java SpringMVC 使用 JSON 返回对象列表
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SpringMVC Returning a List Of Objects With JSON
提问by devdar
I have two select options and i would like when the user selects one option that other is populated with data from the database. However i am having issues in getting the object list returned to the view.
我有两个选择选项，我希望当用户选择一个选项时，另一个选项填充了数据库中的数据。但是，我在将对象列表返回到视图时遇到了问题。
Controller
控制器
@RequestMapping(value="getCrimeTypeList.htm", method = RequestMethod.GET)
public @ResponseBody List<CrimeType> getCrimeTypeList(@RequestParam(value="crimeCatId") Integer crimeCatId) throws Exception{
try {
List<CrimeType> crimeTypeList = this.crimeTypeManager.getCrimeTypeList(crimeCatId);
return crimeTypeList;
} catch (Exception e) {
logger.error(e.getMessage());
return null;
}
}
JQuery
查询
$("select#offenceCatId").change(function(){
$.ajax({
type:'GET',
url:'getCrimeTypeList.htm',
data:{crimeCatId: $(this).val()},
headers: {
Accept: 'application/json'
},
dataType: 'json',
success:function(data){
alert('it worked');
}
});
});
HTML
HTML
<li>
<label>Offence Type</label>
<form:select path="offenceTypeId" id="offenceTypeId" title="Offence Type">
<form:options items="${crimeType.crimeTypeList}" itemValue="crimeTypeId" itemLabel="crimeTypeDesc"/>
</form:select>
<form:errors path="offenceTypeId" class="errors" />
</li>
Error
错误
"NetworkError: 400 Bad Request - http://localhost:8084/crimeTrack/getCrimeTypeList.htm?[object%20Object]"
EDITEDI did some experimentation and found if the Controller is returning a String it works however once its returning an Object i am having the issues stated.
编辑我做了一些实验，发现如果控制器返回一个字符串，它可以工作，但是一旦它返回一个对象，我就会遇到问题。
FireBug
火虫
GET http://localhost:8084/crimeTrack/getCrimeTypeList.htm?crimeCatId=6 406 Not Acceptable
Response Headers
Content-Length 1067
Content-Type text/html;charset=utf-8
Date Fri, 29 Mar 2013 00:58:17 GMT
Server Apache-Coyote/1.1
Request Headers
Accept application/json
Accept-Encoding gzip, deflate
Accept-Language en-US,en;q=0.5
Host localhost:8084
Referer http://localhost:8084/crimeTrack/crime_registration.htm
User-Agent Mozilla/5.0 (Windows NT 6.1; WOW64; rv:19.0) Gecko/20100101 Firefox/19.0
X-Requested-With XMLHttpRequest
回答by OQJF
Firstly please make sure your Spring version is 3.1.1 release and you have added Hymanson.jar in you lib, then try using below code, your code has something reduntant.
首先请确保你的 Spring 版本是 3.1.1 版本并且你已经在你的 lib 中添加了 Hymanson.jar，然后尝试使用下面的代码，你的代码有一些冗余。
@RequestMapping(value="/getCrimeTypeList.htm", method = RequestMethod.GET)
public @ResponseBody List<CrimeType> getCrimeTypeList(@RequestParam(value="crimeCatId") Integer crimeCatId) throws Exception{
try {
return this.crimeTypeManager.getCrimeTypeList(crimeCatId);
//return "true";
} catch (Exception e) {
logger.error(e.getMessage());
return null;
}
}
$("select#offenceCatId").change(function(){
var param={crimeCatId:$(this).val()};
$.ajax({
type:'GET',
url:'getCrimeTypeList.htm',
data:param,
success:function(data){
//append options to list
}
});
});
回答by Arun P Johny
Your controller is expecting an request header Accept=application/json, in your case you are not setting it.
您的控制器需要一个请求标头Accept=application/json，在您的情况下您没有设置它。
Try setting the Acceptheader
尝试设置Accept标题
jQuery.ajax({
type:'GET',
url:'getCrimeTypeList.htm',
data:{crimeCatId:$(this).val()},
processData:false,
headers: {
Accept: 'application/json'
},
dataType: 'json',
success:function(data){
//append options to list
}
});
