A small example of annotation injection of the IOC implementation of spring

First, we'll write a custom annotation

<span style= "FONT-SIZE:14PX;" >package Com.test.aonntion;import Java.lang.annotation.elementtype;import java.lang.annotation.Retention; Import Java.lang.annotation.retentionpolicy;import java.lang.annotation.target;//Life The annotation is scoped to the attribute @target ( Elementtype.field)//indicates that the annotation is run-time injected @retention (retentionpolicy.runtime) public @interface Ioc {// obj is the type of the subclass for which the parameter type is object, and the default parameter is Object.classpublic class< Extends object> obj () default Object.class;} </span>

then we declare three classes to test

First, declare an abstract parent class

<span style= "FONT-SIZE:14PX;" >package Com.test.aonntion;public Abstract class Parent {//abstract method public abstract void Say ();} </span>

in declaring two subclasses, inheriting from our parent class

Son Sub-category

<span style= "FONT-SIZE:14PX;" >package Com.test.aonntion;public class son extends parent{@Overridepublic Void Say () {//son soy sauce go System.out.println (" I ' m my Parent ' Son ');}} </span><span style= "Font-weight:bold;" ></span>

Daughter sub-class

<span style= "FONT-SIZE:14PX;" >package Com.test.aonntion;public class Daughter extends Parent {@Overridepublic void Say () {// The daughter soy sauce goes to System.out.println ("I ' m my Parent's Daughter");}} </span>

The next step is to finish writing our functional class .

<span style= "FONT-SIZE:14PX;" >package Com.test.aonntion;import Java.lang.reflect.field;public class Ioctest {public static void Startioc (String objname) throws exception{//gets the class class<?> clazz = Class.forName (objname);//Instantiate the class object TESTIOC = Clazz.newinstance ();//Get all the properties under the class field[] fields = Clazz.getdeclaredfields ();//Determine if there is a property in the class if (Fields! = null && Fields.length > 0) {//Traverse all properties for (int i =0;i < fields.length; i++) {//Get IOC annotations for current properties IOC IOC = Fields[i].getannotation ( Ioc.class);//If the IOC annotation for the current property is not empty and the value of obj is not NULL if (IOC! = null && ioc.obj () = null) {//Gets the class that we injected obj and instantiates the class to get the instance Ojbobj ECT OJB = Ioc.obj (). newinstance ();//Let the property support forced injection, either-when the property is a private variable and there is no set method//Force Call Set ("Property name", the attribute to be injected); fields[i].setaccessible (true);//Inject the object we instantiate into the attribute Fields[i].set (TESTIOC, OJB);}}} This is my son, soy sauce. @ioc (Obj=son.class)//declares a parent class object 1private Static parent parent;//This is my daughter soy sauce (@ioc) Declares a parent class object 2private static parent parent1;/** * @param args */public static void main (string[] args) {try {//Start note startioc ("Com.test.aonntion.IocTest"),} catch (Exception e) {e.printstacktrace ();} Father a sent soy sauce people said Parent.say ();//father B sent soy sauce said Parent1.say ();}} </span>

Test Results

A small example of annotation injection of the IOC implementation of spring