servlet的过滤器filter类

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先上代码

public class FilterA implements Filter {
    public FilterA() {
        System.out.println("实例化filterA");
    }

    public void destroy() {
        System.out.println("销毁filterA");
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        System.out.println("经过FilterA的前处理");
        chain.doFilter(request, response);
        System.out.println("到达filterA的后处理");
    }

    public void init(FilterConfig fConfig) throws ServletException {
        System.out.println("初始化FilterA");
    }

}

public class FilterB implements Filter {
    public FilterB() {
        System.out.println("实例化filterB");
    }

    public void destroy() {
        System.out.println("销毁filterB");
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        System.out.println("经过FilterB的前处理");
        chain.doFilter(request, response);
        System.out.println("到达filterB的后处理");
    }

    public void init(FilterConfig fConfig) throws ServletException {
        System.out.println("初始化FilterB");
    }

}

public class FilterC implements Filter {
    public FilterC() {
        System.out.println("实例化filterC");
    }

    public void destroy() {
        System.out.println("销毁filterC");
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        System.out.println("经过FilterC的前处理");
        chain.doFilter(request, response);
        System.out.println("到达filterC的后处理");
    }

    public void init(FilterConfig fConfig) throws ServletException {
        System.out.println("初始化FilterC");
    }

}