java如何将InputStream转换为String字符串

使用Apache Utils

 String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);

Guava

String result = CharStreams.toString(new InputStreamReader(
inputStream, Charsets.UTF_8));

Scanner

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

Stream API (Java 8)

将换行符 \r\n 转换为了 \n

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

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

InputStreamReader和StringBuilder

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

StringWriter和IOUtils.copy (Apache Commons)

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

ByteArrayOutputStream和inputStream.read (JDK)

 ByteArrayOutputStream result = new ByteArrayOutputStream();
 byte[] buffer = new byte[1024];
 for (int length; (length = inputStream.read(buffer)) != -1; ) {
     result.write(buffer, 0, length);
 }
 // StandardCharsets.UTF_8.name() > JDK 7
 return result.toString("UTF-8");

BufferedReader

//不同系统，换行符不同
 String newLine = System.getProperty("line.separator");
 BufferedReader reader = new BufferedReader(
         new InputStreamReader(inputStream));
 StringBuilder result = new StringBuilder();
 for (String line; (line = reader.readLine()) != null; ) {
     if (result.length() > 0) {
         result.append(newLine);
     }
     result.append(line);
 }
 return result.toString();

BufferedInputStream 和 ByteArrayOutputStream (JDK)

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

inputStream.read() 和 StringBuilder

StringBuilder sb = new StringBuilder();
for (int ch; (ch = inputStream.read()) != -1; ) {
    sb.append((char) ch);
}
return sb.toString();