Convert a POJO to a JsonObject (GSON 2.4 library...)

BeanToJson.java

package io.milkyway.mongo.json;

import com.google.gson.JsonObject;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * Bean to Json helps to produce a JSON from any POJO.
 * <p/>
 * Look at the template for example.
 *
 * @author jvmvik
 */
public class BeanToJson
{

  public static JsonObject convert(Serializable bean) throws IntrospectionException
  {
    JsonObject json = new JsonObject();

    BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass());
    PropertyDescriptor[] properties = beanInfo.getPropertyDescriptors();

    if (properties == null)
      return json;

    // copy properties into hashtable
    for (PropertyDescriptor property : properties)
    {
      Class paramClass = property.getPropertyType();
      Method getter = property.getReadMethod();
      try
      {
        Object paramValue = getter.invoke(bean);

        if (paramValue != null)
        {
          // converts getBookTitle() to book_title
          String paramName = property.getName();
          paramName = splitCamelCase(paramName);

          if (!(paramValue instanceof String))
            json.addProperty(paramName, (String)paramValue); // Good job json smart
          //TODO Add support for other type...
        }
      } catch (InvocationTargetException e)
      {
        e.printStackTrace();
      } catch (IllegalAccessException e)
      {
        e.printStackTrace();
      }
    }

    return json;
  }

  public static String splitCamelCase(String s)
  {
    return s.replaceAll(
        String.format("%s|%s|%s",
            "(?<=[A-Z])(?=[A-Z][a-z])",
            "(?<=[^A-Z])(?=[A-Z])",
            "(?<=[A-Za-z])(?=[^A-Za-z])"
        ),
        "_"
    ).toLowerCase();
  }

}

BeanToJsonTest.java

package io.milkyway.mongo;

import com.google.gson.JsonObject;
import io.milkyway.mongo.json.BeanToJson;
import org.junit.Before;
import org.junit.Test;

import java.beans.IntrospectionException;
import java.io.Serializable;

import static org.junit.Assert.assertEquals;

/**
 * BeanToJson test...
 * 
 * TODO This may need some minor ajustement...
 * @author jvmvik
 */
public class BeanToJsonTest
{

  @Before
  public void setUp() throws Exception
  {
  }

  @Test
  public void convertSimple() throws IntrospectionException
  {
    SimpleCat cat = new SimpleCat();

    JsonObject json = BeanToJson.convert(cat);

    String result = json.toString();
    assertEquals("{\"head_size\":10.314156,\"weight\":3,\"friends\":10.314156,\"age\":1,\"length\":2,\"gender\":{},\"single_byte\":1,\"alive\":true}", result);
  }


  @Test
  public void convertClass() throws IntrospectionException
  {
    Cat cat = new Cat();

    JsonObject json = BeanToJson.convert(cat);

    String result = json.toString();
    assertEquals("{\"head_size\":10.314156,\"weight\":3,\"friends\":10.314156,\"name\":\"kitty\",\"age\":1,\"length\":2,\"gender\":{},\"single_byte\":1,\"alive\":true}", result);
  }


  public class SimpleCat implements Serializable
  {
    private boolean alive;
    private long length;
    private short weight;
    private int age;
    private double friends;
    private float headSize;
    private char gender;
    private byte singleByte;

    public SimpleCat()
    {
      alive = true;
      weight = 3;
      age = 1;
      length = 2L;
      headSize = 10.314156F;
      gender = 'M';
      singleByte = 1;
      friends = 10.314156D;
    }

    public boolean getAlive()
    {
      return alive;
    }

    public void setAlive(boolean alive)
    {
      this.alive = alive;
    }

    public long getLength()
    {
      return length;
    }

    public void setLength(long length)
    {
      this.length = length;
    }

    public short getWeight()
    {
      return weight;
    }

    public void setWeight(short weight)
    {
      this.weight = weight;
    }

    public int getAge()
    {
      return age;
    }

    public void setAge(int age)
    {
      this.age = age;
    }

    public double getFriends()
    {
      return friends;
    }

    public void setFriends(double friends)
    {
      this.friends = friends;
    }

    public float getHeadSize()
    {
      return headSize;
    }

    public void setHeadSize(float headSize)
    {
      this.headSize = headSize;
    }

    public char getGender()
    {
      return gender;
    }

    public void setGender(char gender)
    {
      this.gender = gender;
    }

    public byte getSingleByte()
    {
      return singleByte;
    }

    public void setSingleByte(byte singleByte)
    {
      this.singleByte = singleByte;
    }
  }

  /**
   * Simple class that model a Cat
   */
  public class Cat implements Serializable
  {
    private Boolean alive;
    private Character gender;
    private Short weight;
    private Integer age;
    private Long length;
    private Float headSize;
    private String name;
    private Byte singleByte;
    private Double friends;

    public Cat()
    {
      alive = true;
      weight = 3;
      length = 2L;
      headSize = 10.314156f;
      gender = 'M';
      singleByte = 1;
      friends = 10.314156D;
      name = "kitty";
      age = 1;
    }

    public Boolean getAlive()
    {
      return alive;
    }

    public void setAlive(Boolean alive)
    {
      this.alive = alive;
    }

    public Character getGender()
    {
      return gender;
    }

    public void setGender(Character gender)
    {
      this.gender = gender;
    }

    public Short getWeight()
    {
      return weight;
    }

    public void setWeight(Short weight)
    {
      this.weight = weight;
    }

    public Integer getAge()
    {
      return age;
    }

    public void setAge(Integer age)
    {
      this.age = age;
    }

    public Long getLength()
    {
      return length;
    }

    public void setLength(Long length)
    {
      this.length = length;
    }

    public Float getHeadSize()
    {
      return headSize;
    }

    public void setHeadSize(Float headSize)
    {
      this.headSize = headSize;
    }

    public String getName()
    {
      return name;
    }

    public void setName(String name)
    {
      this.name = name;
    }

    public Byte getSingleByte()
    {
      return singleByte;
    }

    public void setSingleByte(Byte singleByte)
    {
      this.singleByte = singleByte;
    }

    public Double getFriends()
    {
      return friends;
    }

    public void setFriends(Double friends)
    {
      this.friends = friends;
    }
  }
}