一个请求包含了一个请求的网址+请求头+请求体。可以利用@RequestMapping注解解析请求网址如何解析到请求头和请求体呢？

@RequestParam注解用于解析请求参数

  <form action="helloworld" method="post">
		<input type="text" name="username">
		<input type="password" name ="password">
		<input type="submit" value="POST">
    </form>

@Controller
public class Distributor {
    @RequestMapping(value = "/helloworld", method = RequestMethod.POST)
    public String distribute2Success2(@RequestParam(value="username") String username, @RequestParam(value="password") String password) {
        System.out.println(username);
        System.out.println(password);
        return "success";
    }
}

这样就可以解析出请求参数；但是如果请求参数为空就会报错

有三个参数，value为参数名，required为是否是必须的参数，默认为true
defaultValue默认值

@RequestParam(value="username", required=false, defaultValue = "xiaoming") String username

@RequestHeader用于解析请求头的数据

@Controller
public class Distributor {
    @RequestMapping(value = "/helloworld", method = RequestMethod.POST)
    public String distribute2Success2(@RequestHeader(value="Host",required=false,defaultValue="hahaha") String host) {
        System.out.println(host);
        return "success";
    }
}

程序执行打印localhost:8080

@CookieValue 注解解析Cookie对象的值

这里有个JSESSIONID的值，我们解析该值

@Controller
public class Distributor {
    @RequestMapping(value = "/helloworld", method = RequestMethod.POST)
    public String distribute2Success2(@CookieValue(value="JSESSIONID",required=false,defaultValue="hahaha") String sessionId) {
        System.out.println(sessionId);
        return "success";
    }
}