On renaming and moving a file using java code,the contents of the file is removed.How to rename and move a file using java code without erasing the content
Please use below code, it can rename and copy the file into different folder
package han.code.development;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class FileRenameandMove
{
public static void main(String[] args) throws IOException
{
File file=new File("D:\\Haneef\\Stackoverflow\\files.txt");
FileReader fileR=new FileReader(file);
BufferedReader bufferedReader=new BufferedReader(fileR);
String str=bufferedReader.readLine();
FileWriter fileW=new FileWriter(new File("D:\\Haneef\\Stackoverflow\\Move\\File1.txt"));
fileW.write(str);
fileW.close();
}
}
try{
File afile =new File("C:\\Users\\Jen\\Downloads\\usage.csv");
File bfile =new File("C:\\Users\\Jen\\Desktop\\BJ\\");
inStream = new FileInputStream(afile);
outStream = new FileOutputStream(bfile + "\\"+ dd.get(j).getText()+ "_March _2018.csv");
Thread.sleep(1000);
byte[] buffer = new byte[1024];
int length;
//copy the file content in bytes
while ((length = inStream.read(buffer)) > 0){
outStream.write(buffer, 0, length);
}
inStream.close();
outStream.close();
// if file copied successfully then delete the original file
afile.delete();
System.out.println("File moved successfully");
}catch(IOException e){
e.printStackTrace();
}
}
I am trying to to extract files out of a nested zip archive and process them in memory.
What this question is not about:
How to read a zip file in Java: NO, the question is how to read a zip file within a zip file within a zip and so on and so forth (as in nested zip files).
Write temporary results on disk: NO, I'm asking about doing it all in memory. I found many answers using the not-so-efficient technique of writing results temporarily to disk, but that's not what I want to do.
Example:
Zipfile -> Zipfile1 -> Zipfile2 -> Zipfile3
Goal: extract the data found in each of the nested zip files, all in memory and using Java.
ZipFile is the answer, you say? NO, it is not, it works for the first iteration, that is for:
Zipfile -> Zipfile1
But once you get to Zipfile2, and perform a:
ZipInputStream z = new ZipInputStream(zipFile.getInputStream( zipEntry) ) ;
you will get a NullPointerException.
My code:
public class ZipHandler {
String findings = new String();
ZipFile zipFile = null;
public void init(String fileName) throws AppException{
try {
//read file into stream
zipFile = new ZipFile(fileName);
Enumeration<?> enu = zipFile.entries();
exctractInfoFromZip(enu);
zipFile.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
//The idea was recursively extract entries using ZipFile
public void exctractInfoFromZip(Enumeration<?> enu) throws IOException, AppException{
try {
while (enu.hasMoreElements()) {
ZipEntry zipEntry = (ZipEntry) enu.nextElement();
String name = zipEntry.getName();
long size = zipEntry.getSize();
long compressedSize = zipEntry.getCompressedSize();
System.out.printf("name: %-20s | size: %6d | compressed size: %6d\n",
name, size, compressedSize);
// directory ?
if (zipEntry.isDirectory()) {
System.out.println("dir found:" + name);
findings+=", " + name;
continue;
}
if (name.toUpperCase().endsWith(".ZIP") || name.toUpperCase().endsWith(".GZ")) {
String fileType = name.substring(
name.lastIndexOf(".")+1, name.length());
System.out.println("File type:" + fileType);
System.out.println("zipEntry: " + zipEntry);
if (fileType.equalsIgnoreCase("ZIP")) {
//ZipFile here returns a NULL pointer when you try to get the first nested zip
ZipInputStream z = new ZipInputStream(zipFile.getInputStream(zipEntry) ) ;
System.out.println("Opening ZIP as stream: " + name);
findings+=", " + name;
exctractInfoFromZip(zipInputStreamToEnum(z));
} else if (fileType.equalsIgnoreCase("GZ")) {
//ZipFile here returns a NULL pointer when you try to get the first nested zip
GZIPInputStream z = new GZIPInputStream(zipFile.getInputStream(zipEntry) ) ;
System.out.println("Opening ZIP as stream: " + name);
findings+=", " + name;
exctractInfoFromZip(gZipInputStreamToEnum(z));
} else
throw new AppException("extension not recognized!");
} else {
System.out.println(name);
findings+=", " + name;
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("Findings " + findings);
}
public Enumeration<?> zipInputStreamToEnum(ZipInputStream zStream) throws IOException{
List<ZipEntry> list = new ArrayList<ZipEntry>();
while (zStream.available() != 0) {
list.add(zStream.getNextEntry());
}
return Collections.enumeration(list);
}
I have not tried it but using ZipInputStream you can read any InputStream that contains a ZIP file as data. Iterate through the entries and when you found the correct entry use the ZipInputStreamto create another nestedZipInputStream`.
The following code demonstrates this. Imagine we have a readme.txt inside 0.zip which is again zipped in 1.zip which is zipped in 2.zip. Now we read some text from readme.txt:
try (FileInputStream fin = new FileInputStream("D:/2.zip")) {
ZipInputStream firstZip = new ZipInputStream(fin);
ZipInputStream zippedZip = new ZipInputStream(findEntry(firstZip, "1.zip"));
ZipInputStream zippedZippedZip = new ZipInputStream(findEntry(zippedZip, "0.zip"));
ZipInputStream zippedZippedZippedReadme = findEntry(zippedZippedZip, "readme.txt");
InputStreamReader reader = new InputStreamReader(zippedZippedZippedReadme);
char[] cbuf = new char[1024];
int read = reader.read(cbuf);
System.out.println(new String(cbuf, 0, read));
.....
public static ZipInputStream findEntry(ZipInputStream in, String name) throws IOException {
ZipEntry entry = null;
while ((entry = in.getNextEntry()) != null) {
if (entry.getName().equals(name)) {
return in;
}
}
return null;
}
Note the code is really ugly and does not close anything nor does it checks for errors. It is just a minimized version that demonstrates how it works.
Theoretically there is no limit how many ZipInputStreams you cascade into another. The data is never written into a temporary file. The decryption is only performed on-demand when you read each InputStream.
this is the way I found to unzip file in memory:
The code is not clean AT ALL, but i understand the rules are to post something working, so i have this hopefully to help so
What I do is use a recursive method to navigate the complex ZIP file and extract
folder
other inner zips
files
and save the results in memory to later work with them.
Main things I found I want to share with you:
1 ZipFile is useless if you have nested zip files
2 You have to use the basic Zip InputStream and Outputstream
3 I only use recursive programming to unzip nested zips
package course.hernan;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;
import org.apache.commons.io.IOUtils;
public class FileReader {
private static final int BUFFER_SIZE = 2048;
public static void main(String[] args) {
try {
File f = new File("DIR/inputs.zip");
FileInputStream fis = new FileInputStream(f);
BufferedInputStream bis = new BufferedInputStream(fis);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BufferedOutputStream bos = new BufferedOutputStream(baos);
byte[] buffer = new byte[BUFFER_SIZE];
while (bis.read(buffer, 0, BUFFER_SIZE) != -1) {
bos.write(buffer);
}
bos.flush();
bos.close();
bis.close();
//This STACK has the output byte array information
Deque<Map<Integer, Object[]>> outputDataStack = ZipHandler1.unzip(baos);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
package course.hernan;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.SortedMap;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import org.apache.commons.lang3.StringUtils;
public class ZipHandler1 {
private static final int BUFFER_SIZE = 2048;
private static final String ZIP_EXTENSION = ".zip";
public static final Integer FOLDER = 1;
public static final Integer ZIP = 2;
public static final Integer FILE = 3;
public static Deque<Map<Integer, Object[]>> unzip(ByteArrayOutputStream zippedOutputFile) {
try {
ZipInputStream inputStream = new ZipInputStream(
new BufferedInputStream(new ByteArrayInputStream(
zippedOutputFile.toByteArray())));
ZipEntry entry;
Deque<Map<Integer, Object[]>> result = new ArrayDeque<Map<Integer, Object[]>>();
while ((entry = inputStream.getNextEntry()) != null) {
LinkedHashMap<Integer, Object[]> map = new LinkedHashMap<Integer, Object[]>();
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
System.out.println("\tExtracting entry: " + entry);
int count;
byte[] data = new byte[BUFFER_SIZE];
if (!entry.isDirectory()) {
BufferedOutputStream out = new BufferedOutputStream(
outputStream, BUFFER_SIZE);
while ((count = inputStream.read(data, 0, BUFFER_SIZE)) != -1) {
out.write(data, 0, count);
}
out.flush();
out.close();
// recursively unzip files
if (entry.getName().toUpperCase().endsWith(ZIP_EXTENSION.toUpperCase())) {
map.put(ZIP, new Object[] {entry.getName(), unzip(outputStream)});
result.add(map);
//result.addAll();
} else {
map.put(FILE, new Object[] {entry.getName(), outputStream});
result.add(map);
}
} else {
map.put(FOLDER, new Object[] {entry.getName(), unzip(outputStream)});
result.add(map);
}
}
inputStream.close();
return result;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
Thanks to JMax.
In my case, The result of reading the pdf file is different from the expected result, It becomes bigger and cannot be opened.
Finally I found that I had made a mistake, The buffer may not be full，
The following is the error code.
while((n = zippedZippedZippedReadme.read(buffer)) != -1) {
fos.write(buffer);
}
Here is the correct code,
try (FileInputStream fin = new FileInputStream("1.zip")) {
ZipInputStream firstZip = new ZipInputStream(fin);
ZipInputStream zippedZip = new ZipInputStream(findEntry(firstZip, "0.zip"));
ZipInputStream zippedZippedZippedReadme = findEntry(zippedZip, "test.pdf");
long startTime = System.currentTimeMillis();
byte[] buffer = new byte[4096];
File outputFile = new File("test.pdf");
try (FileOutputStream fos = new FileOutputStream(outputFile)) {
int n;
while((n = zippedZippedZippedReadme.read(buffer)) != -1) {
fos.write(buffer, 0 ,n);
}
fos.flush();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("time consuming:" + (System.currentTimeMillis() - startTime)/1000.0);
}
hope to be helpful!
How to create zip inside zip file
enter image description here
got bellow Error:
D:\sagar\my work\Package Maker\DirectoryStruct>java zipStructure
java.io.FileNotFoundException: Additional_Sub_Folder\Additional_file.zip (The sy
stem cannot find the path specified)
at java.io.FileOutputStream.open(Native Method)
at java.io.FileOutputStream.<init>(FileOutputStream.java:221)
at java.io.FileOutputStream.<init>(FileOutputStream.java:110)
at zipStructure.main(zipStructure.java:22)
D:\sagar\my work\Package Maker\DirectoryStruct> that is Additional_sub_folder and Digital_sub_folder. inside Additional_sub_folder 1 zip file created(Additional_file.zip),inside that zip 2 folder are created like xml folder and pdf folder
and inside Digital_sub_folder create Artical_sub_folder,and inside Artical_sub_folder 3 new folder are created that is xml folder,pdf folder and Graphics folder. i try it be below java code but not works properly,please help to create the this structure.
import java.io.*;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.*;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
public class zipStructure {
public static void main(String[] args) {
try {
FileOutputStream fos = new FileOutputStream("main.zip");
ZipOutputStream zos = new ZipOutputStream(fos);
zos.putNextEntry(new ZipEntry("Additional_Sub_Folder/"));
zos.putNextEntry(new ZipEntry("Digital_Sub_Folder/"));
FileOutputStream fos1 = new FileOutputStream("Additional_Sub_Folder/Additional_file.zip");
ZipOutputStream zos1 = new ZipOutputStream(fos1);
/*zos1.putNextEntry(new ZipEntry("Additional_file.zip/xml/"));
zos1.putNextEntry(new ZipEntry("Additional_file.zip/pdf/"));*/
zos1.putNextEntry(new ZipEntry("Additional_file1.zip/xml/"));
zos1.putNextEntry(new ZipEntry("Additional_file1.zip/pdf/"));
zos1.close();
fos1.close();
zos.close();
fos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void addToZipFile(String fileName, ZipOutputStream zos) throws FileNotFoundException, IOException {
System.out.println("Writing '" + fileName + "' to zip file");
File file = new File(fileName);
FileInputStream fis = new FileInputStream(file);
ZipEntry zipEntry = new ZipEntry(fileName);
zos.putNextEntry(zipEntry);
byte[] bytes = new byte[1024];
int length;
while ((length = fis.read(bytes)) >= 0) {
zos.write(bytes, 0, length);
}
zos.closeEntry();
fis.close();
}
}
[1]: http://i.stack.imgur.com/TNA8b.jpg
I did not have the problem with the zip-I/O, I had the FileNotFoundException with every type of I/O that uses the fileSystem.
What helped for me was, if you're working with eclipse, that there is function like "refresh project" or something like this. Everytime I had problems with I/O, that worked.
I generated .tar.gz file in java.
When I tried to open that,I m getting exception as "Unable to read header of that file" and it asks for some over writing also.
It is also throwing error as
cannot open file:it does not appear to be a valid archive.
My code is as follows
import java.io.File;
import java.io.FileInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
public class Tarzlatest {
public static void main(String[] args) {
File file =new File(path);
String gzipFile = path;
String newFile = path ;
compressGzipFile(file, gzipFile);
decompressGzipFile(gzipFile, newFile);
}
private static void decompressGzipFile(String gzipFile, String newFile) {
try {
FileInputStream fis = new FileInputStream(gzipFile);
GZIPInputStream gis = new GZIPInputStream(fis);
FileOutputStream fos = new FileOutputStream(newFile);
byte[] buffer = new byte[1024];
int len;
while((len = gis.read(buffer)) != -1){
fos.write(buffer, 0, len);
}
//close resources
fos.close();
gis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
private static void compressGzipFile(File dir, String gzipFile) {
try {
File[] flist = dir.listFiles();
for(int i=0; i<flist.length; i++)
{
FileInputStream fis = new FileInputStream(flist[i]);
FileOutputStream fos = new FileOutputStream(gzipFile);
GZIPOutputStream gzipOS = new GZIPOutputStream(fos);
byte[] buffer = new byte[1024];
int len;
while((len=fis.read(buffer)) != -1){
gzipOS.write(buffer, 0, len);
}
//close resources
gzipOS.close();
fos.close();
fis.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
It means that you generated your .tar.gz incorrectly. Simple as that.
I want to be able to copy an excel file from my android app res\raw folder to the client phone's internal storage, and be able to retrieve the data from the excel file and update the excel file in the internal storage as needed. So far all I have is this:
http://developer.android.com/guide/topics/data/data-storage.html#filesInternal
--- write files to internal storage and
http://www.vogella.com/articles/JavaExcel/article.html
--- using jexcel to retrieve data from and edit an excel file
I can't seem to be able to link the two. How do I go on implementing this app?
Thanks
For Read and Write To use Apache POI library
To some sample example is there for android through read and write excel sheet
1) Creating/Reading an Excel file in Android
2) Android Read Write EXCEL file using Apache POI
For Assets to SDcard Follow this link Or use this code.
package com.paresh.copyfileassetstoAssets;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.app.Activity;
import android.content.res.AssetManager;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
public class CopyFileAssetsToSDCardActivity extends Activity
{
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
CopyAssets();
}
private void CopyAssets() {
AssetManager assetManager = getAssets();
String[] files = null;
try {
files = assetManager.list("Files");
} catch (IOException e) {
Log.e("tag", e.getMessage());
}
for(String filename : files) {
System.out.println("File name => "+filename);
InputStream in = null;
OutputStream out = null;
try {
in = assetManager.open("Files/"+filename); // if files resides inside the "Files" directory itself
out = new FileOutputStream(Environment.getExternalStorageDirectory().toString() +"/" + filename);
copyFile(in, out);
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch(Exception e) {
Log.e("tag", e.getMessage());
}
}
}
private void copyFile(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int read;
while((read = in.read(buffer)) != -1){
out.write(buffer, 0, read);
}
}
}