Java中单例实现

1:、经典懒汉：

代码如下：

 package org.pine.test;

 public class Person {
     private String name;
     private int age;

     public static Person person;

     private Person(){

     }

     public int getAge() {
         return age;
     }

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

     public String getName() {
         return name;
     }

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

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

     public static synchronized Person getInstance(){
       if(person==null){
          person = new Person();
       }
       return person;
     }
 }

测试类：

 package org.pine.test;

 public class PersonTest {

     public static void main(String[] args){
       Person p0 = Person.getInstance();
       p0.setName("张泰松");
       p0.setAge(27);
       System.out.println(p0);

       Person p1 = Person.getInstance();
       System.out.println(p1);

       System.out.println(p0==p1);
     }

 }

2、经典饿汉

代码如下：

 package org.pine.test;

 public class Animal {

     private int footCount;

     public static /*final*/ Animal animal = new Animal();

     private Animal () {

     }

     public int getFootCount() {
         return footCount;
     }

     public void setFootCount(int footCount) {
         this.footCount = footCount;
     }

     @Override
     public String toString() {
         return "Animal{" +
                 "footCount=" + footCount +
                 '}';
     }

     public static Animal getInstance(){
         return animal;
     }
 }

测试类：

 package org.pine.test;

 public class AnimalTest {
   public static void main(String[] args){
     Animal a0 = Animal.getInstance();
     a0.setFootCount(4);
     System.out.println(a0);

     Animal a1 = Animal.getInstance();
     System.out.println(a1);

     System.out.println(a0==a1);
   }
 }