1.1

 

 

函数的返回值为空，因为可以使用response对象向浏览器返回数据。声明了request对象和response对象，dispatcherservlet自动将这两个对象传入

@RequestMapping("/http")
    public void http(HttpServletRequest request, HttpServletResponse response) {
        //获取请求数据
        System.out.println(request.getMethod());
        System.out.println(request.getServletPath());
        Enumeration<String> headerNames = request.getHeaderNames();
        while(headerNames.hasMoreElements()) {
            String name = headerNames.nextElement();
            String value = request.getHeader(name);
            System.out.println(name + ": " + value);
        }
        System.out.println(request.getParameter("code"));

        //返回响应数据
        //新语法，直接在try后面括号内写创建write对象，就不需要再关闭流。
        response.setContentType("text/html;charset=utf-8");
        try(PrintWriter writer = response.getWriter();) {
            writer.write("<h1>牛客网</h1>");
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

问号后面传参数，可以使用request.getParameter("code")获取。

//GET请求
    //students?current=1&limit=20
    @RequestMapping(path = "/students", method = RequestMethod.GET)//只能处理GET请求
    @ResponseBody
    public String getStudents(
            @RequestParam(name = "current", required = false, defaultValue = "1") int current,
            @RequestParam(name = "limit", required = false, defaultValue = "10") int limit) {
        System.out.println(current);
        System.out.println(limit);
        return "some student";
    }

    //GET传参的第二种方法，一种是像上面使用问号传参数，另一种是直接拼在路径中
    @RequestMapping(path = "/student/{id}", method = RequestMethod.GET)
    @ResponseBody
    public String getStudent(@PathVariable("id") int id) {
        System.out.println(id);
        return "a student";
    }

//POST浏览器向服务器提交数据
@RequestMapping(path = "/student", method = RequestMethod.POST)
@ResponseBody
public String saveStudent(String name, int age) {//和表单的name一样
    System.out.println(name);
    System.out.println(age);
    return "success";
}

//响应html数据
@RequestMapping(path = "/teacher", method = RequestMethod.GET)
public ModelAndView getTeacher() {
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.addObject("name", "张三");
    modelAndView.addObject("age", "22");
    modelAndView.setViewName("/demo/view");
    return modelAndView;
}

@RequestMapping(path = "/school", method = RequestMethod.GET)
public String getSchool(Model model) {
    model.addAttribute("name", "北京大学");
    model.addAttribute("age", "120");
    return "/demo/view";
}

//响应JSON请求数据,一般用于异步请求
//Java对象-> JSON字符串 -> JS对象
@RequestMapping(path = "/emp", method = RequestMethod.GET)
@ResponseBody//dispatcherservlet看见加了这个注解，会自动将Map转成JSON数据
public List<Map<String, Object>> getEmp() {
    List<Map<String, Object>> list = new ArrayList<>();
    Map<String, Object> emp = new HashMap<>();
    emp.put("name", "张三");
    emp.put("age", 22);
    list.add(emp);
    return  list;
}