如何使用BufferedWriter写入标准输出

问题描述

我目前正在编写一个使用BufferedWriter生成多个日志文件的应用程序。但是，在调试时，我想写入System.out而不是文件。我想我可以改变：

I am currently writing an application that produces several log files using BufferedWriter. While debugging, however, I want to write to System.out instead of a file. I figured I could change from:

log = new BufferedWriter(new FileWriter(tokenizerLog));

to：

BufferedWriter log = new BufferedWriter(new OutputStreamWriter(System.out));
log.write("Log output\n");

而不是：

System.out.println("log output")

新 OutputStreamWriter 选项虽然没有工作。如何仅更改BufferedWriter构造函数中的Object以从文件重定向到Standard out。因为我有几个日志文件，我将写入，在任何地方使用System.out并将输出更改为文件实际上不是一个选项。

The new OutputStreamWriter option has not been working though. How do I change just the Object inside the BufferedWriter constructor to redirect from a file to Standard out. Because I have several log files I will be writing to, using System.out everywhere and changing the output to a file isn't really an option.

推荐答案

你的方法确实有效，你只是忘记刷新输出：

Your approach does work, you are just forgetting to flush the output:

try {
  BufferedWriter log = new BufferedWriter(new OutputStreamWriter(System.out));

  log.write("This will be printed on stdout!\n");
  log.flush();
}
catch (Exception e) {
  e.printStackTrace();
}

两者 OutputStreamWriter 和 PrintWriter 是 Writer 个实例，所以你可以这样做：

The both OutputStreamWriter and PrintWriter are Writer instances so you can just do something like:

BufferedWriter log;

Writer openForFile(String fileName) {
  if (fileName != null)
    return new PrintWriter(fileName);
  else
    return new OutputStreamWriter(System.out);
}

log = new BufferedWriter(openForFile(null)); //stdout
log = new BufferedWriter(openForFile("mylog.log")); // using a file

或者其他什么，它只是为了给你一个想法..

or whatever, it is just to give you the idea..

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