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！
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