java 反射很重要

1.創建一個User類

public class User {
	
	private String username;
	
	private String password;
	
	private String name;
	
	public User(){
		
	}
	
	public User(String name){
		this.name = name;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	@Override
	public String toString() {
		return "User [username=" + username + ", password=" + password + ", name=" + name + "]";
	}
	
	

}

2.創建ReflexTest測試類

public class ReflexTest {

	/**
	 * 獲取屬性名
	 */
	public static void fieldTest(){
		Field[] declaredFields = User.class.getDeclaredFields();
		for (Field field : declaredFields) {
			System.out.println(field.getName());
		}
	}
	
	/**
	 * 屬性賦值
	 * @throws IllegalAccessException 
	 * @throws IllegalArgumentException 
	 * @throws SecurityException 
	 * @throws NoSuchFieldException 
	 * @throws InstantiationException 
	 */
	public static void fieldAssignmentTest() throws IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException, InstantiationException{
		Object paraen = User.class.newInstance();
		Field declaredFields = User.class.getDeclaredField("name");
		declaredFields.setAccessible(true);
		declaredFields.set(paraen,"123");
		System.out.println(declaredFields.get(paraen));
	}
	
	/**
	 * 獲取構造
	 * @throws SecurityException 
	 * @throws NoSuchMethodException 
	 * @throws IllegalAccessException 
	 * @throws InstantiationException 
	 */
	public static void structure() throws NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException{
		Object paraen = User.class.newInstance();
		Constructor<?>[] constructors = User.class.getConstructors();
		for (Constructor<?> constructor : constructors) {
			System.out.println(constructor);
		}
	}
	
	/**
	 * 獲取set方法賦值
	 * get方法輸出
	 * @throws SecurityException 
	 * @throws NoSuchMethodException 
	 * @throws IllegalAccessException 
	 * @throws InstantiationException 
	 * @throws InvocationTargetException 
	 * @throws IllegalArgumentException 
	 */
	public static void setMethod() throws NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
		Object paraen = User.class.newInstance();
		Method method = User.class.getMethod("setName", String.class);
		method.invoke(paraen, "小雞雞");
		
		Method methods = User.class.getMethod("getName");
		String name = (String)methods.invoke(paraen);
		System.out.println(name);
	}
	
	public static void main(String[] args) throws NoSuchFieldException, SecurityException, InstantiationException, NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
//		獲取屬性名
//		fieldTest();
		
		/*try {
			//屬性賦值
			fieldAssignmentTest();
		} catch (IllegalArgumentException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}*/
		
		//獲取所有構造方法
//		structure();
		
		//獲取set方法並賦值，get方法輸出
//		setMethod();
		
	}
	
}