java创建对象的5种方式

1.new

2.使用反射Class.forName(“com.cn.mybatisDemo.util.Student”).newInstance()或Student.class.newInstance();

3.使用构造器

Constructor constructor=Student.class.getConstructor();

Student newInstance = constructor.newInstance();

或Student student4 = Student.class.getConstructor().newInstance();

4.clone()

必须在实体类中实现Cloneable接口，重写clone()方法，并将其改为public修饰，Cloneable接口和我们在编写IO程序的时候序列化接口一样，只是一个标志，这个接口是不包含任何方法的，这个标志主要是为了检测Object类中的clone方法，若我们定义的类想要实现拷贝功能，但是没有实现该接口而调用Object的clone方法，那么就会出现语句中catch块里面的异常错误，抛出CloneNotSupportedException。

5.使用反序列化的方式，切记实体需要实现Serializable接口

import java.io.Serializable;

public class Student implements Cloneable,Serializable{

private int id;

private String name;

private int age;

private String sex;

private String content;

public Student() {
}

public Student(int id, String name, int age, String sex, String content) {
super();
this.id = id;
this.name = name;
this.age = age;
this.sex = sex;
this.content = content;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

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

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public String getSex() {
return sex;
}

public void setSex(String sex) {
this.sex = sex;
}

public String getContent() {
return content;
}

public void setContent(String content) {
this.content = content;
}
@Override
public  Student clone() throws CloneNotSupportedException {

return (Student)super.clone();
}

}

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.OutputStream;

import java.lang.reflect.Constructor;

import java.lang.reflect.InvocationTargetException;

public class TestObjectCreate {

public static void main(String[] args) throws InstantiationException, IllegalAccessException,

ClassNotFoundException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException,

SecurityException, CloneNotSupportedException, FileNotFoundException, IOException {

Student student1 = new Student();
System.out.println(student1);

Student student2 = (Student) Class.forName("com.cn.mybatisDemo.util.Student").newInstance();
System.out.println(student2);

Student student3 = Student.class.newInstance();
System.out.println(student3);

Constructor<Student> constructor=Student.class.getConstructor();
Student newInstance = constructor.newInstance();
System.out.println(newInstance);

Student student4 = Student.class.getConstructor().newInstance();
System.out.println(student4);

Student student5 = student4.clone();
System.out.println(student5);

ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("data"));
objectOutputStream.writeObject(student5);

ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream("data"));
Student student6 = (Student) inputStream.readObject();
System.out.println(student6);
}

}