這篇文章主要介紹了java中文件復(fù)制的方式有哪些,具有一定借鑒價(jià)值,感興趣的朋友可以參考下,希望大家閱讀完這篇文章之后大有收獲,下面讓小編帶著大家一起了解一下。
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1. 使用FileStreams復(fù)制
比較經(jīng)典的一個(gè)代碼,使用FileInputStream讀取文件A的字節(jié),使用FileOutputStream寫入到文件B。
public static void copy(String source, String dest, int bufferSize) { InputStream in = null; OutputStream out = null; try { in = new FileInputStream(new File(source)); out = new FileOutputStream(new File(dest)); byte[] buffer = new byte[bufferSize]; int len; while ((len = in.read(buffer)) > 0) { out.write(buffer, 0, len); } } catch (Exception e) { Log.w(TAG + ":copy", "error occur while copy", e); } finally { safelyClose(TAG + ":copy", in); safelyClose(TAG + ":copy", out); } } 2.
Java NIO包括transferFrom方法,根據(jù)文檔應(yīng)該比文件流復(fù)制的速度更快。
public static void copyNio(String source, String dest) { FileChannel input = null; FileChannel output = null; try { input = new FileInputStream(new File(from)).getChannel(); output = new FileOutputStream(new File(to)).getChannel(); output.transferFrom(input, 0, input.size()); } catch (Exception e) { Log.w(TAG + "copyNio", "error occur while copy", e); } finally { safelyClose(TAG + "copyNio", input); safelyClose(TAG + "copyNio", output); } } 3、 使用Apache Commons IO復(fù)制 Appache Commons IO 提供了一個(gè)FileUtils.copyFile(File from, File to)方法用于文件復(fù)制,如果項(xiàng)目里使用到了這個(gè)類庫,使用這個(gè)方法是個(gè)不錯(cuò)的選擇。 它的內(nèi)部也是使用Java NIO的FileChannel實(shí)現(xiàn)的。 commons-io的路徑:http://commons.apache.org/proper/commons-io/javadocs/api-release/index.html。里面還有很多實(shí)用的方法,如拷貝目錄、拷貝指定格式文件等。
private static void copyFileByApacheCommonsIO(File source, File dest) throws IOException { FileUtils.copyFile(source, dest); }
4、使用Java7的Files類復(fù)制
private static void copyFileUsingJava7Files(File source, File dest) throws IOException { Files.copy(source.toPath(), dest.toPath()); }
我沒有親測,找了下網(wǎng)友的測試程序和輸出,性能數(shù)據(jù)供大家參考
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.nio.channels.FileChannel; import java.nio.file.Files; import org.apache.commons.io.FileUtils; public class CopyFilesExample { public static void main(String[] args) throws InterruptedException, IOException { File source = new File("C:\\Users\\nikos7\\Desktop\\files\\sourcefile1.txt"); File dest = new File("C:\\Users\\nikos7\\Desktop\\files\\destfile1.txt"); // copy file using FileStreams long start = System.nanoTime(); long end; copyFileUsingFileStreams(source, dest); System.out.println("Time taken by FileStreams Copy = " + (System.nanoTime() - start)); // copy files using java.nio.FileChannel source = new File("C:\\Users\\nikos7\\Desktop\\files\\sourcefile2.txt"); dest = new File("C:\\Users\\nikos7\\Desktop\\files\\destfile2.txt"); start = System.nanoTime(); copyFileUsingFileChannels(source, dest); end = System.nanoTime(); System.out.println("Time taken by FileChannels Copy = " + (end - start)); // copy file using Java 7 Files class source = new File("C:\\Users\\nikos7\\Desktop\\files\\sourcefile3.txt"); dest = new File("C:\\Users\\nikos7\\Desktop\\files\\destfile3.txt"); start = System.nanoTime(); copyFileUsingJava7Files(source, dest); end = System.nanoTime(); System.out.println("Time taken by Java7 Files Copy = " + (end - start)); // copy files using apache commons io source = new File("C:\\Users\\nikos7\\Desktop\\files\\sourcefile4.txt"); dest = new File("C:\\Users\\nikos7\\Desktop\\files\\destfile4.txt"); start = System.nanoTime(); copyFileUsingApacheCommonsIO(source, dest); end = System.nanoTime(); System.out.println("Time taken by Apache Commons IO Copy = " + (end - start)); } private static void copyFileUsingFileStreams(File source, File dest) throws IOException { InputStream input = null; OutputStream output = null; try { input = new FileInputStream(source); output = new FileOutputStream(dest); byte[] buf = new byte[1024]; int bytesRead; while ((bytesRead = input.read(buf)) > 0) { output.write(buf, 0, bytesRead); } } finally { input.close(); output.close(); } } private static void copyFileUsingFileChannels(File source, File dest) throws IOException { FileChannel inputChannel = null; FileChannel outputChannel = null; try { inputChannel = new FileInputStream(source).getChannel(); outputChannel = new FileOutputStream(dest).getChannel(); outputChannel.transferFrom(inputChannel, 0, inputChannel.size()); } finally { inputChannel.close(); outputChannel.close(); } } private static void copyFileUsingJava7Files(File source, File dest) throws IOException { Files.copy(source.toPath(), dest.toPath()); } private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException { FileUtils.copyFile(source, dest); } }
輸出:
Time taken by FileStreams Copy = 127572360
Time taken by FileChannels Copy = 10449963
Time taken by Java7 Files Copy = 10808333
Time taken by Apache Commons IO Copy = 17971677
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