Android Open Source - bad Freezer

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License

The source code is released under:

Copyright (C) 2013 Madis Pink Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Softwa...

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Java Source Code

package com.madisp.bad;
/* w w w.  j  a  v  a2  s .  co m*/
import android.content.Context;
import android.content.SharedPreferences;
import android.text.TextUtils;
import com.madisp.bad.eval.BadVar;
import com.madisp.bad.eval.Scope;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

/**
 * Created with IntelliJ IDEA.
 * User: madis
 * Date: 5/17/13
 * Time: 10:55 PM
 */
public class Freezer {
  private SharedPreferences prefs;

  public Freezer(Context context) {
    prefs = context.getSharedPreferences("bad_freezer", Context.MODE_PRIVATE);
  }

  private List<FrozenStringWatcher> watchers = new LinkedList<FrozenStringWatcher>();

  @SuppressWarnings("unchecked")
  public void start(Scope scope) {
    for (Field f : scope.getBase().getClass().getFields()) {
      if (f.getType().equals(BadVar.class) && f.isAnnotationPresent(Persist.class)) {
        for (Annotation a : f.getAnnotations()) {
          if (a instanceof Persist) {
            Class type = (Class) ((ParameterizedType) f.getGenericType()).getActualTypeArguments()[0];
            if (!isPersistable(type)) {
              continue;
            }
            String key = ((Persist)a).key();
            if (TextUtils.isEmpty(key)) {
              key = f.getName();
              //TODO warn that we are defaulting to field name
            }
            final String fkey = key;
            try {
              BadVar bv = (BadVar) f.get(scope.getBase());
              bv.set(retrieve(prefs, key, type));
              prefs.registerOnSharedPreferenceChangeListener(new FrozenStringWatcher(bv, key, type));
            } catch (IllegalAccessException e) {
              e.printStackTrace();
            }
            break;
          }
        }
      }
    }
  }

  public void stop() {
    for (FrozenStringWatcher w : watchers) {
      prefs.unregisterOnSharedPreferenceChangeListener(w);
    }
  }

  private boolean isPersistable(Class type) {
    return (type.equals(Integer.class)) || (type.equals(Boolean.class)) || (type.equals(String.class));
  }

  public class FrozenStringWatcher implements SharedPreferences.OnSharedPreferenceChangeListener, BadVar.BadWatcher<String> {
    private final BadVar var;
    private final String key;
    private final Class type;

    public FrozenStringWatcher(BadVar<String> bv, String key, Class type) {
      this.key = key;
      this.var = bv;
      this.type = type;
      bv.addWatcher(this);
    }

    @Override
    public void fire(BadVar<String> var) {
      store(prefs, key, var.get());
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
      if (this.key.equals(key)) {
        var.set(retrieve(sharedPreferences, key, type), this);
      }
    }
  }

  private static void store(SharedPreferences prefs, String key, Object value) {
    SharedPreferences.Editor editor = prefs.edit();
    if (value == null) {
      editor.remove(key);
    } else if (value instanceof String) {
      editor.putString(key, (String)value);
    } else if (value instanceof Integer) {
      editor.putInt(key, (Integer) value);
    } else if (value instanceof Boolean) {
      editor.putBoolean(key, (Boolean) value);
    }
    editor.apply();
  }

  private static Object retrieve(SharedPreferences prefs, String key, Class type) {
    if (type.equals(String.class)) {
      return prefs.getString(key, "");
    } else if (type.equals(Integer.class)) {
      return prefs.getInt(key, 0);
    } else if (type.equals(Boolean.class)) {
      return prefs.getBoolean(key, false);
    }
    return null;
  }
}

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