Java uses reflection to get comments on classes, methods, properties

Sometimes we want to use reflection to get a comment on a class, a comment on a method, a comment on a property.

The following is a simple example. It includes the three points mentioned above.

Package Com.mine.practice.reflectfield;import Java.lang.annotation.annotation;import Java.lang.reflect.Field; Import Java.lang.reflect.method;import Javax.xml.bind.annotation.xmlaccesstype;import Javax.xml.bind.annotation.xmlaccessortype;import Javax.xml.bind.annotation.xmlattribute;import Javax.xml.bind.annotation.xmlelement;import javax.xml.bind.annotation.xmlrootelement;/** * * @author 2014-11-10 PM 01 : 54:48 * @version V1.0 */@XmlRootElement (name= "user") @XmlAccessorType (Xmlaccesstype.field) public class User {private S Tring pwd; @XmlElement (name = "ID") private int ID, @XmlAttribute @xmlelementprivate String name;/*** * 1, gets a comment of the specified type on the property * 2, Gets a comment of the specified type on the property specified method * 3, gets all comments on the property * 4, gets all comments on the class * 5, gets all comments on the method * @author 2014-11-10 pm 02:18:24 * @param args * * @Supp Resswarnings ("Rawtypes") public static void main (string[] args) {field[] fields = User.class.getDeclaredFields (); Field f:fields) {String filedname = F.getname (); System.out.println ("Property name:" "+filedname+" "),//1, gets the specified type of note on the propertyrelease annotation annotation = F.getannotation (xmlelement.class);//There is a comment of that type exists if (annotation!=null) {//cast to the corresponding comment XmlElement XmlElement = (xmlElement) ANNOTATION;//3, gets the specified method of the annotation of the specified type on the property//is not the default value can go to see the source code if (Xmlelement.name (). Equals ("# # Default ") {System.out.println (the name used by the attribute" +filedname+ "annotation is the defaults:" +xmlelement.name ());} else {System.out.println ("+filedname+" annotation uses a name that is a custom value: "+xmlelement.name ());}} 2. Get all annotations on attributes annotation[] allannotations = F.getannotations (); for (Annotation an:allannotations) {Class Annotationtype = An.annotationtype (); System.out.println (the annotation type for "attribute" "+filedname+" is: "+ Annotationtype);} System.out.println ("----------Gorgeous split-line--------------");} 4. Get all comments on the class annotation[] classannotation = User.class.getAnnotations (); for (Annotation cannotation:classannotation ) {Class Annotationtype = Cannotation.annotationtype (); System.out.println ("Comments on the user class are:" +annotationtype);} System.out.println ("----------Gorgeous split Line--------------");//5, get all comments on method Method;try {method = User.class.getMethod ("SetpWD ", String.class);  annotation[] methodannotations = Method.getannotations (); for (Annotation me:methodannotations) {Class Annotationtype = Me.annotationtype (); System.out.println ("Comments on the SetPwd method are:" + Annotationtype);}} catch (SecurityException e) {e.printstacktrace ();} catch (Nosuchmethodexception e) {e.printstacktrace ()}} @XmlElementpublic void SetPwd (String pwd) {this.pwd = pwd;} Public String getpwd () {return pwd;}}

The result of the operation is as follows

Property name: "pwd"----------Gorgeous split Line--------------property name: "ID" property "id" comment using the name is a custom value: The comment type for id attribute "ID" is: interface Javax.xml.bind.annotation.XmlElement----------Gorgeous Split line--------------property name: The name of the "name" property "name" comment uses the default value: # #default属性 The comment types for "name" are: interface Javax.xml.bind.annotation.XmlAttribute the comment type for the property "name" is: interface Javax.xml.bind.annotation.XmlElement----------Gorgeous Split line--------------comments on the user class are: interface The annotations on the Javax.xml.bind.annotation.XmlAccessorTypeUser class are: interface Javax.xml.bind.annotation.XmlRootElement----------Gorgeous Split line--------------comments on the SetPwd method are: interface Javax.xml.bind.annotation.XmlElement

Java uses reflection to get comments on classes, methods, properties