InputStream

字符串转输入流
new ByteArrayInputStream("abcd".getBytes());

文件获取输入流
file.getInputStream();

代码获取web部署后resources目录资源文件内容
InputStream in = this.getClass().getResourceAsStream("/customer_faq");

String --> InputStream
ByteArrayInputStream stream = new ByteArrayInputStream(str.getBytes());

File --> InputStream
InputStream in = new FileInputStream(file);

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();
}

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();
}