用java读取文件上载的内容
我知道如何上传文件：用java读取文件上载的内容,java,file-upload,apache-poi,struts,Java,File Upload,Apache Poi,Struts,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=
<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>
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();
}
}
}
公共类ReadExcelDemo
{
公共静态void main（字符串[]args）
{
尝试
{
FileInputStream file=newfileinputstream（新文件（“howtodoinjava_demo.xlsx”）；
//创建包含对.xlsx文件引用的工作簿实例
XSSF工作簿=新XSSF工作簿（文件）；
//从工作簿中获取第一张/所需的工作表
XSSFSheet sheet=workbook.getSheetAt（0）；
//逐个遍历每一行
迭代器rowIterator=sheet.Iterator（）；
while（roweiterator.hasNext（））
{
行=行迭代器。下一步（）；
//对于每一行，遍历所有列
迭代器cellIterator=row.cellIterator（）；
while（cellIterator.hasNext（））
{
Cell=cellIterator.next（）；
//检查相应的单元格类型和格式
开关（cell.getCellType（））
{
case Cell.Cell\u类型\u数值：
System.out.print（cell.getNumericCellValue（）+“t”）；
打破
case Cell.Cell\u类型\u字符串：
System.out.print（cell.getStringCellValue（）+“t”）；
打破
}
}
System.out.println（“”）；
}
file.close（）；
}
捕获（例外e）
{
e、 printStackTrace（）；
}
}
}
3.0约翰·阿德沃兹 4.0布莱恩·舒尔茨
但是如何将上传的文件和servlet文件缝合在一起呢。如何读取上传的文件？与Java中的许多操作一样，读取上传的文件不必要地复杂，而且很难从javadocs中计算出来。 您已经计划使用Apache库来读取上载的文件，因此我建议您也使用Apache.commons.fileupload来上载文件 此代码片段将CSV文件上载到字符串中：
...
import org.apache.commons.fileupload.*;
import org.apache.commons.fileupload.disk.*;
import org.apache.commons.fileupload.servlet.*;
...
if (ServletFileUpload.isMultipartContent(request)) {
int i=0;
DiskFileItemFactory factory = new DiskFileItemFactory();
// files smaller than 5MB will be held in memory
factory.setSizeThreshold(5000000);
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setFileSizeMax(10000000); // max size of attachment 10MB
List list = upload.parseRequest(request);
Iterator iter = list.iterator();
String csv = null;
while (iter.hasNext()) {
FileItem param = (FileItem)iter.next();
if (!param.isFormField()) {
csv = param.getString();
break;
}
}
if (csv==null) {
throw new Exception("CSV buffer not uploaded");
}
}
您可以通过将整个过程分为两个步骤来实现 1） 上传文件
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
if (!isMultipart) {
return;
}
// Create a factory for disk-based file items
DiskFileItemFactory factory = new DiskFileItemFactory();
// Sets the size threshold beyond which files are written directly to
// disk.
factory.setSizeThreshold(MAX_MEMORY_SIZE);
// Sets the directory used to temporarily store files that are larger
// than the configured size threshold. We use temporary directory for
// java
factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
// constructs the folder where uploaded file will be stored
String uploadFolder = getServletContext().getRealPath("")
+ File.separator + DATA_DIRECTORY;
// Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload(factory);
// Set overall request size constraint
upload.setSizeMax(MAX_REQUEST_SIZE);
try {
// Parse the request
List items = upload.parseRequest(request);
Iterator iter = items.iterator();
while (iter.hasNext()) {
FileItem item = (FileItem) iter.next();
if (!item.isFormField()) {
String fileName = new File(item.getName()).getName();
String filePath = uploadFolder + File.separator + fileName;
File uploadedFile = new File(filePath);
System.out.println(filePath);
// saves the file to upload directory
item.write(uploadedFile);
}
}
// displays done.jsp page after upload finished
getServletContext().getRequestDispatcher("/done.jsp").forward(
request, response);
} catch (FileUploadException ex) {
throw new ServletException(ex);
} catch (Exception ex) {
throw new ServletException(ex);
}
File uploadedFile=新文件（filePath）对象以获取文件位置。我找到了。索引文件（html）用于上传文件（如我的问题中所述）
它的java类是：
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.");
}
}
import java.io.*；
导入java.util.*；
导入javax.servlet.ServletConfig；
导入javax.servlet.ServletException；
导入javax.servlet.http.HttpServlet；
导入javax.servlet.http.HttpServletRequest；
导入javax.servlet.http.HttpServletResponse；
导入org.apache.commons.fileupload.FileItem；
导入org.apache.commons.fileupload.FileUploadException；
导入org.apache.commons.fileupload.disk.DiskFileItemFactory；
导入org.apache.commons.fileupload.servlet.ServletFileUpload；
导入org.apache.commons.io.output.*；
公共类UploadServlet扩展了HttpServlet{
私有布尔是多重的；
私有字符串文件路径；
private int maxFileSize=50*1024；
私有整数maxmesize=4*1024；
私有文件；
公共void init（）{
//获取文件存储位置。
文件路径=
getServletContext（）.getInitParameter（“文件上载”）；
}
public void doPost（HttpServletRequest请求，
HttpServletResponse（响应）
抛出ServletException，java.io.IOException{
//检查我们是否有文件上传请求
isMultipart=ServletFileUpload.isMultipartContent（请求）；
response.setContentType（“text/html”）；
java.io.PrintWriter out=response.getWriter（）；
如果（！isMultipart）{
out.println（“”）；
out.println（“”）；
out.println（“Servlet上传”）；
out.println（“”）；
out.println（“”）；
out.println（“没有上传文件””；
out.println（“”）；
out.println（“”）；
返回；
}
DiskFileItemFactory=新的DiskFileItemFactory（）；
//将存储在内存中的最大大小
factory.setSizeThreshold（maxMemSize）；
//保存大于maxMemSize的数据的位置。
setRepository（新文件（“c:\\temp”）；
//创建新的文件上载处理程序
ServletFileUpload upload=新的ServletFileUpload（工厂）；
//要上载的最大文件大小。
upload.setSizeMax（maxFileSize）；
试试{
//解析请求以获取文件项。
List fileItems=upload.parseRequest（请求）；
//处理上载的文件项
迭代器i=fileItems.Iterator（）；
out.println（“”）；
out.println（“”）；
out.println（“Servlet上传”）；
out.println（“”）；
out.println（“”）；
字符串fileName=“”；
而（i.hasNext（））
{
FileItem fi=（FileItem）i.next（）；
如果（！fi.isFormField（））
{
//获取上传的文件参数
字符串fieldName=fi.getFieldName（）；
fileName=fi.getName（）；
字符串contentType=fi.getContentType（）；
布尔值isInMemory=fi.isInMemory（）；
long-sizeInBytes=fi.getSize（）；
//写文件
如果(
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.");
}
}
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();
}
}
}