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我正在使用Java 1.8。代理对象抛出NullPointerException
这里是我的接口,扩展ExecutorService
:
public interface ConsumerExecutor extends ExecutorService{
boolean closed();
}
这里是我InvocationHandler
类:
public class ExecutorInvocationHandler implements InvocationHandler {
private boolean close = false;
private ExecutorService executor;
public ExecutorInvocationHandler(ExecutorService exec) {
this.executor = exec;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if (method.getName().equals("closed")) {
return closed();
} else if (method.getName().equals("shutdown")) {
_close();
executor.shutdown();
} else if (method.getName().equals("shutdownNow")) {
_close();
executor.shutdownNow();
} else {
method.invoke(executor, args);
}
return null;
}
public synchronized void _close() {
close = true;
}
public synchronized boolean closed() {
return close;
}
}
现在,下面的代码,从JUnit测试运行:
ConsumerExecutor exec = ConsumerFactory.newInstance(ExecutorInvocationHandler.class,
Executors.newCachedThreadPool());
//do something here
while (!exec.isTerminated()) {//line 52
}
//do soemthing
引发此异常:
java.lang.NullPointerException
at com.sun.proxy.$Proxy3.isTerminated(Unknown Source)
at test.de.edigrid.util.upgrade_test.tasks.ContextsCollectorTest.collectorTest(ContextsCollectorTest.java:52)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:252)
at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:141)
at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:112)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:189)
at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:165)
at org.apache.maven.surefire.booter.ProviderFactory.invokeProvider(ProviderFactory.java:85)
at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:115)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:75)
代理工厂方法是在这里:
public static ConsumerExecutor newInstance(Class clazz, ExecutorService exec) {
if (clazz == ExecutorInvocationHandler.class) {
return (ConsumerExecutor) Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),
new Class[] { ConsumerExecutor.class }, new ExecutorInvocationHandler(exec));
}
return null;
}
任何人都可以给我一个提示,为什么这个异常?