将犀牛脚本豆迁移到纳什霍恩

Question

我有一个可编写脚本的bean，如下所示

package test.rhino;

import java.util.HashMap;

import org.mozilla.javascript.Scriptable;

public class SomeBean implements Scriptable {

    /**
     * The current values for this object.
     */
    private HashMap<String, Object> values = new HashMap<>();

    /**
     * 
     */
    public SomeBean() {
        System.out.println("SomeBean();");
    }

    /*
     * @see org.mozilla.javascript.Scriptable#getClassName()
     */
    @Override
    public String getClassName() {
        return "SomeBean";
    }

    /*
     * @see org.mozilla.javascript.Scriptable#get(java.lang.String,
     * org.mozilla.javascript.Scriptable)
     */
    @Override
    public Object get(String name, Scriptable start) {

        System.out.println("Get is called.");
        System.out.println("Called for this" + name + " and returned :" + values.get(name));

        return values.get(name);
    }

    /*
     * @see org.mozilla.javascript.Scriptable#put(java.lang.String,
     * org.mozilla.javascript.Scriptable, java.lang.Object)
     */
    @Override
    public void put(String name, Scriptable start, Object value) {
        System.out.println("Put is called. Input name: " + name + "\n Input values: " + value);

        values.put(name, value);

    }

    @Override
    public Object get(int index, Scriptable start) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public boolean has(String name, Scriptable start) {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public boolean has(int index, Scriptable start) {
        // TODO Auto-generated method stub
        return false;
    }

    @Override
    public void put(int index, Scriptable start, Object value) {
        // TODO Auto-generated method stub

    }

    @Override
    public void delete(String name) {
        // TODO Auto-generated method stub

    }

    @Override
    public void delete(int index) {
        // TODO Auto-generated method stub

    }

    @Override
    public Scriptable getPrototype() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void setPrototype(Scriptable prototype) {
        // TODO Auto-generated method stub

    }

    @Override
    public Scriptable getParentScope() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void setParentScope(Scriptable parent) {
        // TODO Auto-generated method stub

    }

    @Override
    public Object[] getIds() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Object getDefaultValue(Class<?> hint) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public boolean hasInstance(Scriptable instance) {
        // TODO Auto-generated method stub
        return false;
    }

}

在Rhino中，使用javascript，我可以将底层HashMap中的键作为bean的属性访问。

var bean = new SomeBean();"
                + "bean.nomen = 'John Doe';\n"
                + "bean.nomen2 = bean.nomen + ' is cool';

输出显示被调用的get和put --从HashMap‘值’添加和访问的键和值。通过这种方式，我还可以添加额外的功能来获取()和put()方法定义。

在将此bean移植到Nashorn时，我无法找到具有相同功能的方法。Nashorn确实在Javascript中公开了HashMap，并且允许我们添加条目，但是对于我来说，这个行为应该可以通过一个普通的setter或getter从bean实例中访问，这样我就可以在添加和从HashMap中检索值时做更多的事情。

所以它应该是这样的:-

Assume bean = new SomeBean(); 
bean.name = 'John Doe' // Adds name and John Doe to the HashMap
print(bean.name) // Retrieves John Doe. 

在纳什霍恩有办法做到这一点吗？我知道我的bean实例可以使用公共类变量，但这并不能提供上面所示的相同功能。我也不想直接访问HashMap。

谢谢。

Answer 1

经过大量的挖掘，我能够通过从'AbstractJSObject‘类扩展我的bean来解决这个问题。这个类有代理get、set和方法，当我们尝试使用点运算符访问/更改对象属性时，这些方法将被调用。

更改后的类如下所示。

package test.nashorn;

import java.util.HashMap;

import jdk.nashorn.api.scripting.AbstractJSObject;

public class NSomeOtherBean extends AbstractJSObject {

    /**
     * The current values for this object.
     */
    private HashMap<String, Object> values = new HashMap<>();

    public NSomeOtherBean() {
        System.out.println("Constructor called.");
    }

    // do you have a property of that given name?
    @Override
    public boolean hasMember(String name) {
        return has(name);
    }

    // get the value of that named property
    @Override
    public Object getMember(String name) {

        return get(name);

    }

    // get the value of that named property
    @Override
    public void setMember(String name,Object value) {

         put(name,value);

    }

    public Object get(String name) {

        System.out.println("JAVA Get is called.");
        // System.out.println("Called for this"+name+" and returned
        // :"+values.get(name));

        return values.get(name);
    }

    public void put(String name, Object value) {
        System.out.println("JAVA Put is called. Input name: " + name + "\n Input values: " + value);

        values.put(name, value);

    }

    public boolean has(String name) {
        System.out.println("JAVA Has is called. Input name: " + name);

        return values.containsKey(name);

    }
}