java - 在Java中执行shell脚本总是返回null

Question

我的主目录 ~ 中有一个名为 test.sh 的 shell 脚本文件。我想使用java执行shell文件。我使用以下代码:

Runtime runtime = Runtime.getRuntime();
        Process process = null;
        String cmd[] = {"/bin/bash","~/test.sh"};
        String[] env = {"PATH=/bin:/usr/bin/"};

        try
        {
            process = runtime.exec(cmd,env);
            process.waitFor();

            BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
            StringBuilder stringBuilder = new StringBuilder();

            String line = reader.readLine();
            stringBuilder.append(line);

            System.out.println("The token is " + stringBuilder.toString() );

        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

当我尝试执行以下程序时，我得到 null 结果如下:

The token is null

我哪里出错了？

编辑:

test.sh 只有

echo "Hello"

Answer 1

您需要在进程处于 Activity 状态时从流中读取数据。 waitFor() 返回后访问 getInputStream 没有意义，因为此时进程已经死亡。您应该启动一个线程来读取 getInputStream()。

类似于:

process = runtime.exec(cmd,env);

final BufferedReader reader = new BufferedReader(new InputStreamReader (process.getInputStream()));
final StringBuilder stringBuilder = new StringBuilder();

new Thread () {
    public void run () {
        String line = reader.readLine();
        stringBuilder.append(line);
    }
}.start ();
process.waitFor();