Java中InputStream、String、File相互转化

小记(未测试)：

1. String --> InputStream

ByteArrayInputStream stream = new ByteArrayInputStream(str.getBytes());

2. InputStream --> String

String inputStream2String(InputStream is){
 BufferedReader in = new BufferedReader(new InputStreamReader(is));
   StringBuffer buffer = new StringBuffer();
   String line = "";
   while ((line = in.readLine()) != null){
     buffer.append(line);
   }
   return buffer.toString();
}

3. File --> InputStream

InputStream in = new FileInputStream(file);

4. InputStream --> File

public void inputstreamtofile(InputStream ins,File file){
   OutputStream os = new FileOutputStream(file);
   int bytesRead = 0;
   byte[] buffer = new byte[8192];
   while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) {
      os.write(buffer, 0, bytesRead);
   }
   os.close();
   ins.close();

5. BufferedImage --> inputStream、BufferedImage --> String

public static InputStream encode(String content, String logoPath, boolean needCompress) throws Exception {
        BufferedImage image = QrCodeUtil.createImage(content, logoPath, true);
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        ImageIO.write(image, FORMAT, outputStream);
        //String streamEncoded = Base64Util.encode(outputStream.toByteArray());
        InputStream inputStream = new ByteArrayInputStream(outputStream.toByteArray());
        return inputStream;
  }