Java反射实践总结

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;


public class TestReflect {

	public static void main(String[] args) throws NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, ClassNotFoundException, NoSuchFieldException {
		
		
		//1.1 默认构造函数
		Constructor<Test> tConstructor = (Constructor<Test>) Class.forName("Test").getConstructor();
		Test test = tConstructor.newInstance(new Object[]{});
		
		//1.2 带参数构造函数
		Constructor<Test> tConstructor2 = (Constructor<Test>) Class.forName("Test").getConstructor(int.class);
		Test test2 = tConstructor2.newInstance(new Object[]{200});
		
		//2.1 普通无参数成员函数
		Method method1 = Class.forName("Test").getMethod("sayHello");
		method1.invoke(test);
		
		//2.2 带普通参数成员函数
		Method method2 = Class.forName("Test").getMethod("run",String.class);
		method2.invoke(test2, "haha");
		
		//2.3 参数为数组的成员函数
		
		Method method3 = Class.forName("Test").getMethod("printArray", String[].class);
		//method3.invoke(test2, new String[]{"i","am","hello world"})这样子数组会被打开，认为是有四个参数;
		method3.invoke(test2, new Object[]{new String[]{"i","am","hello world"}});
		
		//3.静态函数
		Method method4 = Class.forName("Test").getMethod("service");
		method4.invoke(null);
		
		//4 普通成员
		
		Field afield = Test.class.getDeclaredField("a");
		afield.setAccessible(true);
		afield.set(test, 99999);
		Field bField = Test.class.getDeclaredField("str");
		bField.setAccessible(true);
		bField.set(test, "i am a  field");
		System.out.println(test);
		
		//5 静态成员
		Field cfield = Test.class.getDeclaredField("c");
		cfield.setAccessible(true);
		cfield.set(null, 11111);
		
		Test.printStatic();
	}
	
}
//目标类
class Test {

	private int a;
	private String str;
	private static int  c;
	public Test(int a) {
		System.out.println("a: "+a);
	}
	public Test() {
		System.out.println("default constructor");
	}
	public void sayHello(){
		System.out.println("hello world");
	}
	
	public int run(String arg) {
		System.out.println("run: "+arg);
		return 0;
	}
	
	public void printArray(String[] array) {
		for(String str:array){
			System.out.print(str+" ");
		}
		System.out.println();
	}
	@Override
	public String toString() {
		return "a: "+a+" str: "+str;
	}
	
	public static void service() { 
		System.out.println("I am service function");
	}
	
	public static void printStatic() {
		System.out.println("c: "+c);
	}
}