Java tutorial
/* * Copyright 2009 Google Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ package com.google.gwt.ajaxloader.client; import com.google.gwt.core.client.JavaScriptException; import com.google.gwt.core.client.JavaScriptObject; import java.util.Date; /** * A collection of properties of arbitrary type, for interoperability with * non-GWT JavaScript libraries. */ public class Properties extends JavaScriptObject { /** * An exception thrown by the get methods when the key is found but the * value has an unexpected type. */ @SuppressWarnings("serial") public static class TypeException extends Exception { private TypeException(String key, String expected, String actual) { super("Properties.get" + expected + "(" + key + ") failed. Unexpected type : " + actual + "."); } private TypeException() { } } /** * Create an empty Properties object. * @return An empty Properties object. */ public static Properties create() { return JavaScriptObject.createObject().cast(); } protected Properties() { } /** * Get a Boolean value mapped to the specified key. * * @param key The name of the Boolean property. * @return A Boolean value, or null if the key is not found. * @throws TypeException if the key is found but the object returned * is not a Boolean. */ public final Boolean getBoolean(String key) throws TypeException { if (containsKey(key)) { String type = typeof(key); if (type.equals("boolean")) { return nativeGetBoolean(key); } else { throw new TypeException(key, "Boolean", type); } } else { return null; } } /** * Get a Date object mapped to the specified key. * * @param key The name of the Date property. * @return A Date object, or null if the key is not found. * @throws JavaScriptException if the key is found but the object returned * is not a Date. * @throws TypeException If the key is found but the value is not an object. */ public final Date getDate(String key) throws JavaScriptException, TypeException { return JsDate.toJava((JsDate) getObject(key)); } /** * Get a Double value mapped to the specified key. * * @param key The name of the Double property. * @return A Double value, or null if the key is not found. * @throws TypeException If the key is found but the value is not a * number (integers are fine). */ public final Double getNumber(String key) throws TypeException { if (containsKey(key)) { String type = typeof(key); if (type.equals("number")) { return nativeGetNumber(key); } else { throw new TypeException(key, "Number", type); } } else { return null; } } /** * Get a JavaScriptObject mapped to the specified key. * * @param key The name of the JavaScriptObject property. * @return A JavaScriptObject, or null if the key is not found. * @throws TypeException If the key is found but the value is not a * JavaScriptObject. */ public final JavaScriptObject getObject(String key) throws TypeException { if (containsKey(key)) { String type = typeof(key); if (type.equals("object")) { return nativeGetObject(key); } else { throw new TypeException(key, "Object", type); } } else { return null; } } /** * Get a String mapped to the specified key. * * @param key The name of the String property. * @return A String, or null if the key is not found. * @throws TypeException If the key is found but the value is not a * String. */ public final String getString(String key) throws TypeException { if (containsKey(key)) { String type = typeof(key); if (type.equals("string")) { return nativeGetString(key); } else { throw new TypeException(key, "String", type); } } else { return null; } } /** * Remove the property at the specified key. * * @param key The name of the property to remove. */ public final native void remove(String key) /*-{ delete this[key]; }-*/; /** * Set a property. * * @param key The name of the property. * @param value The value of the property. */ public final void set(String key, Boolean value) { if (value == null) { remove(key); } else { setBoolean(key, value); } } /** * Set a property. * * @param key The name of the property. * @param value The value of the property. */ public final void set(String key, Date value) { set(key, JsDate.toJs(value)); } /** * Set a property. * * @param key The name of the property. * @param value The value of the property. */ public final void set(String key, Double value) { if (value == null) { remove(key); } else { setNumber(key, value); } } /** * Set a property. * * @param key The name of the property. * @param value The value of the property. */ public final native void set(String key, JavaScriptObject value) /*-{ this[key] = value; }-*/; /** * Set a property. * * @param key The name of the property. * @param value The value of the property. */ public final native void set(String key, String value) /*-{ this[key] = value; }-*/; /** * Executes the JavaScript typeof operator against the property with the * given key. Note that the typeof undefined is "undefined" and the typeof * null is "object". * * @param key The name of the property to type check. * @return The JavaScript type of the property, as defined by the JavaScipt * typeof operator. */ public final native String typeof(String key) /*-{ return typeof this[key]; }-*/; private native boolean containsKey(String key) /*-{ return this[key] != null; }-*/; private native boolean nativeGetBoolean(String key) /*-{ return this[key]; }-*/; private native double nativeGetNumber(String key) /*-{ return this[key]; }-*/; private native JavaScriptObject nativeGetObject(String key) /*-{ return this[key]; }-*/; private native String nativeGetString(String key) /*-{ return this[key]; }-*/; private native void setBoolean(String key, boolean value) /*-{ this[key] = value; }-*/; private native void setNumber(String key, double value) /*-{ this[key] = value; }-*/; }