从进程打印 Java InputStream [英] Printing a Java InputStream from a Process

问题描述

UPDATE:我发现了为什么这可能不起作用的关键部分！我使用 System.setOut(out);其中 out 是一个特殊的 PrintStream 到 JTextArea

这是代码，但我遇到的问题是信息只有在我结束过程后才会打印出来.

This is the code, but the issue I'm having is that the information is only printed out once I end the process.

public Constructor() {
    main();
}

private void main() {
    btnStart.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            try {
                ProcessBuilder builder = new ProcessBuilder("java", textFieldMemory.getText(), "-jar", myJar);
                Process process = builder.start();
                InputStream inputStream = process.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream), 1);
                String line;
                while ((line = bufferedReader.readLine()) != null) {
                    System.out.println(line);
                }
                inputStream.close();
                bufferedReader.close();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }
    });
} 

当前输出:

Line 1
Line 2
Line 3
Line 4
Line 5

这是正确的输出，但是当我结束这个过程时它只被打印为一个大块.

This is the correct output, but it is only being printed as one big block when I end the process.

有谁知道这是什么问题?如果是这样，您能帮我解释一下为什么会发生这种情况吗，提前致谢.

Does anyone know what the issue is? If so can you help explain to me why this is happening, thank-you in advance.

推荐答案

在单独的线程中处理进程的输出流可能会有所帮助.您还希望在继续您的逻辑之前明确等待流程结束:

Processing the output stream of the process in a separate thread might help here. You also want to explicitly wait for the process to end before continuing with your logic:

ProcessBuilder builder = new ProcessBuilder("java",
        textFieldMemory.getText(), "-jar", myJar);
final Process process = builder.start();
final Thread ioThread = new Thread() {
    @Override
    public void run() {
        try {
            final BufferedReader reader = new BufferedReader(
                    new InputStreamReader(process.getInputStream()));
            String line = null;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
            reader.close();
        } catch (final Exception e) {
            e.printStackTrace();
        }
    }
};
ioThread.start();

process.waitFor();

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