Copy specific fields by using BeanUtils.copyProperties?

Question

springframework.beans.BeanUtils is very useful to copy objects, and I use the "ignoreProperties" option frequently. However, sometimes I want to copy only specific objects (basically, the opposite of "ignore Properties"). Does anyone know how can I do that? Any help will be appreciated.

import org.springframework.beans.BeanUtils;  public class Sample {         public static void main(String[] args) {             DemoADto demoADto = new DemoADto();         demoADto.setName("Name of Demo A");         demoADto.setAddress("Address of Demo A");          DemoBDto demoBDto = new DemoBDto();          // This is "ignoreProperties" option         // But I want to know how I can copy only name field by using BeanUtils or something.         BeanUtils.copyProperties(demoADto, demoBDto, new String[] {"address"});          System.out.println(demoBDto.getName());         System.out.println(demoBDto.getAddress());         }     }  public class DemoADto {         private String name;         private String address;      public String getName() {         return name;     }      public void setName(String name) {         this.name = name;     }      public String getAddress() {         return address;     }      public void setAddress(String address) {         this.address = address;     }     }  public class DemoBDto {         private String name;         private String address;      public String getName() {         return name;     }      public void setName(String name) {         this.name = name;     }      public String getAddress() {         return address;     }      public void setAddress(String address) {         this.address = address;     }     } 

Answer 1

You can use the BeanWrapper technology. Here's a sample implementation:

public static void copyProperties(Object src, Object trg, Iterable<String> props) {      BeanWrapper srcWrap = PropertyAccessorFactory.forBeanPropertyAccess(src);     BeanWrapper trgWrap = PropertyAccessorFactory.forBeanPropertyAccess(trg);      props.forEach(p -> trgWrap.setPropertyValue(p, srcWrap.getPropertyValue(p)));  } 

Or, if you really, really want to use BeanUtils, here's a solution. Invert the logic, gather excludes by comparing the full property list with the includes:

public static void copyProperties2(Object src, Object trg, Set<String> props) {     String[] excludedProperties =              Arrays.stream(BeanUtils.getPropertyDescriptors(src.getClass()))                   .map(PropertyDescriptor::getName)                   .filter(name -> !props.contains(name))                   .toArray(String[]::new);      BeanUtils.copyProperties(src, trg, excludedProperties); } 

Answer 2

If you don't want to use Commons BeanUtils you can still use Spring by using the BeanWrapper.

You will have to manually loop through all the properties so you will want to make a static helper method.

You can always just copy what copyProperties is doing and adjust to your liking: http://tinyurl.com/BeanUtils-copyProperties