1、将File、FileInputStream 转换为byte数组：

File file = new File("file.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);

1. public static byte[] getStreamBytes(InputStream is) throws Exception {
2. ByteArrayOutputStream baos = new ByteArrayOutputStream();
3. byte[] buffer = new byte[1024];
4. int len = 0 ;
5. while (( len = is .read(buffer)) != -1) {
6. baos.write(buffer, 0, len);
7. }
8. byte[] b = baos .toByteArray();
9. is.close();
10. baos.close();
11. return b;
12. }

1. default byte[] readFileBytes(InputStream is){
2. byte[] data = null ;
3. try {
4. if(is.available()==0){//严谨起见,一定要加上这个判断,不要返回data[]长度为0的数组指针
5. return data;
6. }
7. data = new byte[is.available()];
8. is.read(data);
9. is.close();
10. return data;
11. } catch (IOException e) {
12. LogCore.BASE.error("readFileBytes, err", e);
13. return data;
14. }
15. }