對應Python版:加密文件之Python版Java版比Python版要快得多,兩個版本不在一個量級上。在加密解密1G大文件時,Java版花費的時間是秒級,而Python版花費的時間是10分鐘級。 ...
對應Python版:加密文件之Python版
Java版比Python版要快得多,兩個版本不在一個量級上。在加密解密1G大文件時,Java版花費的時間是秒級,而Python版花費的時間是10分鐘級。
import java.io.File; import java.io.IOException; import java.io.RandomAccessFile; import java.nio.MappedByteBuffer; import java.nio.channels.FileChannel; import java.nio.charset.Charset; /** * Script: Encode.java Encode file or decode file. Java implementation and * upgrade Encoding: UTF-8 Version: 0.2 Java version: 1.8 Usage: java Encode * [encode | decode] filename [key] * */ public class Encode { private static final String DEFAULT_KEY = "TESTKEY"; private static final String DEFAULT_CHARSET = "UTF-8"; private static final long SLEEP_TIME = 100; public boolean isEncode; public MappedByteBuffer mappedBuffer; private String filename; private String charset; private byte[] keyBytes; private EncodeThread[] workThreads; public Encode(boolean isEncode, String filename, String key) { this.isEncode = isEncode; this.filename = filename; this.charset = DEFAULT_CHARSET; this.keyBytes = key.getBytes(Charset.forName(charset)); } public void run() { try { // read file RandomAccessFile raf = new RandomAccessFile(filename, "rw"); FileChannel channel = raf.getChannel(); long fileLength = channel.size(); int bufferCount = (int) Math.ceil((double) fileLength / (double) Integer.MAX_VALUE); if (bufferCount == 0) { channel.close(); raf.close(); return; } int bufferIndex = 0; long preLength = 0; // repeat part long regionSize = Integer.MAX_VALUE; if (fileLength - preLength < Integer.MAX_VALUE) { regionSize = fileLength - preLength; } mappedBuffer = channel.map(FileChannel.MapMode.READ_WRITE, preLength, regionSize); preLength += regionSize; // create work threads int threadCount = keyBytes.length; System.out.println( "File size: " + fileLength + ", buffer count: " + bufferCount + ", thread count: " + threadCount); long startTime = System.currentTimeMillis(); System.out.println("Start time: " + startTime + "ms"); System.out.println("Buffer " + bufferIndex + " start ..."); workThreads = new EncodeThread[threadCount]; for (int i = 0; i < threadCount; i++) { workThreads[i] = new EncodeThread(this, keyBytes[i], keyBytes.length, i); workThreads[i].start(); } // loop while (true) { Thread.sleep(SLEEP_TIME); // wait until all threads completed boolean completed = true; for (int i = 0; i < workThreads.length; i++) { if (!workThreads[i].isCompleted()) { completed = false; break; } } if (!completed) { continue; } // check if finished bufferIndex++; if (bufferIndex >= bufferCount) { // stop threads for (int i = 0; i < workThreads.length; i++) { workThreads[i].flag = false; } break; } // repeat part regionSize = Integer.MAX_VALUE; if (fileLength - preLength < Integer.MAX_VALUE) { regionSize = fileLength - preLength; } mappedBuffer = channel.map(FileChannel.MapMode.READ_WRITE, preLength, regionSize); preLength += regionSize; // restart threads System.out.println("Buffer " + bufferIndex + " start ..."); for (int i = 0; i < workThreads.length; i++) { workThreads[i].restart(); } } // over loop while (true) { Thread.sleep(SLEEP_TIME); boolean isOver = true; for (int i = 0; i < workThreads.length; i++) { if (workThreads[i].isAlive()) { isOver = false; break; } } if (isOver) { break; } } // close file relatives channel.close(); raf.close(); long endTime = System.currentTimeMillis(); System.out.println("End time: " + endTime + "ms, use time: " + (endTime - startTime) + "ms"); System.out.println("ok!"); } catch (IOException | InterruptedException e) { e.printStackTrace(); } } public static void main(String[] args) { String usage = "Usage: java -jar encode.jar [encode | decode] filename [key]"; // parse args if (args.length < 2) { System.out.println("There must be two or more arguments!"); System.out.println(usage); return; } if (!args[0].equals("encode") && !args[0].equals("decode")) { System.out.println("The first argument must be \"encode\" or \"decode\""); System.out.println(usage); return; } boolean isEncode = (args[0].equals("encode")); String filename = args[1]; File file = new File(filename); if (!file.isFile()) { System.out.println("The file doesn't exist!"); System.out.println(usage); return; } String key = DEFAULT_KEY; if (args.length > 2) { key = args[2]; } // encode or decode new Encode(isEncode, filename, key).run(); } } class EncodeThread extends Thread { private static final long SLEEP_TIME = 50; public boolean flag; private Encode encoder; private int key; private int dataIndex; private int interval; private int regionSize; private boolean completed; public EncodeThread(Encode encoder, byte key, int interval, int index) { this.encoder = encoder; this.key = key & 0xff; this.dataIndex = index; this.interval = interval; this.regionSize = encoder.mappedBuffer.limit(); this.completed = false; this.flag = true; } public void restart() { this.dataIndex -= regionSize; regionSize = encoder.mappedBuffer.limit(); completed = false; } public boolean isCompleted() { return completed; } @Override public void run() { try { if (encoder.isEncode) { encode(); } else { decode(); } } catch (InterruptedException e) { e.printStackTrace(); } } private void encode() throws InterruptedException { while (flag) { // completed here ensure restart() synchronized if (completed) { Thread.sleep(SLEEP_TIME); continue; } if (dataIndex >= regionSize) { completed = true; System.out.println("Encode thread " + this.getName() + " is completed!"); continue; } // do encode byte b = encoder.mappedBuffer.get(dataIndex); // added as unsigned byte b = (byte) (((b & 0xff) + key) % 256); encoder.mappedBuffer.put(dataIndex, b); dataIndex += interval; } } private void decode() throws InterruptedException { while (flag) { // completed here ensure restart() synchronized if (completed) { Thread.sleep(SLEEP_TIME); continue; } if (dataIndex >= regionSize) { completed = true; System.out.println("Encode thread " + this.getName() + " is completed!"); continue; } // do decode byte b = encoder.mappedBuffer.get(dataIndex); // substracted as unsigned byte b = (byte) (((b & 0xff) + 256 - key) % 256); encoder.mappedBuffer.put(dataIndex, b); dataIndex += interval; } } }