1 /*
2 * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH
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 de.smartics.properties.api.core.annotations;
17
18 import java.lang.annotation.Documented;
19 import java.lang.annotation.ElementType;
20 import java.lang.annotation.Retention;
21 import java.lang.annotation.RetentionPolicy;
22 import java.lang.annotation.Target;
23
24 /**
25 * Defines a default expression for the property to evaluate a value, if not
26 * specified otherwise.
27 * <p>
28 * The expression may contain a plain default value or the names of properties
29 * to evaluate prior to the translation of the evaluated value to the designated
30 * type. This type is determined by the return value of the annotated method of
31 * the interface. The value is always specified as a {@link String} value.
32 * </p>
33 * <pre>
34 * {@source "Examples"
35 * {@annotation}PropertySet("myprops")
36 * public interface MyProperties {
37 * ...
38 * {@annotation}PropertyExpression("42")
39 * int name();
40 *
41 * {@annotation}PropertyExpression("http://localhost:8080")
42 * URL baseUrl();
43 *
44 * {@annotation}PropertyExpression("${myprops.baseUrl}/reports/index.html")
45 * URL reportIndexUrl();
46 * }
47 * }
48 * </pre>
49 * <p>
50 * Please note that you may use properties of any type to be used as
51 * placeholders in a property value, not just strings. By referencing property
52 * from a placeholder please be reminded to specify the fully qualified name
53 * of the property (which includes the name of the {@link PropertySet property
54 * set}.
55 * </p>
56 */
57 @Documented
58 @Target(ElementType.METHOD)
59 @Retention(RetentionPolicy.RUNTIME)
60 public @interface PropertyExpression
61 {
62 /**
63 * The expression to be evaluated to the property's value type.
64 */
65 String value();
66 }