Java List to JSON array using Jackson with UTF-8 encoding

Question

Now I'm trying to convert Java List object to JSON array, and struggling to convert UTF-8 strings. I've tried all followings, but none of them works.

Settings.

response.setContentType("application/json");

PrintWriter out = response.getWriter();
ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
final ObjectMapper mapper = new ObjectMapper();

Test#1.

// Using writeValueAsString
String json = ow.writeValueAsString(list2);

Test#2.

// Using Bytes
final byte[] data = mapper.writeValueAsBytes(list2);
String json = new String(data, "UTF-8");

Test#3.

// Using ByteArrayOutputStream with new String()
final OutputStream os = new ByteArrayOutputStream();
mapper.writeValue(os, list2);
final byte[] data = ((ByteArrayOutputStream) os).toByteArray();
String json = new String(data, "UTF-8");

Test#4.

// Using ByteArrayOutputStream
final OutputStream os = new ByteArrayOutputStream();
mapper.writeValue(os, list2);
String json = ((ByteArrayOutputStream) os).toString("UTF-8");

Test#5.

// Using writeValueAsString
String json = mapper.writeValueAsString(list2);

Test#6.

// Using writeValue
mapper.writeValue(out, list2);

Like I said, none of above works. All displays characters like "???". I appreciate your helps. I'm using Servlet to send JSON response to clients.

This problem only happens when I write java.util.List object. If I write single data object, e.g. customer object in below example, then there is no ??? characters, and UTF-8 is working with the following code.

PrintWriter out = response.getWriter();
ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
String json = ow.writeValueAsString(customer);
out.print(json);

Answer 1

The answer was very simple. You need to specify UTF-8 charset encoding in response.setContentType too.

response.setContentType("application/json;charset=UTF-8");

Then, many of above code will work correctly. I will leave my question as is, since it will show you several ways of writing JSON to clients.

Answer 2

On RequestMapping in Controller:

@RequestMapping(value = "/user/get/sth",
                method = RequestMethod.GET,
                produces = { "application/json;**charset=UTF-8**" })