Java reflection, developing framework-required skills

Using the reflection technology, we map the Uniform Resource Locator (URL) above to the class equivalent

Class:news

Method:list

Parameter:2

It's almost like that.

Class news{

public string list (string catagory_id) {

...

...

}

}

We only need to parse the URL in the framework core and then call the corresponding method to download , at the same time pass the parameters in the past.

Class<?> cls = Class.forName ("Cn.netkiller.reflect.News"); Object obj= cls.newinstance (); method = Cls.getdeclaredmethod ("list", Int.class); return Method.invoke (obj, 2);

1.9. Reflection Reflex

This.getclass (). GetName ()//Current class name Thread.CurrentThread (). Getstacktrace () [1].getmethodname ()]; Current method Name

1.9.1. Get all variables

field[] fields = Objclass.getfields (), for (Field field:fields) {System.out.println (Field.getname ());}

Note: Only public variables can be removed

1.9.2. Batch assignment 1.9.3. Method Operation Download

The steps for invoking a method in Java reflection are three-step

Gets the class that is called to call the method method call (Invoke) in the class to be called

1.9.3.1. Get all the methods

Class<?> objclass = A.getclass (); Method[] methods = Objclass.getdeclaredmethods (); for (method Method:methods) {System.out.println (method);}

1.9.3.2. Set/get Method Download

package cn.netkiller.reflect;import java.lang.reflect.invocationtargetexception;import  Java.lang.reflect.method;public class member {public string name;private int  age;public string getname ()  {return name;} Public void setname (String name)  {this.name = name;} Public int getage ()  {return age;} Public void setage (Int age)  {this.age = age;} @Overridepublic  string tostring ()  {return  "Classa [name="  + name +   ",  age="  + age +  "]";} Public member ()  {// todo auto-generated constructor stub}public static  void main (String[] args)  throws classnotfoundexception, instantiationexception,  IllegalAccessException, NoSuchMethodException, SecurityException,  Illegalargumentexception, invocationtargetexceptIon {class<?> cls = class.forname ("Cn.netkiller.reflect.Member"); object member  = cls.newinstance (); Method setmethod = cls.getdeclaredmethod ("Setage",  int.class); SetMethod.invoke (Member, &NBSP;15); Method getmethod = cls.getdeclaredmethod ("Getage"); System.out.println (Getmethod.invoke (member));}}

Package cn.netkiller.reflect;public class classa {public string name;private  int age;public string getname ()  {return name;} Public void setname (String name)  {this.name = name;} Public int getage ()  {return age;} Public void setage (Int age)  {this.age = age;} Public classa ()  {// todo auto-generated constructor stub} @Overridepublic   String tostring ()  {return  "classa [name="  + name +  ",  age="   + age +  "]";}} PACKAGE&NBSP;CN.NETKILLER.REFLECT;PUBLIC&NBSP;CLASS&NBSP;CLASSB&NBSP;EXTENDS&NBSP;CLASSA{PUBLIC&NBSP;CLASSB ()  {// todo auto-generated constructor stub}private string address;public  string getaddress ()  {return address;} Public void setaddress (string address)  {this.address = adDress;} @Overridepublic  string tostring ()  {return  "classb [address="  + address  +  "]";}} package cn.netkiller.reflect;import java.lang.reflect.field;import  java.lang.reflect.invocationtargetexception;import java.lang.reflect.method;public class  Reflectiontest {public reflectiontest ()  {// todo auto-generated constructor  stub} download Public void testsetmethod ()  throws NoSuchMethodException,  Securityexception, illegalaccessexception, illegalargumentexception, invocationtargetexception,  instantiationexception {// classa a = new classa (); CLASSB&NBSP;B&NBSP;=&NBSP;NEW&NBSP;CLASSB (); B.setaddress ("Shenzhen"); class<classa> classa = classa.class; Classa a = classa.newinstance (); A.setname ("Neo"); A.setage (30); System.out.println (Classa.getdeclaredmethod ("Getage"). Invoke (a)); Method m&nbsP;= classa.getdeclaredmethod ("Setage",  int.class); M.setaccessible (true); //  because it is written as private   So it must be set M.invoke (B,&NBSP;26); System.out.println (A.tostring ()); System.out.println (B.tostring ()); System.out.println (B.getname ()); System.out.println (B.getage ());} Public static void main (String[] args)  throws invocationtargetexception { Reflectiontest rt = new reflectiontest (); Try {rt.testsetmethod ();}  catch  (nosuchmethodexception e)  {// TODO Auto-generated catch  Blocke.printstacktrace ();}  catch  (securityexception e)  {// TODO Auto-generated catch  Blocke.printstacktrace ();}  catch  (illegalaccessexception e)  {// TODO Auto-generated catch  Blocke.printstacktrace ();}  catch  (illegalargumentexception e)  {// TODO Auto-generated catch  Blocke.printstacktrace ();}  catch&nBSP; (instantiationexception e)  {// TODO Auto-generated catch  Blocke.printstacktrace ();}}}

Set method

System.out.println (Classa.getdeclaredmethod ("Getage"). Invoke (a));

Get method

Method m = Classa.getdeclaredmethod ("Setage", Int.class); m.setaccessible (true);//Because it is written in private, it must be set to M.invoke (b, 26) ;

1.9.3.3. Static method invocation

Class cls = Class.forName ("cn.netkiller.reflect.Student"); Method Setmethod = Cls.getdeclaredmethod ("Setage", Int.class); Setmethod.invoke (Cls.newinstance (), 15);

Java reflection, developing framework-required skills