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多选题
Which statements about Java code security are true？（）
A
The bytecode verifier loads all classes needed for the execution of a program.
B
Executing code is performed by the runtime interpreter.
C
At runtime the bytecodes are loaded， checked and run in an interpreter.
D
The class loader adds security by separating the namespaces for the classes of the local file system from those imported from network sources.
参考答案
参考解析
解析：
SL275中描述的Java程序运行的过程是这样的：类加载器（class loader）加载程序运行所需要的所有类，它通过区分本机文件系统的类和网络系统导入的类增加安全性，这可以限制任何的特洛伊木马程序，因为本机类总是先被加载，一旦所有的类被加载完，执行文件的内存划分就固定了，在这个时候特定的内存地址被分配给对应的符号引用，查找表（lookuo table）也被建立，由于内存划分发生在运行时，解释器在受限制的代码区增加保护防止未授权的访问；然后字节码校验器（byte code verifier）进行校验，主要执行下面的检查：类符合JVM规范的类文件格式，没有违反访问限制，代码没有造成堆栈的上溢或者下溢，所有操作 代码的参数类型都是正确的，没有非法的数据类型转换（例如将整型数转换成对象类型）发生；校验通过的字节码被解释器（interpreter）执行，解释器在必要时通过运行时系统执行对底层硬件的合适调用。后三个答案是SL275中的原话。
更多 “多选题Which statements about Java code security are true？（）AThe bytecode verifier loads all classes needed for the execution of a program.BExecuting code is performed by the runtime interpreter.CAt runtime the bytecodes are loaded， checked and run in an interpreter.DThe class loader adds security by separating the namespaces for the classes of the local file system from those imported from network sources.” 相关考题
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