byte 读写文件

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

public class FileHelper {
//第一种获取文件内容方式
	public byte[] getContent(String filePath) throws IOException {
		File file = new File(filePath);

		long fileSize = file.length();
		if (fileSize > Integer.MAX_VALUE) {
			System.out.println("file too big...");
			return null;
		}

		FileInputStream fi = new FileInputStream(file);

		byte[] buffer = new byte[(int) fileSize];

		int offset = 0;

		int numRead = 0;

		while (offset < buffer.length

		&& (numRead = fi.read(buffer, offset, buffer.length - offset)) >= 0) {

			offset += numRead;

		}

		// 确保所有数据均被读取

		if (offset != buffer.length) {

			throw new IOException("Could not completely read file "
					+ file.getName());

		}

		fi.close();

		return buffer;
	}
	
	//第二种获取文件内容方式
	public byte[] getContent2(String filePath) throws IOException
	{
		FileInputStream in=new FileInputStream(filePath);
		
		ByteArrayOutputStream out=new ByteArrayOutputStream(1024);
		
		System.out.println("bytes available:"+in.available());
		
		byte[] temp=new byte[1024];
		
		int size=0;
		
		while((size=in.read(temp))!=-1)
		{
			out.write(temp,0,size);
		}
		
		in.close();
		
		byte[] bytes=out.toByteArray();
		System.out.println("bytes size got is:"+bytes.length);
		
		return bytes;
	}
        //将byte数组写入文件
	public void createFile(String path, byte[] content) throws IOException {

		FileOutputStream fos = new FileOutputStream(path);

		fos.write(content);
		fos.close();
	}

}