diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..6b468b6
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.class
diff --git a/IP.java b/IP.java
index d0b3a81..6cbfca0 100644
--- a/IP.java
+++ b/IP.java
@@ -72,21 +72,48 @@ public static void load(String filename, boolean strict) throws Exception {
         }
     }
 
+    private static int quickFindInIndexBuffer(long ip2long_value, int start, int end) {
+        while(true){
+            int middle = (start + end) / 2;
+            middle = middle & 0xFFFFFFF8;
+            if (middle <= start) return end;
+            long middleValue = int2long(indexBuffer.getInt(middle));
+            if (middleValue == ip2long_value) {
+                return middle;
+            } else if (middleValue > ip2long_value) {
+                if (middle + 8 == end) {
+                    return middle;
+                }
+                end = middle;
+            } else {
+                if (middle + 8 == end) {
+                    return end;
+                }
+                start = middle;
+            }
+        }
+    }
+
     public static String[] find(String ip) {
-        int ip_prefix_value = new Integer(ip.substring(0, ip.indexOf(".")));
         long ip2long_value  = ip2long(ip);
+        int ip_prefix_value = ((int)ip2long_value >> 24) & 0xFF;
         int start = index[ip_prefix_value];
         int max_comp_len = offset - 1028;
+        if(ip_prefix_value < index.length-1) {
+          max_comp_len = index[ip_prefix_value+1] * 8 + 1024;
+        }
         long index_offset = -1;
         int index_length = -1;
         byte b = 0;
-        for (start = start * 8 + 1024; start < max_comp_len; start += 8) {
-            if (int2long(indexBuffer.getInt(start)) >= ip2long_value) {
-                index_offset = bytesToLong(b, indexBuffer.get(start + 6), indexBuffer.get(start + 5), indexBuffer.get(start + 4));
-                index_length = 0xFF & indexBuffer.get(start + 7);
-                break;
-            }
+
+        int index = start * 8 + 1024;
+        if (int2long(indexBuffer.getInt(index)) < ip2long_value) {
+            index = quickFindInIndexBuffer(ip2long_value, index, max_comp_len);
         }
+        index_offset = bytesToLong(b, indexBuffer.get(index + 6), indexBuffer.get(index + 5), indexBuffer.get(index + 4));
+        index_length = 0xFF & indexBuffer.get(index + 7);
+        if (index_length <= 0)
+            return new String[0];
 
         byte[] areaBytes;
 
diff --git a/IPOld.java b/IPOld.java
new file mode 100644
index 0000000..4a2ea25
--- /dev/null
+++ b/IPOld.java
@@ -0,0 +1,183 @@
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.util.Arrays;
+import java.nio.charset.Charset;
+import java.util.Random;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.ReentrantLock;
+
+class IPOld {
+
+    public static String randomIp() {
+        Random r = new Random();
+        StringBuffer str = new StringBuffer();
+        str.append(r.nextInt(1000000) % 255);
+        str.append(".");
+        str.append(r.nextInt(1000000) % 255);
+        str.append(".");
+        str.append(r.nextInt(1000000) % 255);
+        str.append(".");
+        str.append(0);
+
+        return str.toString();
+    }
+
+    public static void main(String[] args){
+        IP.load("H:\\loveapp\\codebase\\17mon\\17monipdb.dat");
+
+        Long st = System.nanoTime();
+        for (int i = 0; i < 1000000; i++)
+        {
+            IP.find(randomIp());
+        }
+        Long et = System.nanoTime();
+        System.out.println((et - st) / 1000 / 1000);
+
+        System.out.println(Arrays.toString(IP.find("118.28.8.8")));
+    }
+
+    public static boolean enableFileWatch = false;
+
+    private static int offset;
+    private static int[] index = new int[256];
+    private static ByteBuffer dataBuffer;
+    private static ByteBuffer indexBuffer;
+    private static Long lastModifyTime = 0L;
+    private static File ipFile ;
+    private static ReentrantLock lock = new ReentrantLock();
+
+    public static void load(String filename) {
+        ipFile = new File(filename);
+        load();
+        if (enableFileWatch) {
+            watch();
+        }
+    }
+
+    public static void load(String filename, boolean strict) throws Exception {
+        ipFile = new File(filename);
+        if (strict) {
+            int contentLength = Long.valueOf(ipFile.length()).intValue();
+            if (contentLength < 512 * 1024) {
+                throw new Exception("ip data file error.");
+            }
+        }
+        load();
+        if (enableFileWatch) {
+            watch();
+        }
+    }
+
+    public static String[] find(String ip) {
+        int ip_prefix_value = new Integer(ip.substring(0, ip.indexOf(".")));
+        long ip2long_value  = ip2long(ip);
+        int start = index[ip_prefix_value];
+        int max_comp_len = offset - 1028;
+        long index_offset = -1;
+        int index_length = -1;
+        byte b = 0;
+        for (start = start * 8 + 1024; start < max_comp_len; start += 8) {
+            if (int2long(indexBuffer.getInt(start)) >= ip2long_value) {
+                index_offset = bytesToLong(b, indexBuffer.get(start + 6), indexBuffer.get(start + 5), indexBuffer.get(start + 4));
+                index_length = 0xFF & indexBuffer.get(start + 7);
+                break;
+            }
+        }
+
+        byte[] areaBytes;
+
+        lock.lock();
+        try {
+            dataBuffer.position(offset + (int) index_offset - 1024);
+            areaBytes = new byte[index_length];
+            dataBuffer.get(areaBytes, 0, index_length);
+        } finally {
+            lock.unlock();
+        }
+
+        return new String(areaBytes, Charset.forName("UTF-8")).split("\t", -1);
+    }
+
+    private static void watch() {
+        Executors.newScheduledThreadPool(1).scheduleAtFixedRate(new Runnable() {
+            @Override
+            public void run() {
+                long time = ipFile.lastModified();
+                if (time > lastModifyTime) {
+                    lastModifyTime = time;
+                    load();
+                }
+            }
+        }, 1000L, 5000L, TimeUnit.MILLISECONDS);
+    }
+
+    private static void load() {
+        lastModifyTime = ipFile.lastModified();
+        FileInputStream fin = null;
+        lock.lock();
+        try {
+            dataBuffer = ByteBuffer.allocate(Long.valueOf(ipFile.length()).intValue());
+            fin = new FileInputStream(ipFile);
+            int readBytesLength;
+            byte[] chunk = new byte[4096];
+            while (fin.available() > 0) {
+                readBytesLength = fin.read(chunk);
+                dataBuffer.put(chunk, 0, readBytesLength);
+            }
+            dataBuffer.position(0);
+            int indexLength = dataBuffer.getInt();
+            byte[] indexBytes = new byte[indexLength];
+            dataBuffer.get(indexBytes, 0, indexLength - 4);
+            indexBuffer = ByteBuffer.wrap(indexBytes);
+            indexBuffer.order(ByteOrder.LITTLE_ENDIAN);
+            offset = indexLength;
+
+            int loop = 0;
+            while (loop++ < 256) {
+                index[loop - 1] = indexBuffer.getInt();
+            }
+            indexBuffer.order(ByteOrder.BIG_ENDIAN);
+        } catch (IOException ioe) {
+            ioe.printStackTrace();
+        } finally {
+            try {
+                if (fin != null) {
+                    fin.close();
+                }
+            } catch (IOException e){
+                e.printStackTrace();
+            }
+            lock.unlock();
+        }
+    }
+
+    private static long bytesToLong(byte a, byte b, byte c, byte d) {
+        return int2long((((a & 0xff) << 24) | ((b & 0xff) << 16) | ((c & 0xff) << 8) | (d & 0xff)));
+    }
+
+    private static int str2Ip(String ip)  {
+        String[] ss = ip.split("\\.");
+        int a, b, c, d;
+        a = Integer.parseInt(ss[0]);
+        b = Integer.parseInt(ss[1]);
+        c = Integer.parseInt(ss[2]);
+        d = Integer.parseInt(ss[3]);
+        return (a << 24) | (b << 16) | (c << 8) | d;
+    }
+
+    private static long ip2long(String ip)  {
+        return int2long(str2Ip(ip));
+    }
+
+    private static long int2long(int i) {
+        long l = i & 0x7fffffffL;
+        if (i < 0) {
+            l |= 0x080000000L;
+        }
+        return l;
+    }
+}
diff --git a/TestMain.java b/TestMain.java
new file mode 100644
index 0000000..b815a26
--- /dev/null
+++ b/TestMain.java
@@ -0,0 +1,61 @@
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.util.Arrays;
+import java.nio.charset.Charset;
+import java.util.Random;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.ReentrantLock;
+
+
+class TestMain {
+  
+  public static void main(String[] args){
+      IPOld.load("/Users/york/htdocs/kankan-mp4-extractor/libs/ipip/17monipdb.dat");
+      IP.load("/Users/york/htdocs/kankan-mp4-extractor/libs/ipip/17monipdb.dat");
+      
+      final int testSize = 100 * 10000;
+      String[] ips = new String[testSize];
+      for(int i=0; i<testSize; i++){
+        ips[i] = IP.randomIp();
+      }
+      ips[0] = "119.147.158.186";
+      ips[1] = "223.136.200.228";
+      ips[2] = "68.104.105.223";
+      ips[3] = "1.64.29.228";
+      System.out.println("ip random completed");
+      
+      
+      // check that the return value of new implement and old implement are the same
+      for(int i=0; i<testSize; i++){
+        String[] newReturn = IP.find(ips[i]);
+        String[] oldReturn = IPOld.find(ips[i]);
+        if (!Arrays.deepEquals(newReturn, oldReturn)) {
+            System.out.println("ip info not equal for: " + ips[i]);
+            System.out.println(Arrays.toString(newReturn));
+            System.out.println(Arrays.toString(oldReturn));
+            System.exit(1);
+        }
+      }
+      
+      // compare the performance
+      Long startNew = System.nanoTime();
+      for(int i=0; i<testSize; i++){
+          IP.find(ips[i]);
+      }
+      Long endNew = System.nanoTime();
+      System.out.println("execute time of new implement is: " + (endNew - startNew) / 1000 / 1000);
+
+      Long startOld = System.nanoTime();
+      for(int i=0; i<testSize; i++){
+          IPOld.find(ips[i]);
+      }
+      Long endOld = System.nanoTime();
+      System.out.println("execute time of old implement is: " + (endOld - startOld) / 1000 / 1000);
+  }
+  
+  
+}
\ No newline at end of file