Reflection combines XML simple simulation spring to create beans

The bottom of the frame is actually implemented by reflection, just like Spring, when you configure a variety of beans to be configured as a configuration file, which beans you need to match, and the spring container to dynamically load according to your needs , Here is a simple example to simulate:

1. Deepen the understanding of reflection,

2. See how the framework is implemented

3. Parsing of XML by dom4j

Two simple classes:

User:

public class User {private string Username;private  string userpwd;private string Userage;public string Getuserage () { return userage;} public void Setuserage (String userage) {this.userage = Userage;} Public String GetUserName () {return userName;} public void Setusername (String userName) {this.username = UserName;} Public String getuserpwd () {return userpwd;} public void Setuserpwd (String userpwd) {this.userpwd = Userpwd;}}

Student class:

public class Student {private string Stuname;private string Stuno;public string Getstuname () {return stuname;} public void Setstuname (String stuname) {this.stuname = Stuname;} Public String Getstuno () {return stuno;} public void Setstuno (String stuno) {This.stuno = Stuno;}}

Config XML file:<bean-class> inside is the package name of the Class + class name

<?XML version= "1.0" encoding= "UTF-8"?><Beans>    <Bean>        <Bean-name>User</Bean-name>        <Bean-class>Com.bwf.test.User</Bean-class>        <Init>            < Propertyname= "UserName">Zhangsan</ Property>            < Propertyname= "Userage">18</ Property>            < Propertyname= "Userpwd">123456</ Property>        </Init>    </Bean>        <Bean>        <Bean-name>User1</Bean-name>        <Bean-class>Com.bwf.test.User</Bean-class>        <Init>            < Propertyname= "UserName">Lisi</ Property>            < Propertyname= "Userpwd">654321</ Property>            < Propertyname= "Userage">24</ Property>        </Init>    </Bean>        <Bean>        <Bean-name>Student</Bean-name>        <Bean-class>Com.bwf.test.Student</Bean-class>        <Init>            < Propertyname= "Stuname">Wangwu</ Property>            < Propertyname= "Stuno">1</ Property>        </Init>    </Bean>    </Beans>

Parse XML assigns values and tests to objects:

Import Java.io.file;import java.io.fileinputstream;import Java.io.filenotfoundexception;import Java.io.InputStream ; Import Java.lang.reflect.field;import Java.lang.reflect.invocationtargetexception;import Java.lang.reflect.method;import Java.util.list;import Org.dom4j.document;import org.dom4j.DocumentException; Import Org.dom4j.element;import org.dom4j.io.saxreader;import Com.bwf.test.student;import com.bwf.test.User;public Class Xmlrefelct {public static void main (string[] args) {try {ReadXML ();} catch (Exception e) {e.printstacktrace ();}} /** * Read XML file * @throws Exception */public static void ReadXML () throws Exception{inputstream in = null;try {in = new file InputStream (New File ("Src/spring.xml"));} catch (FileNotFoundException e) {e.printstacktrace ();}   Saxreader reader = new Saxreader (); try {Document document = Reader.read (in); Read XmlElement root = Document.getrootelement (); list<element> beans = root.elements ();//Gets all the <bean>for in the XML (Element Bean:beans) {bean.element ("bean-class "). GetStringValue (); Gets the full path name of the configured class//<bean-class>com.bwf.test.user</bean-class>//system.out.println (Bean.element (" Bean-class "). GetStringValue ());//The Class object is reflected by the full path name class<?> C = class.forname (Bean.element (" Bean-class "). GetStringValue ()); list<element> properties = bean.element ("init"). Elements ("property");//Gets all the properties inside the Configuration object o = C.newinstance (); Reflection creates an object for (Element property:properties) {//Determines whether the property exists in the class's properties and configures the value for object initialization o = Checkpropertyesxit (Property.attribute ("NA Me "). GetStringValue (), O,c,property.getstringvalue ());} Test (O);//Call testing Method}} catch (Documentexception e) {e.printstacktrace ();}} /** * Determines whether a property exists in the properties of the class and the value configured for object initialization * @param propertyname * @param o * @param c * @param propertyvalue * @return */publi  C Static Object checkpropertyesxit (String propertyname,object o,class<?> c,string propertyvalue) {field[] fields = C.getdeclaredfields (); Boolean isexsit = false;//initialized to not exist for (Field Field:fields) {if (Field.getname (). Equals ( PropertyName)) {//description attribute existsIsexsit = true;//splicing The canonical name of the Set method String Setmethod = "Set" +string.valueof (Field.getname (). CharAt (0)). toUpperCase () + Field.getname (). substring (1); try {//Get Set method M = C.getdeclaredmethod (Setmethod, Field.gettype ()); try {// Call the Set method to initialize the value of the property M.invoke (O, New Object[]{propertyvalue});} catch (Illegalaccessexception e) {e.printstacktrace ();} catch (IllegalArgumentException e) {e.printstacktrace ();} catch (InvocationTargetException e) {e.printstacktrace ();}} catch (Nosuchmethodexception e) {e.printstacktrace ();} catch (SecurityException e) {e.printstacktrace ()}}} if (isexsit) {//system.out.println (propertyname+ "exists");} Else{//system.out.println (propertyname+ "does not exist"), try {throw new Nosuchfieldexception (PropertyName + "property does not exist");} catch ( Nosuchfieldexception e) {e.printstacktrace ();}} return o;} /** * Test whether the object has been initialized * @param o */public static void Test (object o) {if (o instanceof user) {User user = (user) O; System.out.println (User.getusername ()); System.out.println (User.getuserpwd ()); System.out.println (User.getuseRAge ()); System.out.println ("----------------");} else if (o instanceof Student) {Student s = (Student) o; System.out.println (S.getstuno ());}}}

　　

Result: configured with two user one Student output two user information and Student information

　

Reflection combines XML simple simulation spring to create beans