Return JSON string from spring controller - json

Question

I have written a service which query through an AJAX call from solr and return search results as json. I want to return this json from my controller to AJAX.
public class SearchServiceImpl implements SearchService {
private String getSearchResults(String url) throws ClientProtocolException,
IOException {
HttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet(url);
HttpResponse response = client.execute(get);
//logger.info("Response: " + response.getEntity().getContent());
BufferedReader rd = new BufferedReader(new InputStreamReader(response
.getEntity().getContent()));
StringBuilder sb = new StringBuilder();
String line = "";
while ((line = rd.readLine()) != null) {
sb.append(line);
}
return sb.toString();
}
public String performSearch(String term) {
String result = "";
try {
result = getSearchResults(getSolrURL(term)); // getSolrURL() prepares the solr url
} catch (ClientProtocolException e) {
logger.error(e);
} catch (IOException e) {
logger.error(e);
}
return result;
}
}
This is handleRequest() method in my controller -
public ModelAndView handleRequest(HttpServletRequest request,
HttpServletResponse response) throws Exception {
logger.info("Perform search view");
String term = request.getParameter("term");
String result = searchService.performSearch(term);
// Here I need to return result which is a json
ModelAndView mav = new ModelAndView(new MappingJackson2JsonView());
// mav.addObject("key1", "value1");
// mav.addObject("key2", "value2");
return mav;
}

Answer 1

The best thing to do is to let Jackson automatically do all the serialization. So your controller would look like this
#RequestMapping(value = "/payment/{id}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public #ResponseBody Payment get(#PathVariable Long id) {
return paymentService.getById(id);
}
The Payment class has all it's getters and setters for Jackson
package net.isban.example.vo;
public class Payment {
private Long id;
private String sort;
private String account;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getSort() {
return sort;
}
public void setSort(String sort) {
this.sort = sort;
}
public String getAccount() {
return account;
}
public void setAccount(String account) {
this.account = account;
}
#Override
public String toString() {
return "Payment [id=" + id + ", sort=" + sort + ", account="
+ account + "]";
}
}
And make sure you include Jackson in the classpath
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.6.0</version>
</dependency>
This assumes you are using Spring, if not you can still use Jackson to generate json:
String json = new ObjectMapper().writeValueAsString(payment);