create And Compile Java Source - Java javax.tools

Java examples for javax.tools:JavaCompiler

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Description

create And Compile Java Source

Demo Code


import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;

public class Main{

    /**//from  ww w.j a  va  2 s  .  c o  m
     *
     *
     * @param javaFile
     * @param source
     * @param compilerOptions
     * @return
     * @throws java.io.IOException
     * @throws java.lang.ClassNotFoundException
     */
    public static Class<?> createAndCompileJavaSource(File javaFile,
            String source, String[] compilerOptions) throws IOException,
            ClassNotFoundException {

        // Save Java code in temporary directory for source code
        PrintWriter out = new PrintWriter(javaFile);
        out.print(source);
        out.close();

        // Return compiled class
        return compileJavaSource(javaFile, compilerOptions);

    }
    /**
     *
     *
     * @param javaFile
     * @param compilerOptions
     * @return
     * @throws java.io.IOException
     * @throws java.lang.ClassNotFoundException
     */
    public static Class<?> compileJavaSource(File javaFile,
            String[] compilerOptions) throws IOException,
            ClassNotFoundException {

        File parentFile = null;
        JavaCompiler javaCompiler = null;
        StandardJavaFileManager fileManager = null;
        Iterable<? extends JavaFileObject> fileObjects = null;
        JavaNameScanner nameScanner = null;
        URL[] urls = null;
        URLClassLoader urlClassLoader = null;
        Class<?> clazz = null;

        // Parent directory for Java source file
        parentFile = javaFile.getParentFile();

        // Java compiler object
        javaCompiler = ToolProvider.getSystemJavaCompiler();

        // Standard Java file manager object
        fileManager = javaCompiler.getStandardFileManager(null, null, null);

        //
        fileObjects = fileManager.getJavaFileObjects(javaFile);

        // Start reading Java source file for finding package name as
        // thread
        nameScanner = new JavaNameScanner(javaFile);
        new Thread(nameScanner).start();

        // Compiler options
        List<String> opt = null;
        opt = new LinkedList<String>();
        for (String s : compilerOptions) {
            opt.add(s);
        }
        opt.add("-d");
        opt.add(javaFile.getParent());

        // Start compilation (thread)
        javaCompiler.getTask(null, fileManager, null, opt, null,
                fileObjects).call();

        // Close file manager
        fileManager.close();

        // Load generated class via URLClassLoader
        urls = new URL[] { parentFile.toURI().toURL() };
        urlClassLoader = new URLClassLoader(urls);

        // Wait for thread to complete
        synchronized (nameScanner) {

            try {

                while (nameScanner.getPackageName() == null
                        && nameScanner.getClassName() == null) {

                    nameScanner.wait();

                }

                clazz = urlClassLoader.loadClass(nameScanner
                        .getPackageName()
                        + "."
                        + nameScanner.getClassName());

            } catch (InterruptedException ex) {
                ex.printStackTrace();
            }

        }

        javaFile.delete();

        return clazz;

    }
}

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