I want to copy a file from one location to another location in Java.
我想将文件从一个位置复制到Java中的另一个位置。
Here is what I have so far:
这是我到目前为止:
import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.List;
public class TestArrayList {
public static void main(String[] args) {
File f = new File(
"D:\\CBSE_Demo\\Demo_original\\fscommand\\contentplayer\\config");
List<String>temp=new ArrayList<String>();
temp.add(0, "N33");
temp.add(1, "N1417");
temp.add(2, "N331");
File[] matchingFiles = null;
for(final String temp1: temp){
matchingFiles = f.listFiles(new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.startsWith(temp1);
}
});
System.out.println("size>>--"+matchingFiles.length);
}
}
}
This does not copy the file, what is the best way to do this?
这不会复制文件,这样做的最佳方法是什么?
4 个解决方案
#1
72
You can use this (or any variant):
您可以使用此(或任何变体):
Files.copy(src, dst, StandardCopyOption.REPLACE_EXISTING);
Also, I'd recommend using File.separator
or /
instead of \\
to make it compliant across multiple OS, question/answer on this available here.
此外,我建议使用File.separator或/而不是\\使其兼容多个操作系统,问题/答案可在此处获得。
Since you're not sure how to temporarily store files, take a look at ArrayList
:
由于您不确定如何临时存储文件,请查看ArrayList:
List<File> files = new ArrayList();
files.add(foundFile);
To move a List
of files into a single directory:
要将文件列表移动到单个目录中:
List<File> files = ...;
String path = "C:/destination/";
for(File file : files) {
Files.copy(file.toPath(),
(new File(path + file.getName())).toPath(),
StandardCopyOption.REPLACE_EXISTING);
}
#2
51
Using Stream
使用Stream
private static void copyFileUsingStream(File source, File dest) throws IOException {
InputStream is = null;
OutputStream os = null;
try {
is = new FileInputStream(source);
os = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer)) > 0) {
os.write(buffer, 0, length);
}
} finally {
is.close();
os.close();
}
}
Using Channel
使用频道
private static void copyFileUsingChannel(File source, File dest) throws IOException {
FileChannel sourceChannel = null;
FileChannel destChannel = null;
try {
sourceChannel = new FileInputStream(source).getChannel();
destChannel = new FileOutputStream(dest).getChannel();
destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
}finally{
sourceChannel.close();
destChannel.close();
}
}
Using Apache Commons IO lib:
使用Apache Commons IO lib:
private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException {
FileUtils.copyFile(source, dest);
}
Using Java SE 7 Files class:
使用Java SE 7 Files类:
private static void copyFileUsingJava7Files(File source, File dest) throws IOException {
Files.copy(source.toPath(), dest.toPath());
}
Performance test:
性能测试:
File source = new File("/Users/pankaj/tmp/source.avi");
File dest = new File("/Users/pankaj/tmp/dest.avi");
//copy file conventional way using Stream
long start = System.nanoTime();
copyFileUsingStream(source, dest);
System.out.println("Time taken by Stream Copy = "+(System.nanoTime()-start));
//copy files using java.nio FileChannel
source = new File("/Users/pankaj/tmp/sourceChannel.avi");
dest = new File("/Users/pankaj/tmp/destChannel.avi");
start = System.nanoTime();
copyFileUsingChannel(source, dest);
System.out.println("Time taken by Channel Copy = "+(System.nanoTime()-start));
//copy files using apache commons io
source = new File("/Users/pankaj/tmp/sourceApache.avi");
dest = new File("/Users/pankaj/tmp/destApache.avi");
start = System.nanoTime();
copyFileUsingApacheCommonsIO(source, dest);
System.out.println("Time taken by Apache Commons IO Copy = "+(System.nanoTime()-start));
//using Java 7 Files class
source = new File("/Users/pankaj/tmp/sourceJava7.avi");
dest = new File("/Users/pankaj/tmp/destJava7.avi");
start = System.nanoTime();
copyFileUsingJava7Files(source, dest);
System.out.println("Time taken by Java7 Files Copy = "+(System.nanoTime()-start));
RESULTS:
结果:
/*
* File copy:
* Time taken by Stream Copy = 44582575000
* Time taken by Channel Copy = 104138195000
* Time taken by Apache Commons IO Copy = 108396714000
* Time taken by Java7 Files Copy = 89061578000
*/
Link:
链接:
http://www.journaldev.com/861/4-ways-to-copy-file-in-java
http://www.journaldev.com/861/4-ways-to-copy-file-in-java
#3
4
public static void copyFile(File oldLocation, File newLocation) throws IOException {
if ( oldLocation.exists( )) {
BufferedInputStream reader = new BufferedInputStream( new FileInputStream(oldLocation) );
BufferedOutputStream writer = new BufferedOutputStream( new FileOutputStream(newLocation, false));
try {
byte[] buff = new byte[8192];
int numChars;
while ( (numChars = reader.read( buff, 0, buff.length ) ) != -1) {
writer.write( buff, 0, numChars );
}
} catch( IOException ex ) {
throw new IOException("IOException when transferring " + oldLocation.getPath() + " to " + newLocation.getPath());
} finally {
try {
if ( reader != null ){
writer.close();
reader.close();
}
} catch( IOException ex ){
Log.e(TAG, "Error closing files when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}
} else {
throw new IOException("Old location does not exist when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}
#4
3
Use the New Java File classes in Java >=7.
使用Java> = 7中的New Java File类。
Create the below method and import the necessary libs.
创建以下方法并导入必要的库。
public static void copyFile( File from, File to ) throws IOException {
Files.copy( from.toPath(), to.toPath() );
}
Use the created method as below within main:
在main中使用如下所示的创建方法:
File dirFrom = new File(fileFrom);
File dirTo = new File(fileTo);
try {
copyFile(dirFrom, dirTo);
} catch (IOException ex) {
Logger.getLogger(TestJava8.class.getName()).log(Level.SEVERE, null, ex);
}
NB:- fileFrom is the file that you want to copy to a new file fileTo in a different folder.
注意: - fileFrom是要复制到新文件fileTo到另一个文件夹的文件。
Credits - @Scott: Standard concise way to copy a file in Java?
Credits - @Scott:用Java复制文件的标准简洁方法?
#1
72
You can use this (or any variant):
您可以使用此(或任何变体):
Files.copy(src, dst, StandardCopyOption.REPLACE_EXISTING);
Also, I'd recommend using File.separator
or /
instead of \\
to make it compliant across multiple OS, question/answer on this available here.
此外,我建议使用File.separator或/而不是\\使其兼容多个操作系统,问题/答案可在此处获得。
Since you're not sure how to temporarily store files, take a look at ArrayList
:
由于您不确定如何临时存储文件,请查看ArrayList:
List<File> files = new ArrayList();
files.add(foundFile);
To move a List
of files into a single directory:
要将文件列表移动到单个目录中:
List<File> files = ...;
String path = "C:/destination/";
for(File file : files) {
Files.copy(file.toPath(),
(new File(path + file.getName())).toPath(),
StandardCopyOption.REPLACE_EXISTING);
}
#2
51
Using Stream
使用Stream
private static void copyFileUsingStream(File source, File dest) throws IOException {
InputStream is = null;
OutputStream os = null;
try {
is = new FileInputStream(source);
os = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer)) > 0) {
os.write(buffer, 0, length);
}
} finally {
is.close();
os.close();
}
}
Using Channel
使用频道
private static void copyFileUsingChannel(File source, File dest) throws IOException {
FileChannel sourceChannel = null;
FileChannel destChannel = null;
try {
sourceChannel = new FileInputStream(source).getChannel();
destChannel = new FileOutputStream(dest).getChannel();
destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
}finally{
sourceChannel.close();
destChannel.close();
}
}
Using Apache Commons IO lib:
使用Apache Commons IO lib:
private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException {
FileUtils.copyFile(source, dest);
}
Using Java SE 7 Files class:
使用Java SE 7 Files类:
private static void copyFileUsingJava7Files(File source, File dest) throws IOException {
Files.copy(source.toPath(), dest.toPath());
}
Performance test:
性能测试:
File source = new File("/Users/pankaj/tmp/source.avi");
File dest = new File("/Users/pankaj/tmp/dest.avi");
//copy file conventional way using Stream
long start = System.nanoTime();
copyFileUsingStream(source, dest);
System.out.println("Time taken by Stream Copy = "+(System.nanoTime()-start));
//copy files using java.nio FileChannel
source = new File("/Users/pankaj/tmp/sourceChannel.avi");
dest = new File("/Users/pankaj/tmp/destChannel.avi");
start = System.nanoTime();
copyFileUsingChannel(source, dest);
System.out.println("Time taken by Channel Copy = "+(System.nanoTime()-start));
//copy files using apache commons io
source = new File("/Users/pankaj/tmp/sourceApache.avi");
dest = new File("/Users/pankaj/tmp/destApache.avi");
start = System.nanoTime();
copyFileUsingApacheCommonsIO(source, dest);
System.out.println("Time taken by Apache Commons IO Copy = "+(System.nanoTime()-start));
//using Java 7 Files class
source = new File("/Users/pankaj/tmp/sourceJava7.avi");
dest = new File("/Users/pankaj/tmp/destJava7.avi");
start = System.nanoTime();
copyFileUsingJava7Files(source, dest);
System.out.println("Time taken by Java7 Files Copy = "+(System.nanoTime()-start));
RESULTS:
结果:
/*
* File copy:
* Time taken by Stream Copy = 44582575000
* Time taken by Channel Copy = 104138195000
* Time taken by Apache Commons IO Copy = 108396714000
* Time taken by Java7 Files Copy = 89061578000
*/
Link:
链接:
http://www.journaldev.com/861/4-ways-to-copy-file-in-java
http://www.journaldev.com/861/4-ways-to-copy-file-in-java
#3
4
public static void copyFile(File oldLocation, File newLocation) throws IOException {
if ( oldLocation.exists( )) {
BufferedInputStream reader = new BufferedInputStream( new FileInputStream(oldLocation) );
BufferedOutputStream writer = new BufferedOutputStream( new FileOutputStream(newLocation, false));
try {
byte[] buff = new byte[8192];
int numChars;
while ( (numChars = reader.read( buff, 0, buff.length ) ) != -1) {
writer.write( buff, 0, numChars );
}
} catch( IOException ex ) {
throw new IOException("IOException when transferring " + oldLocation.getPath() + " to " + newLocation.getPath());
} finally {
try {
if ( reader != null ){
writer.close();
reader.close();
}
} catch( IOException ex ){
Log.e(TAG, "Error closing files when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}
} else {
throw new IOException("Old location does not exist when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}
#4
3
Use the New Java File classes in Java >=7.
使用Java> = 7中的New Java File类。
Create the below method and import the necessary libs.
创建以下方法并导入必要的库。
public static void copyFile( File from, File to ) throws IOException {
Files.copy( from.toPath(), to.toPath() );
}
Use the created method as below within main:
在main中使用如下所示的创建方法:
File dirFrom = new File(fileFrom);
File dirTo = new File(fileTo);
try {
copyFile(dirFrom, dirTo);
} catch (IOException ex) {
Logger.getLogger(TestJava8.class.getName()).log(Level.SEVERE, null, ex);
}
NB:- fileFrom is the file that you want to copy to a new file fileTo in a different folder.
注意: - fileFrom是要复制到新文件fileTo到另一个文件夹的文件。
Credits - @Scott: Standard concise way to copy a file in Java?
Credits - @Scott:用Java复制文件的标准简洁方法?