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spring 自定参数解析器（HandlerMethodArgumentResolver）
由于之前用@RequestParam无法接收request payload 正文格式为json格式的字符串，只能使用@RequestBody整个接收，觉得麻烦，但是spring自带的参数解析器不具有这种功能，只能尝试着用自定义参数解析器去解决。
自定义解析器需要实现HandlerMethodArgumentResolver接口，HandlerMethodArgumentResolver接口包含两个接口：
接口说明：
supportsParameter：用于判定是否需要处理该参数分解，返回true为需要，并会去调用下面的方法resolveArgument。
resolveArgument：真正用于处理参数分解的方法，返回的Object就是controller方法上的形参对象。
1、自定义注解
package com.manqian.crm.resolver;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
public @interface JsonParam {
String value();boolean required() default true;String defaultValue() default "";
}
若不想自定义注解，可以直接在实现HandlerMethodArgumentResolver的supportsParameter直接返回true
2、自定义参数解析器，实现HandlerMethodArgumentResolver接口
package com.manqian.crm.resolver;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.PathNotFoundException;
import com.manqian.crm.api.exception.ParamCheckException;
import org.apache.commons.io.IOUtils;
import org.springframework.context.annotation.Configuration;
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;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
public class JsonPathArgumentResolver implements HandlerMethodArgumentResolver {
private static final String JSON_REQUEST_BODY = "JSON_REQUEST_BODY";//判断是否支持要转换的参数类型
@Override
public boolean supportsParameter(MethodParameter parameter) {return parameter.hasParameterAnnotation(JsonParam.class);
}//当支持后进行相应的转换
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {String body = getRequestBody(webRequest);Object val = null;try {val = JsonPath.read(body, parameter.getParameterAnnotation(JsonParam.class).value());if (parameter.getParameterAnnotation(JsonParam.class).required() && val == null) {throw new ParamCheckException(parameter.getParameterAnnotation(JsonParam.class).value() + "不能为空");}} catch (PathNotFoundException exception) {System.out.println(exception.getStackTrace());if (parameter.getParameterAnnotation(JsonParam.class).required()) {
// throw new ParamCheckException(parameter.getParameterAnnotation(JsonParam.class).value() + “不能为空”);
throw exception;
}
}
return val;
}
private String getRequestBody(NativeWebRequest webRequest) {HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);String jsonBody = (String) servletRequest.getAttribute(JSON_REQUEST_BODY);if (jsonBody == null) {try {jsonBody = IOUtils.toString(servletRequest.getInputStream());servletRequest.setAttribute(JSON_REQUEST_BODY, jsonBody);} catch (IOException e) {throw new RuntimeException(e);}}return jsonBody;}
}
3、注册自定义参数解析器
springboot方式：
package com.demo;
import java.util.List;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
import com.demo.mvc.component.MultiPersonArgumentResolver;
import com.demo.mvc.component.PersonArgumentResolver;
@SpringBootApplication
public class WebMvcConfiguration extends WebMvcConfigurationSupport {
@Override
protected void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {// 注册JsonPathArgumentResolver的参数分解器argumentResolvers.add(new JsonPathArgumentResolver());
}
}
package com.manqian.crm.resolver;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import java.util.List;
@Configuration
public class ClientResourcesConfig extends WebMvcConfigurerAdapter {
@Override
public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
// super.addArgumentResolvers(argumentResolvers);
argumentResolvers.add(new JsonPathArgumentResolver());
}
}
传统XML格式：
mvc:annotation-driven
mvc:argument-resolvers
</mvc:argument-resolvers>
</mvc:annotation-driven>
使用：
1、依赖：
com.jayway.jsonpath
json-path
2、controller方法使用@JsonParam接收参数
参考：https://stackoverflow.com/questions/12893566/passing-multiple-variables-in-requestbody-to-a-spring-mvc-controller-using-ajax/12897632#12897632
https://my.oschina.net/sugarZone/blog/704575
作者：逆流_Jun
来源：CSDN
原文：https://blog.csdn.net/u010187242/article/details/73647670
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