Question

我正在使用以下代码。

BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line = null;

StringBuilder responseData = new StringBuilder();
while((line = in.readLine()) != null) {
    responseData.append(line);
}

但阅读200行需要超过12秒。

请帮忙

Answer 1

我强烈怀疑这是因为网络连接或你正在与之交谈的网络服务器 - 这不是BufferedReader的错。试着测量一下：

InputStream stream = conn.getInputStream();
byte[] buffer = new byte[1000];
// Start timing
while (stream.read(buffer) > 0)
{
}
// End timing

我认为你会发现它几乎与解析文本的时间完全相同。

请注意，您还应该为InputStreamReader提供适当的编码 - 平台默认编码几乎肯定不您应该使用的内容。

Answer 2

我有更长的考试要尝试。这需要平均160 ns来读取每一行，因为它将它添加到List（这可能是你想要的，因为删除换行不是很有用。

public static void main(String... args) throws IOException {
    final int runs = 5 * 1000 * 1000;

    final ServerSocket ss = new ServerSocket(0);
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                Socket serverConn = ss.accept();
                String line = "Hello World!\n";
                BufferedWriter br = new BufferedWriter(new OutputStreamWriter(serverConn.getOutputStream()));
                for (int count = 0; count < runs; count++)
                    br.write(line);
                serverConn.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }).start();

    Socket conn = new Socket("localhost", ss.getLocalPort());

    long start = System.nanoTime();
    BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
    String line;

    List<String> responseData = new ArrayList<String>();
    while ((line = in.readLine()) != null) {
        responseData.add(line);
    }
    long time = System.nanoTime() - start;
    System.out.println("Average time to read a line was " + time / runs + " ns.");
    conn.close();
    ss.close();
}

打印

Average time to read a line was 158 ns.

如果你想构建一个StringBuilder，保留换行符，我会建议采用以下方法。

Reader r = new InputStreamReader(conn.getInputStream());
String line;

StringBuilder sb = new StringBuilder();
char[] chars = new char[4*1024];
int len;
while((len = r.read(chars))>=0) {
    sb.append(chars, 0, len);
}

仍打印

Average time to read a line was 159 ns.

在这两种情况下，速度都受发送者而非接收者的限制。通过优化发送器，我将这个时间降低到每行105 ns。

使用BufferedReader.readLine（）读取inputStream太慢了

2 个答案: