文件分割与合并

通过RandomAccessFile对象进行文件分割与合并

SplitFile类的初始化

类包含的变量

	private String filePath;		//源文件路径
	private String fileName;		//源文件名
	private long blockSize;			//块大小
	private long length;			//总长度
	private String destPath;		//目标路径
	private List<String> blockPath;	//块路径
	private int size;				//块数量

构建函数

	//均需调用无参构造器，初始化块路径ArrayList
	public SplitFile() {
		blockPath = new ArrayList<String>();
	}
	//未指定块大小时默认1024
	public SplitFile(String filePath, String destPath) {
		this(filePath, 1024, destPath);
	}
	//接收三个参数：源文件路径，块大小，目标文件路径
	public SplitFile(String filePath, long blockSize, String destPath) {
		this();
		this.filePath = filePath;
		this.blockSize = blockSize;
		this.destPath = destPath;
		init();
	}

构造器中调用的初始化函数

	//进行基本判断，确定文件存在且不是目录并确定块数以此确定每一块文件名
	private void init() {
		File src = null;
		//判断文件是否存在
		if (null == filePath || !(((src = new File(filePath)).exists()))) {
			return;
		}
		//判断是否为目录
		if (src.isDirectory())
			return;
		//为对象的文件名字段赋值
		this.fileName = src.getName();
		//确定总长度
		length = src.length();
		//计算块数:总长度/块大小向上取整
		size = (int) (Math.ceil(length * 1.0 / blockSize));
		//确定每一块文件名及路径
		initPathName();
	}

	private void initPathName() {
		for (int i = 0; i < size; i++) {
			this.blockPath.add(destPath + "\\" + i);
		}
	}

分割文件

	public void split() {
		//开始位置
		long beginPos = 0;
		//实际块大小
		long actualBlockSize = blockSize;
		for (int i = 0; i < size; i++) {
			//如果是最后一块
			if (i == size - 1) {
				//总长度-已经分割完毕的长度
				actualBlockSize = length - beginPos;
			}
			//分割文件实现细节
			splitDetail(i, beginPos, actualBlockSize);
			//将开始位置移动到下一个位置
			beginPos += actualBlockSize;
		}
	}

分割文件实现细节

	private void splitDetail(int i, long beginPos, long actualBlockSize) {
		//对源文件和目标文件进行关联
		File src = new File(filePath);
		File dest = new File(this.blockPath.get(i));
		//建立随机访问流和缓冲输出流
		RandomAccessFile raf = null;
		BufferedOutputStream bos = null;
		try {
			//设定模式为只读
			raf = new RandomAccessFile(src, "r");
			bos = new BufferedOutputStream(new FileOutputStream(dest));
			//设定偏移，确定下次读取的位置
			raf.seek(beginPos);
			//中间变量，与其他流读取一致
			byte[] flush = new byte[1024];
			int len = 0;
			while (-1 != (len = raf.read(flush))) {
				//判断是否为到达文件尾
				if (actualBlockSize - len >= 0) {
					bos.write(flush, 0, len);
					actualBlockSize -= len;
				} else {
					//到达文件尾部，写入实际大小数据
					bos.write(flush, 0, (int) actualBlockSize);
					break;
				}
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				bos.close();
				raf.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

合并文件

采用迭代器以及合并流进行文件合并

	public void merge(aString destPath) {
		File dest = new File(destPath);
		BufferedOutputStream bos = null;
		SequenceInputStream sis = null;
		//创立新迭代器
		Vector<InputStream> vi = new Vector<InputStream>();
		try {
			//将每个文件名存储到迭代器中
			for (int i = 0; i < blockPath.size(); i++) {
				vi.add(new BufferedInputStream(new FileInputStream(new File(blockPath.get(i)))));
			}
			bos = new BufferedOutputStream(new FileOutputStream(dest));
			sis = new SequenceInputStream(vi.elements());

			byte[] flush = new byte[1024];
			int len = 0;
			//读取合并流中的数据并写入到新文件中
			while (-1 != (len = sis.read(flush))) {
				bos.write(flush, 0, len);
			}
			bos.flush();
			sis.close();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				bos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

采用普通方法合并文件

	public void merge1(String destPath) {
		File dest = new File(destPath);
		BufferedOutputStream bos = null;
		try {
			bos = new BufferedOutputStream(new FileOutputStream(dest));
			BufferedInputStream bis = null;
			for (int i = 0; i < blockPath.size(); i++) {
				bis = new BufferedInputStream(new FileInputStream(new File(blockPath.get(i))));

				byte[] flush = new byte[1024];
				int len = 0;
				while (-1 != (len = bis.read(flush))) {
					bos.write(flush, 0, len);
				}
				bos.flush();
				bis.close();
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				bos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

主函数

	public static void main(String[] args) {
		SplitFile sp = new SplitFile("D:\\aa\\b\\新建 Microsoft Excel 工作表.xlsx", 50, "d:/aa");
		System.out.println(sp.length);
		sp.split();
		sp.merge("d:/aa/新建 Microsoft Excel 工作表.xlsx");
	}

完整代码

package cn.hxh.io.other;

import java.util.*;
import java.io.*;
import java.lang.Math;

public class SplitFile {
	private String filePath;		//源文件路径
	private String fileName;		//源文件名
	private long blockSize;			//块大小
	private long length;			//总长度
	private String destPath;		//目标路径
	private List<String> blockPath;	//块路径
	private int size;				//块数量

	public SplitFile() {
		blockPath = new ArrayList<String>();
	}

	public SplitFile(String filePath, String destPath) {
		this(filePath, 1024, destPath);
	}

	public SplitFile(String filePath, long blockSize, String destPath) {
		this();
		this.filePath = filePath;
		this.blockSize = blockSize;
		this.destPath = destPath;
		init();
	}

	private void init() {
		File src = null;
		if (null == filePath || !(((src = new File(filePath)).exists()))) {
			return;
		}
		if (src.isDirectory())
			return;
		this.fileName = src.getName();
		length = src.length();
		size = (int) (Math.ceil(length * 1.0 / blockSize));
		initPathName();

	}

	private void initPathName() {
		for (int i = 0; i < size; i++) {
			this.blockPath.add(destPath + "\\" + i);
		}
	}

	public void split() {
		long beginPos = 0;
		long actualBlockSize = blockSize;
		for (int i = 0; i < size; i++) {
			if (i == size - 1) {
				actualBlockSize = length - beginPos;
			}
			splitDetail(i, beginPos, actualBlockSize);
			beginPos += actualBlockSize;
		}
	}

	private void splitDetail(int i, long beginPos, long actualBlockSize) {
		File src = new File(filePath);
		File dest = new File(this.blockPath.get(i));
		RandomAccessFile raf = null;
		BufferedOutputStream bos = null;
		try {
			raf = new RandomAccessFile(src, "r");
			bos = new BufferedOutputStream(new FileOutputStream(dest));

			raf.seek(beginPos);

			byte[] flush = new byte[1024];
			int len = 0;
			while (-1 != (len = raf.read(flush))) {
				if (actualBlockSize - len >= 0) {
					bos.write(flush, 0, len);
					actualBlockSize -= len;
				} else {
					bos.write(flush, 0, (int) actualBlockSize);
					break;
				}
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				bos.close();
				raf.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

	}

	public void merge(String destPath) {
		File dest = new File(destPath);
		BufferedOutputStream bos = null;
		SequenceInputStream sis = null;
		Vector<InputStream> vi = new Vector<InputStream>();
		try {
			for (int i = 0; i < blockPath.size(); i++) {
				vi.add(new BufferedInputStream(new FileInputStream(new File(blockPath.get(i)))));
			}
			bos = new BufferedOutputStream(new FileOutputStream(dest));
			sis = new SequenceInputStream(vi.elements());

			byte[] flush = new byte[1024];
			int len = 0;
			while (-1 != (len = sis.read(flush))) {
				bos.write(flush, 0, len);
			}
			bos.flush();
			sis.close();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				bos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	public void merge1(String destPath) {
		File dest = new File(destPath);
		BufferedOutputStream bos = null;
		try {
			bos = new BufferedOutputStream(new FileOutputStream(dest));
			BufferedInputStream bis = null;
			for (int i = 0; i < blockPath.size(); i++) {
				bis = new BufferedInputStream(new FileInputStream(new File(blockPath.get(i))));

				byte[] flush = new byte[1024];
				int len = 0;
				while (-1 != (len = bis.read(flush))) {
					bos.write(flush, 0, len);
				}
				bos.flush();
				bis.close();
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				bos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	public static void main(String[] args) {
		SplitFile sp = new SplitFile("D:\\aa\\b\\新建 Microsoft Excel 工作表.xlsx", 50, "d:/aa");
		System.out.println(sp.length);
		sp.split();
		sp.merge("d:/aa/新建 Microsoft Excel 工作表.xlsx");
	}

}