Java 如果只有类的对象，如何重写类的行为？
这个问题问起来可能很愚蠢，但请帮我解决这个问题。 我需要重写一个类的行为，但我将只得到它的对象。 下面是代码示例 我想在所有地方使用方法Util.newChildComponent（字符串id）本身Java 如果只有类的对象，如何重写类的行为？,java,Java,这个问题问起来可能很愚蠢，但请帮我解决这个问题。 我需要重写一个类的行为，但我将只得到它的对象。 下面是代码示例 我想在所有地方使用方法Util.newChildComponent（字符串id）本身 class ParentComponent{ public ParentComponent(String id){} protected void someBehavior(){} } class ChildComponent extends ParentComponent{
class ParentComponent{
public ParentComponent(String id){}
protected void someBehavior(){}
}
class ChildComponent extends ParentComponent{
public ChildComponent(String id){
super(id);
}
protected void childsBehavior(){}
}
public class Util {
public static ParentComponent newChildComponent(String id)
{
ParentComponent fc = new ChildComponent(id);
// Initialize the object, and performs some common configuration.
// Performs different operations on the generated child object.
// The child class has many members apart from childsBehavior().
return fc;
}
}
// The above classes belongs to a jar, so I cannot edit the code.
// I need to use Util.newChildComponent(String id)
// But I need to override the behavior as mentioned below.
public void f1()
{
// TODO: How to override childsBehavior() method using the object
// I have it in pc? Is it possible?
// Util.newChildComponent(id) method decorates the ChildComponent
// So I need to use the same object and just override childsBehavior() method only.
ParentComponent pc = Util.newChildComponent("childId");
// I need to achieve the result below
/*
ParentComponent pc = new ChildComponent(id){
@Override
protected void childsBehavior(){
super.someBehavior();
// Do the stuff here.
}
}; */
}
提前感谢。看看Java的动态代理。这应该允许您通过创建调用处理程序来处理对方法的调用，从而在运行时更改行为。如果需要，您甚至可以将其转发到原始方法。看看Java的动态代理。这应该允许您通过创建调用处理程序来处理对方法的调用，从而在运行时更改行为。如果需要，您甚至可以将其转发到原始方法。声明一个新类，该类使用您要更改的方法扩展该类
public class MyClass extends ChildComponent {
@Override
protected void childsBehavior()
{
.....
}
}
MyClass pc = new MyClass("childId");
UtilUtilMyClass现在
pcParentComponentChildComponentchildsBehaviorpublic class MyClass extends ChildComponent {
@Override
protected void childsBehavior()
{
.....
}
}
MyClass pc = new MyClass("childId");
UtilUtilMyClass现在
pcParentComponentChildComponentchildsBehaviorUtilUtilChildComponentUtilUtilChildComponentstatic class ParentComponent {
protected void someBehavior() {
System.out.println("ParentComponent someBehavior");
}
}
static class ChildComponent extends ParentComponent {
private ChildComponent(String id) {
}
protected void childsBehavior() {
System.out.println("childsBehavior");
}
}
public static class Util {
public static ParentComponent newChildComponent(String id) {
ParentComponent fc = new ChildComponent(id);
// Initialize the object, and performs some common configuration.
return fc;
}
}
interface Parent {
void someBehavior();
}
// The adaptor.
public static class Adapter implements Parent {
final ParentComponent parent;
private Adapter(ParentComponent pc) {
this.parent = pc;
}
// Override the parent behaviour.
public void someBehavior() {
System.out.println("Adapter invoke someBehaviour()");
parent.someBehavior();
System.out.println("Adapter finished someBehaviour()");
}
}
public void test() {
ParentComponent pc = Util.newChildComponent("childId");
Parent adapted = DynamicObjectAdapterFactory.adapt(pc, Parent.class, new Adapter(pc));
adapted.someBehavior();
}
Adapter invoke someBehaviour()
someBehavior
Adapter finished someBehaviour()
听起来你在找一个新的工作 这是他优秀作品的一个用途
static class ParentComponent {
protected void someBehavior() {
System.out.println("ParentComponent someBehavior");
}
}
static class ChildComponent extends ParentComponent {
private ChildComponent(String id) {
}
protected void childsBehavior() {
System.out.println("childsBehavior");
}
}
public static class Util {
public static ParentComponent newChildComponent(String id) {
ParentComponent fc = new ChildComponent(id);
// Initialize the object, and performs some common configuration.
return fc;
}
}
interface Parent {
void someBehavior();
}
// The adaptor.
public static class Adapter implements Parent {
final ParentComponent parent;
private Adapter(ParentComponent pc) {
this.parent = pc;
}
// Override the parent behaviour.
public void someBehavior() {
System.out.println("Adapter invoke someBehaviour()");
parent.someBehavior();
System.out.println("Adapter finished someBehaviour()");
}
}
public void test() {
ParentComponent pc = Util.newChildComponent("childId");
Parent adapted = DynamicObjectAdapterFactory.adapt(pc, Parent.class, new Adapter(pc));
adapted.someBehavior();
}
Adapter invoke someBehaviour()
someBehavior
Adapter finished someBehaviour()
因此，您希望覆盖
childsBehaviorUtil.newChildComponentchildsBehaviorUtil.newChildComponent