回憶：之前聽一個老師提過侠畔，學(xué)語言就是學(xué)關(guān)鍵字，如果把所有的關(guān)鍵字都搞懂了损晤，這門語言你就屬于很熟悉了（很贊同這句話）软棺。
實現(xiàn)Cloneable這個標(biāo)記接口，重寫Object的clone方法尤勋，完成拷貝功能
拷貝分為淺拷貝和深拷貝
如果拷貝的對象中的屬性都是基本類型喘落，使用淺拷貝就行，如果拷貝的對象中含有引用類型最冰，就需要實現(xiàn)深拷貝
注意：實現(xiàn)深拷貝時瘦棋，引用對象也要重寫clone方法，如果引用對象是繼承其他對象的話暖哨，上級對象也要重寫clone方法赌朋。

對象

package com.example.java8.model.copy;
import java.math.BigDecimal;

public class Dog implements Cloneable {

    private Integer id;

    private String name;

    private BigDecimal weight;

    private Food food;

    public Dog(Integer id, String name, BigDecimal weight) {
        this.id = id;
        this.name = name;
        this.weight = weight;
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public BigDecimal getWeight() {
        return weight;
    }

    public void setWeight(BigDecimal weight) {
        this.weight = weight;
    }

    public Food getFood() {
        return food;
    }

    public void setFood(Food food) {
        this.food = food;
    }

    @Override
    public String toString() {
        return "Dog{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", weight=" + weight +
                ", food=" + food +
                '}';
    }

    // 淺拷貝(使用時兩者選其一)
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    // 深拷貝(使用時兩者選其一)
    @Override
    protected Object clone() throws CloneNotSupportedException {
        Object object = super.clone();
        Food food = ((Dog) object).getFood();
        ((Dog) object).setFood((Food) food.clone());
        return object;
    }
}

引用對象

package com.example.java8.model.copy;

public class Food implements Cloneable {

    private String name;

    public Food(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "Food{" +
                "name='" + name + '\'' +
                '}';
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

測試方法

package com.example.java8.model.copy;
import org.junit.Test;
import java.math.BigDecimal;

public class DogTest {

    // 測試淺拷貝
    @Test
    public void test() throws CloneNotSupportedException {
        Dog jack = new Dog(18, "jack", BigDecimal.TEN);
        Dog tom = (Dog) jack.clone();
        tom.setId(19);
        tom.setName("tom");
        tom.setWeight(BigDecimal.ONE);
        System.out.println(jack);
        System.out.println(tom);
    }

    // 測試深拷貝
    @Test
    public void test2() throws CloneNotSupportedException {
        Dog jack = new Dog(18, "jack", BigDecimal.TEN);
        jack.setFood(new Food("冰淇淋"));
        Dog tom = (Dog) jack.clone();
        tom.setId(19);
        tom.setName("tom");
        tom.setWeight(BigDecimal.ONE);
        tom.getFood().setName("三明治");
        System.out.println(jack);
        System.out.println(tom);
    }
}