自定义解析器需要实现HandlerMethodArgumentResolver接口，HandlerMethodArgumentResolver接口包含两个接口函数：
public interface HandlerMethodArgumentResolver {
boolean supportsParameter(MethodParameter var1);
@Nullable
Object resolveArgument(MethodParameter var1, @Nullable ModelAndViewContainer var2, NativeWebRequest var3, @Nullable WebDataBinderFactory var4) throws Exception;
}
自定义一个解析器CurrentUserMethodArgumentResolver
我们在解析器中返回一个固定的UserBeannew UserBean(1L,"admin")，实际情况是从Session、数据库或者缓存中查。
import org.springframework.core.MethodParameter;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
/**
* 用于绑定@CurrentUser的方法参数解析器
*
* @author lism
*/
public class CurrentUserMethodArgumentResolver implements HandlerMethodArgumentResolver {
public CurrentUserMethodArgumentResolver() {
}
@Override
public boolean supportsParameter(MethodParameter parameter) {
if (parameter.getParameterType().isAssignableFrom(UserBean.class) && parameter.hasParameterAnnotation(CurrentUser.class)) {
return true;
}
return false;
}
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
CurrentUser currentUserAnnotation = parameter.getParameterAnnotation(CurrentUser.class);
//从Session 获取用户
Object object = webRequest.getAttribute(currentUserAnnotation.value(), NativeWebRequest.SCOPE_SESSION);
//从 accessToken获得用户信息
if (object == null) {
String token = webRequest.getHeader("Authorization");
if (token == null) {
token = webRequest.getParameter("accessToken");
}
//为了测试先写死用户名
//TODO: 取真实用户
return new UserBean(1L,"admin");
}
return object;
}
}
自定义注解@CurrentUser
import java.lang.annotation.*;
/**
* <p>绑定当前登录的用户</p>
* <p>不同于@ModelAttribute</p>
*
* @author lism
*/
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CurrentUser {
/**
* 当前用户在request中的名字
*
* @return
*/
String value() default "user";
}
在控制器中使用@CurrentUser
在控制器方法上加入@CurrentUser UserBean userBean即可自动注入userBean的值
@RestController
@RequestMapping(value = "/test")
public class TestController {
/**
* 根据name查询
*
* @param request
* @return
*/
@RequestMapping(value = "/testCurrentUser", method = RequestMethod.POST, produces = "application/json", consumes = "application/json")
@ResponseBody
public void test(@CurrentUser UserBean userBean, @RequestBody SubjectRequest request) {
String createdBy = userBean.getUsername();
log.info(createdBy);
}
}
User实体UserBean
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.io.Serializable;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class UserBean implements Serializable {
private Long id;
private String username;
}
总结
我们可以通过实现HandlerMethodArgumentResolver接口来实现对自定义的参数进行解析。
比如可以解析自定义的时间格式、自定义解析Map对象等这些spring原本不支持的对象格式。
