Spring自定义注解实现json参数传递
实现（POST,GET）传参自动转换成Json对象，所有参数为Json格式然后再Base64加密
Spring Request详解：
Spring 的DispatcherServlet 实现了Servlet方法，来处理一次请求
DispatcherServlet主要是执行了两个方法doService(HttpServletRequest request, HttpServletResponse response)，doDispatch(HttpServletRequest request, HttpServletResponse response)
在doDispatch方法中
// Determine handler for the current request.
mappedHandler = getHandler(processedRequest);
获取当前请求的handler，也就是获取到执行当前request的bean。
HandlerMapping有多个实现，具体的还需自己看下实现
// Determine handler adapter for the current request.
HandlerAdapterha = getHandlerAdapter(mappedHandler.getHandler());
获取到当前请求的HandlerAdapter
protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
for (HandlerMapping hm : this.handlerMappings) {
if (logger.isTraceEnabled()) {
logger.trace(
"Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'");
}
HandlerExecutionChain handler = hm.getHandler(request);
if (handler != null) {
return handler;
}
}
return null;
}
获取ha.supports(handler) 返回为true的HandlerAdapter
eg.
如果这个bean实现了HttpRequestHandler接口则返回HttpRequestHandlerAdapter
@Override
public boolean supports(Object handler) {
return (handler instanceof HttpRequestHandler);
}
如果这个bean实现了Controller接口则返回SimpleControllerHandlerAdapter
@Override
public boolean supports(Object handler) {
return (handler instanceof Controller);
}
目前常用的方式是通过@Controller、@RequestMapping和Spring配置中添加<context:component-scan/>
此时使用的是RequestMappingHandlerAdapter
RequestMappingHandlerAdapter 主要实现了请求参数的封装处理，返回参数的封装处理，支持注入argumentResolvers、returnValueHandlers、messageConverters等来实现扩展
RequestMappingHandlerAdapter.invokeHandlerMethod.invokeAndHandle.invokeForRequest.getMethodArgumentValues
if (this.argumentResolvers.supportsParameter(parameter)) {
try {
args[i] = this.argumentResolvers.resolveArgument(
parameter, mavContainer, request, this.dataBinderFactory);
continue;
}
catch (Exception ex) {
if (logger.isDebugEnabled()) {
logger.debug(getArgumentResolutionErrorMessage("Error resolving argument", i), ex);
}
throw ex;
}
}
首先会调用argumentResolver的supportsParameter判断是否可用，然后再执行resolveArgument方法
SpecialArgumentsResolver，自定义argumentResolver
通过上面我们可以发现，基于自定义注解实现Json的参数传递，需要实现自定的argumentResolver并注入到RequestMappingHandlerAdapter中
- 实现自定义Json注解
/**
* Created by zhaoqi on 2016/5/5.
*/
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Json {
Class[] types() default java.lang.Object.class;
String path() default "";
}
- spring配置文件增加自定义argumentResolver
注意，如果是注入的argumentResolver，会覆盖默认的argumentResolver。
<!--RequestMappingHandlerAdapter加入自定义ArgumentsResolver-->
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
<property name="synchronizeOnSession" value="true" />
<property name="argumentResolvers">
<list>
<bean class="com.zhaoqi.component.annotation.SpecialArgumentsResolver"/>
</list>
</property>
<property name="messageConverters">
<list>
<ref bean="stringConverter" />
<ref bean="jsonConverter" />
</list>
</property>
</bean>
如果不想覆盖默认的argumentResolver，请注入customArgumentResolvers。
// Custom arguments
if(getCustomArgumentResolvers() !=null) {
resolvers.addAll(getCustomArgumentResolvers());
}
- 实现SpecialArgumentsResolver
/**
* Created by zhaoqi on 2016/5/6.
*/
public class SpecialArgumentsResolver implements HandlerMethodArgumentResolver {
@Resource
DotaJsonHttpMessageConverter dotaJsonHttpMessageConverter;
@Override
public boolean supportsParameter(MethodParameter parameter) {
return parameter.hasParameterAnnotation(Json.class);
}
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
return this.readArguments(webRequest, parameter, parameter.getGenericParameterType());
}
private Object readArguments(NativeWebRequest webRequest, MethodParameter parameter, Type genericParameterType) {
HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
ServletServerHttpRequest inputMessage = new ServletServerHttpRequest(servletRequest);
Object arg =null;
try {
// get方式取queryString
if (servletRequest.getMethod().equals(RequestMappingHandlerAdapter.METHOD_GET)) {
// base64解码
String decodedQueryString = new String(Base64Utils.decodeFromString(servletRequest.getQueryString()));
return JsonUtil.toObject(decodedQueryString, Class.forName(genericParameterType.getTypeName()));
}
// Json注解使用dotaJsonHttpMessageConverter读取参数
arg = dotaJsonHttpMessageConverter.readInternal(Class.forName(genericParameterType.getTypeName()), inputMessage);
if (null == arg) {
throw new HttpMessageNotReadableException("Required request body is missing: " +
parameter.getMethod().toGenericString());
}
} catch (IOException | ClassNotFoundException e) {
//
}
return arg;
}
}
实际使用
@RequestMapping("/sayHi")
@ResponseBody
public ResponseVo getFeedback(@Json HelloRequest hello){
ResponseVo responseVo = new ResponseVo();
responseVo.setMsg("success");
responseVo.setData(hello.getHello());
return responseVo;
}
好处
- 目前前端页面调用后台接口，GET和POST的参数形式不一样。GET方式是将参数拼接在url中，而POST是可以直接传Json对象的
后台通过使用@Json注解，可以实现GET和POST参数的统一，如果需要切换请求方式，无需重新拼装参数 - 本例采用的为base64加密，实际可以根据情况自行使用加密方式。可以伪装请求的参数，增强安全性
