CODEWITHSUNDEEP
javahttpjsphttp-headerscontent-type
Julias
Julias

Reputation: 5892

Set Content-Type to application/json in jsp file

I am created some jsp file that returns as a response some json string. But I see that the Content-Type is set to txt automatically

My jsp code looks like 

<%@ page import="java.util.Random" %>
<%@ page language="java" %>
<%@ page session="false" %>

<%
  String retVal = "// some json string";

     int millis = new Random().nextInt(1000);
     //    System.out.println("sleeping for " + millis + " millis");
     Thread.sleep(millis);
%>
<%=retVal%>

How can I perform something like 

setHeader("Content-Type", "application/json");

in this example?

Upvotes: 39

Views: 126111

Answers (3)

Gael
Gael

Reputation: 634

@Petr Mensik & kensen john

Thanks, I could not used the page directive because I have to set a different content type according to some URL parameter. I will paste my code here since it's something quite common with JSON:

    <%
        String callback = request.getParameter("callback");
        response.setCharacterEncoding("UTF-8");
        if (callback != null) {
            // Equivalent to: <@page contentType="text/javascript" pageEncoding="UTF-8">
            response.setContentType("text/javascript");
        } else {
            // Equivalent to: <@page contentType="application/json" pageEncoding="UTF-8">
            response.setContentType("application/json");
        }
    
        [...]
    
        String output = "";
    
        if (callback != null) {
            // IMPORTANT! Sanitise the "callback",
            // do not use user input directly in the response!
            // This is vulnerable to XSS attacks.
            output += callback + "(";
        }
    
        output += jsonObj.toString();
    
        if (callback != null) {
            output += ");";
        }
    %>
    <%=output %>

When callback is supplied, returns:

    callback({...JSON stuff...});

with content-type "text/javascript"

When callback is NOT supplied, returns:

    {...JSON stuff...}

with content-type "application/json"

[EDIT] I'm reviewing my old post. If you use this solution, please sanitise your input! It's dangerous to put user input string directly in the response.

Upvotes: 3

Petr Mensik
Petr Mensik

Reputation: 27496

Try this piece of code, it should work too

<%
    //response.setContentType("Content-Type", "application/json"); // this will fail compilation
    response.setContentType("application/json"); //fixed
%>

Upvotes: 12

Pau Kiat Wee
Pau Kiat Wee

Reputation: 9505

You can do via Page directive.

For example:

<%@ page language="java" contentType="application/json; charset=UTF-8"
    pageEncoding="UTF-8"%>
  • contentType="mimeType [ ;charset=characterSet ]" | "text/html;charset=ISO-8859-1"

The MIME type and character encoding the JSP file uses for the response it sends to the client. You can use any MIME type or character set that are valid for the JSP container. The default MIME type is text/html, and the default character set is ISO-8859-1.

Upvotes: 71

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