全面了解java byte数组与文件读写
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import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;public class FileHelper {<span style="white-space:pre"> </span>//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(); }} |
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