java - 为什么 BufferedReader 无法读取 InputStream 的最后一行？

Question

*注意:澄清一下，也许这个问题关于 InputStream 是“活着的”不是很清楚。与 telnet 天气服务的连接(请参阅下面的链接)保持打开状态。目标是获取来自服务器的所有行。*

从示例 Apache WeatherTelnet 构建 code ，我正在使用 InputStream.read使用 chars 方法一次输出一个字符(受 javamex tutorial 习语启发):

thufir@dur:~$ 
thufir@dur:~$ java -jar NetBeansProjects/Teln/dist/Teln.jar 
------------------------------------------------------------------------------
*               Welcome to THE WEATHER UNDERGROUND telnet service!            *
------------------------------------------------------------------------------
*                                                                            *
*   National Weather Service information provided by Alden Electronics, Inc. *
*    and updated each minute as reports come in over our data feed.          *
*                                                                            *
*   **Note: If you cannot get past this opening screen, you must use a       *
*   different version of the "telnet" program--some of the ones for IBM      *
*   compatible PC's have a bug that prevents proper connection.              *
*                                                                            *
*           comments: jmasters@wunderground.com                              *
------------------------------------------------------------------------------

Press Return to continue:
^Cthufir@dur:~$ 

这是期望的输出。但是，使用 BufferedReader 读取 InputStream 会导致删除最后一行。 (或者，至少，它没有打印到控制台。)错误的输出，使用 lines 方法:

thufir@dur:~$ 
thufir@dur:~$ java -jar NetBeansProjects/Teln/dist/Teln.jar 

------------------------------------------------------------------------------

*               Welcome to THE WEATHER UNDERGROUND telnet service!            *

------------------------------------------------------------------------------

*                                                                            *

*   National Weather Service information provided by Alden Electronics, Inc. *

*    and updated each minute as reports come in over our data feed.          *

*                                                                            *

*   **Note: If you cannot get past this opening screen, you must use a       *

*   different version of the "telnet" program--some of the ones for IBM      *

*   compatible PC's have a bug that prevents proper connection.              *

*                                                                            *

*           comments: jmasters@wunderground.com                              *

------------------------------------------------------------------------------



^Cthufir@dur:~$ 
thufir@dur:~$ 

StreamReader代码:

package teln;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class StreamReader {

    private StreamReader() {
    }

    StreamReader(InputStream inputStream) throws IOException {
        lines(inputStream);
    }

    private void chars(InputStream inputStream) throws IOException {
        do {
            char ch = (char) inputStream.read();
            System.out.print(ch);
        } while (true);
    }

    private void lines(InputStream inputStream) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
        String line = "";
        do {
            System.out.println(line);
        } while ((line = br.readLine()) != null);

        System.out.println(line);

    }
}

大概最后一行不知何故是“空”？是否可以更改逻辑以便从 lines 打印最后一行，就像从 chars 打印一样？

Answer 1

您还没有解释数据的来源，但我怀疑它来自某个末尾没有行终止符并且没有关闭流的来源。

如果流已关闭 - 例如通过终止连接，如果这是一个客户端/服务器应用程序 - 那么您会看到最后一行。 BufferedReader 肯定会返回最后一行数据，即使它没有以行结束符结束，但只有当它知道它到达了流的末尾时。