本文介绍Spring框架中FileSystemUtils和FileCopyUtils两个工具类的使用，包括递归删除和复制文件的功能，适用于系统文件管理和批量操作。
一、前言
这边基于spring-core提供的org.springframework.util.FileSystemUtils、org.springframework.util.FileCopyUtils等工具类对系统文件进行递归复制、递归删除等.
二、代码
1.FileSystemUtils文件系统工具类
package org.springframework.util;
import java.io.File;
import java.io.IOException;
/**
* Utility methods for working with the file system.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 2.5.3
*/
public abstract class FileSystemUtils {
/**
* Delete the supplied {@link File} - for directories,
* recursively delete any nested directories or files as well.
* @param root the root {@code File} to delete
* @return {@code true} if the {@code File} was deleted,
* otherwise {@code false}
*/
public static boolean deleteRecursively(File root) {
if (root != null && root.exists()) {
if (root.isDirectory()) {
File[] children = root.listFiles();
if (children != null) {
for (File child : children) {
deleteRecursively(child);
}
}
}
return root.delete();
}
return false;
}
/**
* Recursively copy the contents of the {@code src} file/directory
* to the {@code dest} file/directory.
* @param src the source directory
* @param dest the destination directory
* @throws IOException in the case of I/O errors
*/
public static void copyRecursively(File src, File dest) throws IOException {
Assert.isTrue(src != null && (src.isDirectory() || src.isFile()), "Source File must denote a directory or file");
Assert.notNull(dest, "Destination File must not be null");
doCopyRecursively(src, dest);
}
/**
* Actually copy the contents of the {@code src} file/directory
* to the {@code dest} file/directory.
* @param src the source directory
* @param dest the destination directory
* @throws IOException in the case of I/O errors
*/
private static void doCopyRecursively(File src, File dest) throws IOException {
if (src.isDirectory()) {
dest.mkdir();
File[] entries = src.listFiles();
if (entries == null) {
throw new IOException("Could not list files in directory: " + src);
}
for (File entry : entries) {
doCopyRecursively(entry, new File(dest, entry.getName()));
}
}
else if (src.isFile()) {
try {
dest.createNewFile();
}
catch (IOException ex) {
IOException ioex = new IOException("Failed to create file: " + dest);
ioex.initCause(ex);
throw ioex;
}
FileCopyUtils.copy(src, dest);
}
else {
// Special File handle: neither a file not a directory.
// Simply skip it when contained in nested directory...
}
}
}
2.FileCopyUtils - 文件复制工具类
package org.springframework.util;
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.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;
/**
* Simple utility methods for file and stream copying. All copy methods use a block size
* of 4096 bytes, and close all affected streams when done. A variation of the copy
* methods from this class that leave streams open can be found in {@link StreamUtils}.
*
* <p>Mainly for use within the framework, but also useful for application code.
*
* @author Juergen Hoeller
* @since 06.10.2003
* @see StreamUtils
*/
public abstract class FileCopyUtils {
public static final int BUFFER_SIZE = StreamUtils.BUFFER_SIZE;
//---------------------------------------------------------------------
// Copy methods for java.io.File
//---------------------------------------------------------------------
/**
* Copy the contents of the given input File to the given output File.
* @param in the file to copy from
* @param out the file to copy to
* @return the number of bytes copied
* @throws IOException in case of I/O errors
*/
public static int copy(File in, File out) throws IOException {
Assert.notNull(in, "No input File specified");
Assert.notNull(out, "No output File specified");
return copy(new BufferedInputStream(new FileInputStream(in)),
new BufferedOutputStream(new FileOutputStream(out)));
}
/**
* Copy the contents of the given byte array to the given output File.
* @param in the byte array to copy from
* @param out the file to copy to
* @throws IOException in case of I/O errors
*/
public static void copy(byte[] in, File out) throws IOException {
Assert.notNull(in, "No input byte array specified");
Assert.notNull(out, "No output File specified");
ByteArrayInputStream inStream = new ByteArrayInputStream(in);
OutputStream outStream = new BufferedOutputStream(new FileOutputStream(out));
copy(inStream, outStream);
}
/**
* Copy the contents of the given input File into a new byte array.
* @param in the file to copy from
* @return the new byte array that has been copied to
* @throws IOException in case of I/O errors
*/
public static byte[] copyToByteArray(File in) throws IOException {
Assert.notNull(in, "No input File specified");
return copyToByteArray(new BufferedInputStream(new FileInputStream(in)));
}
//---------------------------------------------------------------------
// Copy methods for java.io.InputStream / java.io.OutputStream
//---------------------------------------------------------------------
/**
* Copy the contents of the given InputStream to the given OutputStream.
* Closes both streams when done.
* @param in the stream to copy from
* @param out the stream to copy to
* @return the number of bytes copied
* @throws IOException in case of I/O errors
*/
public static int copy(InputStream in, OutputStream out) throws IOException {
Assert.notNull(in, "No InputStream specified");
Assert.notNull(out, "No OutputStream specified");
try {
return StreamUtils.copy(in, out);
}
finally {
try {
in.close();
}
catch (IOException ex) {
}
try {
out.close();
}
catch (IOException ex) {
}
}
}
/**
* Copy the contents of the given byte array to the given OutputStream.
* Closes the stream when done.
* @param in the byte array to copy from
* @param out the OutputStream to copy to
* @throws IOException in case of I/O errors
*/
public static void copy(byte[] in, OutputStream out) throws IOException {
Assert.notNull(in, "No input byte array specified");
Assert.notNull(out, "No OutputStream specified");
try {
out.write(in);
}
finally {
try {
out.close();
}
catch (IOException ex) {
}
}
}
/**
* Copy the contents of the given InputStream into a new byte array.
* Closes the stream when done.
* @param in the stream to copy from
* @return the new byte array that has been copied to
* @throws IOException in case of I/O errors
*/
public static byte[] copyToByteArray(InputStream in) throws IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream(BUFFER_SIZE);
copy(in, out);
return out.toByteArray();
}
//---------------------------------------------------------------------
// Copy methods for java.io.Reader / java.io.Writer
//---------------------------------------------------------------------
/**
* Copy the contents of the given Reader to the given Writer.
* Closes both when done.
* @param in the Reader to copy from
* @param out the Writer to copy to
* @return the number of characters copied
* @throws IOException in case of I/O errors
*/
public static int copy(Reader in, Writer out) throws IOException {
Assert.notNull(in, "No Reader specified");
Assert.notNull(out, "No Writer specified");
try {
int byteCount = 0;
char[] buffer = new char[BUFFER_SIZE];
int bytesRead = -1;
while ((bytesRead = in.read(buffer)) != -1) {
out.write(buffer, 0, bytesRead);
byteCount += bytesRead;
}
out.flush();
return byteCount;
}
finally {
try {
in.close();
}
catch (IOException ex) {
}
try {
out.close();
}
catch (IOException ex) {
}
}
}
/**
* Copy the contents of the given String to the given output Writer.
* Closes the writer when done.
* @param in the String to copy from
* @param out the Writer to copy to
* @throws IOException in case of I/O errors
*/
public static void copy(String in, Writer out) throws IOException {
Assert.notNull(in, "No input String specified");
Assert.notNull(out, "No Writer specified");
try {
out.write(in);
}
finally {
try {
out.close();
}
catch (IOException ex) {
}
}
}
/**
* Copy the contents of the given Reader into a String.
* Closes the reader when done.
* @param in the reader to copy from
* @return the String that has been copied to
* @throws IOException in case of I/O errors
*/
public static String copyToString(Reader in) throws IOException {
StringWriter out = new StringWriter();
copy(in, out);
return out.toString();
}
}
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