全面瞭解java byte數組與檔案讀寫_java

全面瞭解java byte數組與檔案讀寫

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>//第一種擷取檔案內容方式  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;    }    // 確保所有資料均被讀取    if (offset != buffer.length) {      throw new IOException("Could not completely read file "          + file.getName());    }    fi.close();    return buffer;  }    //第二種擷取檔案內容方式  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;  }    //將byte數組寫入檔案  public void createFile(String path, byte[] content) throws IOException {    FileOutputStream fos = new FileOutputStream(path);    fos.write(content);    fos.close();  }}

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