目录

二、 构造器获取

1. getConstructor(Class parameterTypes……)【public】

代码：

！！！无论是protected还是private都会报错，getConstructor()方法只获取public的构造方法

2.  getConstructors()方法【public】

代码：

！！依然只能public

3. getDeclaredConstructor()方法【public/protected/private/..】

代码：

！！可以显示protected和private的构造方法啦~耶

4. getDeclaredConstructors() 【public/protected/private/..】

代码：

！！又可以显示protected和private的构造方法啦~耶

二、 构造器获取

1. getConstructor(Class parameterTypes……)【public】

代码：

public class Person {
	public Person() {}
	public Person(String name) {}
	public Person(String name, int age) {}
	protected Person(boolean sex) {}
	private Person(Date birthday) {}
}

package people.constructor;

import java.lang.reflect.Constructor;
import java.util.Date;




public class Bootstrap2 {
  public static void main(String[] args) throws SecurityException, NoSuchMethodException{
	  Class clazz = Person.class;
	  Constructor constructor1 = clazz.getConstructor();
	  System.out.println(constructor1.toString());
	  Constructor constructor2 = clazz.getConstructor(String.class);
	  System.out.println(constructor2.toString());
	  Constructor constructor3 = clazz.getConstructor(String.class,int.class);
	  System.out.println(constructor3.toString());
	  
	  Constructor consturctor4 = clazz.getConstructor(boolean.class); //测试protected权限
	  //Constructor consturctor5 = clazz.getConstructor(Date.class); //测试private权限
  }
}

public people.constructor.Person()
public people.constructor.Person(java.lang.String)
public people.constructor.Person(java.lang.String,int)
Exception in thread "main" java.lang.NoSuchMethodException: people.constructor.Person.(boolean)
	at java.base/java.lang.Class.getConstructor0(Class.java:3508)
	at java.base/java.lang.Class.getConstructor(Class.java:2244)
	at studentsa/people.constructor.Bootstrap2.main(Bootstrap2.java:22)

！！！无论是protected还是private都会报错，getConstructor()方法只获取public的构造方法

2.  getConstructors()方法【public】

代码：

package people.constructor;

import java.lang.reflect.Constructor;
import java.util.Date;




public class Bootstrap2 {
  public static void main(String[] args) throws SecurityException, NoSuchMethodException{
	  Class clazz = Person.class;
	  Constructor[] constructors = clazz.getConstructors();
	  for(Constructor constructor: constructors) {
		  System.out.println(constructor.toString());
	  }
  }
}

public people.constructor.Person(java.lang.String,int)
public people.constructor.Person(java.lang.String)
public people.constructor.Person()

！！依然只能public

3. getDeclaredConstructor()方法【public/protected/private/..】

代码：

将1. 中的getConstructor()全部改成getDeclaredConstructor()

package people.constructor;

import java.lang.reflect.Constructor;
import java.util.Date;




public class Bootstrap2 {
  public static void main(String[] args) throws SecurityException, NoSuchMethodException{
	  Class clazz = Person.class;
	  Constructor constructor1 = clazz.getDeclaredConstructor();
	  System.out.println(constructor1.toString());
	  Constructor constructor2 = clazz.getDeclaredConstructor(String.class);
	  System.out.println(constructor2.toString());
	  Constructor constructor3 = clazz.getDeclaredConstructor(String.class,int.class);
	  System.out.println(constructor3.toString());
	  
	  Constructor constructor4 = clazz.getDeclaredConstructor(boolean.class); //测试protected权限
	  System.out.println(constructor4.toString());
	  Constructor constructor5 = clazz.getDeclaredConstructor(Date.class); //测试private权限
	  System.out.println(constructor5.toString());
	  
  }
}

public people.constructor.Person()
public people.constructor.Person(java.lang.String)
public people.constructor.Person(java.lang.String,int)
protected people.constructor.Person(boolean)
private people.constructor.Person(java.util.Date)

！！可以显示protected和private的构造方法啦~耶

4. getDeclaredConstructors() 【public/protected/private/..】

代码：

package people.constructor;

import java.lang.reflect.Constructor;
import java.util.Date;




public class Bootstrap2 {
  public static void main(String[] args) throws SecurityException, NoSuchMethodException{
	  Class clazz = Person.class;
	  Constructor[] constructors = clazz.getDeclaredConstructors();
	  for(Constructor constructor: constructors) {
		  System.out.println(constructor.toString());
	  }
	  
  }
}

private people.constructor.Person(java.util.Date)
protected people.constructor.Person(boolean)
public people.constructor.Person(java.lang.String,int)
public people.constructor.Person(java.lang.String)
public people.constructor.Person()

！！又可以显示protected和private的构造方法啦~耶