System.out转换为字符串 [英] System.out to string

问题描述

我有一个通过Windows命令行运行的应用程序，我希望能够复制已发送到控制台的所有数据，并将其附加到文件中以进行调试.每当发生异常时，报告就会保存到文件系统中，其中包括异常堆栈跟踪和完整的控制台.

I have an application that runs through the windows command line, and I want to be able to copy all of the data that has been sent to the console and append it to a file for debugging purposes. Whenever an exception happens, a report is saved to the file system that includes the exception stack trace and the full console.

我无法将整个控制台重定向到我的文件，因为我需要能够从用户那里获取控制台输入.

I cannot redirect the entire console to my file because I need to be able to obtain console input from the user.

System.out.toString()不返回控制台，而是对象本身的字符串表示形式.

System.out.toString() doesn't return the console, but a string representation of the object itself.

推荐答案

即使不是最好的主意，一种解决方案可能是:

Even if not the best idea, one solution could be:

public static void main(String[] xxx) {
    System.setOut(new DoublePrintStream(System.out, "/myfile.txt"));
    System.setErr(new DoublePrintStream(System.err, "/errors.txt"));

    System.out.println("this works");
    try { throw new RuntimeException("oulala");} catch(Exception e) { e.printStackTrace(); }

    //System.out.close(); // maybe required at the end of execution
}

class DoublePrintStream extends PrintStream {
        private final OutputStream fos;

        DoublePrintStream(OutputStream out, String filename){
            super(out);

            try {
                fos = new FileOutputStream(new File(filename));
            } catch (FileNotFoundException e) {
                throw new AssertionError("cant create file", e);
            }
        }

        @Override
        public void write(byte[] buf, int off, int len) {
            super.write(buf, off, len);

            try {
                fos.write(buf, off, len);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

        @Override
        public void close() {
            try {
                fos.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            } finally {
                super.close();
            }
        }
    }

因此您在控制台+中有一个文件输出，而所有错误都在一个单独的文件中.

so you have output in the console + in a file, and all errors in a separate file.

即使日志记录框架更好，该解决方案也具有根本不需要更改代码的优点.

Even if logging frameworks are way better, this solution has the advantage to require no code change at all.

PS:在多线程上下文中，您还应该同步 DoublePrintStream

PS: in a multithreaded context, you should also synchronize the methods of DoublePrintStream

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