java - 从 Java 执行 Shell 脚本，具有读取操作的 Shell 脚本

Question

我有一个读取输入的 Shell 脚本

#!/bin/bash
echo "Type the year that you want to check (4 digits), followed by [ENTER]:"
read year
echo $year  

我正在使用 JAVA API 执行此 shell 脚本

ProcessBuilder pb = new ProcessBuilder("/bin/bash", "/junk/leaptest.sh");
final Process process = pb.start();

InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line;


while ((line = br.readLine()) != null) {
    System.out.println(line);       
}
System.out.println("Program terminated!");

在 Java 控制台中我可以看到输出

Type the year that you want to check (4 digits), followed by [ENTER]:

现在的实际问题是如何将值传递给脚本中的 Shell 脚本如何读取变量“year”

---

我已经按照建议编辑了代码，但在我们更正它的地方不起作用

ProcessBuilder pb = new ProcessBuilder("/bin/bash", "-c", "/junk/leaptest.sh");
final Process process = pb.start();
InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line;
/*
 * OutputStream os = process.getOutputStream(); PrintWriter pw = new
 * PrintWriter(os);
 */

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(process.getOutputStream()));
while ((line = br.readLine()) != null) {
    System.out.println(line);
    // pw.println("8999");
    bw.write("2012");
}
System.out.println("Program terminated!");

Answer 1

您可以使用 Process 类的 OutputStream:

OutputStream os = process.getOutputStream();
PrintWriter pw = new PrintWriter(os);

pw.println("1997");

您写入此输出流的内容将成为 shell 脚本的输入流。所以 read year 会将 1987 读取到 year 变量。

编辑:

我也试了一下，终于找到了问题所在。 1997 字符串尚未到达脚本，因为 PrintWriter 缓冲了写入它的数据。您必须在 println() 之后使用 pw.flush() 刷新 PrintWriter 流，或者您必须设置 auto-flush 属性创建时为 true:

PrintWriter pw = new PrintWriter(os, true);

这是对我来说工作正常的完整代码:

leaptest.sh:

#!/bin/bash
echo "Type the year that you want to check (4 digits), followed by [ENTER]:"
read year
echo $year

测试.java:

import java.io.*;

class Test {

    public static void main(String[] args) {
        try {
            ProcessBuilder pb = new ProcessBuilder("/bin/bash", "leaptest.sh");
            final Process process = pb.start();

            BufferedReader br = new BufferedReader(new InputStreamReader(process.getInputStream()));
            PrintWriter pw = new PrintWriter(process.getOutputStream());
            String line;

            while ((line = br.readLine()) != null) {
                System.out.println(line);
                pw.println("1997");
                pw.flush();
            }
            System.out.println("Program terminated!");
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
}

输出:

$ java Test
Type the year that you want to check (4 digits), followed by [ENTER]:
1997
Program terminated!