Servlets 面试题与答案
相关差异对比
问题 6. What's the difference between GenericServlet and HttpServlet?
HttpServlet class extends GenericServlet class which is an abstract class to provide HTTP protocol-specific functionalities. Most of the java application developers extend HttpServlet class as it provides more HTTP protocol-specific functionalities. You can see in HttpServlet class doGet (), doPOst () methods which are more targeted towards HTTP protocol specific functionalities. For instance we can inherit from GenericServlet class to make something like MobileServlet. So GenericServlet class should be used when we want to write protocol specific implementation which is not available. But when we know we are making an internet application where HTTP is the major protocol its better to use HttpServlet.
问题 7. What’s the architecture of a Servlet package?
At the top of all is the main servlet interface which is implemented by the generic servlet. But generic servlet does not provide implementation specific to any protocol. HTTP servlet further inherits from the generic servlet and provides HTTP implementation like "Get" and "Post". Finally comes our custom servlet which inherits from HTTP Servlet.
问题 8. Why is HTTP protocol called as a stateless protocol?
A protocol is stateless if it can remember difference between one client request and the other. HTTP is a stateless protocol because each request is executed independently without any knowledge of the requests that came before it.
问题 9. What are the different ways we can maintain state between requests?
Following are the different ways of maintaining state’s between stateless requests:-
>> URL rewriting
>> Cookies
>> Hidden fields
>> Sessions
问题 10. What is Servlet?
A servlet is a Java technology-based Web component, managed by a container called servlet container or servlet engine, that generates dynamic content and interacts with web clients via a request/response paradigm.
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- What is Servlet?
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