如何将Process Builder的输出重定向到字符串？

Question

我正在使用以下代码来启动进程构建器.我想知道如何将其输出重定向到String.

ProcessBuilder pb = new ProcessBuilder(System.getProperty("user.dir")+"/src/generate_list.sh", filename);
Process p = pb.start();

我试过使用,ByteArrayOutputStream但它似乎没有用.

Answer 1

从中读取InputStream.您可以将输出附加到StringBuilder:

BufferedReader reader = 
                new BufferedReader(new InputStreamReader(process.getInputStream()));
StringBuilder builder = new StringBuilder();
String line = null;
while ( (line = reader.readLine()) != null) {
   builder.append(line);
   builder.append(System.getProperty("line.separator"));
}
String result = builder.toString();

Answer 2

使用Apache Commons IOUtils,您可以在一行中完成:

ProcessBuilder pb = new ProcessBuilder("pwd");
String output = IOUtils.toString(pb.start().getInputStream(), StandardCharsets.UTF_8);

Answer 3

Java 8示例:

public static String runCommandForOutput(List<String> params) {
    ProcessBuilder pb = new ProcessBuilder(params);
    Process p;
    String result = "";
    try {
        p = pb.start();
        final BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));

        StringJoiner sj = new StringJoiner(System.getProperty("line.separator"));
        reader.lines().iterator().forEachRemaining(sj::add);
        result = sj.toString();

        p.waitFor();
        p.destroy();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return result;
}

用法:

List<String> params = Arrays.asList("/bin/sh", "-c", "cat /proc/cpuinfo");
String result = runCommandForOutput(params);

我使用这个确切的代码,它适用于单行或多行结果.您也可以添加错误流处理程序.

Answer 4

你可能会这样做:

private static BufferedReader getOutput(Process p) {
    return new BufferedReader(new InputStreamReader(p.getInputStream()));
}

private static BufferedReader getError(Process p) {
    return new BufferedReader(new InputStreamReader(p.getErrorStream()));
}
...
Process p = Runtime.getRuntime().exec(commande);
BufferedReader output = getOutput(p);
BufferedReader error = getError(p);
String ligne = "";

while ((ligne = output.readLine()) != null) {
    System.out.println(ligne);
}

while ((ligne = error.readLine()) != null) {
 System.out.println(ligne);
}

Answer 5

从Java 9 开始，我们终于有了一个单行代码：

ProcessBuilder pb = new ProcessBuilder("pwd");
Process process = pb.start();

String result = new String(process.getInputStream().readAllBytes());

Answer 6

只需添加.inheritIO();到流程构建器行。

IE：

ProcessBuilder pb = new ProcessBuilder(script.sh).inheritIO();

Answer 7

For Java 7 and 8 this should work:

private String getInputAsString(InputStream is)
{
   try(java.util.Scanner s = new java.util.Scanner(is)) 
   { 
       return s.useDelimiter("\\A").hasNext() ? s.next() : ""; 
   }
}

Then in your code, do this:

String stdOut = getInputAsString(p.getInputStream());
String stdErr = getInputAsString(p.getErrorStream());

I shamelessly stole that from: How to redirect Process Builder's output to a string?