Here's an article on Dozer: https://www.baeldung.com/dozer. It's a mapper that uses reflection to map same-name fields from one object to another (of a completely unrelated class).
I was wondering if this works flexibly with private fields, getters, and setters. That is,
Will private String a map to another object's private String a without either having any getters or setters?
What if only one side has a getter or setter (and the private field is named something different to make sure it's not directly accessing private fields)?
What if one has a getter and the other has a setter for totally mismatching private fields? (But the getter and setter names match.)
I wrote a test program to run in https://www.jdoodle.com/online-java-compiler:
import org.dozer.DozerBeanMapper;
public class Main {
public static class MySource {
// a -> a
private String a;
// getB() -> b
private String hidden_b;
public String getB() { return hidden_b; }
// c -> setC(c)
private String c;
// getD() -> setD(d)
private String hidden_d;
// proper getters and setters on both sides
private String proper;
public String getProper() { return proper; }
// public void setProper(String proper_) { proper = proper_; }
public MySource() {
a = "A Room with a View";
hidden_b = "The Bridge of San Luis Rey";
c = "Civilwarland in Bad Decline";
hidden_d = "Darkness at Noon";
proper = "This should copy, at minimum.";
}
public void print() {
System.out.println("Source");
System.out.println("================================");
System.out.println("a = " + a);
System.out.println("hidden_b = " + hidden_b);
System.out.println("c = " + c);
System.out.println("hidden_d = " + hidden_d);
System.out.println("--------------------------------");
System.out.println("proper = " + proper);
System.out.println("");
}
}
public static class MyTarget {
private String a;
private String b;
private String hidden_c;
private String hidden_e;
public void setC(String param) { hidden_c = param; }
public void setD(String param) { hidden_e = param; }
private String proper;
// public String getProper() { return proper; }
public void setProper(String proper_) { proper = proper_; }
public MyTarget() {}
public void print() {
System.out.println("Target");
System.out.println("================================");
System.out.println("a = " + a);
System.out.println("b = " + b);
System.out.println("hidden_c = " + hidden_c);
System.out.println("hidden_e = " + hidden_e);
System.out.println("--------------------------------");
System.out.println("proper = " + proper);
System.out.println("");
}
}
public static void main(String args[]) {
MySource s = new MySource();
s.print();
System.out.println("Now dozing...");
System.out.println("");
MyTarget t = new DozerBeanMapper().map(s, MyTarget.class);
t.print();
}
}
Note that to run the above code you must add a maven dependency:
Group ID: net.sf.dozer
Artifact ID: dozer
Version: 5.5.1
And also you must try executing a few times because of random timeouts depending on whether the dependency loads fast enough.
Anyway, my output was:
Source
================================
a = A Room with a View
hidden_b = The Bridge of San Luis Rey
c = Civilwarland in Bad Decline
hidden_d = Darkness at Noon
--------------------------------
proper = This should copy, at minimum.
Now dozing...
Target
================================
a = null
b = null
hidden_c = null
hidden_e = null
--------------------------------
proper = This should copy, at minimum.
So, it appears Dozer only works through a getter on the source and a setter on the target, which is disappointing. Or, I'm not using it correctly!
Is there a way to make Dozer more flexible? Or, another mapper library that can achieve this?
Okay, here are my findings. Hopefully this helps someone.
Dozer 5.5.1 was supposed to be able to do this via "class-level is-accessible." However, there was a bug. It was fixed for future releases, e.g. Dozer 6.1+. (The package moved to a new group, org.github.dozermapper.) The steps were a little complicated though, and eventually I gave up to try ModelMapper, which was much nicer. So here's my code.
Include this package:
Group ID: org.modelmapper
Artifact ID: modelmapper
Version: 2.3.2
Here's how to use it:
import org.modelmapper.ModelMapper;
import org.modelmapper.config.Configuration;
public class Main {
public static class MySource {
// a -> a
private String a;
// getB() -> b
private String hidden_b;
public String getB() { return hidden_b; }
// c -> setC(c)
private String c;
// getD() -> setD(d)
private String hidden_d;
// proper getters and setters on both sides
private String proper;
public String getProper() { return proper; }
// public void setProper(String proper_) { proper = proper_; }
public MySource() {
a = "A Room with a View";
hidden_b = "The Bridge of San Luis Rey";
c = "Civilwarland in Bad Decline";
hidden_d = "Darkness at Noon";
proper = "This should copy, at minimum.";
}
public void print() {
System.out.println("Source");
System.out.println("================================");
System.out.println("a = " + a);
System.out.println("hidden_b = " + hidden_b);
System.out.println("c = " + c);
System.out.println("hidden_d = " + hidden_d);
System.out.println("--------------------------------");
System.out.println("proper = " + proper);
System.out.println("");
}
}
public static class MyTarget {
private String a;
private String b;
private String hidden_c;
private String hidden_e;
public void setC(String param) { hidden_c = param; }
public void setD(String param) { hidden_e = param; }
private String proper;
// public String getProper() { return proper; }
public void setProper(String proper_) { proper = proper_; }
public MyTarget() {}
public void print() {
System.out.println("Target");
System.out.println("================================");
System.out.println("a = " + a);
System.out.println("b = " + b);
System.out.println("hidden_c = " + hidden_c);
System.out.println("hidden_e = " + hidden_e);
System.out.println("--------------------------------");
System.out.println("proper = " + proper);
System.out.println("");
}
}
public static void main(String args[]) {
ModelMapper modelMapper = new ModelMapper();
modelMapper.getConfiguration()
.setFieldMatchingEnabled(true)
.setFieldAccessLevel(Configuration.AccessLevel.PRIVATE);
MySource s = new MySource();
s.print();
System.out.println("Now dozing...");
System.out.println("");
MyTarget t = modelMapper.map(s, MyTarget.class);
t.print();
}
}
Here's my output:
Source
================================
a = A Room with a View
hidden_b = The Bridge of San Luis Rey
c = Civilwarland in Bad Decline
hidden_d = Darkness at Noon
--------------------------------
proper = This should copy, at minimum.
Now dozing...
Target
================================
a = A Room with a View
b = The Bridge of San Luis Rey
hidden_c = Civilwarland in Bad Decline
hidden_e = null
--------------------------------
proper = This should copy, at minimum.
The fourth case didn't copy over but I don't really care about that case. I think it can easily achieved with a different ModelMapper configuration though. Maybe try LOOSE copying. Or worst case, manually bind the getter and setter methods in the config.