内容简介：版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/thc1987/article/details/83001079
版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/thc1987/article/details/83001079
题目：有一个接口Processor，分别被ServiceA和ServiceB实现。
interface Processor {
void process();
}
class ServiceA implements Processor {
@Override
public void process() {
System.out.println("run ServiceA...");
}
}
class ServiceB implements Processor {
@Override
public void process() {
System.out.println("run ServiceB...");
}
}
要求前10次由ServiceA运行，超过10次后自动切换成ServiceB运行。
代码如下：
interface Processor {
void process();
}
class ServiceA implements Processor {
@Override
public void process() {
System.out.println("run ServiceA...");
}
}
class ServiceB implements Processor {
@Override
public void process() {
System.out.println("run ServiceB...");
}
}
public class DynamicRun {
static class ProcessRunner implements Processor {
private DelegateProcess target;
private int runCount;
private ServiceA defaultProcessor = new ServiceA();
@Override
public void process() {
int count = ++this.runCount;
System.out.println("默认运行次数：" + count);
if (count >= 10) {
System.out.println("默认运行次数到达10次，切换为ServiceB运行");
// 将真正processor改为ServiceB
this.target.setDelegate(new ServiceB());
}
defaultProcessor.process();
}
public void setTarget(DelegateProcess target) {
this.target = target;
}
}
static class DelegateProcess implements Processor {
private Processor delegate;
private DelegateProcess(Processor delegate) {
this.delegate = delegate;
}
@Override
public void process() {
delegate.process();
}
public void setDelegate(Processor delegate) {
this.delegate = delegate;
}
}
public static void main(String[] args) {
// 拿到这个processor，可在其它地方运行，不受约束
Processor processor = buildProcessor();
for (int i = 0; i < 15; i++) {
processor.process();
}
}
private static Processor buildProcessor() {
ProcessRunner processRunner = new ProcessRunner();
DelegateProcess delegateProcess = new DelegateProcess(processRunner);
processRunner.setTarget(delegateProcess);
return delegateProcess;
}
}
此方式在JDK中也有出现，可以参考 sun.reflect.ReflectionFactory.newMethodAccessor()
方法。该方法在使用 Method.invoke()
时用到。代码片段如下：
NativeMethodAccessorImpl var2 = new NativeMethodAccessorImpl(var1); DelegatingMethodAccessorImpl var3 = new DelegatingMethodAccessorImpl(var2); var2.setParent(var3);
以上所述就是小编给大家介绍的《动态改变执行方法》，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对 码农网 的支持！
猜你喜欢:
本站部分资源来源于网络，本站转载出于传递更多信息之目的，版权归原作者或者来源机构所有，如转载稿涉及版权问题，请联系我们。
JavaScript Patterns
Stoyan Stefanov / O'Reilly Media, Inc. / 2010-09-21 / USD 29.99
What's the best approach for developing an application with JavaScript? This book helps you answer that question with numerous JavaScript coding patterns and best practices. If you're an experienced d......一起来看看 《JavaScript Patterns》 这本书的介绍吧!
