4、若ExtClassLoader也加载失败,则会使用AppClassLoader来加载,如果AppClassLoader也加载失败,则会报出异常ClassNotFoundException。 参考: 1、http://www.codeceo.com/article/java-class-loading-mechanism.html 2、https://juejin.im/post/6844903862575300622...
其实很简单,把BootstrapClassLoader想象为核心高层领导人,ExtClassLoader想象为中层干部,AppClassLoader想象为普通公务员。每次需要加载一个类,先获取一个系统加载器AppClassLoader的实例(ClassLoader.getSystemClassLoader()),然后向上级层层请求,由最上级优先去加载,如果上级觉得这些类不属于核心类,就可以下放到各子级负责...
The Java Class Loading Mechanism The Java platform uses a delegation model for loading classes. The basic idea is that every class loader has a "parent" class loader. When loading a class, a class loader first "delegates" the search for the class to its parent class loader before attempting...
Keywords:Javavirtualmachine;classloader;delegationmodel;dynamicclassloadingmechanism;experimentteachingsystem O 引 言 Java体系结构包括Java语言、Javaclass文件、JavaAPI和 Java虚拟机(JVM)4大部分,核心是JVM。JVM的主要特征是 支持Java动态类加载,允许在程序运行时动态加载程序组件, 而不影响其它功能模块的正常运行。本...
The Java Virtual Machine(JVM)supports a novel and powerful class loading mechanism which incorporates all of the following features: lazy loading, type-safety linkage, user-definable class loading policy and multiple names- paces. However, that class loading methanism contained a seerious type-...
protected Object getClassLoadingLock(String className) { // 不开启并发加载的情况下,使用ClassLoader对象本身加锁 Object lock = this; // 开启并发加载的情况下,从ConcurrentHashMap中获取需要加载的类对象进行加锁。 if (parallelLockMap != null) { ...
这就是因为ServiceLoader.load(Search.class)在加载某接口时,会去META-INF/services下找接口的全限定名文件,再根据里面的内容加载相应的实现类。 这就是spi的思想,接口的实现由provider实现,provider只用在提交的jar包里的META-INF/services下根据平台定义的接口新建文件,并添加进相应的实现类内容就好。
If you change the definition of class A by adding a new field to it, the dependency mechanism in Oracle9i flags classes B and C as invalid. Before you use any of these classes again, Oracle9i attempts to resolve them again and recompile, if necessary. Note that classes can be recompiled...
public class HelloImpl2 implements HelloSpi { public void sayHello() { System.out.println("Hello Impl 2"); } } 1. 2. 3. 4. 5. 6. 在META-INF/services(对于maven工程可在src/main/resources下新建META-INF目录)创建文件,名字就是org.ifool.spiDemo.HelloSpi,然后内容为两个实现类。
Agent-Class:class 挂载到目标JVM 将编写的Agent打成jar包后,就可以挂载到目标JVM上去了。如果选择在目标JVM启动时加载Agent,则可以使用 "-javaagent:<jarpath>[=]",具体的使用方法可以使用“Java -Help”来查看。如果想要在运行时挂载Agent到目标JVM,就需要做一些额外的开...