Chet Haase | b39f051 | 2011-05-24 14:36:40 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2011 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package android.util; |
| 17 | |
| 18 | import java.lang.reflect.Field; |
| 19 | import java.lang.reflect.InvocationTargetException; |
| 20 | import java.lang.reflect.Method; |
| 21 | |
| 22 | /** |
| 23 | * Internal class to automatically generate a Property for a given class/name pair, given the |
| 24 | * specification of {@link Property#of(java.lang.Class, java.lang.Class, java.lang.String)} |
| 25 | */ |
| 26 | class ReflectiveProperty<T, V> extends Property<T, V> { |
| 27 | |
| 28 | private static final String PREFIX_GET = "get"; |
| 29 | private static final String PREFIX_IS = "is"; |
| 30 | private static final String PREFIX_SET = "set"; |
| 31 | private Method mSetter; |
| 32 | private Method mGetter; |
| 33 | private Field mField; |
| 34 | |
| 35 | /** |
| 36 | * For given property name 'name', look for getName/isName method or 'name' field. |
| 37 | * Also look for setName method (optional - could be readonly). Failing method getters and |
| 38 | * field results in throwing NoSuchPropertyException. |
| 39 | * |
| 40 | * @param propertyHolder The class on which the methods or field are found |
| 41 | * @param name The name of the property, where this name is capitalized and appended to |
| 42 | * "get" and "is to search for the appropriate methods. If the get/is methods are not found, |
| 43 | * the constructor will search for a field with that exact name. |
| 44 | */ |
| 45 | public ReflectiveProperty(Class<T> propertyHolder, Class<V> valueType, String name) { |
| 46 | // TODO: cache reflection info for each new class/name pair |
| 47 | super(valueType, name); |
| 48 | char firstLetter = Character.toUpperCase(name.charAt(0)); |
| 49 | String theRest = name.substring(1); |
| 50 | String capitalizedName = firstLetter + theRest; |
| 51 | String getterName = PREFIX_GET + capitalizedName; |
| 52 | try { |
| 53 | mGetter = propertyHolder.getMethod(getterName, (Class<?>[])null); |
| 54 | } catch (NoSuchMethodException e) { |
| 55 | // getName() not available - try isName() instead |
| 56 | getterName = PREFIX_IS + capitalizedName; |
| 57 | try { |
| 58 | mGetter = propertyHolder.getMethod(getterName, (Class<?>[])null); |
| 59 | } catch (NoSuchMethodException e1) { |
| 60 | // Try public field instead |
| 61 | try { |
| 62 | mField = propertyHolder.getField(name); |
| 63 | Class fieldType = mField.getType(); |
| 64 | if (!typesMatch(valueType, fieldType)) { |
| 65 | throw new NoSuchPropertyException("Underlying type (" + fieldType + ") " + |
| 66 | "does not match Property type (" + valueType + ")"); |
| 67 | } |
| 68 | return; |
| 69 | } catch (NoSuchFieldException e2) { |
| 70 | // no way to access property - throw appropriate exception |
| 71 | throw new NoSuchPropertyException("No accessor method or field found for" |
| 72 | + " property with name " + name); |
| 73 | } |
| 74 | } |
| 75 | } |
| 76 | Class getterType = mGetter.getReturnType(); |
| 77 | // Check to make sure our getter type matches our valueType |
| 78 | if (!typesMatch(valueType, getterType)) { |
| 79 | throw new NoSuchPropertyException("Underlying type (" + getterType + ") " + |
| 80 | "does not match Property type (" + valueType + ")"); |
| 81 | } |
| 82 | String setterName = PREFIX_SET + capitalizedName; |
| 83 | try { |
| 84 | mSetter = propertyHolder.getMethod(setterName, getterType); |
| 85 | } catch (NoSuchMethodException ignored) { |
| 86 | // Okay to not have a setter - just a readonly property |
| 87 | } |
| 88 | } |
| 89 | |
| 90 | /** |
| 91 | * Utility method to check whether the type of the underlying field/method on the target |
| 92 | * object matches the type of the Property. The extra checks for primitive types are because |
| 93 | * generics will force the Property type to be a class, whereas the type of the underlying |
| 94 | * method/field will probably be a primitive type instead. Accept float as matching Float, |
| 95 | * etc. |
| 96 | */ |
| 97 | private boolean typesMatch(Class<V> valueType, Class getterType) { |
| 98 | if (getterType != valueType) { |
| 99 | if (getterType.isPrimitive()) { |
| 100 | return (getterType == float.class && valueType == Float.class) || |
| 101 | (getterType == int.class && valueType == Integer.class) || |
| 102 | (getterType == boolean.class && valueType == Boolean.class) || |
| 103 | (getterType == long.class && valueType == Long.class) || |
| 104 | (getterType == double.class && valueType == Double.class) || |
| 105 | (getterType == short.class && valueType == Short.class) || |
| 106 | (getterType == byte.class && valueType == Byte.class) || |
| 107 | (getterType == char.class && valueType == Character.class); |
| 108 | } |
| 109 | return false; |
| 110 | } |
| 111 | return true; |
| 112 | } |
| 113 | |
| 114 | @Override |
| 115 | public void set(T object, V value) { |
| 116 | if (mSetter != null) { |
| 117 | try { |
| 118 | mSetter.invoke(object, value); |
| 119 | } catch (IllegalAccessException e) { |
| 120 | throw new AssertionError(); |
| 121 | } catch (InvocationTargetException e) { |
| 122 | throw new RuntimeException(e.getCause()); |
| 123 | } |
| 124 | } else if (mField != null) { |
| 125 | try { |
| 126 | mField.set(object, value); |
| 127 | } catch (IllegalAccessException e) { |
| 128 | throw new AssertionError(); |
| 129 | } |
| 130 | } else { |
Chet Haase | accb54c | 2011-06-09 08:38:12 -0700 | [diff] [blame] | 131 | throw new UnsupportedOperationException("Property " + getName() +" is read-only"); |
Chet Haase | b39f051 | 2011-05-24 14:36:40 -0700 | [diff] [blame] | 132 | } |
| 133 | } |
| 134 | |
| 135 | @Override |
| 136 | public V get(T object) { |
| 137 | if (mGetter != null) { |
| 138 | try { |
| 139 | return (V) mGetter.invoke(object, (Object[])null); |
| 140 | } catch (IllegalAccessException e) { |
| 141 | throw new AssertionError(); |
| 142 | } catch (InvocationTargetException e) { |
| 143 | throw new RuntimeException(e.getCause()); |
| 144 | } |
| 145 | } else if (mField != null) { |
| 146 | try { |
| 147 | return (V) mField.get(object); |
| 148 | } catch (IllegalAccessException e) { |
| 149 | throw new AssertionError(); |
| 150 | } |
| 151 | } |
| 152 | // Should not get here: there should always be a non-null getter or field |
| 153 | throw new AssertionError(); |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * Returns false if there is no setter or public field underlying this Property. |
| 158 | */ |
| 159 | @Override |
| 160 | public boolean isReadOnly() { |
| 161 | return (mSetter == null && mField == null); |
| 162 | } |
| 163 | } |