Java通過反射調用方法

下面代碼演示如何通過反射調用方法。

首先通過Class實例的getDeclaredMethods()獲得所有方法的定義，然后通過Method的invoke方法觸發方法調用，invoke方法的第一個參數是方法所屬對象，第二個參數是方法調用的參數列表。

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

public class Main {

/**
 * Invokes the methods of an object using the Reflection api.
 */
public void invokeMethodsUsingReflection() {

    //Obtain the Class instance
    Class computerClass = Computer.class;

    //Get the methods
    Method[] methods = computerClass.getDeclaredMethods();

    //Create the object that we want to invoke the methods on
    Computer computer = new Computer();

    //Loop through the methods and invoke them
    for (Method method : methods) {
        Object result;
        try {
            //Call the method. Since none of them takes arguments we just
            //pass an empty array as second parameter.
            result = method.invoke(computer, new Object[0]);
        } catch (IllegalArgumentException ex) {
            ex.printStackTrace();
            return;
        } catch (InvocationTargetException ex) {
            ex.printStackTrace();
            return;
        } catch (IllegalAccessException ex) {
            ex.printStackTrace();
            return;
        }
        System.out.println(method.getName() + ": " + result);
    }
}

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    new Main().invokeMethodsUsingReflection();
}

class Computer {

    private String brand = "DELL";
    private String type = "Laptop";
    private int harddiskSize_GB = 300;
    private boolean AntiVirusInstalled = true;

    public String getBrand() {
        return brand;
    }

    public String getType() {
        return type;
    }

    public int getHarddiskSize_GB() {
        return harddiskSize_GB;
    }

    public boolean isAntiVirusInstalled() {
        return AntiVirusInstalled;
    }
}

}</pre>