The class loader is simply an object that is responsible for loading and verifying a Java class. The class loader checks for imported classes that are referenced in the class by searching through the CLASSPATH . The class loader also checks for any security manager and, after the class is loaded, the class is handed off to the Java Runtime Environment (JRE) for execution. The java.lang.ClassLoader is the base class that creates the class loader object. The ClassLoader class is an abstract class because it returns the current instance when calling the Class.getClassLoader ( ) method. All Java classes can call the Class.getClassLoader ( ) method to retrieve the reference to the executing class loader that will load itself. The class could be as simple as an Array class and execute the Class.getClassLoader ( ), and it will return the class loader that loaded the Array class. Some applications may implement subclasses of the ClassLoader class to extend operations when loading a class. Several come deployed with Java 2. Figure 18-2 displays the extended classes that are also deployed in JDK 1.4. Figure 18-2: Some ClassLoader extension classes A class loader is any class that adheres to the ClassLoader interface. These interfaces include the following:
Java Security Solutions ISBN: 0764549286
EAN: 2147483647 Year: 2001
Pages: 222 Authors: Rich Helton, Johennie Helton
flylib.com © 2008-2017. If you may any questions please contact us: flylib@qtcs.net |