diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/Config.java b/binding/java/src/main/java/org/lionsoul/ip2region/Config.java
index 196c6a0..3012ef8 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/Config.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/Config.java
@@ -6,7 +6,7 @@ package org.lionsoul.ip2region;
 import java.io.IOException;
 
 import org.lionsoul.ip2region.xdb.Header;
-import org.lionsoul.ip2region.xdb.Searcher;
+import org.lionsoul.ip2region.xdb.LongByteArray;
 import org.lionsoul.ip2region.xdb.Version;
 import org.lionsoul.ip2region.xdb.XdbException;
 
@@ -23,55 +23,60 @@ public class Config {
 
     // search cache policy
     public final int cachePolicy;
+    public final Version ipVersion;
 
     // xdb file path
     public final String xdbPath;
     public final Header header;
-    public final Version ipVersion;
 
-    // searcher pool limitation
-    public final int minSearchers;
-    public final int maxSearchers;
+    public final byte[] vIndex;
+    public final LongByteArray cBuffer;
+
+    public final int searchers;
 
     // config builder
     public static ConfigBuilder custom() {
         return new ConfigBuilder();
     }
 
-    public Config(int cachePolicy, Version ipVersion, String xdbPath) throws IOException, XdbException {
-        this(cachePolicy, ipVersion, xdbPath, 10, 50);
-    }
-
-    public Config(int cachePolicy, Version ipVersion, String xdbPath, int minSearchers, int maxSearchers) throws IOException, XdbException {
+    protected Config(int cachePolicy, Version ipVersion, String xdbPath, 
+        Header header, byte[] vIndex, LongByteArray cBuffer, int searchers) throws IOException, XdbException {
         this.cachePolicy = cachePolicy;
-        this.xdbPath = xdbPath;
-
-        // load the header from the xdb path
-        final Header header = Searcher.loadHeaderFromFile(xdbPath);
-        this.header = header;
-        final Version xVersion = Version.fromHeader(header);
-
-        // this.ipVersion = Version.fromHeader(header);
         this.ipVersion = ipVersion;
 
+        this.xdbPath = xdbPath;
+        this.header = header;
+        this.vIndex = vIndex;
+        this.cBuffer = cBuffer;
+
+        final Version xVersion = Version.fromHeader(header);
         // verify the ip version (ipVersion and the version of the xdb file should be the same)
         if (header.ipVersion != ipVersion.id) {
-            throw new XdbException("ip verison not match: xdb file " + xdbPath + " (" + xVersion.name + "), as " + ipVersion.name + " expected");
+            throw new XdbException("ip verison not match: xdb file " 
+                + xdbPath + " (" + xVersion.name + "), as " + ipVersion.name + " expected");
         }
 
-        this.minSearchers = minSearchers;
-        this.maxSearchers = maxSearchers;
+        this.searchers = searchers;
     }
 
     @Override public String toString() {
         final StringBuffer sb = new StringBuffer();
         sb.append('{');
         sb.append("cache_policy:").append(cachePolicy).append(',');
+        sb.append("version:").append(ipVersion.toString()).append(',');
         sb.append("xdb_path:").append(xdbPath).append(',');
         sb.append("header:").append(header.toString()).append(',');
-        sb.append("version:").append(ipVersion.toString()).append(',');
-        sb.append("min_searchers:").append(minSearchers).append(',');
-        sb.append("max_searchers:").append(maxSearchers);
+        if (vIndex == null) {
+            sb.append("v_index: null, ");
+        } else {
+            sb.append("v_index: {bytes: ").append(vIndex.length).append("},");
+        }
+        if (cBuffer == null) {
+            sb.append("c_buffer: null, ");
+        } else {
+            sb.append("c_buffer: {bytes: ").append(cBuffer.length()).append("},");
+        }
+        sb.append("searchers:").append(searchers);
         sb.append('}');
         return sb.toString();
     }
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/ConfigBuilder.java b/binding/java/src/main/java/org/lionsoul/ip2region/ConfigBuilder.java
index d0ee092..4bdb77d 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/ConfigBuilder.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/ConfigBuilder.java
@@ -5,7 +5,11 @@
 package org.lionsoul.ip2region;
 
 import java.io.IOException;
+import java.io.RandomAccessFile;
 
+import org.lionsoul.ip2region.xdb.Header;
+import org.lionsoul.ip2region.xdb.LongByteArray;
+import org.lionsoul.ip2region.xdb.Searcher;
 import org.lionsoul.ip2region.xdb.Version;
 import org.lionsoul.ip2region.xdb.XdbException;
 
@@ -22,11 +26,8 @@ public class ConfigBuilder {
     // xdb file path
     private String xdbPath = null;
 
-    // min searchers
-    private int minSearchers = 10;
-
-    // max searchers
-    private int maxSearchers = 30;
+    // searchers
+    private int searchers = 20;
 
     public ConfigBuilder() {}
 
@@ -44,24 +45,39 @@ public class ConfigBuilder {
         return this;
     }
 
-    public ConfigBuilder setMinSearchers(int minSearchers) {
-        this.minSearchers = minSearchers;
+    public ConfigBuilder setSeachers(int searchers) {
+        this.searchers = searchers;
         return this;
     }
 
-    public ConfigBuilder setMaxSearchers(int maxSearchers) {
-        this.maxSearchers = maxSearchers;
-        return this;
+    private Config build(Version ipVersion) throws IOException, XdbException {
+        // load the header and the cache buffer
+        final RandomAccessFile raf = new RandomAccessFile(xdbPath, "r");
+
+        // 1, verify the xdb
+        Searcher.verify(raf);
+
+        // 2, load the header
+        final Header header = Searcher.loadHeader(raf);
+
+        // 3, check and load the vector index buffer
+        final byte[] vIndex = cachePolicy == Config.VIndexCache ? Searcher.loadVectorIndex(raf) : null;
+
+        // 4, check and load the content buffer
+        final LongByteArray cBuffer = cachePolicy == Config.BufferCache ? Searcher.loadContent(raf) : null;
+
+        raf.close();
+        return new Config(cachePolicy, ipVersion, xdbPath, header, vIndex, cBuffer, searchers);
     }
 
     // build the final #Config instance for IPv4
     public Config asV4() throws IOException, XdbException {
-        return new Config(cachePolicy, Version.IPv4, xdbPath, minSearchers, maxSearchers);
+        return build(Version.IPv4);
     }
 
     // build the final #Config instance for IPv6
     public Config asV6() throws IOException, XdbException {
-        return new Config(cachePolicy, Version.IPv6, xdbPath, minSearchers, maxSearchers);
+        return build(Version.IPv6);
     }
 
 }
\ No newline at end of file
diff --git a/binding/java/src/test/java/org/lionsoul/ip2region/ConfigTest.java b/binding/java/src/test/java/org/lionsoul/ip2region/ConfigTest.java
index c86b0d0..5664012 100644
--- a/binding/java/src/test/java/org/lionsoul/ip2region/ConfigTest.java
+++ b/binding/java/src/test/java/org/lionsoul/ip2region/ConfigTest.java
@@ -4,7 +4,6 @@ import java.security.CodeSource;
 
 import org.junit.Test;
 import org.lionsoul.ip2region.xdb.Log;
-import org.lionsoul.ip2region.xdb.Version;
 import org.lionsoul.ip2region.xdb.XdbException;
 
 public class ConfigTest {
@@ -22,19 +21,22 @@ public class ConfigTest {
     }
 
     @Test
-    public void testConfig() throws IOException, XdbException {
-        final Config config = new Config(Config.VIndexCache, Version.IPv4, getDataPath("ip2region_v4.xdb"), 5, 10);
-        log.debugf("config: %s", config);
+    public void testBuildV4Config() throws IOException, XdbException {
+        final Config v4Config = Config.custom()
+            .setCachePolicy(Config.BufferCache)
+            .setXdbPath(getDataPath("ip2region_v4.xdb"))
+            .setSeachers(20)
+            .asV4();
+        log.debugf("builded config: %s", v4Config);
     }
 
     @Test
-    public void testBuildConfig() throws IOException, XdbException {
-        final Config config = Config.custom()
-            .setCachePolicy(Config.BufferCache)
+    public void testBuildV6Config() throws IOException, XdbException {
+        final Config v4Config = Config.custom()
+            .setCachePolicy(Config.VIndexCache)
             .setXdbPath(getDataPath("ip2region_v6.xdb"))
-            .setMinSearchers(10)
-            .setMaxSearchers(30)
+            .setSeachers(20)
             .asV6();
-        log.debugf("builded config: %s", config);
+        log.debugf("builded config: %s", v4Config);
     }
 }
\ No newline at end of file