com.alibaba.qlexpress4.DefaultClassSupplier Maven / Gradle / Ivy

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package com.alibaba.qlexpress4;

import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Author: DQinYuan
 */
public class DefaultClassSupplier implements ClassSupplier {

    private static final DefaultClassSupplier INSTANCE = new DefaultClassSupplier();

    public static DefaultClassSupplier getInstance() {
        return INSTANCE;
    }

    private final Map>> cache = new ConcurrentHashMap<>();

    /**
     * @param clsQualifiedName qualified name of class
     * @return loaded class
     */
    @Override
    public Class loadCls(String clsQualifiedName) {
        Optional> clsOp = cache.computeIfAbsent(clsQualifiedName, this::loadClsInner);
        return clsOp.orElse(null);
    }

    private Optional> loadClsInner(String clsQualifiedName) {
        try {
            Class aClass = Class.forName(clsQualifiedName);
            return Optional.of(aClass);
        } catch (ClassNotFoundException | NoClassDefFoundError e) {
            return Optional.empty();
        }
    }
}