javax.servlet.ServletConfig、javax.servlet.ServletContext和javax.servlet.Filter

1.javax.servlet.ServletConfig

写在标签中：

    ConfigServlet
    com.cy.web.servlet.ConfigServlet
   
    a
    sichuan
   
   
    b
    dazhou
   
   
    c
    tongchuan
   
 


获取对象，获取值
ServletConfig config = this.getServletConfig();
String a = config.getInitParameter("a");
String b = config.getInitParameter("b");
String c = config.getInitParameter("c");
System.out.println(a+"  "+b+"  "+c);

2.javax.servlet.ServletContext（服务器不关就有效）

配置context参数（全局的）

jdbcDriver
jdbcDriver



获取对象，获取值
ServletContext context = this.getServletContext();
String driver = context.getInitParameter("jdbcDriver");

3.javax.servlet.Filter

Filter的生命周期：
        public void destroy() {
System.out.println("Filter销毁.");
}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
System.out.println("doFilter.");
}


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