java bean布尔值提交到json＆boolean vs Boolean

Question

I met a problem that is , when I use smart-json to convert java bean to JSON Object, then i found some boolean filed was lost, can some boby tell me why? the who codes are below:

package com.huoli.crawler.test;

import java.util.HashMap;
import java.util.Map;

import net.minidev.json.JSONObject;


public class MiniDevJSONTest {
public static void main(String[] args) {
    MyBean mybean = new MyBean();
    mybean.setReturn(true);
    mybean.setArrivingAirportCode("dadsa");
    Map<String, MyBean> map = new HashMap<>();
    map.put("mybean", mybean);
    // output smart-json:{"mybean":{"arrivingAirportCode":"dadsa"}}
    // so where is isRetrun ??
    System.out.println("smart-json:" + JSONObject.toJSONString(map));

}

}

class MyBean {
private boolean isReturn;

public boolean isReturn() {
    return isReturn;
}

public void setReturn(boolean isReturn) {
    this.isReturn = isReturn;
}

private String arrivingAirportCode;

public String getArrivingAirportCode() {
    return arrivingAirportCode;
}

public void setArrivingAirportCode(String arrivingAirportCode) {
    this.arrivingAirportCode = arrivingAirportCode;
}

}

My question is why the boolean field value was lost?

Answer 1

This is a getter versus "is"-er problem:

Modify your code in MyBean as I have the following snippet, and change the set of the boolean in your MiniDevJSONTest class to match "setIsReturn". You will now get the value you are looking for. Not very familiar with the minidev.json classes, but there appears to be reflection going on underneath the covers that is looking for the getter for your boolean value and not the "is"-er. Since it doesn't find it, it's like it's not there..

I have seen this kind of behavior before in other libraries. In some libraries the choice between whether the code seeks out the is-er or the getter changes based on whether or not the boolean you are looking for is the primitive or the fully boxed type.

public class  MyBean {
  private boolean isReturn;
  private String arrivingAirportCode;

  public boolean getIsReturn() {
    return isReturn;
  }

  public void setIsReturn(boolean isReturn) {
    this.isReturn = isReturn;
  }

  public String getArrivingAirportCode() {
    return arrivingAirportCode;
  }

  public void setArrivingAirportCode(String arrivingAirportCode) {
    this.arrivingAirportCode = arrivingAirportCode;
  }
}

Just a little more followup:

In eclipse, when you establish a class attribute for a class, if you use the "create getter and setter" shortcut, you will see that it automatically creates a getter for a big B Boolean, and a is-er for the primitive type.

Many libraries use this standard when trying to figure out the reflection pattern for examining a class. However, it appears that the library you are using does not. I tested it, and it is expecting the getter whether the attribute is a boxed type or the primitive.