Java InputStream 转换成 String

淡淡的烟草味﹌ 2023-02-14 10:23 81阅读 0赞

参考文章：[Java InputStream 转换成 String][Java InputStream _ String]

如下, 一共存在11种实现方式及其对应的性能测试结果:

# 1. 使用IOUtils.toString (Apache Utils) #

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

# 2. 使用CharStreams (guava) #

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

# 3. 使用Scanner (JDK) #

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

# 4. 使用Stream Api (Java 8). 提醒: 这种方式会将不同的换行符 (比如\\r\\n) 都替换为 \\n. #

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

# 5. 使用parallel Stream Api (Java 8). 提醒: 这种方式会将不同的换行符 (比如\\r\\n) 都替换为 \\n. #

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

# 6. 使用InputStreamReader 和StringBuilder (JDK) #

final int bufferSize = 1024;
    final char[] buffer = new char[bufferSize];
    final StringBuilder out = new StringBuilder();
    Reader in = new InputStreamReader(inputStream, "UTF-8");
    for (; ; ) {
        int rsz = in.read(buffer, 0, buffer.length);
        if (rsz < 0)
            break;
        out.append(buffer, 0, rsz);
    }
    return out.toString();

# 7. 使用StringWriter 和 IOUtils.copy (Apache Commons) #

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

# 8. 使用ByteArrayOutputStream 和 inputStream.read (JDK) #

ByteArrayOutputStream result = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int length;
    while ((length = inputStream.read(buffer)) != -1) {
        result.write(buffer, 0, length);
    }
    return result.toString("UTF-8");

# 9. 使用BufferedReader (JDK). 提醒: 这种方式会将不同的换行符 (比如\\r\\n) 都替换为当前系统的换行符(例如, 在windows下是"\\r\\n"). #

StringBuilder sbf = new StringBuilder();
    try (
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
    ) {
        String tempStr;
        while ((tempStr = reader.readLine()) != null) {
            sbf.append(tempStr);
        }
        reader.close();
        
        return sbf.toString();
    } catch (IOException e) {
        e.printStackTrace();
    }
    
    return sbf.toString();

# 10. 使用BufferedInputStream 和 ByteArrayOutputStream (JDK) #

BufferedInputStream bis = new BufferedInputStream(inputStream);
    ByteArrayOutputStream buf = new ByteArrayOutputStream();
    int result = bis.read();
    while(result != -1) {
        buf.write((byte) result);
        result = bis.read();
    }
    return buf.toString();

# 11. 使用 inputStream.read() 和 StringBuilder (JDK). 提醒: 这种方式处理Unicode时存在问题, 例如俄文, 仅在非Unicode字符串下工作正常. #

int ch;
    StringBuilder sb = new StringBuilder();
    while((ch = inputStream.read()) != -1)
        sb.append((char)ch);
    reset();
    return sb.toStrin

[Java InputStream _ String]: https://www.jianshu.com/p/6a7229ecfa21