一、自定义参数解析器说明
spring最为优秀的地方在于，它的设计方式。依赖注入的bean管理方式、和面向接口编程的设计方式。很多模块或者功能，它提供了接口规范，和默认实现。开发者可以很方便的去自己实现它定义的接口，就具备了相应的功能。spring mvn 的自定义参数解析器，就是这样的设计思想，它提供了默认的实现。但是你可以自定义自己的实现方式。这使得spring 大受欢迎。
二、自定义参数解析器
用途说明：spring mvc 默认是不能接收List
1、以spring boot为例，首先定义一个参数解析器。
package com.github.dgw.config;
import com.github.dgw.annotation.List;
import com.github.dgw.annotation.Page;
import com.github.dgw.common.JsonUtil;
import com.github.dgw.common.PageInfo;
import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.WebDataBinder;
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;
import javax.servlet.http.HttpServletRequest;
import java.util.ArrayList;
@Component
public class ListArgumentsResolver implements HandlerMethodArgumentResolver {
/**
* 解析器是否支持当前参数
* @param methodParameter
* @return
*/
@Override
public boolean supportsParameter(MethodParameter methodParameter) {
// 指定参数如果被应用MyParam注解，则使用该解析器。
// 如果直接返回true，则代表将此解析器用于所有参数
return methodParameter.hasParameterAnnotation(List.class);
}
/**
* 将request中的请求参数解析到当前Controller参数上
* @param methodParameter 需要被解析的Controller参数，此参数必须首先传给{@link #supportsParameter}并返回true
* @param modelAndViewContainer 当前request的ModelAndViewContainer
* @param nativeWebRequest 当前request
* @param webDataBinderFactory 生成{@link WebDataBinder}实例的工厂
* @return
* @throws Exception
*/
@Nullable
@Override
public Object resolveArgument(MethodParameter methodParameter, @Nullable ModelAndViewContainer modelAndViewContainer, NativeWebRequest nativeWebRequest, @Nullable WebDataBinderFactory webDataBinderFactory) throws Exception {
//获取HttpServletRequest
HttpServletRequest request = nativeWebRequest.getNativeRequest(HttpServletRequest.class);
//获取方法参数注解
List methodAnnotation = methodParameter.getParameterAnnotation(List.class);
//获取注解value字段
String value = methodAnnotation.value();
Class clazz=methodAnnotation.clazz();
String jsonList = request.getParameter(value);
return JsonUtil.jsonToList(jsonList, clazz);
}
}
2、创建一个web 配置类
package com.github.dgw.config;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
import javax.annotation.Resource;
import java.util.List;
@Configuration
public class WebConfig extends WebMvcConfigurationSupport{
@Resource
private PageArgumentsResolver pageArgumentsResolver;
@Resource
private ListArgumentsResolver listArgumentsResolver;
@Override
protected void addArgumentResolvers(List argumentResolvers) {
argumentResolvers.add(pageArgumentsResolver);
argumentResolvers.add(listArgumentsResolver);
super.addArgumentResolvers(argumentResolvers);
}
@Override
protected void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("swagger-ui.html").addResourceLocations("classpath:/META-INF/resources/");
registry.addResourceHandler("/**").addResourceLocations("classpath:/static/");
registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
super.addResourceHandlers(registry);
}
}
3、在Controller中接受参数进行测试
@RequestMapping(value = "saveUser", method = {RequestMethod.POST })
@ResponseBody
public void saveUsers(@com.github.dgw.annotation.List(value = "userList",clazz = User.class) List userList) {
for (User user:userList) {
System.out.println(user.toString());
}
} 4、User类
package com.github.dgw.entity;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.github.dgw.common.JsonUtil;
import java.io.Serializable;
import java.util.List;
@JsonIgnoreProperties(ignoreUnknown = true)
public class User implements Serializable{
private String name;
private String pwd;
public User() {
}
public User(String name, String pwd) {
this.name = name;
this.pwd = pwd;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPwd() {
return pwd;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
@Override
public String toString() {
return "User{name=" + name + ", pwd=" + pwd + "}";
}
}
三、进行测试
1、前端请求
2、后端接收
参考文献：https://www.jianshu.com/p/0347bdde0c6d