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package csv; import java.io.*; /** * A class to take a file and split it into smaller files * (for example, for fitting a file on floppy disks). * <P>To execute the program to split files apart, pass the -split * option and specify a filename:<BR> * <I>java FileSplitter -split bigFile.zip</I> * <P>To join a file back together, specify the -join flag and * give the base filename:<BR> * <I>java FileSplitter -join bigFile.zip</I><BR> * @author Keith Trnka */ public class FileSplitter { /** * a constant representing the size of a chunk that would go on a floppy disk. * 1.4 MB is used instead of 1.44 MB so that it isn't too close to the limit. */ public static final long fileSize = (long)(25 * 1024 * 1024); /** the maximum size of each file "chunk" generated, in bytes */ public static long chunkSize = 26214400; public static void main(String[] args) throws Exception { if (args.length != 2) { System.out.println("Must specify a flag -split or -join and a file argument. The file argument for splitting is the file to split and for joining is the base filename to join on."); System.exit(0); } try { if (args[0].equalsIgnoreCase("-split")) split(args[1]); else if (args[0].equalsIgnoreCase("-join")) join(args[1]); else { System.out.println("The first argument must be an option:"); System.out.println("\t-split: split the specified file"); System.out.println("\t-join: join all splitter outfiles with the specified base filename"); System.exit(0); } } catch (FileNotFoundException e) { System.out.println("File not found: " + args[1]); } catch (IOException e) { System.out.println("IO Error"); } } /** * split the file specified by filename into pieces, each of size * chunkSize except for the last one, which may be smaller */ public static void split(String filename) throws FileNotFoundException, IOException { // open the file BufferedInputStream in = new BufferedInputStream(new FileInputStream(filename)); // get the file length File f = new File(filename); long fileSize = f.length(); // loop for each full chunk int subfile; for (subfile = 0; subfile < fileSize / chunkSize; subfile++) { // open the output file BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(filename + "." + subfile)); // write the right amount of bytes for (int currentByte = 0; currentByte < chunkSize; currentByte++) { // load one byte from the input file and write it to the output file out.write(in.read()); } // close the file out.close(); } // loop for the last chunk (which may be smaller than the chunk size) if (fileSize != chunkSize * (subfile - 1)) { // open the output file BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(filename + "." + subfile)); // write the rest of the file int b; while ((b = in.read()) != -1) out.write(b); // close the file out.close(); } // close the file in.close(); } /** * list all files in the directory specified by the baseFilename * , find out how many parts there are, and then concatenate them * together to create a file with the filename <I>baseFilename</I>. */ public static void join(String baseFilename) throws IOException { int numberParts = getNumberParts(baseFilename); // now, assume that the files are correctly numbered in order (that some joker didn't delete any part) BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(baseFilename)); for (int part = 0; part < numberParts; part++) { BufferedInputStream in = new BufferedInputStream(new FileInputStream(baseFilename + "." + part)); int b; while ( (b = in.read()) != -1 ) out.write(b); in.close(); } out.close(); } /** * find out how many chunks there are to the base filename */ private static int getNumberParts(String baseFilename) throws IOException { // list all files in the same directory File directory = new File(baseFilename).getAbsoluteFile().getParentFile(); final String justFilename = new File(baseFilename).getName(); String[] matchingFiles = directory.list(new FilenameFilter() { public boolean accept(File dir, String name) { return name.startsWith(justFilename) && name.substring(justFilename.length()).matches("^\\.\\d+$"); } }); return matchingFiles.length; } } 调用方式：-split 文件全路径 |
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