Java tutorial
/* * ljal - Java App Engine library * * Copyright (C) 2012 Steve Liedtke <sliedtke57@gmail.com> * * This program is free software; you can redistribute it and/or modify it under the terms of the * GNU General Public License as published by the Free Software Foundation; either version 3 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See * the GNU General Public License for more details. * * You can find a copy of the GNU General Public License on http://www.gnu.org/licenses/gpl.html. * * Contributors: * Steve Liedtke <sliedtke57@gmail.com> */ package de.hackerspacebremen.format; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.logging.Logger; import org.json.JSONException; import org.json.JSONObject; import com.google.appengine.api.datastore.Key; import com.google.appengine.api.datastore.KeyFactory; import com.google.appengine.api.datastore.Text; import de.hackerspacebremen.data.annotations.Entity; import de.hackerspacebremen.data.annotations.FormatPart; import de.hackerspacebremen.data.entities.BasicEntity; public class JSONFormatter<T extends BasicEntity> implements Formatter<T> { /** * static attribute used for logging. */ private static final Logger logger = Logger.getLogger(JSONFormatter.class.getName()); @Override public String format(final T entity, final String... levels) throws FormatException { final JSONObject json = new JSONObject(); boolean allAttributes = (levels == null || levels.length == 0); final List<String> levelList; if (levels == null || levels.length == 0) { levelList = new ArrayList<String>(); } else { levelList = Arrays.asList(levels); } if (entity.getClass().isAnnotationPresent(Entity.class)) { final Field[] fields = entity.getClass().getDeclaredFields(); for (final Field field : fields) { if (field.isAnnotationPresent(FormatPart.class) && (allAttributes || levelList.contains(field.getAnnotation(FormatPart.class).level()))) { try { final Method method = entity.getClass() .getMethod(this.getGetter(field.getName(), field.getType()), (Class<?>[]) null); final Object methodResult = method.invoke(entity); if (methodResult != null) { final String type = field.getType().toString(); if (type.equals("class com.google.appengine.api.datastore.Key")) { json.put(field.getAnnotation(FormatPart.class).key(), KeyFactory.keyToString((Key) methodResult)); } else if (type.equals("class com.google.appengine.api.datastore.Text")) { json.put(field.getAnnotation(FormatPart.class).key(), ((Text) methodResult).getValue()); } else { json.put(field.getAnnotation(FormatPart.class).key(), methodResult.toString()); } } } catch (IllegalAccessException e) { logger.warning("IllegalAccessException occured: " + e.getMessage()); throw new FormatException(); } catch (NoSuchMethodException e) { logger.warning("NoSuchMethodException occured: " + e.getMessage()); throw new FormatException(); } catch (SecurityException e) { logger.warning("SecurityException occured: " + e.getMessage()); throw new FormatException(); } catch (IllegalArgumentException e) { logger.warning("IllegalArgumentException occured: " + e.getMessage()); throw new FormatException(); } catch (InvocationTargetException e) { logger.warning("InvocationTargetException occured: " + e.getMessage()); throw new FormatException(); } catch (JSONException e) { logger.warning("JSONException occured: " + e.getMessage()); throw new FormatException(); } } } } return json.toString(); } @Override public T reformat(final String object, final Class<T> entityClass) throws FormatException { T result = null; final Map<String, Field> fieldMap = new HashMap<String, Field>(); if (entityClass.isAnnotationPresent(Entity.class)) { final Field[] fields = entityClass.getDeclaredFields(); for (final Field field : fields) { if (field.isAnnotationPresent(FormatPart.class)) { fieldMap.put(field.getAnnotation(FormatPart.class).key(), field); } } try { final JSONObject json = new JSONObject(object); result = entityClass.newInstance(); for (final String key : fieldMap.keySet()) { if (json.has(key)) { final Field field = fieldMap.get(key); final Method method = entityClass.getMethod(this.getSetter(field.getName()), new Class<?>[] { field.getType() }); final String type = field.getType().toString(); if (type.equals("class com.google.appengine.api.datastore.Key")) { method.invoke(result, KeyFactory.stringToKey(json.getString(key))); } else if (type.equals("class com.google.appengine.api.datastore.Text")) { method.invoke(result, new Text(json.getString(key))); } else if (type.equals("boolean")) { method.invoke(result, json.getBoolean(key)); } else if (type.equals("long")) { method.invoke(result, json.getLong(key)); } else if (type.equals("int")) { method.invoke(result, json.getInt(key)); } else { method.invoke(result, json.get(key)); } } } } catch (JSONException e) { logger.warning("JSONException occured: " + e.getMessage()); throw new FormatException(); } catch (NoSuchMethodException e) { logger.warning("NoSuchMethodException occured: " + e.getMessage()); throw new FormatException(); } catch (SecurityException e) { logger.warning("SecurityException occured: " + e.getMessage()); throw new FormatException(); } catch (IllegalAccessException e) { logger.warning("IllegalAccessException occured: " + e.getMessage()); throw new FormatException(); } catch (IllegalArgumentException e) { logger.warning("IllegalArgumentException occured: " + e.getMessage()); throw new FormatException(); } catch (InvocationTargetException e) { logger.warning("InvocationTargetException occured: " + e.getMessage()); throw new FormatException(); } catch (InstantiationException e) { logger.warning("InstantiationException occured: " + e.getMessage()); throw new FormatException(); } } return result; } private String getGetter(final String fieldName, final Class<?> type) { final StringBuilder sBuilder = new StringBuilder(); if (type.toString().equals("boolean")) { sBuilder.append("is"); } else { sBuilder.append("get"); } sBuilder.append(this.firstToUpperCharacter(fieldName)); return sBuilder.toString(); } private String getSetter(final String fieldName) { final StringBuilder sBuilder = new StringBuilder(); sBuilder.append("set"); sBuilder.append(this.firstToUpperCharacter(fieldName)); return sBuilder.toString(); } private String firstToUpperCharacter(final String string) { final StringBuilder sBuilder = new StringBuilder(); final char[] characters = string.toCharArray(); for (int i = 0; i < characters.length; i++) { if (i == 0) { sBuilder.append(("" + characters[i]).toUpperCase()); } else { sBuilder.append(characters[i]); } } return sBuilder.toString(); } }