快速将输入流(InputStream)转化为字符串(String)

建议使用方法6，性能更好！ 方法1(使用 Scanner (JDK))：

Scanner s = new Scanner(inputStream).useDelimiter("\A");
String result = s.hasNext() ? s.next() : "";

方法2：使用 Stream API (Java 8):

Warning: This solution converts different line breaks (like rn) to n.

String result = new BufferedReader(new InputStreamReader(inputStream))
  .lines().collect(Collectors.joining("n"));

方法3：使用 parallel Stream API (Java 8).

Warning: This solution converts different line breaks (like rn) to n.

String result = new BufferedReader(new InputStreamReader(inputStream)).lines()
   .parallel().collect(Collectors.joining("n"));

方法4：使用 InputStreamReader and StringBuilder (JDK)

final int bufferSize = 1024;
final char[] buffer = new char[bufferSize];
final StringBuilder out = new StringBuilder();
Reader in = new InputStreamReader(stream, StandardCharsets.UTF_8);
int charsRead;
while((charsRead = in.read(buffer, 0, buffer.length)) > 0) {
    out.append(buffer, 0, charsRead);
}
return out.toString();

方法5：使用 StringWriter and IOUtils.copy (Apache Commons)

StringWriter writer = new StringWriter();
IOUtils.copy(inputStream, writer, "UTF-8");
return writer.toString();

方法6：使用 ByteArrayOutputStream and inputStream.read (JDK) 

BufferedInputStream bis = new BufferedInputStream(inputStream);
ByteArrayOutputStream buf = new ByteArrayOutputStream();
int result = bis.read();
while(result != -1) {
    buf.write((byte) result);
    result = bis.read();
}
// StandardCharsets.UTF_8.name() > JDK 7
return buf.toString("UTF-8");

 建议使用方法6，性能更好！