1 package book.jcp.ch01.basic; 2  3 import java.math.BigInteger; 4  5 public class CachedFactorizer { 6  7     private BigInteger lastNumberBigInteger; 8     private BigInteger[] lastFactorsBigIntegers; 9     private long hits;10     private long cacheHits;11 12     public synchronized long getHits() {13         return hits;14     }15 16     public synchronized double getHitRatio() {17         return (double) cacheHits / (double) hits;18     }19 20     public void service(int req, int resp) {21         BigInteger i = extractFromRequest(req);22         BigInteger[] newFactors = null;23         synchronized (this) {24             ++hits;25             if (i.equals(lastNumberBigInteger)) {26                 ++cacheHits;27                 newFactors = lastFactorsBigIntegers.clone();28             }29         }30         if (newFactors == null) {31             newFactors = factor(i);32             synchronized (this) {33                 lastNumberBigInteger = i;34                 lastFactorsBigIntegers = newFactors.clone();35             }36         }37         encodeIntoResponse(resp, newFactors);38     }39 40     private BigInteger[] factor(BigInteger i) {41         // TODO Auto-generated method stub42         return null;43     }44 45     private void encodeIntoResponse(int resp, BigInteger[] factors) {46         // TODO Auto-generated method stub47 48     }49 50     private BigInteger extractFromRequest(int req) {51         // TODO Auto-generated method stub52         return null;53     }54 }