Spring Boot Web 请求参数之注解

1. @RequestParam

• 修饰参数，将名字与参数进行绑定，相当于ServletRequest.getParameter()

请求URL：http://localhost:8080/hello?name=111

@RequestMapping("/hello")
public String hello(String name) {
    return "hello: " + name;
}

若请求参数与接收参数名不一致
请求URL：http://localhost:8080/hello?username=111

@RequestMapping("/hello")
public String hello(@RequestParam("username") String name) {
    return "hello: " + name;
}

1.1 参数封装为 Map<String, String>

请求地址的参数默认封装在 Map<String, String>

@RequestMapping("/show")
public Map<String, Object> show(@RequestParam("name") String name, @RequestParam Integer age,
                                 @RequestParam Map<String, String> params) {
    Map<String, Object> map = new HashMap<>();
    map.put("name", name);
    map.put("age", age);
    map.put("params", params);
    return map;
}

请求地址 http://localhost:8080/show?name=tinyspot&age=20

1.2 @RequestAttribute

required = false 表示不是必须的

@GetMapping("/show")
public Map<String, Object> show(@RequestAttribute(value = "name", required = false) String name, HttpServletRequest request) {
}

2. ＠PathVariable

• 获取 URL 上的值

请求URL：http://localhost:8080/path/tinyspot/1001

@RequestMapping("/path/{name}/{code}")
public Map<String, Object> path(@PathVariable String name, @PathVariable String code,
                                @PathVariable Map<String, String> kv) {
    Map<String, Object> map = new HashMap<>();
    map.put("name", name);
    map.put("code", code);
    map.put("kv", kv);
    return map;
}

打印结果 {"code":"1001","name":"tinyspot","kv":{"code":"1001","name":"tinyspot"}}

3. @RequestHeader

@RequestMapping("/header/{name}/{code}")
public Map<String, Object> header(@RequestHeader("user-agent") String userAgent, 
                                  @RequestHeader Map<String, String> header) {
    Map<String, Object> map = new HashMap<>();
    map.put("userAgent", userAgent);
    map.put("header", header);
    return map;
}

4. @CookieValue

@RequestMapping("/user/cookie")
public Map<String, Object> cookie(@CookieValue("Idea-42dd4fb8") String value, @CookieValue("Idea-42dd4fb8") Cookie cookie) {
    Map<String, Object> map = new HashMap<>();
    map.put("value", value);
    map.put("cookie", cookie);
    return map;
}

5. ＠RequestBody

<form action="/save" method="post">
    用户名：<input name="userName" /> <br>
    邮箱：<input name="email" /> <br>
    <input type="submit" value="save" >
</form>

获取请求体的数据

@PostMapping("/save")
public Map<String, Object> save(@RequestBody String content) {
    Map<String, Object> map = new HashMap<>();
    map.put("content", content);
    return map;
}

参数自动封装

@RequestMapping("/show")
public String show(User user) {
    return "";
}

6. 矩阵变量 @MatrixVariable

6.1 请求示例

<a href="/matrix/user;name=tinyspot;job=java,c++">/matrix/{path;k=key;v=value1,value2}</a> <br>
<a href="/matrix/user;name=tinyspot;job=java;job=c++">/matrix/{path;k=key,v=value1,v=value2}</a> <br>

// 矩阵变量必须有 url 路径变量才能被解析
@RequestMapping("/matrix/{path}")
public Map<String, Object> matrix(@PathVariable String path,
                                  @MatrixVariable("name") String name, @MatrixVariable("job") List<String> jobs) {
    Map<String, Object> map = new HashMap<>();
    map.put("path", path);
    map.put("name", name);
    map.put("jobs", jobs);
    return map;
}

6.2 请求实例2

<a href="/matrix2/animal;name=AAA/type;name=BBB">/matrix2/{category}/{type}</a>

@GetMapping("/matrix2/{category}/{type}")
public Map<String, Object> matrix2(@MatrixVariable(value = "name", pathVar = "category") String category,
                                   @MatrixVariable(value = "name", pathVar = "type") String type) {
    Map<String, Object> map = new HashMap<>();
    map.put("category", category);
    map.put("type", type);
    return map;
}

6.3 开启矩阵变量

• spring boot 默认禁用矩阵变量

方式一：@Configuration + WebMvcConfigurer

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        UrlPathHelper urlPathHelper = new UrlPathHelper();
        // 不移除 ; 后面的内容，使矩阵变量生效
        urlPathHelper.setRemoveSemicolonContent(false);
        configurer.setUrlPathHelper(urlPathHelper);
    }
}

方式二：直接使用 WebMvcConfigurer

@Configuration
public class WebMVCConfig {
    @Bean
    public WebMvcConfigurer webMvcConfigurer() {
        return new WebMvcConfigurer() {
            @Override
            public void configurePathMatch(PathMatchConfigurer configurer) {
                UrlPathHelper urlPathHelper = new UrlPathHelper();
                urlPathHelper.setRemoveSemicolonContent(false);
                configurer.setUrlPathHelper(urlPathHelper);
            }
        };
    }
}

6.4 源码解析

public class WebMvcAutoConfiguration {
    public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer, ServletContextAware {
        public void configurePathMatch(PathMatchConfigurer configurer) {
            UrlPathHelper urlPathHelper = new UrlPathHelper();
        }
    }
}