Generate a Json from Strings using Jackson library

Question

I am pretty new to Java and I got a requirement of converting Strings to a json structure. My below codes works fine but I have to create multiple objects and my code looks bit ugly. I want to know the better approach.

I want the below Json Structure from three Strings SourceApplication, messagType and payload

Required Json Structure

{
 "request": {
 "header": {
 "sourceApplication": "SomeString"
 "messageType": "SomeString"
 },
 "body": {
 "payload": "SomeString"
 }
 }
}

Below is my code.

POJO Class (For mapping)

package com.test.transformer;
import java.io.Serializable;
public class JsonMapper implements Serializable {
 private Request request;
 public Request getRequest ()
 {
 return request;
 }
 public void setRequest (Request request)
 {
 this.request = request;
 }
 public static class Request implements Serializable{
 private Body body;
 private Header header;
 public Body getBody ()
 {
 return body;
 }
 public void setBody (Body body)
 {
 this.body = body;
 }
 public Header getHeader ()
 {
 return header;
 }
 public void setHeader (Header header)
 {
 this.header = header;
 }
 }
 public static class Header implements Serializable{
 private String sourceApplication;
 private String messageType;
 public String getSourceApplication ()
 {
 return sourceApplication;
 }
 public void setSourceApplication (String sourceApplication)
 {
 this.sourceApplication = sourceApplication;
 }
 public String getMessageType ()
 {
 return messageType;
 }
 public void setMessageType (String messageType)
 {
 this.messageType = messageType;
 }
 }
 public static class Body implements Serializable{
 private String payload;
 public String getPayload ()
 {
 return payload;
 }
 public void setPayload (String payload)
 {
 this.payload = payload;
 }
 }
}

My Main Class

package com.test.transformer;
import org.codehaus.jackson.map.ObjectMapper;
import java.io.IOException;
public class JsonTest {
 public static void main(String[] args) {
 ObjectMapper mapper = new ObjectMapper();
 String srcApp = "TestSrc";
 String msgType = "msgtype";
 String payload = "mainMsg";
 JsonMapper.Header h = new JsonMapper.Header();
 JsonMapper.Body b = new JsonMapper.Body();
 JsonMapper.Request r = new JsonMapper.Request();
 h.setSourceApplication(srcApp);
 h.setMessageType(msgType);
 b.setPayload(payload);
 r.setHeader(h);
 r.setBody(b);
 JsonMapper j = new JsonMapper();
 j.setRequest(r);
 String jsonInString = null;
 try {
 jsonInString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(j);
 } catch (IOException e) {
 e.printStackTrace();
 }
 System.out.println(jsonInString);
 }
}

Answer 1

A few things:

• Use descriptive variable names. A common Java convention is a camelCase version of the class name such as JsonMapper jsonMapper = new JsonMapper();
• Unwrap your classes into separate files. This makes the code much easier to read and reuse.
• test in your package name is very unusual, and probably not intended.
• Test classes typically have the same name as the class they test suffixed with Test, such as JsonMapperTest.
• Tests are not written in main methods.
• Having getters and setters for everything is a code smell - not necessarily bad, but often misused. Your application doesn't do anything yet, so it's difficult to tell whether any of them will be necessary, but in general I would not add getters and setters until I know I need them.

• sparker: Thanks for the feedback. Other than standard things, the way I implemented is fine right? I will take care of things you mentioned.
• l0b0: Once you do you could post another question here to get further feedback. It's a bit easier to give feedback when the overall structure is in order.