在代码开发过程中，参数的定义非常重要，目前springmvc提供的较多的参数获取方式，譬如 @PathVariable 和 @RequestParam，
或者通过增加如下注解
<mvc:annotation-driven>
</mvc:annotation-driven>
mvc:annotation-driven默认增加了MappingJackson2HttpMessageConverter，可以将传递进来的body体解析成对应的JAVA对象。
但是存入如下问题
1、@PathVariable 和 @RequestParam只能解析基础的Java格式，int string boolean等，
2、MappingJackson2HttpMessageConverter只能将对象转变为一个JAVA Bean，
如果我们有两个java bean 定义如下：
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public class Student {
private String name;
private int year;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getYear() {
return year;
}
public void setYear(int year) {
this.year = year;
}
}
|
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public class Info {
private String city;
private String address;
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
|
如果我们定义了一个接口，需要传递这两个对象信息,采用MappingJackson2HttpMessageConverter就会比较麻烦。
这里讲解一个如何实现同时传递多个对象的方法，我们最终定义的接口如下
public Student addstudentpost(@JsonObject Student student,@JsonObject Info info)
原理是实现我们自定义的HandlerMethodArgumentResolver，并且插入到springMvc的参数解析队列中。
1、首先定义一个注解类
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@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface JsonObject {
}
|
2、其次实现自定义的参数解析类JsonObjectArgResolverHandler
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public class JsonObjectArgResolverHandler implements HandlerMethodArgumentResolver {
@Override public boolean supportsParameter(MethodParameter methodParameter) {
return methodParameter.hasParameterAnnotation(JsonObject.class);
}
@Override public Object resolveArgument(MethodParameter methodParameter,
ModelAndViewContainer modelAndViewContainer, NativeWebRequest nativeWebRequest,
WebDataBinderFactory webDataBinderFactory) throws Exception {
try {
JSONObject para = getRequestInfo(nativeWebRequest);
Class<?> type = methodParameter.getParameterType();
String name = methodParameter.getParameterName();
if (null != para && para.containsKey(name)) {
return JSON.parseObject(para.getString(name), type);
}
} catch (Exception e) {
}
return null;
}
private JSONObject getRequestInfo(NativeWebRequest webRequest) throws IOException {
JSONObject para = new JSONObject();
HttpServletRequest httpServletRequest =
(HttpServletRequest) webRequest.getNativeRequest(HttpServletRequest.class);
String method = httpServletRequest.getMethod();
if (!method.equals("GET") && !method.equals("DELETE")) {
if (null != httpServletRequest.getAttribute("para")) {
try {
para = JSON.parseObject(httpServletRequest.getAttribute("para").toString());
} catch (Exception e) {
}
} else {
StringBuilder buffer = new StringBuilder();
BufferedReader reader = httpServletRequest.getReader();
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
httpServletRequest.setAttribute("para", buffer.toString());
try {
para = JSON.parseObject(buffer.toString());
} catch (Exception e) {
}
}
} else {
Map<String, String[]> parameterMap = webRequest.getParameterMap();
for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
String key = entry.getKey();
String values = StringUtils.join(entry.getValue());
para.put(key, values);
}
}
return para;
}
}
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注意：
a、supportsParameter表明我们的类只支持解析带有JsonObject的对象解析。
b、httpServletRequest的body体只能读取一次，再次读取后就返回空，因为带有JsonObject注解的对象都会执行一遍，在第一次获取后需要将body体保存下来，以便下次使用。所有有如下的代码
将body体保存
| 1 |
httpServletRequest.setAttribute("para", buffer.toString());
|
读取Attribute，没有则从body体读取。
1 if (null != httpServletRequest.getAttribute("para")) {
2 try {
3 para = JSON.parseObject(httpServletRequest.getAttribute("para").toString());
4 } catch (Exception e) {
5 }
6 } else {
3、将 JsonObjectArgResolverHandler配置进xml文件中。
<mvc:annotation-driven>
<mvc:argument-resolvers>
<bean class="com.nuaa.handler.JsonObjectArgResolverHandler"></bean>
</mvc:argument-resolvers>
<mvc:return-value-handlers>
<bean class="com.nuaa.handler.ReponseJsonBodyMethodReturnValueHandler">
<property name="messageConverters">
<list>
<bean class="com.nuaa.handler.Base64JsonHttpMessageConverter"/>
</list>
</property>
</bean>
</mvc:return-value-handlers>
</mvc:annotation-driven>
这个我们可以定义如下的接口，
@RequestMapping(value="/addstudentpost", method = RequestMethod.POST,produces="application/json")
@ResponseJsonBody
public Student addstudentpost(@JsonObject Student student,@JsonObject Info info){
student.setName(JSON.toJSONString(student)+JSON.toJSONString(info)+(new Date()));
return student;
}
整个函数的定义就比较明了和直观。
关于 ResponseJsonBody的注解，请查看http://www.cnblogs.com/wangjiuyong/articles/7162207.html
在readme中有测试方法：
http://localhost:8080/spring/controlhandler/addstudentget?student={"name":"zhang","year":100}&info={"address":"yuhuataiqu","city":"nanjing"}
http://localhost:8080/spring/controlhandler/addstudentpost
{
"student": {
"name": "wangjiuyong",
"year": 2000
},
"info": {
"address": "yuhuataiqu",
"city": "nanjing"
}
}