springMvc如何接受多個物件引數
阿新 • • 發佈：2020-08-03
在程式碼開發過程中，引數的定義非常重要，目前springmvc提供的較多的引數獲取方式，譬如 @PathVariable 和@RequestParam，
或者通過增加如下註解
<mvc:annotation-driven>
</mvc:annotation-driven>
mvc:annotation-driven預設增加了MappingJackson2HttpMessageConverter，可以將傳遞進來的body體解析成對應的JAVA物件。
但是存入如下問題
1、@PathVariable 和@RequestParam只能解析基礎的Java格式，int string boolean等，2、MappingJackson2HttpMessageConverter只能將物件轉變為一個JAVA Bean，
如果我們有兩個java bean 定義如下：
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publicclassStudent {
privateString name;
privateintyear;
publicString getName() {
returnname;
}
publicvoidsetName(String name) {
this.name = name;
}
publicintgetYear() {
returnyear;
}
publicvoidsetYear(intyear) {
this.year = year;
}
}
|
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 |
publicclassInfo {
privateString city;
privateString address;
publicString getCity() {
returncity;
}
publicvoidsetCity(String city) {
this.city = city;
}
publicString getAddress() {returnaddress;
}
publicvoidsetAddress(String address) {
this.address = address;
}
}
|
如果我們定義了一個介面，需要傳遞這兩個物件資訊,採用MappingJackson2HttpMessageConverter就會比較麻煩。
這裡講解一個如何實現同時傳遞多個物件的方法，我們最終定義的介面如下
public Student addstudentpost(@JsonObject Student student,@JsonObject Info info)
原理是實現我們自定義的HandlerMethodArgumentResolver，並且插入到springMvc的引數解析佇列中。
1、首先定義一個註解類
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@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public@interfaceJsonObject {
}
|
2、其次實現自定義的引數解析類JsonObjectArgResolverHandler
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 |
publicclassJsonObjectArgResolverHandlerimplementsHandlerMethodArgumentResolver {
@OverridepublicbooleansupportsParameter(MethodParameter methodParameter) {
returnmethodParameter.hasParameterAnnotation(JsonObject.class);
}
@OverridepublicObject resolveArgument(MethodParameter methodParameter,
ModelAndViewContainer modelAndViewContainer, NativeWebRequest nativeWebRequest,
WebDataBinderFactory webDataBinderFactory)throwsException {
try{
JSONObject para = getRequestInfo(nativeWebRequest);
Class<?> type = methodParameter.getParameterType();
String name = methodParameter.getParameterName();
if(null!= para && para.containsKey(name)) {
returnJSON.parseObject(para.getString(name), type);
}
}catch(Exception e) {
}
returnnull;
}
privateJSONObject getRequestInfo(NativeWebRequest webRequest)throwsIOException {
JSONObject para =newJSONObject();
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 =newStringBuilder();
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);
}
}
returnpara;
}
}
|
注意：
a、supportsParameter表明我們的類只支援解析帶有JsonObject的物件解析。
b、httpServletRequest的body體只能讀取一次，再次讀取後就返回空，因為帶有JsonObject註解的物件都會執行一遍，在第一次獲取後需要將body體儲存下來，以便下次使用。所有有如下的程式碼
將body體儲存
| 1 |
httpServletRequest.setAttribute("para", buffer.toString());
|
讀取Attribute，沒有則從body體讀取。
1 if (null != httpServletRequest.getAttribute("para")) {
2 try {
3 para = JSON.parseObject(httpServletRequest.getAttribute("para").toString());
4 } catch (Exception e) {
5 }
6 } else {
3、將JsonObjectArgResolverHandler配置進xml檔案中。
<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>
這個我們可以定義如下的介面，
@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;
}
整個函式的定義就比較明瞭和直觀。
關於ResponseJsonBody的註解，請檢視http://www.cnblogs.com/wangjiuyong/articles/7162207.html
在readme中有測試方法：
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"
}
}
https://www.cnblogs.com/wangjiuyong/articles/7182650.html