自己实现的随机数生产器

src/main/java/chapter10/random/MyRandom.java

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+package chapter10.random;
+
+
+public class MyRandom {
+	private static final int A=48271;
+	private static final int M=2147483647;
+	private static final int Q=M/A;
+	private static final int R=M%A;
+	private int state;
+	public MyRandom(){
+		state=(int) (System.currentTimeMillis()%Integer.MAX_VALUE);
+	}
+
+	/**
+	 * //防止移除的随机数 Xi+1=A(xi mod Q)-R[xi/Q]+Ms(xi)
+	 * @return
+	 */
+	public int randomInt(){
+		int tmpState=A*(state%Q)-R*(state/Q);
+		if(tmpState>=0){
+			state=tmpState;
+		}else{
+			state=tmpState+M;
+		}
+		return state;
+	}
+	public double random0_1(){
+		return (double)randomInt()/M;
+	}
+public static void main(String[] args) {
+	System.out.println(0xBL);
+	System.out.println(0x5DEECE66DL);
+	System.out.println((1L << 48) - 1);
+	//^ 异或
+	//>>> 无符号右移动
+	System.out.println((16l*0x5DEECE66DL+11)%((1L << 48) - 1));
+	System.out.println((16l*0x5DEECE66DL+11)&((1L << 48) - 1));
+	MyRandom rand=new MyRandom();
+	System.out.println(rand.randomInt());
+}
+}

src/main/java/chapter10/random/MyRandom2.java

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+package chapter10.random;
+
+import java.util.concurrent.atomic.AtomicLong;
+
+/**
+ * 仿Java实现 Xi+1=(multiplier*Xi+addend)%mask
+ * multiplier=25214903917
+ * addend=11
+ * mask=2^48-1
+ * nextInt截取前32位
+ * @author wenl
+ */
+public class MyRandom2 {
+
+	private static final Long multiplier=25214903917l;
+	private static final long addend = 11l;
+	private static final long mask = (1L << 48) - 1;
+	private AtomicLong seed;//保证线程安全
+	public MyRandom2(){
+		this.seed = new AtomicLong((8682522807148012L*181783497276652981L )^System.nanoTime());
+	}
+
+    public int nextInt() {
+        return next(32);
+    }
+    private int next(int bits) {
+        long oldseed, nextseed;
+        AtomicLong seed = this.seed;
+        do {
+            oldseed = seed.get();
+            nextseed = (oldseed * multiplier + addend) % mask;
+        } while (!seed.compareAndSet(oldseed, nextseed));
+        return (int)(nextseed >>> (48 - bits));
+    }
+
+    /**
+     * 26与27和53的选择，基于实际经验，这样会产生最后的随机数
+     * @return
+     */
+    public double next0_1() {
+        return (((long)(next(26)) << 27) + next(27))
+            / (double)(1L << 53);
+    }
+
+public static void main(String[] args) {
+	System.out.println(0xBL);
+	System.out.println(0x5DEECE66DL);
+	System.out.println((1L << 48) - 1);
+	//^ 异或
+	//>>> 无符号右移动
+	System.out.println((16l*0x5DEECE66DL+11)%((1L << 48) - 1));
+	System.out.println((16l*0x5DEECE66DL+11)&((1L << 48) - 1));
+	MyRandom2 rand=new MyRandom2();
+	System.out.println(rand.nextInt());
+}
+}