Customizing Java Annotation, reading annotation values

1. The first is custom annotations:

Java code

1. PACKAGE CN.VEJI.HIBERNATE.PO;  
2.   
3. import java.lang.annotation.elementtype;  
4. import java.lang.annotation.retention;  
5. span class= "keyword" >import java.lang.annotation.retentionpolicy;  
6. IMPORT JAVA.LANG.ANNOTATION.TARGET;  
7.   
8. @Target (Elementtype.method)   
9. @Retention ( Retentionpolicy.runtime)   
10. public @ interface privilege {  
11.     string[] value ( );   
12.   
13. }  

2. define the use of the annotation class:

Java code

2. Package Cn.veji.hibernate.po;
6. Package Cn.veji.hibernate.po;
10. Public class Testprivilege {
14. @Privilege ({ "a"})
16. public Void A () {
18. }
22. @Privilege ({ "B"})
24. public void B () {
26. }
30. @Privilege ({ "C"})
32. public void C () {
34. }
38. }

3. read the annotation value Help class:

Java code

2. Package Cn.veji.hibernate.po;
6. Package cn.veji.hibernate.test;
10. Import java.lang.annotation.Annotation;
12. Import Java.lang.reflect.Method;
14. Import Java.util.HashMap;
16. Import Java.util.Map;
20. Import Cn.veji.hibernate.po.Privilege;
22. Import Cn.veji.hibernate.po.TestPrivilege;
26. Public class Annotationutil {
30. public static Annotationutil anno = null;
34. public static Annotationutil getinstance () {
36. if (anno = = null) {
38. Anno = new Annotationutil ();
40. }
42. return anno;
44. }
48. /** 
50. * Read annotation values
52. *
54. * @param annotationclasss Processing Annotation class name
56. * @param annotationfield Processing Annotation Class Property names
58. * @param className processing annotation Use class name
60. * @return
62. * @throws Exception
64. */
66. @SuppressWarnings ("All")
68. Public map<string, string> Loadvlaue (Class annotationclasss,
70. String Annotationfield, String className) throws Exception {
74. SYSTEM.OUT.PRINTLN ("processing annotation class name = = =" +annotationclasss.getname ());
76. SYSTEM.OUT.PRINTLN ("Processing annotation class Property name = = =" +annotationfield);
78. SYSTEM.OUT.PRINTLN ("process annotation call Class name = = =" +classname);
80. map<string, string> map = new hashmap<string, string> ();
82. Method[] methods = Class.forName (ClassName). Getdeclaredmethods ();
84. For (Method method:methods) {
86. if (method.isannotationpresent (annotationclasss)) {
88. Annotation p = method.getannotation (ANNOTATIONCLASSS);
90. Method m = P.getclass ()
92. . Getdeclaredmethod (Annotationfield, null);
94. String[] values = (string[]) M.invoke (p, null);
96. For (String key:values) {
98. System.out.println ("annotated value = = =" + key);
100. Map.put (key, key);
102. }
104. }
106. }
108. SYSTEM.OUT.PRINTLN ("map quantity = = =" + map.size ());
110. return map;
112. }
116. public static void Main (string[] args) throws Exception {
120. Annotationutil.getinstance (). Loadvlaue (Privilege. Class, "value",
122. Testprivilege.  class.getname ());
124. }
128. }

4. Implementation results:

Java code

1. Process annotation class name = = = Cn.veji.hibernate.po.Privilege
2. Handling Annotation Class Property names = = = value
3. Call class name for processing annotation = = = Cn.veji.hibernate.po.TestPrivilege
4. Note value = = = C
5. Note value = = = A
6. Note value = = = B
7. Number of maps = = 3

Customizing Java Annotation, reading annotation values