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这篇文章给大家介绍如何进行Spring MVC数据绑定的扩展,内容非常详细,感兴趣的小伙伴们可以参考借鉴,希望对大家能有所帮助。
Spring MVC经过三个版本,功能已经改进和完善了很多。尤其是2.5以来采用的Annotation的参数绑定,极大的方便了开发,3.0对其进行更进一步的完善。对于一些特殊的前台框架,传到后台的不是普通的request中的参数,而是request流中的xml格式,这时就不能采用SpringMVC自带的参数绑定方法。这时候考虑是否能扩展一下。
SpringMVC默认使用的是AnnotationMethodHandlerAdapter.java,可以修改这个类来实现扩展。关键位置在如下方法中:
otected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { ServletHandlerMethodResolver methodResolver= getMethodResolver(handler); Method handlerMethod = methodResolver.resolveHandlerMethod(request); ServletHandlerMethodInvoker methodInvoker=new ServletHandlerMethodInvoker(methodResolver); ServletWebRequest webRequest = new ServletWebRequest(request, response); ExtendedModelMap implicitModel = new BindingAwareModelMap(); Object result=methodInvoker.invokeHandlerMethod(handlerMethod,handler,webRequest, implicitModel); ModelAndView mav=methodInvoker.getModelAndView(handlerMethod,handler.getClass(),result, implicitModel, webRequest); methodInvoker.updateModelAttributes(handler,(mav!=null?mav.getModel():null),implicitModel,webRequest); return mav; }
蓝色位置是关键点,ServletHandlerMethodInvoker.java是内部类,继承自HandlerMethodInvoker.java,invokeHandlerMethod方法需要扩展,继续跟踪这个方法,发现是HandlerMethodInvoker.java这个类的方法,这个方法中的关键方法是resolveHandlerArguments(),关键部分如下:
if (RequestParam.class.isInstance(paramAnn)) { RequestParam requestParam = (RequestParam) paramAnn; paramName = requestParam.value(); required = requestParam.required(); defaultValue = parseDefaultValueAttribute(requestParam.defaultValue()); annotationsFound++; } else if (RequestHeader.class.isInstance(paramAnn)) { RequestHeader requestHeader = (RequestHeader) paramAnn; headerName = requestHeader.value(); required = requestHeader.required(); defaultValue = parseDefaultValueAttribute(requestHeader.defaultValue()); annotationsFound++; }
到此扩展的话需要添加自己的类型,如RequestParamExt,添加在后面,模仿如下:
else if (RequestParamExt.class.isInstance(paramAnn)) { RequestParamExtrequestParam = (RequestParamExt) paramAnn; paramName = requestParam.value(); defaultValue = parseDefaultValueAttribute(requestParam.defaultValue()); miType = requestParam.type(); annotationsFound++; }
在
else if (paramName != null) { args[i] = resolveRequestParam(paramName, required, defaultValue, methodParam, webRequest, handler); }
这个方法上面添加扩展逻辑:
if(!RequestParamExt.TYPE_NONE.equals(miType)){ if(null == platformRequest){ HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class); platformRequest = new PlatformRequest((HttpServletRequest)request, "utf-8"); platformRequest.receiveData(); } if(RequestParamExt.TYPE_PLATFORMREQUEST.equals(miType)){ args[i] = platformRequest; } else if(RequestParamExt.TYPE_STR.equals(miType)){ args[i] = resolveRequestStrParamExt(platformRequest, methodParam); }else{ args[i] = resolveRequestParamExt(miType,platformRequest,paramName, defaultValue, methodParam, webRequest, handler); } }
两个resolveRequest*Ext方法如下:
protected Object resolveRequestStrParamExt(PlatformRequest platformRequest, MethodParameter methodParam){ VariableList inVl = platformRequest.getVariableList(); String paraName = methodParam.getParameterName(); return inVl.getValueAsObject(paraName); } protected Object resolveRequestParamExt(String miType,PlatformRequest platformRequest, String paramName, String defaultValue,MethodParameter methodParam,NativeWebRequest webRequest, Object handler)throws Exception{ if(StringUtils.isBlank(paramName)){ paramName = defaultValue; } Class<?> paramType = methodParam.getParameterType(); DatasetList inDl = platformRequest.getDatasetList(); VariableList inVl = platformRequest.getVariableList(); if(RequestParamExt.TYPE_DS.equals(miType)){//绑定的关键过程 Dataset ds = inDl.getDataset(paramName); Object vo = paramType.newInstance(); MiPDataBinder dataBinder = new MiPDataBinder(vo, false); dataBinder.bind(inVl); return dataBinder.getTarget(); } }
同时还需要一个annotation的定义:示例如下:
package com.company.springext.web.bind.annotation; import java.lang.annotation.Documented; 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) @Documented public @interface RequestParamExt { public static final String TYPE_NONE = "none"; public static final String TYPE_DS = "ds"; public static final String TYPE_VL = "vl"; public static final String TYPE_STR = "string"; String type() default TYPE_NONE; String value() default ""; String defaultValue() default "ds"; }
***是修改Spring配置:
<bean class="com.company.springext.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapterExt"> </bean>
到此就实现了自定义格式的数据绑定。
对于特定格式的输出,如果需要自定义的话,同样需要修改AnnotationMethodHandlerAdapterExt.java这个类,关键位置在getModelAndView()方法。在如下位置:
} else if (AnnotationUtils.findAnnotation(handlerMethod, ResponseBody.class) != null) { handleResponseBody(returnValue, webRequest); return null; }
添加自己的扩展方法:
else if (AnnotationUtils.findAnnotation(handlerMethod, ResponseBodyExt.class) != null) { ResponseBodyExt bodyMi = AnnotationUtils.findAnnotation(handlerMethod, ResponseBodyExt.class); handleResponseBodyExt(returnValue, webRequest, bodyMi); return null; }
定义handleResponseBodyExt方法:
private void handleResponseBodyExt(Object returnValue, ServletWebRequest webRequest, ResponseBodyMI bodyMi) throws Exception { HttpServletResponse servletResponse = (HttpServletResponse) webRequest.getNativeResponse(); writeWithExtConverters(returnValue, servletResponse, bodyMi); }
writeWithExtConverters()方法如下:
private void writeWithExtConverters(Object returnValue, HttpServletResponse response, ResponseBodyMI bodyMi) throws Exception { convertToXML(...); };
使用方式如下:
@RequestMapping(value="/getContractList") @ResponseBodyExt(isCheck=true, resultType="sql", sqlColumns="ID,TUREID") public Page<Contract> getContractList(@RequestParamExt(value = "ds_search", type = "ds") Contract cp) throws Exception { Page<Contract> page = method1(); return page; }
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