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| 1 | +package go_27 |
| 2 | + |
| 3 | +import ( |
| 4 | + "fmt" |
| 5 | + "sync" |
| 6 | + "testing" |
| 7 | + "unsafe" |
| 8 | +) |
| 9 | + |
| 10 | +/* |
| 11 | +其实就是java里面的单例模式,一样理解即可 |
| 12 | +go语言里面有个once方法只会执行一次,使用这个实现线程安全的懒汉单例模式 |
| 13 | +*/ |
| 14 | + |
| 15 | +type Singleton struct { |
| 16 | + data string |
| 17 | +} |
| 18 | + |
| 19 | +var sigleInstance *Singleton |
| 20 | +var once sync.Once |
| 21 | + |
| 22 | +func GetSingletonObj() *Singleton { |
| 23 | + |
| 24 | + //这个方法只会执行一次,不需要像java一样非空判断,第一次是肯定会创建对象的,且只会执行一次 |
| 25 | + once.Do(func() { |
| 26 | + fmt.Println("Create Obj") |
| 27 | + sigleInstance = new(Singleton) |
| 28 | + }) |
| 29 | + return sigleInstance |
| 30 | +} |
| 31 | + |
| 32 | +func TestGetSingletonObj(t *testing.T) { |
| 33 | + var wg sync.WaitGroup |
| 34 | + for i := 0; i < 10; i++ { |
| 35 | + wg.Add(1) |
| 36 | + go func() { |
| 37 | + obj := GetSingletonObj() |
| 38 | + fmt.Printf("对象引用地址:%X\n", unsafe.Pointer(obj)) |
| 39 | + wg.Done() |
| 40 | + }() |
| 41 | + } |
| 42 | + wg.Wait() |
| 43 | +} |
| 44 | + |
| 45 | +/* |
| 46 | +运行结果:可以看到对象只创建了一次,后面都是获取的同一个对象引用,与java单例模式一样理解即可 |
| 47 | +=== RUN TestGetSingletonObj |
| 48 | +Create Obj |
| 49 | +对象引用地址:C000030010 |
| 50 | +对象引用地址:C000030010 |
| 51 | +对象引用地址:C000030010 |
| 52 | +对象引用地址:C000030010 |
| 53 | +对象引用地址:C000030010 |
| 54 | +对象引用地址:C000030010 |
| 55 | +对象引用地址:C000030010 |
| 56 | +对象引用地址:C000030010 |
| 57 | +对象引用地址:C000030010 |
| 58 | +对象引用地址:C000030010 |
| 59 | +--- PASS: TestGetSingletonObj (0.00s) |
| 60 | +PASS |
| 61 | +*/ |
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