How can I run the compiled code (.class) java from the java code itself?
I'm doing a kind of providing service like compiling and running java code on server side and giving output to the end user.
Can anyone suggest an approach that will accomplish this?
import java.io.*;
public class demo {
public static void main(String args[]) throws IOException, InterruptedException {
int result;
try {
System.out.println("command output:");
Process proc = Runtime.getRuntime().exec("java -cp . demoh");
InputStream in = proc.getInputStream();
result = proc.waitFor();
BufferedInputStream buffer = new BufferedInputStream(proc.getInputStream());
BufferedReader commandOutput = new BufferedReader(new InputStreamReader(buffer));
System.out.print(commandOutput);
String line = null;
try {
while ((line = commandOutput.readLine()) != null) {
System.out.print(line);
System.out.println("command output: " + line);
}//end while
commandOutput.close();
} catch (IOException e) {
//log and/or handle it
}
} catch (IOException e) {
System.err.println("IOException raised: " + e.getMessage());
}
}
}
If you have the .class files somewhere on disk, simply spawn a new process and run the java command like you would from a command line:
Process p = Runtime.getRuntime().exec("java <java class file>");
After some testing around, the following code worked for me:
public static void main(String args[]) throws IOException, InterruptedException {
int result;
try {
System.out.println("command output:");
Process proc = Runtime.getRuntime().exec("java -cp . Test");
InputStream errin = proc.getErrorStream();
InputStream in = proc.getInputStream();
BufferedReader errorOutput = new BufferedReader(new InputStreamReader(errin));
BufferedReader output = new BufferedReader(new InputStreamReader(in));
String line1 = null;
String line2 = null;
try {
while ((line1 = errorOutput.readLine()) != null ||
(line2 = output.readLine()) != null) {
if(line1 != null) System.out.print(line1);
if(line2 != null) System.out.print(line2);
}//end while
errorOutput.close();
output.close();
} catch (IOException e) {
e.printStackTrace();
}//end catc
result = proc.waitFor();
} catch (IOException e) {
System.err.println("IOException raised: " + e.getMessage());
}
}
Note two things here:
The runtime errors given by the java process are sent to the error stream, not input stream, so you have to read both of them!
You have to read the stream as the process is running. Waiting for the process to finish before reading the streams causes a deadlock because the process output buffer is filled and is waiting for your parent process to read the data, while the parent is waiting for the child to finish!
Create .jar file and add that file to the build path
There are still a lot of building/compiling tools, i.e. Ant or Maven, you can check before you write your own.
Try
Process process = Runtime.getRuntime().exec("java " + filePath); // without .class
Scanner output = new Scanner(process.getInputStream());
while (output.hasNext) {
String token = output.next();
...
}
One of the options is to create an instance of the class using the class loader. The class loader can take your class as a byte array and then you can create an instance of it and run it. See this method in the JDK docs.
Here's a sample app that will compile the Java source file, load the class, instantiate an instance, and print out the toString() of the class HelloWorld. I believe you'll need tools.jar on the classpath. The sample code expects the source file in the src folder. The src folder is required on the classpath since the .class file will get generated there by default.
For more control of the Java Compiler, read up on the javax.tools package.
package sourcerunner;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;
public class SourceRunner {
public static void main(String[] args) throws IOException, ClassNotFoundException, InstantiationException, IllegalAccessException, InterruptedException {
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
compiler.run(System.in, System.out, System.err, "src/sourcerunner/HelloWorld.java");
TimeUnit.SECONDS.sleep(1L);
Class<?> cls = Class.forName("sourcerunner.HelloWorld");
Object instance = cls.newInstance();
System.out.println(instance);
}
}
And here's the HelloWorld class:
package sourcerunner;
public class HelloWorld {
#Override
public String toString() {
return "Hello Java Compiler World.";
}
}
The above code is insanely insecure. Once you understand the code, modify it to use a new ClassLoader to load and instantiate the class. Make sure the ClassLoader has minimal permissions.
Related
I want to run a python file that can run AWS CloudFormation template using JAVA.
I am passing python file in JAVA code.
When I run the JAVA code it pauses at the following state:
compile-single:
run-single:
If i run the Python file from terminal it works perfectly.
Java Code:
private void RunPythonActionPerformed(java.awt.event.ActionEvent evt) {
String pythonScriptPath = "path to python file";
String[] cmd = new String[2];
cmd[0] = "python"; // check version of installed python: python -V
cmd[1] = pythonScriptPath;
// create runtime to execute external command
Runtime rt = Runtime.getRuntime();
Process pr = null;
try {
pr = rt.exec(cmd);
// retrieve output from python script
} catch (IOException ex) {
Logger.getLogger(Page2.class.getName()).log(Level.SEVERE, null, ex);
}
BufferedReader bfr = new BufferedReader(new InputStreamReader(pr.getInputStream()));
String line = "";
try {
while((line = bfr.readLine()) != null) {
// display each output line form python script
System.out.println(line);
}
// TODO add your handling code here:
} catch (IOException ex) {
Logger.getLogger(Page2.class.getName()).log(Level.SEVERE, null, ex);
}
}
Provide path to your source file at <complete path to your python source file>
Copying working code for you. For me output is Python 3.6.5
package com.samples;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class ProcessBuilderSample {
public static void main(String [] args) throws IOException {
RunPythonActionPerformed();
}
private static void RunPythonActionPerformed() throws IOException {
String pythonScriptPath = "python -V";
Process p = Runtime.getRuntime().exec(pythonScriptPath);
BufferedReader bfr = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = "";
try {
while((line = bfr.readLine()) != null) {
// display each output line form python script
System.out.println(line);
}
// TODO add your handling code here:
} catch (IOException ex) {
}
}
}
I am trying to read the output of Psexec into Java using a BufferedReader on a Process InputStream for use on a network however it is only outputting the first line.
Runtime rt = Runtime.getRuntime();
try {
Process p = rt.exec("C:\\Users\\*****\\Desktop\\PS\\Psexec \\\\" + "******" + " -u ****** -p ****** cmd /c dir D:\\");
BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
log.add("Computer: " + address);
String s = null;
while ((s = stdInput.readLine()) != null) {
log.add(s);
}
} catch (IOException e) {
e.printStackTrace();
}
What would be the reason for this happening and how would this be fixed?
The process is probably producing some of its output on stderr. Either read both the output and the error streams, in separate threads, or use the ProcessBuilder to create the Process, and merge the output streams before you do so, with redirectErrorStream().
So, I spent some time playing around with this, using ProcessBuilder.
I tried redirecting the IO through the INHERITED and PIPE options, but could not get it to display the output of the remote command (the psexec content was fine)
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
public class Test1 {
public static void main(String[] args) {
ProcessBuilder pb = new ProcessBuilder(
"C:\\Users\\shane\\Downloads\\PSTools\\PsExec.exe",
"\\\\builder",
"-u",
"xxx",
"-p",
"xxx",
"cmd",
"/c", "dir", "c:\\"
);
try {
Process p = pb.start();
StreamConsumer.consume(p.getErrorStream());
StreamConsumer.consume(p.getInputStream());
System.out.println("Exited with :" + p.waitFor());
} catch (IOException | InterruptedException exp) {
exp.printStackTrace();
}
}
public static class StreamConsumer implements Runnable {
private InputStream is;
public StreamConsumer(InputStream is) {
this.is = is;
}
public static void consume(InputStream is) {
StreamConsumer consumer = new StreamConsumer(is);
new Thread(consumer).start();
}
#Override
public void run() {
try {
int in = -1;
while ((in = is.read()) != -1) {
System.out.print((char)in);
}
} catch (IOException exp) {
exp.printStackTrace();
}
}
}
}
I even tried redirecting the InputStreams to File without any success. It would seem that whatever mechanism psexec is using to stream the results from the remote machine don't seem to be picked up by Java.
You might try PAExec which did work, but didn't seem to wait to exit after the remote command exited...
It could be the case that you started the process and didn't wait for it to finish before checking it's output. If this is the case, your main thread will exit your while loop because it reads null even though the subprocess is still executing. I would suggest using Process.waitFor() so that all of the output ends up in the stream before you begin polling it.
I made this code to move a folder then hardlink it to it's original destination. The problem it works fully when I'm just trying it from eclipse but when I make it into it's own self executing jar it wont create the hardlink but it will move the folder. The code runs a command line and then enters the commands. I dont know ehy the move command works and not the other one. Please help.
(Mklink command)
import java.io.*;
import javax.swing.JOptionPane;
public class The_Cloud_Setup {
public static void main(String[] args) throws IOException
{
try {
String command = "c:\\cmd.exe";
Runtime.getRuntime().exec(command);
}
catch (IOException e){
JOptionPane.showMessageDialog(null , e.getMessage(), "End Result", 2);
System.err.println(e.getMessage());
}
String[] StringMove = { "cmd.exe", "/c", "move"+" "+"\"C:/Users/%username%/Documents/My Games/Terraria/Players\""+" "+"\"C:/Users/%username%/Google Drive/Players\""};
String[] StringMklink = {"cmd.exe", "/c", "mklink"+" "+"/d"+" "+"\"C:/Users/%username%/Documents/My Games/Terraria/Players\""+" "+"\"C:/Users/%username%/Google Drive/Players\""};
Process ProcessMove = Runtime.getRuntime().exec(StringMove);
Process ProcessMklink = Runtime.getRuntime().exec(StringMklink);
BufferedReader VarMove = new BufferedReader(new InputStreamReader(ProcessMove.getInputStream()));
BufferedReader VarMklink = new BufferedReader(new InputStreamReader(ProcessMklink.getInputStream()));
String temp = "";
while ((temp = VarMove.readLine()) != null) {
System.out.println(temp);
}
VarMove.close();
VarMklink.close();
}
}
Most likely, when you are running natively, the move command has not completed before your program attempts to execute the mklink command. You can't make a link where there is an existing folder.
I am working on a simple java program. It simply compiles and executes another java program. I am using Runtime.exec() function to compile and run. There is no problem with compilation. but when it runs, if the second program needs an input to read from keyboard, I can't give it from the master process. I used getOutputStream() function. but it couldn't help. I will provide my code.
public class sam {
public static void main(String[] args) throws Exception {
try {
Process p = Runtime.getRuntime().exec("javac sam2.java");
Process p2 = Runtime.getRuntime().exec("java sam2");
BufferedReader in = new BufferedReader(
new InputStreamReader(p2.getInputStream()));
OutputStream out = p.getOutputStream();
String line = null;
line = in.readLine();
System.out.println(line);
input=input+"\n";
out.write(input.getBytes());
p.wait(10000);
out.flush();
}catch (IOException e) {
e.printStackTrace();
}
}
}
This is my master program(sam.java).
The following is the code of sam2.java
public class sam2 {
public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String str;
System.out.println("Enter the number..\n");
str = br.readLine();
System.out.println(Integer.parseInt(str));
}
}
There is no problem, if my second program has only printing statements. But the problem arises when I have to read something from the other.
It is a bit strange but you can run the second program without forking it. Just calling the main method in it. So forget the runtime section and do this:
sam2.main(new String[0]);
Of course this way you must compile sam2 at compile time
Each process needs to be allowed to run and finish. You can use Process#waitFor for this purpose. Equally, you need to consume any output from the process at the same time. waitFor will block so you will need use a Thread to read the input (and if you need to, write output to the process)
Depending on the location of the java/class file, you may also need to specify a starting folder from which the execution of the process can start.
Most of this significantly easier using ProcessBuilder
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
public class CompileAndRun {
public static void main(String[] args) {
new CompileAndRun();
}
public CompileAndRun() {
try {
int result = compile("compileandrun/HelloWorld.java");
System.out.println("javac returned " + result);
result = run("compileandrun.HelloWorld");
} catch (IOException | InterruptedException ex) {
ex.printStackTrace();
}
}
public int run(String clazz) throws IOException, InterruptedException {
ProcessBuilder pb = new ProcessBuilder("java", clazz);
pb.redirectError();
pb.directory(new File("src"));
Process p = pb.start();
InputStreamConsumer consumer = new InputStreamConsumer(p.getInputStream());
consumer.start();
int result = p.waitFor();
consumer.join();
System.out.println(consumer.getOutput());
return result;
}
public int compile(String file) throws IOException, InterruptedException {
ProcessBuilder pb = new ProcessBuilder("javac", file);
pb.redirectError();
pb.directory(new File("src"));
Process p = pb.start();
InputStreamConsumer consumer = new InputStreamConsumer(p.getInputStream());
consumer.start();
int result = p.waitFor();
consumer.join();
System.out.println(consumer.getOutput());
return result;
}
public class InputStreamConsumer extends Thread {
private InputStream is;
private IOException exp;
private StringBuilder output;
public InputStreamConsumer(InputStream is) {
this.is = is;
}
#Override
public void run() {
int in = -1;
output = new StringBuilder(64);
try {
while ((in = is.read()) != -1) {
output.append((char) in);
}
} catch (IOException ex) {
ex.printStackTrace();
exp = ex;
}
}
public StringBuilder getOutput() {
return output;
}
public IOException getException() {
return exp;
}
}
}
Now obviously, you should check the return results of the processes, and may be produce a better mechanism for interacting with the processes, but that's the basic idea...
You can just call the main method of the second class. The main method is just like any other static method.
This is what worked for me:
try {
single.main(new String[0]);
} catch (Exception e) {
JOptionPane.showMessageDialog(null, e);
}
Just call the main class file. For example, if your java class file name is xyz.java, you can call and execute the same in java swing application on click of a JButton, code is
private void Btn_createdatabaseActionPerformed(java.awt.event.ActionEvent evt) {
xyz.main(new String[0]);
}
That's it...
I want to create diff of two files. I tried searching for code in Java that does it, but didnt find any simple code/ utility code for this. Hence, I thought if I can somehow run linux diff/sdiff command from my java code and make it return a file that stores the diff then it would be great.
Suppose there are two files fileA and fileB. I should be able to store their diff in a file called fileDiff through my java code. Then fetching data from fileDiff would be no big deal.
You can use java.lang.Runtime.exec to run simple code. This gives you back a Process and you can read its standard output directly without having to temporarily store the output on disk.
For example, here's a complete program that will showcase how to do it:
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class testprog {
public static void main(String args[]) {
String s;
Process p;
try {
p = Runtime.getRuntime().exec("ls -aF");
BufferedReader br = new BufferedReader(
new InputStreamReader(p.getInputStream()));
while ((s = br.readLine()) != null)
System.out.println("line: " + s);
p.waitFor();
System.out.println ("exit: " + p.exitValue());
p.destroy();
} catch (Exception e) {}
}
}
When compiled and run, it outputs:
line: ./
line: ../
line: .classpath*
line: .project*
line: bin/
line: src/
exit: 0
as expected.
You can also get the error stream for the process standard error, and output stream for the process standard input, confusingly enough. In this context, the input and output are reversed since it's input from the process to this one (i.e., the standard output of the process).
If you want to merge the process standard output and error from Java (as opposed to using 2>&1 in the actual command), you should look into ProcessBuilder.
You can also write a shell script file and invoke that file from the java code. as shown below
{
Process proc = Runtime.getRuntime().exec("./your_script.sh");
proc.waitFor();
}
Write the linux commands in the script file, once the execution is over you can read the diff file in Java.
The advantage with this approach is you can change the commands with out changing java code.
You need not store the diff in a 3rd file and then read from in. Instead you make use of the Runtime.exec
Process p = Runtime.getRuntime().exec("diff fileA fileB");
BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}
try to use unix4j. it s about a library in java to run linux command. for instance if you got a command like:
cat test.txt | grep "Tuesday" | sed "s/kilogram/kg/g" | sort
in this program will become:
Unix4j.cat("test.txt").grep("Tuesday").sed("s/kilogram/kg/g").sort();
You can call run-time commands from java for both Windows and Linux.
import java.io.*;
public class Test{
public static void main(String[] args)
{
try
{
Process process = Runtime.getRuntime().exec("pwd"); // for Linux
//Process process = Runtime.getRuntime().exec("cmd /c dir"); //for Windows
process.waitFor();
BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line;
while ((line=reader.readLine())!=null)
{
System.out.println(line);
}
}
catch(Exception e)
{
System.out.println(e);
}
finally
{
process.destroy();
}
}
}
Hope it Helps.. :)
Runtime run = Runtime.getRuntime();
//The best possible I found is to construct a command which you want to execute
//as a string and use that in exec. If the batch file takes command line arguments
//the command can be constructed a array of strings and pass the array as input to
//the exec method. The command can also be passed externally as input to the method.
Process p = null;
String cmd = "ls";
try {
p = run.exec(cmd);
p.getErrorStream();
p.waitFor();
}
catch (IOException e) {
e.printStackTrace();
System.out.println("ERROR.RUNNING.CMD");
}finally{
p.destroy();
}
The suggested solutions could be optimized using commons.io, handling the error stream, and using Exceptions. I would suggest to wrap like this for use in Java 8 or later:
public static List<String> execute(final String command) throws ExecutionFailedException, InterruptedException, IOException {
try {
return execute(command, 0, null, false);
} catch (ExecutionTimeoutException e) { return null; } /* Impossible case! */
}
public static List<String> execute(final String command, final long timeout, final TimeUnit timeUnit) throws ExecutionFailedException, ExecutionTimeoutException, InterruptedException, IOException {
return execute(command, 0, null, true);
}
public static List<String> execute(final String command, final long timeout, final TimeUnit timeUnit, boolean destroyOnTimeout) throws ExecutionFailedException, ExecutionTimeoutException, InterruptedException, IOException {
Process process = new ProcessBuilder().command("bash", "-c", command).start();
if(timeUnit != null) {
if(process.waitFor(timeout, timeUnit)) {
if(process.exitValue() == 0) {
return IOUtils.readLines(process.getInputStream(), StandardCharsets.UTF_8);
} else {
throw new ExecutionFailedException("Execution failed: " + command, process.exitValue(), IOUtils.readLines(process.getInputStream(), StandardCharsets.UTF_8));
}
} else {
if(destroyOnTimeout) process.destroy();
throw new ExecutionTimeoutException("Execution timed out: " + command);
}
} else {
if(process.waitFor() == 0) {
return IOUtils.readLines(process.getInputStream(), StandardCharsets.UTF_8);
} else {
throw new ExecutionFailedException("Execution failed: " + command, process.exitValue(), IOUtils.readLines(process.getInputStream(), StandardCharsets.UTF_8));
}
}
}
public static class ExecutionFailedException extends Exception {
private static final long serialVersionUID = 1951044996696304510L;
private final int exitCode;
private final List<String> errorOutput;
public ExecutionFailedException(final String message, final int exitCode, final List<String> errorOutput) {
super(message);
this.exitCode = exitCode;
this.errorOutput = errorOutput;
}
public int getExitCode() {
return this.exitCode;
}
public List<String> getErrorOutput() {
return this.errorOutput;
}
}
public static class ExecutionTimeoutException extends Exception {
private static final long serialVersionUID = 4428595769718054862L;
public ExecutionTimeoutException(final String message) {
super(message);
}
}
if the opening in windows
try {
//chm file address
String chmFile = System.getProperty("user.dir") + "/chm/sample.chm";
Desktop.getDesktop().open(new File(chmFile));
} catch (IOException ex) {
Logger.getLogger(Frame.class.getName()).log(Level.SEVERE, null, ex);
{
JOptionPane.showMessageDialog(null, "Terjadi Kesalahan", "Error", JOptionPane.WARNING_MESSAGE);
}
}
ProcessBuilder processBuilder = new ProcessBuilder();
// -- Linux --
// Run a shell command
processBuilder.command("bash", "-c", "ls /home/kk/");
// Run a shell script
//processBuilder.command("path/to/hello.sh");
// -- Windows --
// Run a command
//processBuilder.command("cmd.exe", "/c", "dir C:\\Users\\kk");
// Run a bat file
//processBuilder.command("C:\\Users\\kk\\hello.bat");
try {
Process process = processBuilder.start();
StringBuilder output = new StringBuilder();
BufferedReader reader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
output.append(line + "\n");
}
int exitVal = process.waitFor();
if (exitVal == 0) {
System.out.println("Success!");
System.out.println(output);
System.exit(0);
} else {
//abnormal...
}
} catch (IOException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}