servlet中过滤器和监听器的基本使用

一：filter过滤器

1．简单使用

public classSimpleFilter extends HttpServlet implements Filter {

public void init(FilterConfig config)throws ServletException {

String initParm=config.getInitParameter("ref");

System.out.println("初始化过滤器："+initParm);

}

public void doFilter(ServletRequest arg0,ServletResponse arg1,

FilterChain chain) throwsIOException, ServletException {

System.out.println("****执行doFilter()方法前****");

chain.doFilter(arg0, arg1);

System.out.println("****执行doFilter()方法后****");

}

@Override

public void destroy() {

System.out.println("销毁过滤器");

}

}

web.xml下配置过滤器

<filter>

<filter-name>SimpleFilter</filter-name>

<filter-class>com.cloud.day1.SimpleFilter</filter-class>

<init-param>

<param-name>ref</param-name>

<param-value>Spring</param-value>

</init-param>

</filter>

<filter-mapping>

<filter-name>SimpleFilter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

2.过滤编码

http://blog.csdn.net/dzy21/article/details/47042891

该文章详细使用了过滤器解决编码问题。

二：监听器

public class Demo2implements ServletContextListener {

public void contextInitialized(ServletContextEventevent) {

System.out.println("初始化："+event.getServletContext().getContextPath());

}

public voidcontextDestroyed(ServletContextEvent event) {

System.out.println("销毁："+event.getServletContext().getContextPath());

}

}

web.xml下配置监听器

<!-- 配置监听器 -->

<listener>

<listener-class>

com.cloud.day1.Demo2

</listener-class>

</listener>

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