executing ant script from java class

Question

I want to run an ant script runANTScript.xml from my java class. The script is located in SCRIPTS/ folder of my web application. I tried to run file like this

    StringBuffer output = new StringBuffer();

    String command="ant -f SCRIPTS/runANTScript.xml"
    Process p;
    try {

        p = Runtime.getRuntime().exec(command);
        p.waitFor();
        BufferedReader reader = 
                        new BufferedReader(new InputStreamReader(p.getInputStream()));

                    String line = "";           
        while ((line = reader.readLine())!= null) {
            output.append(line + "\n");
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

But this gives an error

java.io.IOException: Cannot run program "ant": CreateProcess error=2, The system cannot find the file specified
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1047)
at java.lang.Runtime.exec(Runtime.java:617)
at java.lang.Runtime.exec(Runtime.java:450)
at java.lang.Runtime.exec(Runtime.java:347)
at my.Abc.executeCommand(Abc.java:48)

I am able to run by using code below but it import classes from ant.jar and i don't want to use jar file.

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.DefaultLogger;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.ProjectHelper;
 Project project = new Project();
    File buildFile = new File(buildXmlFileFullPath);
    project.setUserProperty("ant.file", buildFile.getAbsolutePath());
    project.addBuildListener(consoleLogger);

    // Capture event for Ant script build start / stop / failure
    try {
        project.fireBuildStarted();
        project.init();
        ProjectHelper projectHelper = ProjectHelper.getProjectHelper();
        project.addReference("ant.projectHelper", projectHelper);
        projectHelper.parse(project, buildFile);

        // If no target specified then default target will be executed.
        String targetToExecute = (target != null && target.trim().length() > 0) ? target.trim() : project.getDefaultTarget();
        project.executeTarget(targetToExecute);
        project.fireBuildFinished(null);
        success = true;
    }

Answer 1

You need

1. to include the path of ant executable so that the java exec() knows where to find it.

or

2. Call ant with its absolute path .

The first task is a bit complicated, as PATH environmental variable is evaluated really early during the boot process (eg java -Djava.library.path=/path/to/ant )

Changing the system property later doesn't have any effect. You could still use (or abuse?) the classloader:

System.setProperty( "java.library.path", "/path/to/ant" );

Field fieldSysPath = ClassLoader.class.getDeclaredField( "sys_paths" );
fieldSysPath.setAccessible( true );
fieldSysPath.set( null, null );

Answer 2

如果您不介意将Groovy添加到类路径中，则可以使用AntBuilder

Answer 3

Different Approach

Add Ant libraries to your classapth and replace call Runtmie.exec(...) with org.apachetools.ant.Main.main(...)

This is more stable, and has no dependency on a local Ant installation. Which need to be on the system environment PATH , or called with the full path in the Runtime.exec(...)

This will make Ant part of the created applciation and not a externally called application.