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A browser may only have one security manager. The applet security manager is a mechanism to impose restrictions on Java applets. What is the applet security manager, and what does it provide ? Among other things, the verifier ensures that there are no stack overflows or underflows and that the parameters to all bytecode instructions are correct. Then, those classes loaded by the class loader are passed through the verifier.The verifier checks that the class file conforms to the Java language specification. When a browser loads an applet over the net, that applet’s classes are placed in a private namespace associated with the applet’s origin. Also, the class loader guarantees that a unique namespace exists for classes that come from the local file system, and that a unique namespace exists for each network source. The class loader enforces the Java name space hierarchy. When an applet is loaded over the internet, the applet is loaded by the applet classloader. What is the applet class loader, and what does it provide ? Also, applets loaded via the file system are allowed to execute processes and finally, applets loaded via the file system are not passed through the byte code verifier. Applets loaded via the file system are allowed to read files, write files and to load Regarding the case where an applet is loaded from the client’s local disk,the applet is loaded by the file system loader. Regarding the case where an applet is loaded over the internet, the applet is loaded by the applet classloader and is subject to the restrictions enforced by the applet security manager. What is the difference between applets loaded over the internet and applets loaded via the file system ? By default, all downloaded applets are considered as untrusted. Untrusted applets are those Java applets that cannot access or execute local system files.
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