springMvc源码学习之：spirngMvc获取请求参数的方法

一、      通过@PathVariabl获取路径中的参数

    @RequestMapping(value="user/{id}/{name}",method=RequestMethod.GET)
    public String printMessage1(@PathVariable String id,@PathVariable String name, ModelMap model) {
        
        System.out.println(id);
        System.out.println(name);
        model.addAttribute("message", "111111");
        return "users";
    }

例如，访问user/123/lei路径时，执行以上方法，其中，参数id=123，name=lei

二、      @ModelAttribute获取POST请求的FORM表单数据

JSP表单如下

<form method="post" action="hao.do">
    a: <input id="a" type="text"   name="a"/>
    b: <input id="b" type="text"   name="b"/>
    <input type="submit" value="Submit" />
 </form>

Java  Pojo如下

    public class Pojo{
        private String a;
        private int b;
    }

Java Controller如下

@RequestMapping(method = RequestMethod.POST) 
public String processSubmit(@ModelAttribute("pojo") Pojo pojo) { 
    
    return "helloWorld"; 
}

三、      直接用HttpServletRequest获取

@RequestMapping(method = RequestMethod.GET) 
public String get(HttpServletRequest request, HttpServletResponse response) { 
   System.out.println(request.getParameter("a")); 
    return "helloWorld"; 
}

四、      用注解@RequestParam绑定请求参数

用注解@RequestParam绑定请求参数a到变量a

当请求参数a不存在时会有异常发生,可以通过设置属性required=false解决,

例如: @RequestParam(value="a", required=false)

Controller如下

@RequestMapping(value = "/requestParam", method = RequestMethod.GET) 
public String setupForm(@RequestParam("a") String a, ModelMap model) { 
   System.out.println(a); 
return "helloWorld";
}