Java File和byte数据之间的转换

最新推荐文章于 2024-06-29 02:53:58 发布

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本文介绍了一个Java程序中处理文件的具体实例，包括将文件转换为字节数组并将其写回文件的功能。通过两个不同的方法实现了文件到字节数组及字节数组到文件的操作，演示了如何使用Java标准库进行基本的文件输入输出处理。

package cn.iworker.file;

import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class FileTest
{
	
	public static void main(String[] args)
	{
		file2BetyArray();
		fileToBetyArray();
		BetyToFile("D:\\Study\\Java\\First.class");
	}

	public static byte[] file2BetyArray()
	{
		File file = new File("D:\\Study\\Java\\First.class");
		if (!file.exists()) {
			return null;
		}
		FileInputStream stream = null;
		ByteArrayOutputStream out = null;
		try {
			stream = new FileInputStream(file);
			out = new ByteArrayOutputStream(1000);
			byte[] b = new byte[1000];
			int n;
			while ((n = stream.read(b)) != -1) {
				out.write(b, 0, n);
			}
			return out.toByteArray();// 此方法大文件OutOfMemory
		} catch (Exception e) {
			System.out.println(e.toString());
		} finally {
			try {
				stream.close();
				out.close();
			} catch (IOException e) {
				e.printStackTrace();
			}

		}
		return null;
	}

	public static byte[] fileToBetyArray()
	{
		FileInputStream fileInputStream = null;
		File file = new File("D:\\Study\\Java\\First.class");
		byte[] bFile = null;
		try {
			bFile = new byte[(int) file.length()];
			fileInputStream = new FileInputStream(file);
			fileInputStream.read(bFile);
			fileInputStream.close();
			for (int i = 0; i < bFile.length; i++) {
				System.out.print((char) bFile[i]);
			}
			System.out.println("Done");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				fileInputStream.close();
				bFile.clone();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return bFile;
	}

	public  static File BetyToFile( String filePath)
	{
		File file = new File(filePath);
		BufferedOutputStream stream = null;
		FileOutputStream fstream = null;
		byte[] data=new byte[(int)file.length()];
		try {
			fstream = new FileOutputStream(file);
			stream = new BufferedOutputStream(fstream);
			stream.write(data);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (stream != null) {
					stream.close();
				}
				if (null != fstream) {
					fstream.close();
				}
			} catch (IOException e1) {
				e1.printStackTrace();
			}
		}
		return file;
	}

}