servlet学习之servletAPI编程常用的接口和类

public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println("init");
        //获取初始化参数：servlConfig
        String user=servletConfig.getInitParameter("user");
        System.out.println("user:"+user);
        Enumeration<String> names=servletConfig.getInitParameterNames();
        while(names.hasMoreElements()) {
            String name=names.nextElement();
            String value=servletConfig.getInitParameter(name);
            System.out.println("~~"+name+":"+value);
        }
        //获取servletConfig对象   servletContext
        ServletContext servletcontext=servletConfig.getServletContext();
        String driver=servletcontext.getInitParameter("driver");
        System.out.println("driver:"+driver);
        Enumeration<String> names2=servletcontext.getInitParameterNames();
        while(names2.hasMoreElements()) {
            String name=names2.nextElement();
            System.out.println("-->"+name);
        }
        //获取当前WEB应用的某一个文件在服务器上的绝对路径，而不是部署前的物理路径
        String realpath=servletcontext.getRealPath("/note.txt");
        System.out.println(realpath);
        //获取当前web应用的名称
        String contextPath = servletcontext.getContextPath();
        System.out.println(contextPath); 
        
        try {
            ClassLoader classLoader=getClass().getClassLoader();
            InputStream is=classLoader.getResourceAsStream("jdbc.servlet");
            System.out.println("1."+is);
        } catch (Exception e) {
            e.printStackTrace();
        }
        //获取当前WEB应用的某一个文件对应的输入流：path的/为当前web应用的根目录
        try {
            InputStream is2=servletcontext.getResourceAsStream("/WEB-INF/classes/jdbc.servlet");
            System.out.println("2."+is2);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }