Reflection Primer Basics

Testreflect.java

Package com.huawei.reflect;

public class Testreflect {

int a = 0;

Private String name = "Lisi";

protected long B = 2L;

public double c = 3.0d;

public static short e = 20;

static String fav = "read";


public void Add (int a,int b) {
System.out.println (A+B);
}
public void Add (int a,string b) {
System.out.println (A+B);
}

private static String say () {
Return "Hello static say";
}
private string Say (String msg) {
Return "Hello" +MSG;
}

static int Add (int a) {
return a+100;
}

public static int Add (int a,int b, int c) {
return a+b+c;
}

Public Testreflect () {
System.out.println ("Testrefect.testrefect ()");
}
Testreflect (int a) {
System.out.println ("Testrefect.testrefect ()" +a);
}

Public Testreflect (long B, double c) {
Super ();
this.b = b;
THIS.C = C;
System.out.println ("This is a Test");
}

}

Test.java

Package com.huawei.reflect;

Import Java.lang.reflect.Constructor;
Import Java.lang.reflect.Field;
Import Java.lang.reflect.Method;

public class Test {
public static void Testgetclass () throws ClassNotFoundException {

/**
* Get a Class object
*
* There are several ways
*/

Get a class object directly from the class name. class
class<?> clazz = Testreflect.class;

Through the object. GetClass () method to get
class<?> clazz1 = new Testreflect (). GetClass ();

The Forname method provided by class
class<?> clazz2 = Class.forName ("Com.cdsxt.reflect.TestReflect");

System.out.println (Clazz);
System.out.println (CLAZZ1);
System.out.println (CLAZZ2);


}

/**
* Test to get the attributes inside the class
* @throws nosuchfieldexception
* @throws SecurityException
* @throws illegalaccessexception
* @throws IllegalArgumentException
*/
public static void Testgetfield () throws SecurityException, Nosuchfieldexception, IllegalArgumentException, illegalaccessexception{
Get the structure information of a class
class<?> clazz = Testreflect.class;

Get a Public member field
Field C = Clazz.getfield ("E");

Testreflect t = new Testreflect ();
Object oo = new Testreflect ();
Object oo1 = new Testreflect (3l,50.0d);
T.E;
TESTREFLECT.E;

Oo.c
If the attribute is subordinate to the class, the value is not required to be directly worn by the specified object.
Object o = c.get (oo1);
Object o = c.get (null);


System.out.println (o);
Property name
System.out.println (C.getname ());
Get modifier
System.out.println (C.getmodifiers ());
Get the Class object for field
System.out.println (C.getclass ());
Get the type of the property field
System.out.println (C.gettype ());


System.out.println ("--------------------");
Gets the public properties of all public within a given class
Field []fields = Clazz.getfields ();
for (Field f:fields) {
System.out.println (F.getname ());
Get modifier
System.out.println (F.getmodifiers ());
Get the Class object for field
System.out.println (F.getclass ());
Get the type of the property field
System.out.println (F.gettype ());
}


Get an existing property field

Field name = Clazz.getdeclaredfield ("name");
Get the original state
Boolean flag = Name.isaccessible ();
Then in force open
Name.setaccessible (TRUE);
System.out.println (Name.get (oo1));
Set the original state back to
Name.setaccessible (flag);
System.out.println (Name.get (oo1));
}

/**
* Test access method
*/
public static void Testgetmethod () throws exception{
class<?> clazz = Testreflect.class;
O.add (ON)
Get the object of a method

method = Clazz.getmethod ("Add", Int.class,string.class);
The second type of notation

Method add = Clazz.getmethod ("Add", New Class[]{int.class,int.class});
Object o = new Testreflect ();
O.add ();
Method.invoke (o, 1, "Hello");
Add.invoke (o, New object[]{2,10});

Get static methods
Method add1 = Clazz.getmethod ("Add", New Class[]{int.class,int.class,int.class});
Call through Object
Object rs = Add1.invoke (o, 10,20,30);
To invoke by class
Object rs = Add1.invoke (null, 10,20,30);

System.out.println (RS);

System.out.println ("----------------------");
/**
* When you call a method that has no arguments, you don't pass it back.
*
* Can not be transmitted at the time of execution
*
* Be aware of their accessibility in addition to public methods or properties or constructors
*
*/
Method m = Clazz.getdeclaredmethod ("Say");
M.setaccessible (TRUE);
Object msg = M.invoke (null);
SYSTEM.OUT.PRINTLN (msg);

}

/**
* Test Create Instance
*/
public static void Testcreateinstance () throws exception{
class<?> clazz = Testreflect.class;
Create an instance
If you want to use the following method, you must have an parameterless constructor in a given class
Object o = clazz.newinstance ();

System.out.println (o);

class<ttt> C = ttt.class;
C.newinstance ();

Get a specific constructor and then create an instance
constructor<?> Constructor = Clazz.getconstructor (New Class[]{long.class,double.class});

Object O1 = constructor.newinstance (New object[]{20l,30.0d});
System.out.println (O1);

}



public static void Main (string[] args) throws Exception {
Testgetclass ();
Testgetfield ();
Testgetmethod ();

Testcreateinstance ();
}
}

Class ttt{

Public TTT (int a) {
Super ();
}

}

Reflection Primer Basics