Develop Reference

How to pass multiple argument in the REST api [duplicate]

I have a method;
#POST
#Path("test")
#Consumes(MediaType.APPLICATION_JSON)
public void test(ObjectOne objectOne, ObjectTwo objectTwo)
Now I know I can post a single object in json format, just putting it into the body.
But is it possible to do multiple objects? If so, how?

You can not use your method like this as correctly stated by Tarlog.
However, you can do this:
#POST
#Path("test")
#Consumes(MediaType.APPLICATION_JSON)
public void test(List<ObjectOne> objects)
or this:
#POST
#Path("test")
#Consumes(MediaType.APPLICATION_JSON)
public void test(BeanWithObjectOneAndObjectTwo containerObject)
Furthermore, you can always combine your method with GET parameters:
#POST
#Path("test")
#Consumes(MediaType.APPLICATION_JSON)
public void test(List<ObjectOne> objects, #QueryParam("objectTwoId") long objectTwoId)

The answer is no.
The reason is simple: This about the parameters you can receive in a method. They must be related to the request. Right? So they must be either headers or cookies or query parameters or matrix parameters or path parameters or request body. (Just to tell the complete story there is additional types of parameters called context).
Now, when you receive JSON object in your request, you receive it in a request body. How many bodies the request may have? One and only one. So you can receive only one JSON object.

If we look at what the OP is trying to do, he/she is trying to post two (possibly unrelated) JSON objects. First any solution to try and send one part as the body, and one part as some other param, IMO, are horrible solutions. POST data should go in the body. It's not right to do something just because it works. Some work-arounds might be violating basic REST principles.
I see a few solutions
Use application/x-www-form-urlencoded
Use Multipart
Just wrap them in a single parent object
1. Use application/x-www-form-urlencoded
Another option is to just use application/x-www-form-urlencoded. We can actually have JSON values. For examle
curl -v http://localhost:8080/api/model \
-d 'one={"modelOne":"helloone"}' \
-d 'two={"modelTwo":"hellotwo"}'
public class ModelOne {
public String modelOne;
}
public class ModelTwo {
public String modelTwo;
}
#Path("model")
public class ModelResource {
#POST
#Consumes(MediaType.APPLICATION_FORM_URLENCODED)
public String post(#FormParam("one") ModelOne modelOne,
#FormParam("two") ModelTwo modelTwo) {
return modelOne.modelOne + ":" + modelTwo.modelTwo;
}
}
The one thing we need to get this to work is a ParamConverterProvider to get this to work. Below is one that has been implemented by Michal Gadjos of the Jersey Team (found here with explanation).
#Provider
public class JacksonJsonParamConverterProvider implements ParamConverterProvider {
#Context
private Providers providers;
#Override
public <T> ParamConverter<T> getConverter(final Class<T> rawType,
final Type genericType,
final Annotation[] annotations) {
// Check whether we can convert the given type with Jackson.
final MessageBodyReader<T> mbr = providers.getMessageBodyReader(rawType,
genericType, annotations, MediaType.APPLICATION_JSON_TYPE);
if (mbr == null
|| !mbr.isReadable(rawType, genericType, annotations, MediaType.APPLICATION_JSON_TYPE)) {
return null;
}
// Obtain custom ObjectMapper for special handling.
final ContextResolver<ObjectMapper> contextResolver = providers
.getContextResolver(ObjectMapper.class, MediaType.APPLICATION_JSON_TYPE);
final ObjectMapper mapper = contextResolver != null ?
contextResolver.getContext(rawType) : new ObjectMapper();
// Create ParamConverter.
return new ParamConverter<T>() {
#Override
public T fromString(final String value) {
try {
return mapper.reader(rawType).readValue(value);
} catch (IOException e) {
throw new ProcessingException(e);
}
}
#Override
public String toString(final T value) {
try {
return mapper.writer().writeValueAsString(value);
} catch (JsonProcessingException e) {
throw new ProcessingException(e);
}
}
};
}
}
If you aren't scanning for resource and providers, just register this provider, and the above example should work.
2. Use Multipart
One solution that no one has mentioned, is to use multipart. This allows us to send arbitrary parts in a request. Since each request can only have one entity body, multipart is the work around, as it allows to have different parts (with their own content types) as part of the entity body.
Here is an example using Jersey (see official doc here)
Dependency
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-multipart</artifactId>
<version>${jersey-2.x.version}</version>
</dependency>
Register the MultipartFeature
import javax.ws.rs.ApplicationPath;
import org.glassfish.jersey.media.multipart.MultiPartFeature;
import org.glassfish.jersey.server.ResourceConfig;
#ApplicationPath("/api")
public class JerseyApplication extends ResourceConfig {
public JerseyApplication() {
packages("stackoverflow.jersey");
register(MultiPartFeature.class);
}
}
Resource class
import javax.ws.rs.Consumes;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import org.glassfish.jersey.media.multipart.FormDataParam;
#Path("foobar")
public class MultipartResource {
#POST
#Consumes(MediaType.MULTIPART_FORM_DATA)
public Response postFooBar(#FormDataParam("foo") Foo foo,
#FormDataParam("bar") Bar bar) {
String response = foo.foo + "; " + bar.bar;
return Response.ok(response).build();
}
public static class Foo {
public String foo;
}
public static class Bar {
public String bar;
}
}
Now the tricky part with some clients is that there isn't a way to set the Content-Type of each body part, which is required for the above to work. The multipart provider will look up message body reader, based on the type of each part. If it's not set to application/json or a type, the Foo or Bar has a reader for, this will fail. We will use JSON here. There's no extra configuration but to have a reader available. I'll use Jackson. With the below dependency, no other configuration should be required, as the provider will be discovered through classpath scanning.
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-json-jackson</artifactId>
<version>${jersey-2.x.version}</version>
</dependency>
Now the test. I will be using cURL. You can see I explicitly set the Content-Type for each part with type. The -F signifies to different part. (See very bottom of the post for an idea of how the request body actually looks.)
curl -v -X POST \
-H "Content-Type:multipart/form-data" \
-F "bar={\"bar\":\"BarBar\"};type=application/json" \
-F "foo={\"foo\":\"FooFoo\"};type=application/json" \
http://localhost:8080/api/foobar
Result: FooFoo; BarBar
The result is exactly as we expected. If you look at the resource method, all we do is return this string foo.foo + "; " + bar.bar, gathered from the two JSON objects.
You can see some examples using some different JAX-RS clients, in the links below. You will also see some server side example also from those different JAX-RS implementations. Each link should have somewhere in it a link to the official documentation for that implementation
Jersey example
Resteasy example
CXF example
There are other JAX-RS implementations out there, but you will need to find the documentation for it yourself. The above three are the only ones I have experience with.
As far as Javascript clients, most of the example I see (e.g. some of these involve setting the Content-Type to undefined/false (using FormData), letting the Browser handle the it. But this will not work for us, as the Browser will not set the Content-Type for each part. And the default type is text/plain.
I'm sure there are libraries out there that allow setting the type for each part, but just to show you how it can be done manually, I'll post an example (got a little help from here. I'll be using Angular, but the grunt work of building the entity body will be plain old Javascript.
<!DOCTYPE html>
<html ng-app="multipartApp">
<head>
<script src="js/libs/angular.js/angular.js"></script>
<script>
angular.module("multipartApp", [])
.controller("defaultCtrl", function($scope, $http) {
$scope.sendData = function() {
var foo = JSON.stringify({foo: "FooFoo"});
var bar = JSON.stringify({bar: "BarBar"});
var boundary = Math.random().toString().substr(2);
var header = "multipart/form-data; charset=utf-8; boundary=" + boundary;
$http({
url: "/api/foobar",
headers: { "Content-Type": header },
data: createRequest(foo, bar, boundary),
method: "POST"
}).then(function(response) {
$scope.result = response.data;
});
};
function createRequest(foo, bar, boundary) {
var multipart = "";
multipart += "--" + boundary
+ "\r\nContent-Disposition: form-data; name=foo"
+ "\r\nContent-type: application/json"
+ "\r\n\r\n" + foo + "\r\n";
multipart += "--" + boundary
+ "\r\nContent-Disposition: form-data; name=bar"
+ "\r\nContent-type: application/json"
+ "\r\n\r\n" + bar + "\r\n";
multipart += "--" + boundary + "--\r\n";
return multipart;
}
});
</script>
</head>
<body>
<div ng-controller="defaultCtrl">
<button ng-click="sendData()">Send</button>
<p>{{result}}</p>
</div>
</body>
</html>
The interesting part is the createRequest function. This is where we build the multipart, setting the Content-Type of each part to application/json, and concatenating the stringified foo and bar objects to each part. If you are unfamiliar multipart format see here for more info. The other interesting part is the header. We set it to multipart/form-data.
Below is the result. In Angular I just used the result to show in the HTML, with $scope.result = response.data. The button you see was just to make the request. You will also see the request data in firebug
3. Just wrap them in a single parent object
This option should be self explanatory, as others have already mentioned.

The next approach is usually applied in this kind of cases:
TransferObject {
ObjectOne objectOne;
ObjectTwo objectTwo;
//getters/setters
}
#POST
#Path("test")
#Consumes(MediaType.APPLICATION_JSON)
public void test(TransferObject object){
// object.getObejctOne()....
}

You can't put two separate objects in one single POST call as explained by Tarlog.
Anyway you could create a third container object that contains the first two objects and pass that one within the POS call.

I have also faced with these problem. Maybe this will help.
#POST
#Path("/{par}")
#Produces(MediaType.APPLICATION_JSON)
#Consumes(MediaType.APPLICATION_JSON)
public Object centralService(#PathParam("par") String operation, Object requestEntity) throws JSONException {
ObjectMapper objectMapper=new ObjectMapper();
Cars cars = new Cars();
Seller seller = new Seller();
String someThingElse;
HashMap<String, Object> mapper = new HashMap<>(); //Diamond )))
mapper = (HashMap<String, Object>) requestEntity;
cars=objectMapper.convertValue(mapper.get("cars"), Cars.class);
seller=objectMapper.convertValue(mapper.get("seller"), Seller.class);
someThingElse=objectMapper.convertValue(mapper.get("someThingElse"), String.class);
System.out.println("Cars Data "+cars.toString());
System.out.println("Sellers Data "+seller.toString());
System.out.println("SomeThingElse "+someThingElse);
if (operation.equals("search")) {
System.out.println("Searching");
} else if (operation.equals("insertNewData")) {
System.out.println("Inserting New Data");
} else if (operation.equals("buyCar")) {
System.out.println("Buying new Car");
}
JSONObject json=new JSONObject();
json.put("result","Works Fine!!!");
return json.toString();
}
*******CARS POJO********#XmlRootElement for Mapping Object to XML or JSON***
#XmlRootElement
public class Cars {
private int id;
private String brand;
private String model;
private String body_type;
private String fuel;
private String engine_volume;
private String horsepower;
private String transmission;
private String drive;
private String status;
private String mileage;
private String price;
private String description;
private String picture;
private String fk_seller_oid;
} // Setters and Getters Omitted
*******SELLER POJO********#XmlRootElement for Mapping Object to XML or JSON***
#XmlRootElement
public class Seller {
private int id;
private String name;
private String surname;
private String phone;
private String email;
private String country;
private String city;
private String paste_date;
}//Setters and Getters omitted too
*********************FRONT END Looks Like This******************
$(function(){
$('#post').on('click',function(){
console.log('Begins');
$.ajax({
type:'POST',
url: '/ENGINE/cars/test',
contentType: "application/json; charset=utf-8",
dataType: "json",
data:complexObject(),
success: function(data){
console.log('Sended and returned'+JSON.stringify(data));
},
error: function(err){
console.log('Error');
console.log("AJAX error in request: " + JSON.stringify(err, null, 2));
}
}); //-- END of Ajax
console.log('Ends POST');
console.log(formToJSON());
}); // -- END of click function POST
function complexObject(){
return JSON.stringify({
"cars":{"id":"1234","brand":"Mercedes","model":"S class","body_type":"Sedan","fuel":"Benzoline","engine_volume":"6.5",
"horsepower":"1600","transmission":"Automat","drive":"Full PLag","status":"new","mileage":"7.00","price":"15000",
"description":"new car and very nice car","picture":"mercedes.jpg","fk_seller_oid":"1234444"},
"seller":{ "id":"234","name":"Djonotan","surname":"Klinton","phone":"+994707702747","email":"email#gmail.com", "country":"Azeribaijan","city":"Baku","paste_date":"20150327"},
"someThingElse":"String type of element"
});
} //-- END of Complex Object
});// -- END of JQuery - Ajax

It can be done by having the POST method declared to accept array of objects. Example like this
T[] create(#RequestBody T[] objects) {
for( T object : objects ) {
service.create(object);
}
}

Change #Consumes(MediaType.APPLICATION_JSON)
to #Consumes({MediaType.APPLICATION_FORM_URLENCODED})
Then you can putting multiple objects into the body

My solution is written for CXF, it appears to be quite simple.
import org.apache.cxf.jaxrs.ext.multipart.Multipart;
#POST
#Path("paramTest")
#Consumes(MediaType.MULTIPART_FORM_DATA)
public GenericResult paramTest(
#Multipart(value = "myData", type=MediaType.APPLICATION_JSON)
ObjectOne myData,
#Multipart(value = "infoList", type=MediaType.APPLICATION_JSON)
ObjectTwo[] infoList);
The test code for this with io.restassurred:
#Test
public void paramTest()
{
String payload1 = "" +
"{ \"name\": \"someName\", \"branch\": \"testBranch\" }";
String payload2 =
" [ { \"name\": \"cn\", \"status\": \"ts\" }," +
"{ \"name\": \"cn2\", \"status\": \"ts2\" } ] ]";
RestAssured.
given().
contentType("multipart/form-data").
multiPart("myData", payload1, "application/json").
multiPart("infoList", payload2, "application/json").
post(String.format("%s/paramTest", API_PATH)).
then().
statusCode(HttpStatus.SC_OK).
contentType(ContentType.JSON).
body("success", Matchers.equalTo(true));
}

Getting "malformed syntax" while hitting REST Controller POST method sending "Request Body"

Here is the Rest Controller Service signature
#RequestMapping(value = "/getFilteredReport", method = RequestMethod.POST)
public void getFilteredReport(#RequestBody FilteredReportVO filteredReportVO,HttpServletRequest request,HttpServletResponse response) {
Now below is the JSON structure I am sending
{
"filterAttributesFactory":{
"930000":{
"metaDataId":930000,
"displayText":"Select Category",
"attributeType":211009,
"userInputValue":null,
"dropDownoptions":null,
"isMandatory":false,
"isDropDown":false,
"defaultValue":null,
"isdefaultValue":false,
"constraintId":null
},
"930001":{
"metaDataId":930001,
"displayText":"Item Status",
"attributeType":211005,
"userInputValue":null,
"dropDownoptions":{
"157005":"FC - fake scrap",
"157006":"FH - firearm hold",
"157008":"IN - inventory"
},
"isMandatory":false,
"isDropDown":true,
"defaultValue":null,
"isdefaultValue":false,
"constraintId":213007
}
},
"reportId":132030,
"location":1202
}
Here is the FilteredReportVO POJO
public class FilteredReportVO {
private HashMap<Integer,FilterAttributeVO> filterAttributesFactory=new HashMap<Integer,FilterAttributeVO>();
private Integer reportId;
private Long location; .....GETTERS and setters below
FilterAttributeVO pojo structure is below..
public class FilterAttributeVO {
Integer metaDataId;
//String elementName;
String displayText;
Integer attributeType;
Object userInputValue;
Map<Integer,String> dropDownoptions;
Boolean isMandatory=false;;
Boolean isDropDown=false;
Object defaultValue;
Boolean isdefaultValue=false;
Integer constraintId=null;...Getters n setters..
I am hitting the service through POSTMAN plugin.
Getting error:
"The request could not be understood by the server due to malformed syntax. The client SHOULD NOT repeat the request without modifications".
FYI in POSTMAN I am putting the JSON structure inside "Body", selected "raw", type as "JSON(application/json)".
Notice I am using 2 object type attributes userInputValue and defaultValue inside FilteredAttributeVO. R we allowed to keep object type?
Where is the problem here?

If you see the screen shot of your input JSON with JSONlint your json is not valid.Please fix your json object and validate it using jsonlint
you can try following code in your Test to Resolve this issue coz Spring internally uses Jackson library
ObjectMapper mapper = new ObjectMapper();
Staff obj = mapper.readValue(jsonInString, FilteredReportVO.class);
If this works fine then their should be issue with your Postman RequestBody preparation otherwise you will get detailed stacktrace :)

The problem was with FilteredReportVO POJO. I was setting values of the attributes "location" and "reportId" through a constructor. No setter methods were defined for these 2 attributes.
It was my bad, if I would have posted the complete POJO class u guys must have figured it out. Anyway thanks everyone for ur help

Simple restful JSON POST with java as server and jquery as client

Before I ask my question I have to say that I have read more than 20 questions and articles about this problem and none of them could solve it.
My problem is I have a restful server in java like this:
#RequestMapping (value = "/downloadByCode", method = RequestMethod.POST)
#ResponseBody
public void downloadByCode(#RequestBody final String stringRequest, final HttpServletResponse response)
{
try
{
final ObjectMapper objectMapper = new ObjectMapper();
final JsonNode jsonRequest = objectMapper.readValue(stringRequest, JsonNode.class);
// ...
// some processings here to create the result
// ....
final ServletOutputStream outputStream = response.getOutputStream();
outputStream.write(result);
// Flush the result
outputStream.flush();
}
catch (final Exception exception)
{
LOG.debug("Exception Thrown [downloadByCode]", exception);
}
}
And I have tried different ways to send a json to this server with jquery (but all of them create errors):
$.ajax({
url:"/downloadByCode",
type:"POST",
data: JSON.stringify({"name":"value"}) });
415 "errors message" : "Content type 'application/x-www-form
urlencoded;charset=UTF-8' not supported", "type" :
"HttpMediaTypeNotSupportedError"
So I tried to fix it by adding contentType:
$.ajax({
url:"/downloadByCode",
contentType:"application/json",
type:"POST",
data: JSON.stringify({"name":"value"}) });
400 "errors message" : "Could not instantiate JAXBContext for class
[class java.lang.String]: null; nested exception is
javax.xml.bind.JAXBException\n - with linked
exception:\n[java.lang.NullPointerException", "type"
:"HttpMessageConversionError"
I tried to send json object directly instead of JSON.stringify and it gives the same 400 error.
I tried to add different consumes to the #requestMapping but still no luck.
I tried to define my own class instead of JsonNode but it does not change anything.
Any ideas?

Please try to create new class :
public class InputData{
private String name;
public String getName(){
return name;
}
public void setName(String name){
this.name = name;
}
}
Then
public void downloadByCode(#RequestBody InputData stringRequest, final HttpServletResponse response)
And
$.ajax({
url:"/downloadByCode",
contentType:"application/json",
type:"POST",
data: JSON.stringify({"name":"value"}) });

try #RequestBody final Map<String, String> stringRequest
also you will need consumes = "application/json" on the #RequestMapping because you have that in your AJAX call
You will get 400 if spring doesn't like the format in which you send your ajax - I've had so much trouble with this in the past and it seems better to just ignore header types and content types unless necessary

You might try sending your response back as a ResponseEntity instead of using the HttpServletResponse directly. My hunch is that second argument, the HttpServletRequest argument, is what is causing the problem. I've never used that. I've always send my response back using the spring mvc api.

With Jersey api you can try just:
#POST
public void downloadByCode(String stringRequest)
and I think you'll find the body of your post in stringRequest.

You can take request body as string with usage of org.springframework.http.HttpEntity<String> as request type, here is example with your code as base:
#RequestMapping (value = "/downloadByCode", method = RequestMethod.POST)
#ResponseBody
public void downloadByCode(final HttpEntity<String> request, final HttpServletResponse response)
{
try
{
final ObjectMapper objectMapper = new ObjectMapper();
final JsonNode jsonRequest = objectMapper.readValue(request.getBody(), JsonNode.class);
// ...
// some processings here to create the result
// ....
final ServletOutputStream outputStream = response.getOutputStream();
outputStream.write(result);
// Flush the result
outputStream.flush();
}
catch (final Exception exception)
{
LOG.debug("Exception Thrown [downloadByCode]", exception);
}
}
But maybe it will be better to use also String as return type, if you are planning to return result as string value, like this:
#RequestMapping (value = "/downloadByCode", method = RequestMethod.POST)
#ResponseBody
public String downloadByCode(HttpEntity<String> request) {
String requestBody = request.getBody();
String result;
// ...
// some processings here to create the result text
// ....
return result;
}
I made simple application using Spring Boot with usage of proposed solutions using HttpEntity and also additional example of usage POJO, to run application you need to have Maven and JDK >= 1.7.
#clonning repository with sample
git clone git#github.com:mind-blowing/samples.git
#change current folder to sample application root
cd samples/spring-boot/rest-handler-for-plain-text
#running application using maven spring-boot plugin
mvn spring-boot:run
After application will be started you can open http://localhost:8080 and you will see html page with simple usage of JQuery to send POST requests, text of request and response will visible on html page, in controller I added two handlers, first with usage of HttpEntity and second with usage of POJO.
Controller: SampleRestController.java
HTML page: index.html
Project: https://github.com/mind-blowing/samples/tree/master/spring-boot/rest-handler-for-plain-text

First of all If you are using maven you should add dependency for jackson
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.4.1</version>
</dependency>
or you can download the jar and put it in our project class path (you can use other mapper as well)
then you should create a model or DTO class where you can map your json
public class Data{
private String name;
pubilc Data(){}
//getter and setter
}
THEN you controller
#RequestMapping (value = "/downloadByCode", method = RequestMethod.POST)
#ResponseBody
public Data downloadByCode(#RequestBody final Data data, final HttpServletResponse response)
{
//your code
return data;
}
AJAX CALL
$.ajax({
url:"/downloadByCode",
contentType:"application/json",
type:"POST",
data: JSON.stringify({"name":"value"}) });
(Optional)You can override behavior by telling object mapper not to fail on missing properties by defining the bean as follows:
#Bean
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
converter.setObjectMapper(new ObjectMapper().configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false));
return converter;
}
http://websystique.com/springmvc/spring-mvc-requestbody-responsebody-example/

Looking at your errors, it's clear that you have configured 'Jaxb2RootElementHttpMessageConverter' or similar XML converter in your spring configuration. And since you have registerned an XML converter, the #RequestBody and #ResponseBody work based on the registered message converters.
So, to solve your problem, go with a JSON message converter such as 'MappingJacksonHttpMessageConverter'. Once you register a JSON message converter, create a bean class to hold your json data and use it with RequestBody as below:
// It has to meet the json structure you are mapping it with
public class YourInputData {
//properties with getters and setters
}
Update 1:
Since you have defined multiple message converters, Spring tries to use the first one available by default. In order to use specific message converter(in this case Jackson converter), you should specify 'Accept' header from client like below:
$.ajax({
headers: {
"Accept" : "application/json; charset=utf-8",
"Content-Type": "application/json; charset=utf-8"
}
data: "data",
success : function(response) {
...
} })

The final answer is a combination of a number of answers/comments in this question that I am going to summarize them here:
1- You have to make sure you have an appropriate json converter in your spring config such as MappingJacksonHttpMessageConverter (credits to #java Anto)
2- You have to create a POJO class with same structure as your json object (see #Vinh Vo answer)
3- Your POJO class cannot be an inline class unless it is a static class. It means it should have its own java file or it should be static. (credits to #NTyler)
4- Your POJO class can miss parts of your json object if you set it appropriately in your object mapper (see #Aman Tuladhar answer)
5- Your ajax call requires contentType:"application/json", and you should send your data with JSON.stringify
Here is the Final code that is working perfectly:
public static class InputData
{
private String name
public String getName()
{
return name;
}
public void setName(final String name
{
this.name = name;
}
}
#RequestMapping(value = "/downloadByCode", method = RequestMethod.POST)
#ResponseBody
public void downloadByCode(#RequestBody final InputData request, final HttpServletResponse response)
{
try
{
String codes = request.getName();
// ...
// some processings here to create the result
// ....
final ServletOutputStream outputStream = response.getOutputStream();
outputStream.write(result);
// Flush the result
outputStream.flush();
}
catch (final Exception exception)
{
LOG.debug("Exception Thrown [downloadByCode]", exception);
}
}
And it is the jquery Ajax request:
$.ajax({
url:"/downloadByCode",
contentType:"application/json",
type:"POST",
data: JSON.stringify({"name":"value"}) });

Delete the #ResponseBody on your downloadByCode method

Change your method downloadByCode() return type to String and then return the String
Response body will automatically convert the returned String to JSON and then use the data appropriately

I am not that well versed with java but as much as I know your java code must be something like this.
public class downloadByCode{
#GET
#Produces(MediaType.APPLICATION_JSON + ";charset=utf-8")
public Response downloadByCode(#QueryParam("paramater1") final String parameter 1, #Context HttpServletRequest httpRequest) {
If this not helps you can keep you code somewhere and share it.

Springs MVC JSON Response and convert it to JS Object

I am having a question that how can I send JSON Object from Springs MVC so that I can convert it into a JavaScript Object on my HTML Page.
In a traditional way I do it: Below is a snippet from Java Servlet which sets a request attribute and forward it to the JSP Page.
JSONObject jsonObj = new JSONObject();
jsonObj.put("name","test");
jsonObj.put("age",24);
request.setAttribute("jsonObj",jsonObj);
request.getRequestDispatcher("test.jsp").forward(request,response);
In JSP I retrieve as :
<script type="text/javascript">
var jsonObj =<%=request.getAttribute("jsonObj"); %>;
alert("name = "+jsonObj.name+" ; age = "+jsonObj.age); // This will output name and age from the JSON Object
</script>
So what I need to ask how can I do the same in Springs MVC. How can I send the JSONObject from Dispatcher Servlet, and convert it to JS object in my JSP page ?

An easy way to do this using the ObjectMapper. It will create an JSON String from your Object. And that you can send to your view/jsp.
I put an small example of a controller I do this (just snipped).
#Controller
public class UsersSettingsController {
#Autowired
UserSettingsDefaultService userSettingsService;
#RequestMapping(value="/userSettings/dynamic/userSettings", method=RequestMethod.GET)
public ModelAndView get() throws Exception {
ModelAndView mav = new ModelAndView();
ObjectMapper mapper = new ObjectMapper();
User user = (User)SecurityContextHolder.getContext().getAuthentication().getPrincipal();
UserSettings userSet = userSettingsService.getUserSettingsByUser(user);
mav.addObject("userSettingsJSON", mapper.writeValueAsString(userSet));
mav.setViewName("userSettings/dynamic/filter");
return mav;
}
}
Or course can you create your JSON Object in your Contoller step by step like you did in your example. Then you don't need the Mapper, just sending the String to your View.
In the JSP you load the json String like this into a JS var:
var jsonString = '${userSettingsJSON}';
To get elements from JSON String or parse, see: http://www.json.org/js.html.
I'm an KnockOut Framework Fan would do it with it.

I think you should use ajax(for example jquery),the following is spring mvc
#RequestMapping(value = "/admin/new/list", method = RequestMethod.GET)
#ResponseBody
public List<News> list()
{
return newsDao.findAll();
}
and in the jsp page,you may use ajax util (for example jquery)
$.ajax({
type: "GET",
url: '<c:url value="/admin/new/list"/>',
cache:false,
dataType :'json',
success: function(data){
alert(data);
}
});
the data is json object
I don't know whether the above is what you need

A much easier way to do this is to include the Jackson dependencies in maven and use #ResponseBody to return a JSON representation of the object, without having to manually write the manipulation.
Have a look at the example below, you shouldn't have to write any tranlation to JSON code.
http://www.mkyong.com/spring-mvc/spring-3-mvc-and-json-example/

As per your requirement, I suggest you to use AJAX call with JSON as data type.
For example :
$.ajax({
url: "getFormatIdDescMap?compId="+compId,
global: false,
type: "POST",
dataType:"json",
contanttype:'text/json',
async:false,
error:function(){
alert("Error during retrieving the foramt ID List");
},
success: function(data){
//REMOVE ALL THE OLD VALUES OF FORMAT DROP DOWN
removeDropDownVals('formatList');
var optn;
for(var index=0;index<data.formatKeys.length;index++){
optn = document.createElement("option");
document.getElementById("formatList").options.add(optn);
optn.text =data.formatDescs[index];
optn.value=data.formatKeys[index];
}
}
});
});
In the code above, I am preparing a new list of Formats based on company ID. You can iterate over the response.
It will give response text as per your requirements. But here note that .. if you are getting json Array in the response, it will contain that data in square bracket like..[1,2,3] and If you are getting response in JSON Object then it will be displayed in curly braces like {"data",[1,2,3]}.

Correct way for parsing JSON objects containing arrays in Java Servlets (with Gson for example)

I know this is a topic much talked about, but I still wasn't able to find a correct and clear answer to my specific problem.
I've got a JSON that looks like this:
var myData = { "gameID" : gameID,
"nrOfPlayers" : 2,
"playerUIDs" : [123, 124]
};
The Question I have is exactly what is the correct way (or best way, style wise) to parse this in a Java servlet (using GSON for example)? First I send this JSON to the server using jQuery ajax method like this:
jQuery.ajax({
url : path,
data : myData,
success : successFunction,
error : function(data) {
console.log("Error: ", data);
} ,
type : "post",
timeout : 30000
});
Now in the servlet I've learned that I should have been able to parse that JSON like this:
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Gson gson = new Gson();
String gameID = gson.fromJson(request.getParameter("gameID"), String.class);
String nrOfPlayers = gson.fromJson(request.getParameter("nrOfPlayers"), String.class);
String[] playerUIDs = gson.fromJson(request.getParameter("playerUIDs"), String[].class);
log.info(gameID);
log.info(nrOfPlayers);
log.info(playerUIDs[0] +" "+ playerUIDs[1]);
}
But the playerUIDs variable IS NULL and of course playerUIDs[0] throws an exception!
Digging deeper I found that when looping over the request parameter names, it contained a parameter named "playerUIDs[]" with the value of only 123 (the first int in the array). This was strange cause I didn't seem to be able to access the next values at all.
Then I read that JSON objects should be stringifyed before POST-ing so I added JSON.stringify(myData), but now the request parameter names only contained ONE name which was the JSON object itself in a stringified state:
INFO: Parameter name = {"gameID":"b6a51aabb8364b04bce676eafde1bc87","nrOfPlayers":2,"playerUIDs":[123,124]}
The only way I seemed to get this to work was by creating a inner class:
class GameStart {
protected String gameID;
protected int nrOfPlayers;
protected int[] playerUIDs;
}
And parsing the JSON from the request parameter name, like this:
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Gson gson = new Gson();
Enumeration en = request.getParameterNames();
GameStart start = null;
while (en.hasMoreElements()) {
start = gson.fromJson((String) en.nextElement(), GameStart.class);
}
log.info(start.gameID);
log.info(String.valueOf(start.nrOfPlayers));
log.info(start.playerUIDs[0] +" "+ start.playerUIDs[1]);
}
Now all values are there, but this seems more like a hack (reading JSON from request parameter name) than an elegant solution, so I thought I'd ask you guys what exactly would be the "correct" way of doing this? Am I missing something obvious?
Thanks in advance!

You aren't use JSON to send data to the server:
data : myData,
This specifies parameters as a JavaScript object, but not necessarily as JSON. What this means is that if you do a GET request with:
data: {name1: "value1", name2: "value2"}
The request will be:
http://some/page?name1=value1&name2=value2
This is basically what you're seeing with your first calls, where everything is being converted to a string, then sent as a form parameter.
What you're doing in the second version is almost what you're supposed to do. The only difference is that you need to use a JavaScript object as the parameter to data, not just a string:
data: {arbitraryNameHere: JSON.stringify(myData)}
This will post your "myData" object as JSON, in the parameter named "arbitraryNameHere".

In the real world you typically wouldn't send an actual json object to a servlet and you won't often handle populating values from a request in most circumstances. JSON is JavaScript object notation - and it's great when consumed for use in client side coding.
It's easier to use query string for params rather than a post with json (which it appears you are actually doing).
host/url?gameId=5&nrPlayers=2
As far as how to populate values, convention-over-configuration is the way to go for cleanest code. You can use a frameworks like struts to offload all of the transfer of values onto the framework. Not sure what your whole application looks, your intention for writing (ie writing servlets from scratch is a great way to learn but not common practice in real application development environments) like so this may or may not be a helpful answer.

JSON to the server using jQuery ajax method
function send() {
var myData = {"gameID": 30,
"nrOfPlayers": 2,
"playerUIDs": [123, 124]
};
jQuery.ajax({
url: "servletName",
data: JSON.stringify(myData),
success: function(){
//console.log(JSON.stringify(myData));
},
error: function(data) {
console.log("Error: ", data);
},
type: "post",
timeout: 30000
});
}
Sender Button
<button onclick="send();" id="send">Send</button>
Java servlet processing
public class servletName extends HttpServlet {
class GameStart {
protected String gameID;
protected int nrOfPlayers;
protected int[] playerUIDs;
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Gson gson = new Gson();
Enumeration en = request.getParameterNames();
GameStart start = null;
while (en.hasMoreElements()) {
start = gson.fromJson((String) en.nextElement(), GameStart.class);
}
System.out.println(start.gameID);
System.out.println(start.playerUIDs[0] +" "+ start.playerUIDs[1]);
}
}