java反射-动态调用方法(无参无返回值、有参无返回值、有参有返回值)

public class UserInfo {
 
    private long id;
    private String username;
    private String password;
 
    public UserInfo() {
        System.out.println("public UserInfo()");
    }
 
    public UserInfo(long id) {
        super();
        this.id = id;
    }
 
    public UserInfo(long id, String username) {
        super();
        this.id = id;
        this.username = username;
    }
 
    public UserInfo(long id, String username, String password) {
        super();
        this.id = id;
        this.username = username;
        this.password = password;
        System.out.println("public UserInfo(long id, String username, String password)");
        System.out.println(id + " " + username + " " + password);
 
    }
 
    public long getId() {
        return id;
    }
 
    public void setId(long id) {
        this.id = id;
    }
 
    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 void test() {
        System.out.println("public void test1()");
    }
 
    public void test(String address) {
        System.out.println("public void test2(String address) address=" + address);
    }
 
    public String test(int age) {
        System.out.println("public String test3(int age) age=" + age);
        return "我是返回值";
    }
}

   public static void main(String[] args) throws InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException, NoSuchFieldException {
        Class<UserInfo> userInfoClass = UserInfo.class;
        //1、使用Class对象调用无参构造方法
        //UserInfo userInfo = userInfoClass.newInstance(); 已废弃，不推荐使用
        UserInfo userInfo = userInfoClass.getDeclaredConstructor().newInstance();
        //定义方法名方法名
        String methodName = "test";
        //1、获取无参无返回值方法对象
        Method test1 = userInfoClass.getDeclaredMethod(methodName);
        //执行方法
        test1.invoke(userInfo);
        //    2、获取有参无返回值方法
        Method test2 = userInfoClass.getDeclaredMethod(methodName, String.class);
        test2.invoke(userInfo, "地址参数");
        //    3、获取有参有返回值方法
        Method test3 = userInfoClass.getDeclaredMethod(methodName, int.class);
        String result = (String) test3.invoke(userInfo, 12);
        System.out.println(result);
    }