maybeContains

src/main/java/com/github/bingoohuang/voucherno/BloomFilter.java

@@ -8,7 +8,6 @@
  */
 public class BloomFilter {
     private final RedisBitSet bitSet;
-
     private final int bitSetSize;
     private final int k; // number of hash functions
 
@@ -63,9 +62,7 @@ public boolean add(String element) {
      * @return added without conflicts or not.
      */
     public boolean add(byte[] bytes) {
-        int[] hashes = createHashes(bytes);
-
-        return bitSet.add(hashes);
+        return bitSet.add(createHashes(bytes));
     }
 
     /**
@@ -76,8 +73,8 @@ public boolean add(byte[] bytes) {
      * @param element element to check.
      * @return true if the element could have been inserted into the Bloom filter.
      */
-    public boolean contains(String element) {
-        return contains(element.getBytes(MessageDigestUtils.UTF8));
+    public boolean maybeContains(String element) {
+        return maybeContains(element.getBytes(MessageDigestUtils.UTF8));
     }
 
     /**
@@ -88,10 +85,8 @@ public boolean contains(String element) {
      * @param bytes array of bytes to check.
      * @return true if the array could have been inserted into the Bloom filter.
      */
-    public boolean contains(byte[] bytes) {
-        int[] hashes = createHashes(bytes);
-
-        return bitSet.contains(hashes);
+    public boolean maybeContains(byte[] bytes) {
+        return bitSet.maybeContains(createHashes(bytes));
     }
 
     private int[] createHashes(byte[] bytes) {

src/main/java/com/github/bingoohuang/voucherno/RedisBitSet.java

@@ -19,12 +19,14 @@ public RedisBitSet(BinaryJedis jedis, String name) {
     public boolean add(int[] hashes) {
         val multi = jedis.multi();
         Arrays.stream(hashes).forEach(x -> multi.setbit(name, x, Protocol.BYTES_TRUE));
+        // 只要有一个比特位之前没被设置过，说明曾经不存在，返回为true
         return multi.exec().stream().filter(x -> x == Boolean.FALSE).count() > 0;
     }
 
-    public boolean contains(int[] hashes) {
+    public boolean maybeContains(int[] hashes) {
         val multi = jedis.multi();
         Arrays.stream(hashes).forEach(x -> multi.getbit(name, x));
+        // 所有比特位，都被设置了，那就是可能被包含了。
         return multi.exec().stream().filter(x -> x == Boolean.FALSE).count() == 0;
     }
 }

src/main/java/com/github/bingoohuang/voucherno/Strs.java

@@ -0,0 +1,17 @@
+package com.github.bingoohuang.voucherno;
+
+import java.util.stream.IntStream;
+
+public class Strs {
+    public static StringBuilder fixedLength(StringBuilder s, int len) {
+        int diff = len - s.length();
+        if (diff < 0) return s.delete(len, s.length());
+        if (diff > 0) return padZero(s, diff);
+        return s;
+    }
+
+    public static StringBuilder padZero(StringBuilder s, int diff) {
+        IntStream.range(0, diff).forEach(x -> s.append('0'));
+        return s;
+    }
+}

src/main/java/com/github/bingoohuang/voucherno/VoucherNo.java

@@ -31,34 +31,16 @@ public String next() {
      */
     public String next(int maxTries) {
         for (int i = 1; i <= maxTries; ++i) {
-            val s = new StringBuilder(32);
-            s.append(Math.abs(r.nextLong()));
-            String n = fixedLength(s);
-
-            if (filter.add(n)) return n;
+            val sb = new StringBuilder(32).append(Math.abs(r.nextLong()));
+            val s = Strs.fixedLength(sb, len).toString();
+            if (filter.add(s)) return s;
         }
 
         throw new RuntimeException("try out times");
     }
 
-    String fixedLength(StringBuilder s) {
-        int diff = len - s.length();
-        if (diff < 0) {
-            s.delete(len, s.length());
-        } else if (diff > 0) {
-            padZero(s, diff);
-        }
-
-        return s.toString();
-    }
-
-    void padZero(StringBuilder s, int diff) {
-        for (int i = 0; i < diff; ++i) {
-            s.append('0');
-        }
-    }
 
-    public boolean contains(String no) {
-        return filter.contains(no);
+    public boolean maybeContains(String no) {
+        return filter.maybeContains(no);
     }
 }

src/test/java/com/github/bingoohuang/voucherno/VoucherNoTest.java

@@ -31,18 +31,16 @@ public void test() {
             val no = voucherNo.next();
             log.info("voucher NO:{}", no);
             assertThat(no).containsMatch("\\d{12}");
-            assertThat(voucherNo.contains(no)).isTrue();
+            assertThat(voucherNo.maybeContains(no)).isTrue();
         }
     }
 
     @Test
     public void padZero() {
         StringBuilder sb = new StringBuilder("1");
-        voucherNo.padZero(sb, 10);
-        assertThat(sb.toString()).isEqualTo("10000000000");
+        assertThat(Strs.padZero(sb, 10).toString()).isEqualTo("10000000000");
 
         StringBuilder s = new StringBuilder("1");
-        String n = voucherNo.fixedLength(s);
-        assertThat(n).isEqualTo("100000000000");
+        assertThat(Strs.fixedLength(s, 12).toString()).isEqualTo("100000000000");
     }
 }