读取Java中上传的文件的内容 [英] read the contents of a file upload in java
本文介绍了读取Java中上传的文件的内容的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我知道如何上传文件
<html>
<head>
<title>File Uploading Form</title>
</head>
<body>
<form action="UploadServlet" method="post"
enctype="multipart/form-data">
File :<input type="file" name="file" size="50" />
<input type="submit" value="Upload File"/>
</form>
</body>
</html>
这是用于读取文件的类:
This is the class for reading the file:
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class BufferedReaderExample {
public static void main(String[] args) {
try (BufferedReader br = new BufferedReader(new FileReader("C:\\testing.txt")))
{
String sCurrentLine;
while ((sCurrentLine = br.readLine()) != null) {
System.out.println(sCurrentLine);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
现在如何将这两个链接在一起.用户将文件上传到服务器上，然后服务器对其进行处理.即，它接受文件并打印其内容.我可以为此使用struts框架吗?我想上传Excel工作表并将内容打印到jsp页面.我有使用apache poi在Java中读取Excel工作表的代码.但是读取excel文件的路径是硬编码的.您如何从上传的文件中获取它?
Now how do you link both these together. The user uploads the file onto the server and the server processes it. i.e., it accepts the file and prints it contents. Can I use struts framework for this? I want to upload excel sheet and print the contents to the jsp page. I have the code for reading the excel sheet in java using apache poi. But the path to read the excel file is hard coded. how do you take it from the uploaded file?
这是用于读取Excel工作表的文件:
This is the file for reading excel sheet:
public class ReadExcelDemo
{
public static void main(String[] args)
{
try
{
FileInputStream file = new FileInputStream(new File("howtodoinjava_demo.xlsx"));
//Create Workbook instance holding reference to .xlsx file
XSSFWorkbook workbook = new XSSFWorkbook(file);
//Get first/desired sheet from the workbook
XSSFSheet sheet = workbook.getSheetAt(0);
//Iterate through each rows one by one
Iterator<Row> rowIterator = sheet.iterator();
while (rowIterator.hasNext())
{
Row row = rowIterator.next();
//For each row, iterate through all the columns
Iterator<Cell> cellIterator = row.cellIterator();
while (cellIterator.hasNext())
{
Cell cell = cellIterator.next();
//Check the cell type and format accordingly
switch (cell.getCellType())
{
case Cell.CELL_TYPE_NUMERIC:
System.out.print(cell.getNumericCellValue() + "t");
break;
case Cell.CELL_TYPE_STRING:
System.out.print(cell.getStringCellValue() + "t");
break;
}
}
System.out.println("");
}
file.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
输出:
ID NAME LASTNAME
1.0阿米特(Amit Shukla)
2.0 Lokesh Gupta
3.0 John Adwards
4.0布赖恩·舒尔茨
ID NAME LASTNAME
1.0 Amit Shukla
2.0 Lokesh Gupta
3.0 John Adwards
4.0 Brian Schultz
但是如何将上传的文件和servlet文件缝合在一起.您如何阅读上传的文件?
But how do you stitch the uploaded and the servlet file together. How do you read the uploaded file?
推荐答案
我明白了.索引文件(html)用于上传文件(如我的qquestion所述) 它的Java类是:
I got it. The index file(html) is for uploading the file (as above in my qquestion) The java class for it is:
import java.io.*;
import java.util.*;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.output.*;
public class UploadServlet extends HttpServlet {
private boolean isMultipart;
private String filePath;
private int maxFileSize = 50 * 1024;
private int maxMemSize = 4 * 1024;
private File file ;
public void init( ){
// Get the file location where it would be stored.
filePath =
getServletContext().getInitParameter("file-upload");
}
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, java.io.IOException {
// Check that we have a file upload request
isMultipart = ServletFileUpload.isMultipartContent(request);
response.setContentType("text/html");
java.io.PrintWriter out = response.getWriter( );
if( !isMultipart ){
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet upload</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>No file uploaded</p>");
out.println("</body>");
out.println("</html>");
return;
}
DiskFileItemFactory factory = new DiskFileItemFactory();
// maximum size that will be stored in memory
factory.setSizeThreshold(maxMemSize);
// Location to save data that is larger than maxMemSize.
factory.setRepository(new File("c:\\temp"));
// Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload(factory);
// maximum file size to be uploaded.
upload.setSizeMax( maxFileSize );
try{
// Parse the request to get file items.
List fileItems = upload.parseRequest(request);
// Process the uploaded file items
Iterator i = fileItems.iterator();
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet upload</title>");
out.println("</head>");
out.println("<body>");
String fileName = "";
while ( i.hasNext () )
{
FileItem fi = (FileItem)i.next();
if ( !fi.isFormField () )
{
// Get the uploaded file parameters
String fieldName = fi.getFieldName();
fileName = fi.getName();
String contentType = fi.getContentType();
boolean isInMemory = fi.isInMemory();
long sizeInBytes = fi.getSize();
// Write the file
if( fileName.lastIndexOf("\\") >= 0 ){
file = new File( filePath +
fileName.substring( fileName.lastIndexOf("\\"))) ;
}else{
file = new File( filePath +
fileName.substring(fileName.lastIndexOf("\\")+1)) ;
}
fi.write( file ) ;
out.println("Uploaded Filename: " + fileName + "<br>");
out.println("Uploaded in location: "+filePath);
}
}
out.println("</body>");
out.println("</html>");
ReadExcelDemo rd = new ReadExcelDemo();
System.out.println("file name: "+fileName.substring(fileName.lastIndexOf("\\")));
String s = fileName.substring(fileName.lastIndexOf("\\"));
System.out.println(filePath);
System.out.println(s);
String fileP = filePath.concat(s+"\\");
System.out.println(fileP);
rd.read(fileP);
}catch(Exception ex) {
System.out.println(ex);
}
}
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, java.io.IOException {
throw new ServletException("GET method used with " +
getClass( ).getName( )+": POST method required.");
}
}
这是使用apache poi jars阅读Excel工作表的类:
This is the class for reading the excel sheet using apache poi jars:
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Iterator;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class ReadExcelDemo {
public static void read(String filePath) {
// public static void main(String[] args){
try {
FileInputStream file = new FileInputStream(new File(filePath));
// FileInputStream file = new FileInputStream(new File("C:\\work\\demo.xlsx"));
//Create Workbook instance holding reference to .xlsx file
XSSFWorkbook workbook = new XSSFWorkbook(file);
//Get first/desired sheet from the workbook
XSSFSheet sheet = workbook.getSheetAt(0);
//Iterate through each rows one by one
Iterator<Row> rowIterator = sheet.iterator();
while (rowIterator.hasNext()) {
Row row = rowIterator.next();
//For each row, iterate through all the columns
Iterator<Cell> cellIterator = row.cellIterator();
while (cellIterator.hasNext()) {
Cell cell = cellIterator.next();
//Check the cell type and format accordingly
switch (cell.getCellType()) {
case Cell.CELL_TYPE_NUMERIC: System.out.print(cell.getNumericCellValue() + "\t");
break;
case Cell.CELL_TYPE_STRING: System.out.print(cell.getStringCellValue() + "\t");
break;
}
}
System.out.println("");
}
/* int row=0;
int k=1;
Row myRow = sheet.createRow ((short)row);
myRow.createCell(k).setCellValue ("new data");
myRow = sheet.createRow ((short)row++); */
// Cell cell1 = sheet. // Access the second cell in second row to update the value
// cell1.setCellValue("OverRide Last Name");
Cell cell1 = null; // declare a Cell object
cell1 = sheet.getRow(2).getCell(2); // Access the second cell in second row to update the value
cell1.setCellValue("OverRide Last Name");
file.close();
/* FileOutputStream out = new FileOutputStream(new File("write_demo1.xlsx"));
workbook.write(out);
out.close(); */
}
catch (Exception e) {
e.printStackTrace();
}
}
}
这篇关于读取Java中上传的文件的内容的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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