（无）参数构造函数的最佳方式 - ResponseBody - Spring

Question

Let me introduce my code then I will ask a question. This is just an example. I would like to learn something new if it is possbile.

BaseClass.java

public class BaseClass {

  private String baseName;

  BaseClass(String baseName){
    this.baseName = baseName;
  }
  //getters and setters
}

MyClass.java

public class MyClass extends BaseClass {

  private boolean isTest;
  private String name;

  MyClass(){
  }

  MyClass(String baseName){
    super(baseName);
    this.isTest = true;
  }
  //getters and setters
}

MyClassController.java

@Controller
public class MyClassController {

  @GetMapping(value="/")
  @ResponseBody
  public String myClassController(@RequestBody MyClass myClass) {


    return "index";
  }
}

JSON request:

{
  "name": "Name for BaseClass"
}

So, I send name eg: Name for BaseClass . I want to set this name for variable BaseName in BaseClass through constructor. @RequestBody needs no atribute constructor so I cannot use there this second constructor with arguments. I can handle this eg for using additional method:

Additional method in MyClass.java

  public MyClass setValues(String baseName){
    super(baseName);
    this.isTest = true;
    return this;
  }

New MyController.java

@Controller
public class MyClassController {

  @GetMapping(value="/")
  @ResponseBody
  public String myClassController(@RequestBody MyClass myClass) {

    myClass.setValues(myClass.getName());
    //more uses for myClass

    return "index";
  }
}

Is there any better way to do something like this in more "professional" way?

Answer 1

If you're married to the current inheritance structure, you can use HttpMessageConverter to customize the way Spring deserializes HTTP requests.

public class MyClassConverter extends AbstractHttpMessageConverter<MyClass> {

  public MyClassConverter() {
      super(new MediaType("text", "myClass"));
  }

  @Override
  protected boolean supports(Class<?> clazz) {
      return MyClass.class.isAssignableFrom(clazz);
  }

  @Override
  protected MyClass readInternal(Class<? extends MyClass> clazz, HttpInputMessage inputMessage)
          throws IOException, HttpMessageNotReadableException {

      // Deserialize JSON request

      MyClass inputObject = new MyClass(name);
      return inputObject;
  }

  @Override
  protected void writeInternal(MyClass myClass, HttpOutputMessage outputMessage) {

      // Serialize MyClass object

  }
}

Detailed example

Answer 2

Although it's not clear I'm assuming name and baseName are meant to be the same value. In that case it might make sense for BaseClass to be an abstract class or interface.

abstract class:

public class MyClass extends BaseClass {

    private String name;

    // constructors

    @Override
    String getName() {
        return name;
    }

    // setters
}

public abstract class BaseClass {
    abstract String getName();
}

interface:

public class MyClass implements DtoWithName {

    private String name;

    // constructors

    @Override
    String getName() {
        return name;
    }

    // setters
}

public interface DtoWithName {
    String getName();
}

Also, I can't tell much about your use-case from the given example, but you should read into Composition over inheritance to make sure you're going about it the right way. With DTOs in particular usually simple is best.