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  • context的简单应用

    数据上传

    context.setAttribute

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            ServletContext context = this.getServletContext();
            String username="吴梓超";
            context.setAttribute("username",username);
        }
    

    数据请求

    context.getAttribute

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            ServletContext context = this.getServletContext();
            String username =(String) context.getAttribute("username");
            resp.setContentType("text/html");
            resp.setCharacterEncoding("utf-8");
            resp.getWriter().print("名字:"+username);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            doGet(req, resp);
        }
    

    参数获取

    context.getInitParameter

    context-param>
    	<param-name>url</param-name>
    	<param-value>jdbc:mysql://localhost:3306</param-value>
    </context-param>
    
     @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            ServletContext context = this.getServletContext();
            String url = context.getInitParameter("url");
            resp.getWriter().print(url);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            doGet(req, resp);
        }
    

    请求转发

    context.getRequestDispatcher("/s3").forward(req,resp);

     @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            ServletContext context = this.getServletContext();
            context.getRequestDispatcher("/s3").forward(req,resp);
    
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            doGet(req, resp);
        }
    

    读取资源文件

    需要一个文件流

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        InputStream is = this.getServletContext().getResourceAsStream("/WEB-INF/classes/db.properties");
        Properties prop=new Properties();
        prop.load(is);
        String name = prop.getProperty("username");
        String password = prop.getProperty("password");
        resp.getWriter().print(name+"+"+password);
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
    
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  • 原文地址:https://www.cnblogs.com/chaostudy/p/12921343.html
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