<!-- https://mvnrepository.com/artifact/commons-io/commons-io -->

<dependency>

    <groupId>commons-io</groupId>

    <artifactId>commons-io</artifactId>

    <version>2.6</version>

</dependency>

package com.songxingzhu.utils.compile;

import javax.tools.SimpleJavaFileObject;

import java.net.URI;

public class JavaSourceFromCodeString extends SimpleJavaFileObject {

    final String code;

    public JavaSourceFromCodeString(String name, String code) {

        super(URI.create("string:///" + name.replace('.', '/') + Kind.SOURCE.extension), Kind.SOURCE);

        this.code = code;

    }

    public CharSequence getCharContent(boolean ignoreEncodingErrors) {

        return this.code;

    }

}

package com.songxingzhu.utils.context;

import java.io.File;

public class AppContext {

    public static String baseDirectory() {

        try {

            String path = ClassLoader.getSystemResource("").getPath();

            if (path==null||"".equal(path))

                return getProjectPath();

            return path;

        } catch (Exception ignored) {

        }

        return getProjectPath();

    }

    private static String getProjectPath() {

        java.net.URL url = AppContext.class.getProtectionDomain().getCodeSource()

                .getLocation();

        String filePath = null;

        try {

            filePath = java.net.URLDecoder.decode(url.getPath(), "UTF-8");

        } catch (Exception e) {

            e.printStackTrace();

        }

        if (filePath.endsWith(".jar"))

            filePath = filePath.substring(0, filePath.lastIndexOf(File.separatorChar) + 1);

        java.io.File file = new java.io.File(filePath);

        filePath = file.getAbsolutePath();

        return filePath;

    }

}

package com.songxingzhu.utils.compile;

import org.apache.commons.io.FileUtils;

import com.songxingzhu.utils.context.AppContext;

import javax.tools.JavaCompiler;

import javax.tools.JavaFileManager;

import javax.tools.JavaFileObject;

import javax.tools.ToolProvider;

import java.io.File;

import java.io.IOException;

import java.net.URL;

import java.net.URLClassLoader;

import java.util.ArrayList;

import java.util.List;

public class ClassBuilder {

    public static Class<?> buildClass(String fullClassName, String codeFilePath) throws IOException, ClassNotFoundException {

        return buildClass(fullClassName, codeFilePath, "UTF-8", AppContext.baseDirectory());

    }

    public static Class<?> buildClass(String fullClassName, String codeFilePath, String charsetName, String buildOutput) throws IOException, ClassNotFoundException {

        try {

            String code = FileUtils.readFileToString(FileUtils.getFile(codeFilePath), charsetName);

            JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

            JavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);

            List<JavaFileObject> files = new ArrayList<>();

            files.add(new JavaSourceFromCodeString(fullClassName, code));

            List<String> options = new ArrayList<>();

            options.add("-classpath");

            StringBuilder sb = new StringBuilder();

            URLClassLoader urlClassLoader = (URLClassLoader) Thread.currentThread().getContextClassLoader();

            for (URL url : urlClassLoader.getURLs()) {

                sb.append(url.getFile()).append(File.pathSeparator);

            }

            options.add(sb.toString());

            options.add("-d");

            options.add(buildOutput);

            // execute the compiler

            boolean isok = compiler.getTask(null, fileManager, null, options, null, files).call();

            if (isok) {

                File root = new File(buildOutput);

                if (!root.exists()) root.mkdirs();

                URL[] urls = new URL[]{root.toURI().toURL()};

                ClassLoader classLoader = ClassBuilder.class.getClassLoader();

                Class<?> clazz = Class.forName(fullClassName, true, classLoader);

                return clazz;

            }

            return null;

        } catch (Exception ex) {

            throw ex;

        }

    }

}