rowList.get(i);
for (int j = 0; j < cellDataList.size(); j++) {
Cell cell = row.createCell(j);
cell.setCellValue(cellDataList.get(j));
}
}
} catch (Exception e) {
throw new ServiceException("读取xls文件异常，异常信息为:" + e.getMessage());
}
return workbook;
}
/**
* 读取csv文件流的数据内容
* @param inputStream 文件流
* @date 2024/8/22 11:40
* @return String
**/
public static String getFileDataForCsv(InputStream inputStream) {
StringBuilder data = new StringBuilder();
String CSV_ROW_SEPARATOR = System.lineSeparator();
try (CSVReader reader = new CSVReader(new InputStreamReader(inputStream,"GB2312"))) {
String[] line;
while ((line = reader.readNext()) != null) {
String join = String.join(",", line);
data.append(join).append(CSV_ROW_SEPARATOR);
}
} catch (IOException | CsvValidationException e) {
throw new ServiceException("导出csv文件异常，异常信息为:" + e.getMessage());
}
return data.toString();
}
}
}
3.4 读取zip文件的数据内容（无需解压到本地）
@Slf4j
public class ZipReadUtil {
/**
* 读取未加密的zip文件流数据
* @param inputStream 文件流
* @date 2024/8/22 11:36
* @return data
**/
public static String getFileDataForZIP(InputStream inputStream) {
ZipInputStream zipInputStream = new ZipInputStream(inputStream, StandardCharsets.UTF_8);
ZipEntry zipEntry;
String data = "";
try {
while ((zipEntry = zipInputStream.getNextEntry()) != null) {
if (!zipEntry.isDirectory() && zipEntry.getName().toLowerCase().endsWith(".txt")) {
long size = zipEntry.getSize();
if (size == -1) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
while (true) {
int bytes = zipInputStream.read();
if (bytes == -1) {
break;
}
baos.write(bytes);
data = baos.toString();
}
baos.close();
}
}
}
} catch (IOException e) {
throw new ServiceException("获取zip文件异常，异常信息为:" + e.getMessage());
}
return data;
}
}
3.5 读取txt和无后缀的文件格式的文件内容
@Slf4j
public class TXTAndNoSuffixReadUtil {
/**
* 读取txt文件或无后缀文件流的内容
* @param inputStream 文件流
* @date 2024/8/22 11:39
* @return String
**/
public static String getFileData(InputStream inputStream) {
//无格式文件和txt的读取方式一样
StringBuilder data = new StringBuilder();
try (InputStreamReader reader = new InputStreamReader(inputStream)) {
BufferedReader bufferedReader = new BufferedReader(reader);
String line;
while ((line = bufferedReader.readLine()) != null) {
data.append(line).append(System.lineSeparator());
}
} catch (IOException e) {
throw new ServiceException("对无后缀文件时异常:" + e.getMessage());
}
return data.toString();
}
}
4、文件导出到浏览器的工具类
import com.tr.common.exception.ServiceException;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.apache.poi.ss.usermodel.Workbook;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.Objects;
/**
* @version 1.0
* @date 2024年08月22日 11:32
*/
@Slf4j
public class ExportFileUtil {
/**
* 导出excel文件到浏览器
* @param response 响应
* @param fileName 文件名
* @param workbook workbook
* @date 2024/8/21 17:23
**/
public static void browserDownloadForExcel(HttpServletResponse response, String fileName, Workbook workbook) {
if (Objects.isNull(workbook)) {
throw new ServiceException("要导出的excel文件数据为空，文件名为:" + fileName);
}
try (OutputStream outputStream = response.getOutputStream()) {
response.reset();
response.setContentType("application/octet-stream; charset=utf-8");
response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(fileName, "UTF-8"));
workbook.write(outputStream);
} catch (IOException e) {
log.error(e.getMessage());
} finally {
try {
workbook.close();
} catch (IOException e) {
log.error(e.getMessage());
}
}
}
/**
* 导出txt文件到浏览器
* @param response 响应
* @param fileName 文件名
* @param text 文件内容
* @date 2024/8/21 17:26
**/
public static void browserDownloadForTxt(HttpServletResponse response, String fileName, String text) {
if (StringUtils.isBlank(text)) {
throw new ServiceException("要导出的数据为空，文件名为:" + fileName);
}
try {
response.setCharacterEncoding("utf-8");
//设置响应的内容类型
response.setContentType("text/plain");
//设置名称格式，没有这个中文名称无法显示
response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(fileName, "UTF-8"));
} catch (UnsupportedEncodingException e) {
log.error(e.getMessage());
}
BufferedOutputStream buff = null;
ServletOutputStream outStr = null;
try {
outStr = response.getOutputStream();
buff = new BufferedOutputStream(outStr);
buff.write(text.getBytes(StandardCharsets.UTF_8));
buff.flush();
buff.close();
} catch (Exception e) {
throw new ServiceException("导出文件文件出错:" + e.getMessage());
} finally {
try {
if (buff != null) {
buff.close();
}
if (outStr != null) {
outStr.close();
}
} catch (Exception e) {
log.error("关闭流对象出错:" + e.getMessage());
}
}
}
}
这里需要注意：由于有些文件是有中文名的，所以需要后端通过使用 URLEncoder 将汉字编码为 URL 兼容的格式。前端使用 decodeURIcomponent 将从后端接收到的编码字符串解码为原始汉字。
5、下载的service接口
/**
* @version 1.0
* @date 2024年08月21日 15:20
*/
public interface FileDownLoadService {
void downloadFile(Long filesaveId, String filePath, HttpServletResponse response);
}
6、下载的service实现类
@Slf4j
@Service
@RequiredArgsConstructor
public class FileDownLoadServiceImpl implements FileDownLoadService {
@Override
public void downloadFile(FTPConfig ftpConfig,String filePath,String sourceFileFormat, HttpServletResponse response) {
String fullFileName = filePath.substring(filePath.lastIndexOf("/") + 1);//获取文件名+文件格式
String fileName = filePath.substring(filePath.lastIndexOf("/") + 1, filePath.lastIndexOf(".") + 1);//只要文件名，去掉文件后缀
ChannelSftp channelSftp;
//连接sftp，读取要写入数据库的文件全路径列表
try {
channelSftp = SftpUtil.login(ftpConfig.getFtpUser(), ftpConfig.getFtpHost(), ftpConfig.getFtpPort(),ftpConfig.getFtpPassword());
} catch (JSchException e) {
throw new ServiceException("连接ftp异常，异常信息为:" + e.getMessage());
}
InputStream inputStream = null;
try {
inputStream = channelSftp.get(filePath);
if (Objects.equals(FileFormatEnum.XLSX.getValue(), sourceFileFormat)) {
Workbook workbook = ExcelReadUtil.getWorkbookForXlsx(inputStream);
ExportFileUtil.browserDownloadForExcel(response, fullFileName, workbook);
try {
if (workbook != null) {
workbook.close();
}
} catch (IOException e) {
log.error("关闭流异常，异常信息为:{}", e.getMessage());
}
} else if (Objects.equals(FileFormatEnum.XLS.getValue(), sourceFileFormat)) {
Workbook workbook = ExcelReadUtil.getWorkbookForXls(inputStream);
ExportFileUtil.browserDownloadForExcel(response, fullFileName, workbook);
try {
workbook.close();
} catch (IOException e) {
log.error("关闭流异常，异常信息为:{}", e.getMessage());
}
} else if (Objects.equals(FileFormatEnum.ZIP.getValue(), sourceFileFormat)) {
String data = ZipReadUtil.getFileDataForNoSecret(inputStream);
ExportFileUtil.browserDownloadForTxt(response, fileName + FileFormatEnum.ZIP.getParseFormat(), data);
} else if (Objects.equals(FileFormatEnum.NO_FORMAT.getValue(), sourceFileFormat)
|| Objects.equals(FileFormatEnum.TXT.getValue(), sourceFileFormat)) {
String data = TXTAndNoSuffixReadUtil.getFileData(inputStream);
ExportFileUtil.browserDownloadForTxt(response, fullFileName, data);
} else if (Objects.equals(FileFormatEnum.CSV.getValue(), sourceFileFormat)) {
String data = ExcelReadUtil.getFileDataForCsv(inputStream);
ExportFileUtil.browserDownloadForTxt(response, fullFileName, data);
}
} catch (SftpException e) {
throw new ServiceException("ftp获取文件异常，异常信息为:" + e.getMessage());
} finally {
if (Objects.nonNull(inputStream)) {
try {
inputStream.close();
} catch (IOException e) {
log.error("关闭文件流失败, 异常信息为: {}", e.getMessage());
}
}
if (sftp != null) {
if (sftp.isConnected()) {
sftp.disconnect(); //若sftp正在连接，则断开
}
}
}
}
7、下载的controller
import com.tr.common.exception.ServiceException;
import com.tr.itom.service.FileDownLoadService;
import io.swagger.annotations.ApiOperation;
import io.swagger.v3.oas.annotations.tags.Tag;
import lombok.RequiredArgsConstructor;
import org.apache.commons.lang3.StringUtils;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletResponse;
import javax.validation.constraints.NotNull;
import java.util.Objects;
/**
* @author FanHuiFang
* @version 1.0
* @date 2024年08月21日 15:19
*/
@Tag(name = "文件下载", description = "文件下载")
@RequiredArgsConstructor
@RestController
@RequestMapping("/file")
public class FileDownLoadController {
private final FileDownLoadService fileDownLoadService;
@ApiOperation("文件下载")
@PostMapping(value = "/download")
public void downloadFile(@NotNull Long filesaveId, @NotNull String filePath, HttpServletResponse response) {
if (Objects.isNull(filesaveId) || StringUtils.isBlank(filePath)) {
throw new ServiceException("规则id或文件路径不允许为空!");
}
fileDownLoadService.downloadFile(filesaveId, filePath, response);
}
}
-----------------------你知道的越多，不知道的越多--------------------------
