IO流 应用： 文件的 切割与合并

 

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.SequenceInputStream;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.TreeSet;
/*
 *	容量达1MB就分割文件，，最后合并
 */
public class SplitMergeFile {
	public static void main(String[] args) throws FileNotFoundException {
		String path = "D:abc/";
		String fileName = "网络编程(UDP-聊天).avi";
		//splitFile(path, fileName);  
		mergeFile(path, fileName);
	}
	//合并文件
	static void mergeFile(String path,final String fileName) throws FileNotFoundException {
		File f = new File(path);
		File[] files = null;
		if (!(f.exists() && f.isDirectory())) {
			System.out.println("需要合并的文件 的 路径错误");
			return;
		}
		files = f.listFiles();
		ArrayList<FileInputStream> al = new ArrayList<FileInputStream>();
		/*
		 * 因为 这些切割文件名 是String类型，，一旦文件过多，那么这些文件的排序就是以
		 * 字典顺序排序，，这样加入arraylist中，就顺序错了，所以呢要定义一个
		 * 带比较器的 TreeSet 来保存，，最后才从ts中 迭代  加入 al中
		 */
		TreeSet<File> ts = new TreeSet<File>(new Comparator<File>() {

			@Override
			public int compare(File f1, File f2) {
				// TODO Auto-generated method stub
				//fileName.length() 就是切割文件中计数的开始索引，
				//lastIndexOf(".part")前就是计数的结束索引
				int partIndex1 = f1.getName().lastIndexOf(".part");
				String count1 = f1.getName().substring(fileName.length(),partIndex1);
				int partIndex2 = f2.getName().lastIndexOf(".part");
				String count2 = f2.getName().substring(fileName.length(),partIndex2);
				return Integer.parseInt(count1) - Integer.parseInt(count2);
			}
		});
		for (int i = 0; i < files.length; i++) {
			if (files[i].getName().startsWith(fileName) && 
					files[i].getName().endsWith(".part")) {
				ts.add(files[i]);
				System.out.println(files[i].getName());
			}
		}
		System.out.println();
		for (File temp : ts) {
			al.add(new FileInputStream(temp));
			System.out.println(temp.getName());
		}
		final Iterator<FileInputStream> it = al.iterator();
		Enumeration<FileInputStream> ef = new Enumeration<FileInputStream>() {

			@Override
			public FileInputStream nextElement() {
				// TODO Auto-generated method stub
				return it.next();
			}

			@Override
			public boolean hasMoreElements() {
				// TODO Auto-generated method stub
				return it.hasNext();
			}
		};
		//合并输入 流 SequenceInputStream
		SequenceInputStream sis = new SequenceInputStream(ef);

		FileOutputStream fos = new FileOutputStream(path+fileName);

		byte[] buf = new byte[1024*1024];
		int len = 0;
		try {
			while ((len = sis.read(buf)) != -1) {
				fos.write(buf,0,len);
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			if (fos!=null) {
				try {
					fos.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if (sis!=null) {
				try {
					sis.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	}
	//分割文件
	static void splitFile(String path, String fileName) {
		FileOutputStream fos = null;
		FileInputStream fis = null;
		try {
			fis = new FileInputStream(path+fileName);
			byte[] buf = new byte[1024*1024];// 1024b是1k，1024kb 是1mb
			int len = 0;
			int count = 1;
			while ((len = fis.read(buf)) != -1) {
				fos = new FileOutputStream(path + fileName + (count++) + ".part");
				fos.write(buf,0,len);
				fos.close();
			}
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			if (fis != null) {
				try {
					fis.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	}
}