JAVA单例模式-双重检验锁(防止反射、序列化多个)

简介: JAVA单例模式-双重检验锁(防止反射、序列化多个)
package com.minos.demos.web.pojo;
 
import org.springframework.validation.ObjectError;
 
import java.io.Serializable;
 
public class TestSingleton implements Serializable {
 
    private static TestSingleton INSTANCE;
 
    /**
     * 防止反射多个对象
     */
    private TestSingleton(){
        if (INSTANCE!=null) {
            throw new RuntimeException("singleton");
        }else{
            INSTANCE=this;
        }
    }
    public static TestSingleton getInstance(){
        if (INSTANCE==null) {
            synchronized(TestSingleton.class){
                if (INSTANCE==null) {
                    INSTANCE=new TestSingleton();
                }
            }
        }
        return INSTANCE;
    }
 
    /**
     * 防止序列化多个对象
     * @return
     */
    private Object readResolve(){
        return INSTANCE;
    }
}
   @Test
    void singletonTest() throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
        Constructor<TestSingleton> declaredConstructor = TestSingleton.class.getDeclaredConstructor();
        declaredConstructor.setAccessible(true);
        TestSingleton testSingleton = declaredConstructor.newInstance();
 
        TestSingleton testSingleton1 = declaredConstructor.newInstance();
        System.out.println(testSingleton==testSingleton1);
    }
java.lang.RuntimeException: singleton
 
  at com.minos.demos.web.pojo.TestSingleton.<init>(TestSingleton.java:12)
  at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
  at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
  at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
  at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
  at com.minos.EffectiveJavaDemo01ApplicationTests.singletonTest(EffectiveJavaDemo01ApplicationTests.java:24)
  at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.base/java.lang.reflect.Method.invoke(Method.java:566)
  at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
  at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
  at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
  at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
  at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
  at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
  at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
  at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
  at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
  at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
  at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
  at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
  at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
  at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
  at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
  at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
  at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
  at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
  at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
  at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
  at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
  at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
  at java.base/java.util.ArrayList.forEach(ArrayList.java:1540)
  at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
  at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
  at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
  at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
  at java.base/java.util.ArrayList.forEach(ArrayList.java:1540)
  at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
  at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
  at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
  at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
  at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
  at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
  at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
  at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
  at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
  at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
  at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
  at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
  at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
  at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
  at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
  at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
  at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
  at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:57)
  at com.intellij.rt.junit.IdeaTestRunner$Repeater$1.execute(IdeaTestRunner.java:38)
  at com.intellij.rt.execution.junit.TestsRepeater.repeat(TestsRepeater.java:11)
  at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:35)
  at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:232)
  at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:55)
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