java 中 byte[]、File、InputStream 互相转换

1、将File、FileInputStream 转换为byte数组：

File file = new File("test.txt");

InputStream input = new FileInputStream(file);

byte[] byt = new byte[input.available()];

input.read(byt);

 

2、将byte数组转换为InputStream：

byte[] byt = new byte[1024];

InputStream input = new ByteArrayInputStream(byt);

 

3、将byte数组转换为File：

File file = new File('');

OutputStream output = new FileOutputStream(file);

BufferedOutputStream bufferedOutput = new BufferedOutputStream(output);

bufferedOutput.write(byt);

 

4、byte数组写出到outputstream输出流

 byte[] file = clientFile.getFile();
 outputStream=new BufferedOutputStream(response.getOutputStream());
 int off=0;
 int fileLength=file.length;
 int count=fileLength/1024 +1;
 int lastLength=1024;
 for(int i=0;i<count;i++){
     if(i==count-1){
         lastLength= fileLength-off;
     }
     outputStream.write(file,off,lastLength);
     off=off+1024;
 }
//将字节数组的数据全部写入到输出流中
 outputStream.flush();