单例模式
namespace 单例模式
{internal class DanLi{int num = 100;static DanLi d1=null;int v;private DanLi() { }public static DanLi Create() {if (d1==null ){d1 = new DanLi();}return d1 ; }public int M() { return --num; }public int k() { return ++num; }}
namespace 单例模式
{public partial class Form1 : Form{public Form1(){InitializeComponent();}private void button1_Click(object sender, EventArgs e){//Class1 c1=new Class1(); //textBox1.Text=c1.jai();DanLi d = DanLi.Create();textBox1.Text = d.M().ToString();}private void button2_Click(object sender, EventArgs e){//Class2 c2 = new Class2();//textBox1.Text = c2.jian();DanLi d = DanLi.Create();textBox1.Text=d.M().ToString();}}
加锁
namespace _4.线程同步Lock
{internal class Danli{// 按照上节课 单例模式来说 在单线程上使用是完全没有没有问题的// 但是在多线程的情况下 会出现多个Danli的实例 因为在多个线程同时运行时// 调用GetDanli方法 此时两个线程执行判断时(dl==null) 这和条件有可能都返回真 就会创建两个danli 这样就违背了单例模式//对于上面这种情况 我们可以使用lock 同一时间只执行一个private static Danli dl;private Danli() { }//多线程场景//定一个表示符 确保线程同步 private static readonly object locker = new object();//设置一个供外部访问的全局点public static Danli GetDl{get{//当第一个线程运行到这里是 此会对locker对象进行加锁// 当第二个线程运行此方法时 lock首先会检测locker的"加锁"状态 该县就会被挂起等待//等待到lock语句运行完毕解锁lock (locker){if (dl == null){dl = new Danli();}return dl;}}}//双重锁定public static Danli GetDl1(){if (dl ==null){lock(locker){if (dl ==null){dl =new Danli();}}}return dl;}int i = 0;public int _i{get{return i;}set{i = value;}}}class Test1{public void Get(){Danli d1 = Danli.GetDl;d1._i = 100;Console.WriteLine("这是T1访问dl的i值" + d1._i);}}class Test2{public void Get(){Danli d2 = Danli.GetDl;Console.WriteLine("这是T2访问Dl的i值" + d2._i);}}}
namespace _4.线程同步Lock
{public partial class Form1 : Form{public Form1(){InitializeComponent();}Thread T1;Thread T2;private void Form1_Load(object sender, EventArgs e){//多线程场景T1 = new Thread(() =>{Test1 t1 = new Test1();t1.Get();});T1.IsBackground = true;T2 = new Thread(() =>{Test2 t2 = new Test2();t2.Get();});T2.IsBackground = true;T1.Start();T2.Start();}}
}
