我正在尝试使用ProcessBuilder执行命令。该命令应该在stdout上写入二进制数据。如何在我的byte []？
中获取此数据答案 0 :(得分：0)
这是一个有效的示例，为输出true返回1，为输出false返回0（在所有其他情况下均引发Exception）。我还添加了设置工作路径和环境变量的步骤，这对于您的特定示例不是必需的，因此您可以将其删除。
通过设置binaryCommand[0]="touch";和binaryCommand[1]="1";，重新编译并运行.jar文件来验证设置工作目录的作用。
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Map;
import java.util.StringJoiner;
public class GenerateOutput {
/**
* This code can execute a command and return the binary value of it's output if it
* is actually binary.
*
* compile this project into a .jar and run it with for example:
* java -jar readOutputOfCommand.jar
*
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
boolean answerYes = false; // no yes answer to any command prompts is needed.
// to execute a command with spaces in it in terminal, put them in an array of Strings.
String[] binaryCommand = new String[2];
// write a command that gives a binary output:
binaryCommand[0] = "echo";
binaryCommand[1] = "1";
// pass the commands to a method that executes them
System.out.println("The output of the echo command = "+executeCommands(binaryCommand,answerYes));
}
/**
* This executes the commands in terminal.
* Additionally it sets an environment variable (not necessary for your particular solution)
* Additionally it sets a working path (not necessary for your particular solution)
* @param commandData
* @param ansYes
* @throws Exception
*/
public static boolean executeCommands(String[] commands,Boolean ansYes) throws Exception {
String capturedCommandOutput = null;
System.out.println("Incoming commandData = "+Arrays.deepToString(commands));
File workingDirectory = new File("/mnt/c/testfolder b/");
// create a ProcessBuilder to execute the commands in
ProcessBuilder processBuilder = new ProcessBuilder(commands);
// this is not necessary but can be used to set an environment variable for the command
processBuilder = setEnvironmentVariable(processBuilder);
// this is not necessary but can be used to set the working directory for the command
processBuilder.directory(workingDirectory);
// execute the actual commands
try {
Process process = processBuilder.start();
// capture the output stream of the command
BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
StringJoiner sj = new StringJoiner(System.getProperty("line.separator"));
reader.lines().iterator().forEachRemaining(sj::add);
capturedCommandOutput = sj.toString();
System.out.println("The output of this command ="+ capturedCommandOutput);
// here you connect the output of your command to any new input, e.g. if you get prompted for `yes`
new Thread(new SyncPipe(process.getErrorStream(), System.err)).start();
new Thread(new SyncPipe(process.getInputStream(), System.out)).start();
PrintWriter stdin = new PrintWriter(process.getOutputStream());
//This is not necessary but can be used to answer yes to being prompted
if (ansYes) {
System.out.println("WITH YES!");
stdin.println("yes");
}
// write any other commands you want here
stdin.close();
// this lets you know whether the command execution led to an error(!=0), or not (=0).
int returnCode = process.waitFor();
System.out.println("Return code = " + returnCode);
} catch (IOException e1) {
e1.printStackTrace();
}
return retrieveBooleanOutput(capturedCommandOutput);
}
private static boolean retrieveBooleanOutput(String commandOutput) throws Exception {
if (commandOutput != null && commandOutput.length() == 1) {
if (commandOutput.contains("0")) {
return false;
} else if (commandOutput.contains("1")) {
return true;
}
}
throw new Exception("The output is not binary.");
}
/**
* source: https://stackoverflow.com/questions/7369664/using-export-in-java
* @param processBuilder
* @param varName
* @param varContent
* @return
*/
private static ProcessBuilder setEnvironmentVariable(ProcessBuilder processBuilder){
String varName = "variableName";
String varContent = "/mnt/c/testfolder a/";
Map<String, String> env = processBuilder.environment();
System.out.println("Setting environment variable "+varName+"="+varContent);
env.put(varName, varContent);
processBuilder.environment().put(varName, varContent);
return processBuilder;
}
}
class SyncPipe implements Runnable
{
/**
* This class pipes the output of your command to any new input you generated
* with stdin. For example, suppose you run cp /mnt/c/a.txt /mnt/b/
* but for some reason you are prompted: "do you really want to copy there yes/no?
* then you can answer yes since your input is piped to the output of your
* original command. (At least that is my practical interpretation might be wrong.)
* @param istrm
* @param ostrm
*/
public SyncPipe(InputStream istrm, OutputStream ostrm) {
istrm_ = istrm;
ostrm_ = ostrm;
}
public void run() {
try
{
final byte[] buffer = new byte[1024];
for (int length = 0; (length = istrm_.read(buffer)) != -1; )
{
ostrm_.write(buffer, 0, length);
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
private final OutputStream ostrm_;
private final InputStream istrm_;
}