SpringMVC(二)Request Data

桃扇骨 2022-06-01 07:40 146阅读 0赞

本章介绍后台如何接受前台传入的参数(普通传参,RESTFUL路径传参数)

###### url参数 ######

@RequestMapping(value="param", method=RequestMethod.GET)
    public @ResponseBody String withParam(@RequestParam String foo) {
            return "Obtained 'foo' query parameter value '" + foo + "'";
    }

通过`@RequestParam`可以获得url中传递的参数并自动转型，`@RequestParam`对应的方法参数名必须与url参数名完全一样，否则将会报错。如果有多个参数，就在方法中加`@RequestParam`即可。

###### 将参数自动封装成javabean ######

@RequestMapping(value="group", method=RequestMethod.GET)
    public @ResponseBody String withParamGroup(JavaBean bean) {
        return "Obtained parameter group " + bean;
    }

如果方法的参数是一个JavaBean Spring Mvc会将前台传来的参数自动转型，并设置到JavaBean对应的属性上。JavaBean对应的属性名必须完全和参数名一样。

###### 路径变量 ######

SpringMVC 对RESTFUL的支持非常强大，通过路径变更可以非常方便获得RESTFUL url中传递的参数。

@RequestMapping(value="path/{var}", method=RequestMethod.GET)
    public @ResponseBody String withPathVariable(@PathVariable String var) {
        return "Obtained 'var' path variable value '" + var + "'";
    }

在`@RequestMapping`中指定的路径将参数用`{var}`代替，在方法参数中使用`@PathVariable`获得路径中的变量,方法参数名必须和`{var}`中的变量一样。

###### Matrix 参数 ######

Matrix 参数是指在url中以;分割的参数，例：  
[http://moremaps.com/us/ma/cambridge;scale=50000;roads=main][http_moremaps.com_us_ma_cambridge_scale_50000_roads_main]  
SpringMVC支持获取Matrix参数 使用`@MatrixVariable`获取Matrix参数

@RequestMapping(value="{path}/simple", method=RequestMethod.GET)
    public @ResponseBody String withMatrixVariable(@PathVariable String path, @MatrixVariable String foo) {
        return "Obtained matrix variable 'foo=" + foo + "' from path segment '" + path + "'";
    }

通过如上代码可以获取foo参数  
[http://localhost:8080/data/matrixvars;foo=bar/simple][http_localhost_8080_data_matrixvars_foo_bar_simple];

@RequestMapping(value="{path1}/{path2}", method=RequestMethod.GET)
    public @ResponseBody String withMatrixVariablesMultiple (
                @PathVariable String path1, @MatrixVariable(value="foo", pathVar="path1") String foo1,
                @PathVariable String path2, @MatrixVariable(value="foo", pathVar="path2") String foo2) {
    
        return "Obtained matrix variable foo=" + foo1 + " from path segment '" + path1
                    + "' and variable 'foo=" + foo2 + " from path segment '" + path2 + "'";
        }

通过如上代码可以获取  
[http://localhost:8080/data/matrixvars;foo=bar1/multiple;foo=bar2][http_localhost_8080_data_matrixvars_foo_bar1_multiple_foo_bar2]; 中的多个参数

###### 获取 header中的参数 ######

通过`@RequestHeader`可以获取 header中的参数，`@RequestHeader`对应的参数名必须和header中的参数名一样。

@RequestMapping(value="header", method=RequestMethod.GET)
    public @ResponseBody String withHeader(@RequestHeader String Accept) {
        return "Obtained 'Accept' header '" + Accept + "'";
    }

###### 获取 cookie ######

通过`@CookieValue`可以得到cookie值

@RequestMapping(value="cookie", method=RequestMethod.GET)
    public @ResponseBody String withCookie(@CookieValue String openid_provider) {
        return "Obtained 'openid_provider' cookie '" + openid_provider + "'";
        }

###### 获取 json数据 ######

通过`@RequestBody`可以获取前台传入的json数据

###### 获取Http headers 和Body ######

如果方法参数是HttpEntity<String>则可以获取Http实体，通过实体可以得到请求的headers 和body

@RequestMapping(value="entity", method=RequestMethod.POST)
        public @ResponseBody String withEntity(HttpEntity<String> entity) {
        return "Posted request body '" + entity.getBody() + "'; headers = " + entity.getHeaders();
    }

###### 自定义参数解析 ######

SpringMVC允许自定义参数解析，参数解析类需要实现`HandlerMethodArgumentResolver`接口，实现`supportsParameter`来确定满足什么条件调用该解析类，实现`resolveArgument`来完成参数解析操作。

要实现参数自定义解析首先需要注册参数解析器,`argument-resolvers`来注册解析器

<annotation-driven conversion-service="conversionService" enable-matrix-variables="true">
            <argument-resolvers>
                <beans:bean class="org.springframework.samples.mvc.data.custom.CustomArgumentResolver"/>
            </argument-resolvers>
        </annotation-driven>

实现参数解析器,只要方法参数有`@RequestAttribute`注解即调用参数转换器解析参数

public class CustomArgumentResolver implements HandlerMethodArgumentResolver {
    
        public boolean supportsParameter(MethodParameter parameter) {
            return parameter.getParameterAnnotation(RequestAttribute.class) != null;
        }
    
        public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest,
                WebDataBinderFactory binderFactory) throws Exception {
            RequestAttribute attr = parameter.getParameterAnnotation(RequestAttribute.class);
            return webRequest.getAttribute(attr.value(), WebRequest.SCOPE_REQUEST);
        }
    
    }

###### 使用方法如下 ######

@ModelAttribute
        void beforeInvokingHandlerMethod(HttpServletRequest request) {
            request.setAttribute("foo", "bar");
        }
    
        @RequestMapping(value="/data/custom", method=RequestMethod.GET)
        public @ResponseBody String custom(@RequestAttribute("foo") String foo) {
            return "Got 'foo' request attribute value '" + foo + "'";
        }

[http_moremaps.com_us_ma_cambridge_scale_50000_roads_main]: http://moremaps.com/us/ma/cambridge;scale=50000;roads=main
[http_localhost_8080_data_matrixvars_foo_bar_simple]: http://localhost:8080/data/matrixvars;foo=bar/simple
[http_localhost_8080_data_matrixvars_foo_bar1_multiple_foo_bar2]: http://localhost:8080/data/matrixvars;foo=bar1/multiple;foo=bar2