java - 如果 Runtime.getRuntime().exec 失败如何抛出错误

Question

我尝试以下操作:

package ro.gd.ex;

/**
 * Created by roroco on 11/17/14.
 */
public class Ex {
    public static void main(String[] args) {
        try {
            Process process = Runtime.getRuntime().exec("echo -n $(date)|xclip --selection clipboard");
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

如果我在终端中运行这个cmd，它会出现

roroco@roroco ~/Dropbox/jvs/ro-gd $ echo -n $(date)|xclip --selection clipboard
xclip: --selection: No such file or directory
roroco@roroco ~/Dropbox/jvs/ro-gd $ echo $?
1

但是在 java 中，它什么也没有引发，我的问题是如何让这个 cmd 抛出错误。我发现它的退出状态是 1。

我的操作系统:

roroco@roroco ~/Dropbox/jvs/ro-gd $ lsb_release -a
No LSB modules are available.
Distributor ID: LinuxMint
Description:    Linux Mint 17 Qiana
Release:    17
Codename:   qiana

Answer 1

process.waitFor() 将返回命令的错误级别，然后简单地创建一个新的 Exception(可能是一个 IOException) ...

public class Ex {
    public static void main(String[] args) {
        try {
            Process process = Runtime.getRuntime().exec("echo -n $(date)|xclip --selection clipboard");
            int exitCode = process.waitFor();
            if (exitCode != 0) {
                throw new IOException("Command exited with " + exitCode);
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

您还可以考虑使用 ProcessBuilder 而不是 Runtime.getRuntime().exec

public static void main(String[] args) {
    try {
        ProcessBuilder pb = new ProcessBuilder(
                        "echo",
                        "-n",
                        "$(date)|xclip",
                        "--selection",
                        "clipboard"
        );
        pb.redirectError();
        pb.inheritIO();
        Process process = pb.start();
        // Really should be reading the Process's InputStream
        int exitCode = process.waitFor();
        if (exitCode != 0) {
            throw new IOException("Command exited with " + exitCode);
        }
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}