java反射类加载器（Java reflection class loader）.docVIP

java反射类加载器（Java reflection class loader） Read Wang Sens JAVA depth adventure, and made a simple learning notes. The 1. JAVA class loader is loaded on demand when loading the class, and the class loader loads the class and initializes it only when a class is used (to instantiate a class with the new keyword). Class Main: Java code Public, class, Main { Public, static, void, main (String[], args) { A a = new, A (); A.print (); B B = new, B (); B.print (); } } Class A: Java code Public, class, A { Public, void, print () { System.out.println (Using Class A); } } Class B: Java code Public, class, B { Public, void, print () { System.out.println (Using Class B); } } Execute: Java, -varbose:class, Main Execution results: E:/DEVjava -verbose:class Main The [Opened C:/Program Files/Java/jre1.5.0_11/lib/rt.jar] (class loader will first load the rt.jar load base class) . . [Loaded Main from file:/E:/DEV/] (class loader loads the corresponding class and initializes it) [Loaded A from file:/E:/DEV/] Using Class A [Loaded B from file:/E:/DEV/] Using Class B 2. make the JAVA program dynamic Using explicit methods to implement dynamics, we need to do our own processing of the details of class loading. Two methods: 1 + implicit: use the new keyword to let the class loader load the required classes as needed 1 Explicit: 1 By java.lang.Class (forName) loading method 1 By java.lang.ClassLoader (loadClass) loading method (1) using Class.forName () The Class.forName () method has two overloaded methods: Public static Class forName (String className) 1 Public static Class forName (String className, Boolean initialize, ClassLoader loader) Parameter description: ClassName - the fully qualified name of the class required Initialize - must I initialize the class (initialization of the static block of code)? Loader - class loader used to load classes The forName () method that calls only one argument is equivalent to Class.forName (className, true, loader). These two methods are finally connect