springMvc 常用接口HandlerMethodArgumentResolver使用

之前写的http传输json进行服务端接口与客户端对接，以及restful实现这篇文章里提到关于json传输接收，我是在controller里来做json解析处理，如果每个地方都要用到json解析，那每个地方都这么写就显得代码很乱，当然也可以抽取到一个工具类里，但又觉得不优雅，假如我们有这么个注解@Json2Bean在controller参数对象中就能自动帮我们把json解析为我们要对象那将多美好呀。那么这里将应用springmvc  HandlerMethodArgumentResolver这个接口以及自定义注解来实现一个关于json的解析；

实现步骤如下：

1）自定义注解：

package com.cwh.springmvc.Annotation;import java.lang.annotation.Documented;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target({java.lang.annotation.ElementType.PARAMETER})@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface Json2Bean {}

2）利用 HandlerMethodArgumentResolver接口实现数据绑定：

package com.cwh.springmvc.resolver;import java.io.BufferedInputStream;import java.io.BufferedReader;import javax.servlet.http.HttpServletRequest;import net.sf.json.JSONObject;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 com.cwh.springmvc.Annotation.Json2Bean;public class Json2BeanArgumentResolver implements HandlerMethodArgumentResolver{@Overridepublic boolean supportsParameter(MethodParameter paramMethodParameter) {// 仅对有fastjson注解有效return paramMethodParameter.hasParameterAnnotation(Json2Bean.class);}@Overridepublic Object resolveArgument(MethodParameter paramMethodParameter,ModelAndViewContainer paramModelAndViewContainer,NativeWebRequest paramNativeWebRequest,WebDataBinderFactory paramWebDataBinderFactory) throws Exception {HttpServletRequest request = paramNativeWebRequest.getNativeRequest(HttpServletRequest.class);        // content-type不是json的不处理        if (!request.getContentType().contains("application/json")) {            return null;        }        StringBuffer str = new StringBuffer(); try {   BufferedInputStream in = new BufferedInputStream(request.getInputStream());      int i;      char c;      while ((i=in.read())!=-1) {      c=(char)i;      str.append(c);      }     }catch (Exception ex) {   ex.printStackTrace();   }        JSONObject obj= JSONObject.fromObject(str.toString());        return JSONObject.toBean(obj,paramMethodParameter.getParameterType());    }}

3）springmvc配置文件配置：

<mvc:annotation-driven>   <mvc:argument-resolvers>        <bean class="com.cwh.springmvc.resolver.Json2BeanArgumentResolver"/>    </mvc:argument-resolvers>   </mvc:annotation-driven>

注：这个<mvc:annotation-driven>标签是3.1版本的

4）controller实现应用上@json2Bean这个注解：

@RequestMapping("/getUserByName")public @ResponseBody User getUserByName(@Json2Bean User userform){System.out.println(userform);String name = userform.getUsername();User user= userservice.getUserByName(name);return user;}

5）模拟发送一笔json请求测试：

@Testpublic void HttpPostData() {        try {           HttpClient httpclient = new DefaultHttpClient();            String uri = "http://localhost:8080/springMVC/user/getUserByName";           HttpPost httppost = new HttpPost(uri);             //添加http头信息           httppost.addHeader("Content-Type", "application/json");           JSONObject obj = new JSONObject();          obj.put("username", "cwh");           obj.put("password", "password");           httppost.setEntity(new StringEntity(obj.toString()));               HttpResponse response;            response = httpclient.execute(httppost);            //检验状态码，如果成功接收数据            int code = response.getStatusLine().getStatusCode();            System.out.println(code+"code");          if (code == 200) {                String rev = EntityUtils.toString(response.getEntity());//返回json格式： {"id": "","name": ""}                       obj= JSONObject.fromObject(rev);              System.out.println(obj.get("username"));              User user = (User)JSONObject.toBean(obj,User.class);              System.out.println("返回数据==="+user.toString());          }           } catch (ClientProtocolException e) {           e.printStackTrace();          } catch (IOException e) {            e.printStackTrace();          } catch (Exception e) {           e.printStackTrace();          }      }

6）测试结果：

ok！这样服务端看起来代码就简洁多了