Spring MVC使用@RequestParam注解获取参数

小灰灰 2022-05-18 09:53 220阅读 0赞

创建Hello控制器类

package com.controller;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    @Controller
    public class Hello {
    	@RequestMapping("/show")
    	public String show(@RequestParam("name")String userName) {
    		System.out.println(userName);
    		return "index";
    	}
    }

创建index.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
        pageEncoding="utf-8"%>
    <!DOCTYPE html>
    <html>
    <head>
    <meta charset="utf-8">
    <title>首页</title>
    </head>
    <body>
    	<h3>Spring MVC</h3>
    </body>
    </html>

启动Tomcat并访问

![70][]

![70 1][]

注意：如果参数被@RequestParam注解，那么默认情况下该参数不能为空，如果为空则系统会抛出异常。如果希望允许为空，那么要修改它的配置项required为 false。

package com.controller;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    @Controller
    public class Hello {
    	@RequestMapping("/show")
    	public String show(@RequestParam(value="name",required=false)String userName) {
    		System.out.println(userName);
    		return "index";
    	}
    }

启动 Tomcat再次访问

![70 2][]

![70 3][]

[70]: /images/20220518/32175ce758b0418e8dba086e66d7dae3.png
[70 1]: /images/20220518/42665d94a06347d7a7f28fc5316ba686.png
[70 2]: /images/20220518/51d6deb6b7034edebb8179e656a81429.png
[70 3]: /images/20220518/56d7a8548a3e48ec93311d99b871c9c9.png