从Android上的FirebaseDatabase获取位图时出错

Question

I have a class that have a Bitmap object, and when I setValue(MyClass.class) to FirebaseDatabase I discover that is possible! And the RealtimeDatabase save the properties of Bitmap image. The problem occurs when I read the value, the follow error happened:

com.google.firebase.database.DatabaseException: Class android.graphics.Bitmap is missing a constructor with no arguments

but I can't Override the constructor of Bitmap image. How can I get around this situation?

ref.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                Iterator<DataSnapshot> iterator = dataSnapshot.getChildren().iterator();
                log("Init ValueEventListener onDataChange()");

                while( iterator.hasNext() ) {
                    DataSnapshot data = iterator.next();
                    log("Data : " + data.getKey());
                    Treino t = data.getValue(Treino.class);
                }
            }
}

public class Treino implements Serializable{

    String nome;
    List<Exercicio> listaExercicios;
    List<Integer> listaDiasSemana;
    String hora; // hh:mm

    public Treino(String nome, List<Exercicio> listaExercicios, List<Integer> listaDiasSemana, String hora) {
        this.nome = nome;
        this.listaExercicios = listaExercicios;
        this.listaDiasSemana = listaDiasSemana;
        this.hora = hora;
    }

public class Exercicio implements Serializable {

    String nome, tipo, nomeImagem;
    Bitmap imagem;

    public Exercicio() {
    }

    public Exercicio(String nome, Bitmap imagem, String nomeImagem) {
        this.nome = nome;
        this.imagem = imagem;
        this.nomeImagem = nomeImagem;
    }

I omitted the getters and setters.

Answer 1

You must convert Bitmap to String

This is code

  public String BitMapToString(Bitmap bitmap){
        ByteArrayOutputStream ByteStream=new  ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG,100, ByteStream);
        byte [] b=ByteStream.toByteArray();
        String temp=Base64.encodeToString(b, Base64.DEFAULT);
        return temp;
  }

And Exercicio.class

public class Exercicio implements Serializable {

String nome, tipo, nomeImagem;
String bitmapImageString;

public Exercicio() {
}

public Exercicio(String nome, String imagem, String nomeImagem) {
    this.nome = nome;
    this.bitmapImageString = imagem;
    this.nomeImagem = nomeImagem;
}
}

When get String from server. You must convert String to Bitmap

public Bitmap StringToBitMap(String encodedString){
 try{
   byte [] encodeByte=Base64.decode(encodedString,Base64.DEFAULT);
   Bitmap bitmap=BitmapFactory.decodeByteArray(encodeByte, 0, encodeByte.length);
   return bitmap;
 }catch(Exception e){
   e.getMessage();
   return null;
 }
}

HOPE! Help you!