diff --git a/binding/java/ReadMe.md b/binding/java/ReadMe.md
index 363fbe0..7471578 100644
--- a/binding/java/ReadMe.md
+++ b/binding/java/ReadMe.md
@@ -7,7 +7,7 @@
 <dependency>
     <groupId>org.lionsoul</groupId>
     <artifactId>ip2region</artifactId>
-    <version>3.3.0</version>
+    <version>3.3.1</version>
 </dependency>
 ```
 
@@ -21,6 +21,8 @@ import org.lionsoul.ip2region.service.Ip2Region;
 final Config v4Config = Config.custom()
     .setCachePolicy(Config.VIndexCache)     // 指定缓存策略:  NoCache / VIndexCache / BufferCache
     .setSearchers(15)                       // 设置初始化的查询器数量
+    // .setXdbInputStream(InputStream)      // 设置 v4 xdb 文件的 inputstream 对象
+    // .setXdbFile(File)                    // 设置 v4 xdb File 对象
     .setXdbPath("ip2region v4 xdb path")    // 设置 v4 xdb 文件的路径
     .asV4();    // 指定为 v4 配置
 
@@ -28,9 +30,13 @@ final Config v4Config = Config.custom()
 final Config v6Config = Config.custom()
     .setCachePolicy(Config.VIndexCache)     // 指定缓存策略: NoCache / VIndexCache / BufferCache
     .setSearchers(15)                       // 设置初始化的查询器数量
+    // .setXdbInputStream(InputStream)      // 设置 v6 xdb 文件的 inputstream 对象
+    // .setXdbFile(File)                    // 设置 v6 xdb File 对象
     .setXdbPath("ip2region v6 xdb path")    // 设置 v6 xdb 文件的路径
     .asV6();    // 指定为 v6 配置
 
+// 备注：Xdb 三种初始化输入的优先级：XdbInputStream -> XdbFile -> XdbPath
+
 // 3，通过上述配置创建 Ip2Region 查询服务
 final Ip2Region ip2Region = Ip2Region.create(v4Config, v6Config);
 
diff --git a/binding/java/pom.xml b/binding/java/pom.xml
index ce1b62d..248795b 100644
--- a/binding/java/pom.xml
+++ b/binding/java/pom.xml
@@ -4,7 +4,7 @@
 
     <groupId>org.lionsoul</groupId>
     <artifactId>ip2region</artifactId>
-    <version>3.3.0</version>
+    <version>3.3.1</version>
     <packaging>jar</packaging>
 
     <name>ip2region</name>
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/SearcherTest.java b/binding/java/src/main/java/org/lionsoul/ip2region/SearcherTest.java
index 279160f..33506f9 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/SearcherTest.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/SearcherTest.java
@@ -7,7 +7,7 @@
 package org.lionsoul.ip2region;
 
 import org.lionsoul.ip2region.service.Config;
-import org.lionsoul.ip2region.service.InvalidCachePolicyException;
+import org.lionsoul.ip2region.service.InvalidConfigException;
 import org.lionsoul.ip2region.service.Ip2Region;
 import org.lionsoul.ip2region.xdb.InetAddressException;
 import org.lionsoul.ip2region.xdb.XdbException;
@@ -49,7 +49,7 @@ public class SearcherTest {
     }
 
     public static final Ip2Region createService(
-        String v4XdbPath, String v4CachePolicy, String v6XdbPath, String v6CachePolicy) throws IOException, XdbException, InvalidCachePolicyException {
+        String v4XdbPath, String v4CachePolicy, String v6XdbPath, String v6CachePolicy) throws IOException, XdbException, InvalidConfigException {
         final Config v4Config = Config.custom()
             .setCachePolicy(Config.cachePolicyFromName(v4CachePolicy))
             .setSearchers(1)
@@ -89,7 +89,7 @@ public class SearcherTest {
         }
     }
 
-    public static void searchTest(String[] args) throws IOException, XdbException, InvalidCachePolicyException, InterruptedException {
+    public static void searchTest(String[] args) throws IOException, XdbException, InterruptedException, InvalidConfigException {
         String help = "";
         String v4DbPath = "", v4CachePolicy = "vectorIndex";
         String v6DbPath = "", v6CachePolicy = "vectorIndex";
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/service/Config.java b/binding/java/src/main/java/org/lionsoul/ip2region/service/Config.java
index 8e8388b..0cb938c 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/service/Config.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/service/Config.java
@@ -4,6 +4,7 @@
 
 package org.lionsoul.ip2region.service;
 
+import java.io.File;
 import java.io.IOException;
 
 import org.lionsoul.ip2region.xdb.Header;
@@ -22,12 +23,15 @@ public class Config {
     public static final int VIndexCache = 1;
     public static final int BufferCache = 2;
 
+    // alias of BufferCache but easier to understand or Remember
+    public static final int FullCache = 2;
+
     // search cache policy
     public final int cachePolicy;
     public final Version ipVersion;
 
     // xdb file path
-    public final String xdbPath;
+    public final File xdbFile;
     public final Header header;
 
     public final byte[] vIndex;
@@ -40,21 +44,21 @@ public class Config {
         return new ConfigBuilder();
     }
 
-    protected Config(int cachePolicy, Version ipVersion, String xdbPath, 
+    protected Config(int cachePolicy, Version ipVersion, File xdbFile, 
         Header header, byte[] vIndex, LongByteArray cBuffer, int searchers) throws IOException, XdbException {
         this.cachePolicy = cachePolicy;
         this.ipVersion = ipVersion;
 
-        this.xdbPath = xdbPath;
-        this.header = header;
-        this.vIndex = vIndex;
+        this.xdbFile = xdbFile;
+        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");
+                + xdbFile.getAbsolutePath() + " (" + xVersion.name + "), as " + ipVersion.name + " expected");
         }
 
         this.searchers = searchers;
@@ -65,7 +69,7 @@ public class Config {
         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("xdb_path:").append(xdbFile == null ? "null" : xdbFile.getAbsolutePath()).append(',');
         sb.append("header:").append(header.toString()).append(',');
         if (vIndex == null) {
             sb.append("v_index: null, ");
@@ -82,7 +86,7 @@ public class Config {
         return sb.toString();
     }
 
-    public static final int cachePolicyFromName(String name) throws InvalidCachePolicyException {
+    public static final int cachePolicyFromName(String name) throws InvalidConfigException {
         final String lName = name.toLowerCase();
         if (lName.equals("file") || lName.equals("nocache")) {
             return NoCache;
@@ -91,7 +95,7 @@ public class Config {
         } else if (lName.equals("content") || lName.equals("buffercache")) {
             return BufferCache;
         } else {
-            throw new InvalidCachePolicyException("invalid cache policy `" + name + "`");
+            throw new InvalidConfigException("invalid cache policy `" + name + "`");
         }
     }
 }
\ No newline at end of file
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/service/ConfigBuilder.java b/binding/java/src/main/java/org/lionsoul/ip2region/service/ConfigBuilder.java
index dd838bd..06dd6d6 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/service/ConfigBuilder.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/service/ConfigBuilder.java
@@ -4,7 +4,9 @@
 
 package org.lionsoul.ip2region.service;
 
+import java.io.File;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.RandomAccessFile;
 
 import org.lionsoul.ip2region.xdb.Header;
@@ -23,8 +25,11 @@ public class ConfigBuilder {
     // cache policy
     private int cachePolicy = Config.VIndexCache;
 
-    // xdb file path
+    // xdb file path / Object / InputStream.
+    // Priority: InputStream -> File Object -> String path
     private String xdbPath = null;
+    private File xdbFile = null;
+    private InputStream xdbInputStream = null;
 
     // searchers
     private int searchers = 20;
@@ -45,14 +50,53 @@ public class ConfigBuilder {
         return this;
     }
 
+    public ConfigBuilder setXdbFile(File xdbFile) {
+        this.xdbFile = xdbFile;
+        return this;
+    }
+
+    public ConfigBuilder setXdbInputStream(InputStream xdbInputStream) {
+        this.xdbInputStream = xdbInputStream;
+        return this;
+    }
+
     public ConfigBuilder setSearchers(int searchers) {
         this.searchers = searchers;
         return this;
     }
 
-    private Config build(Version ipVersion) throws IOException, XdbException {
+    private Config build(Version ipVersion) throws IOException, XdbException, InvalidConfigException {
+        if (xdbInputStream == null) {
+            // everyting is fine
+        } else if (cachePolicy != Config.BufferCache) {
+            // @Note: we can't directly rewrite the cachePolicy to Config.BufferCache.
+            // you must know what you are doing.
+            throw new InvalidConfigException("SetXdbInputStream could ONLY be used with cachePolicy = Config.BufferCache");
+        } else {
+            // 1, load the content buffer
+            final LongByteArray cBuffer = Searcher.loadContentFromInputStream(xdbInputStream);
+
+            // 2, verify the xdb from the buffer
+            Searcher.verify(Searcher.loadHeaderFromBuffer(cBuffer), cBuffer.length());
+
+            // 3, load the header
+            final Header header = Searcher.loadHeaderFromBuffer(cBuffer);
+
+            // create the config without xdbFile and vIndex
+            return new Config(cachePolicy, ipVersion, null, header, null, cBuffer, searchers);
+        }
+
         // load the header and the cache buffer
-        final RandomAccessFile raf = new RandomAccessFile(xdbPath, "r");
+        final File xdbFile;
+        if (this.xdbFile != null) {
+            xdbFile = this.xdbFile;
+        } else if (this.xdbPath != null) {
+            xdbFile = new File(this.xdbPath);
+        } else {
+            throw new InvalidConfigException("Both xdbFile and xdbPath is null");
+        }
+
+        final RandomAccessFile raf = new RandomAccessFile(xdbFile, "r");
 
         // 1, verify the xdb
         Searcher.verify(raf);
@@ -67,16 +111,16 @@ public class ConfigBuilder {
         final LongByteArray cBuffer = cachePolicy == Config.BufferCache ? Searcher.loadContent(raf) : null;
 
         raf.close();
-        return new Config(cachePolicy, ipVersion, xdbPath, header, vIndex, cBuffer, searchers);
+        return new Config(cachePolicy, ipVersion, xdbFile, header, vIndex, cBuffer, searchers);
     }
 
     // build the final #Config instance for IPv4
-    public Config asV4() throws IOException, XdbException {
+    public Config asV4() throws IOException, XdbException, InvalidConfigException {
         return build(Version.IPv4);
     }
 
     // build the final #Config instance for IPv6
-    public Config asV6() throws IOException, XdbException {
+    public Config asV6() throws IOException, XdbException, InvalidConfigException {
         return build(Version.IPv6);
     }
 
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/service/InvalidCachePolicyException.java b/binding/java/src/main/java/org/lionsoul/ip2region/service/InvalidCachePolicyException.java
deleted file mode 100644
index 348e58f..0000000
--- a/binding/java/src/main/java/org/lionsoul/ip2region/service/InvalidCachePolicyException.java
+++ /dev/null
@@ -1,11 +0,0 @@
-// Copyright 2022 The Ip2Region Authors. All rights reserved.
-// Use of this source code is governed by a Apache2.0-style
-// license that can be found in the LICENSE file.
-
-package org.lionsoul.ip2region.service;
-
-public class InvalidCachePolicyException extends Exception {
-    public InvalidCachePolicyException(String str) {
-        super(str);
-    }
-}
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/service/InvalidConfigException.java b/binding/java/src/main/java/org/lionsoul/ip2region/service/InvalidConfigException.java
new file mode 100644
index 0000000..a46a00c
--- /dev/null
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/service/InvalidConfigException.java
@@ -0,0 +1,7 @@
+package org.lionsoul.ip2region.service;
+
+public class InvalidConfigException extends Exception {
+    public InvalidConfigException(String str) {
+        super(str);
+    }
+}
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/service/Ip2Region.java b/binding/java/src/main/java/org/lionsoul/ip2region/service/Ip2Region.java
index a6fc03a..d55073b 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/service/Ip2Region.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/service/Ip2Region.java
@@ -4,6 +4,7 @@
 
 package org.lionsoul.ip2region.service;
 
+import java.io.File;
 import java.io.IOException;
 
 import org.lionsoul.ip2region.xdb.InetAddressException;
@@ -37,23 +38,28 @@ public class Ip2Region {
         return new Ip2Region(v4Config, v6Config).init();
     }
 
-    public static final Ip2Region create(final String v4XdbPath, final String v6XdbPath) throws IOException, XdbException {
-        return new Ip2Region(v4XdbPath, v6XdbPath).init();
+    public static final Ip2Region create(final String v4XdbPath, final String v6XdbPath) throws IOException, XdbException, InvalidConfigException {
+        return new Ip2Region(new File(v4XdbPath), new File(v6XdbPath)).init();
+    }
+
+    public static final Ip2Region create(final File v4XdbFile, final File v6XdbFile) throws IOException, XdbException, InvalidConfigException {
+        return new Ip2Region(v4XdbFile, v6XdbFile).init();
     }
 
     /**
      * init the ip2reigon with two xdb file path and default cachePolicy vIndex.
      * set it to null to disabled the search for specified version
      * 
-     * @param v4XdbPath
-     * @param v6XdbPath
+     * @param v4XdbFile
+     * @param v6XdbFile
      * @throws XdbException 
      * @throws IOException 
+     * @throws InvalidConfigException 
     */
-    protected Ip2Region(String v4XdbPath, String v6XdbPath) throws IOException, XdbException {
+    protected Ip2Region(File v4XdbFile, File v6XdbFile) throws IOException, XdbException, InvalidConfigException {
         this(
-            v4XdbPath == null ? null : Config.custom().setXdbPath(v4XdbPath).asV4(), 
-            v6XdbPath == null ? null : Config.custom().setXdbPath(v6XdbPath).asV6()
+            v4XdbFile == null ? null : Config.custom().setXdbFile(v4XdbFile).asV4(), 
+            v6XdbFile == null ? null : Config.custom().setXdbFile(v6XdbFile).asV6()
         );
     }
 
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/service/SearcherPool.java b/binding/java/src/main/java/org/lionsoul/ip2region/service/SearcherPool.java
index 48c7473..aa97e00 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/service/SearcherPool.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/service/SearcherPool.java
@@ -60,7 +60,7 @@ public class SearcherPool {
     protected SearcherPool init() throws IOException {
         // create the searchers
         for (int i = pool.size(); i < config.searchers; i++) {
-            final Searcher searcher = new Searcher(config.ipVersion, config.xdbPath, config.vIndex, config.cBuffer);
+            final Searcher searcher = new Searcher(config.ipVersion, config.xdbFile, config.vIndex, config.cBuffer);
             pool.add(searcher);
         }
 
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/xdb/Header.java b/binding/java/src/main/java/org/lionsoul/ip2region/xdb/Header.java
index 4b73150..2a1bbc4 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/xdb/Header.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/xdb/Header.java
@@ -33,13 +33,13 @@ public class Header {
 
     @Override public String toString() {
         return "{" +
-            "Version: " + version + ',' +
-            "IndexPolicy: " + indexPolicy + ',' +
-            "CreatedAt: " + createdAt + ',' +
-            "StartIndexPtr: " + startIndexPtr + ',' +
-            "EndIndexPtr: " + endIndexPtr + ',' + 
-            "IPVersion: " + ipVersion + ',' + 
-            "RuntimePtrBytes: " + runtimePtrBytes +
+            "Version:" + version + ',' +
+            "IndexPolicy:" + indexPolicy + ',' +
+            "CreatedAt:" + createdAt + ',' +
+            "StartIndexPtr:" + startIndexPtr + ',' +
+            "EndIndexPtr:" + endIndexPtr + ',' + 
+            "IPVersion:" + ipVersion + ',' + 
+            "RuntimePtrBytes:" + runtimePtrBytes +
         '}';
     }
 }
diff --git a/binding/java/src/main/java/org/lionsoul/ip2region/xdb/Searcher.java b/binding/java/src/main/java/org/lionsoul/ip2region/xdb/Searcher.java
index 5dd22c4..6152cdd 100644
--- a/binding/java/src/main/java/org/lionsoul/ip2region/xdb/Searcher.java
+++ b/binding/java/src/main/java/org/lionsoul/ip2region/xdb/Searcher.java
@@ -4,11 +4,14 @@
 
 package org.lionsoul.ip2region.xdb;
 
+import java.io.File;
+
 // xdb searcher (Not thread safe implementation)
 // @Author Lion <chenxin619315@gmail.com>
 // @Date   2022/06/23
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.RandomAccessFile;
 
 public class Searcher {
@@ -29,7 +32,7 @@ public class Searcher {
     private final Version version;
 
     // random access file handle for file-based search
-    private final String xdbPath;
+    private final File xdbFile;
     private final RandomAccessFile handle;
 
     private int ioCount = 0;
@@ -46,12 +49,20 @@ public class Searcher {
 
     // --- static method to create searchers
 
-    public static Searcher newWithFileOnly(Version version, String dbPath) throws IOException {
-        return new Searcher(version, dbPath, null, null);
+    public static Searcher newWithFileOnly(Version version, String xdbPath) throws IOException {
+        return new Searcher(version, new File(xdbPath), null, null);
     }
 
-    public static Searcher newWithVectorIndex(Version version, String dbPath, byte[] vectorIndex) throws IOException {
-        return new Searcher(version, dbPath, vectorIndex, null);
+    public static Searcher newWithFileOnly(Version version, File xdbFile) throws IOException {
+        return new Searcher(version, xdbFile, null, null);
+    }
+
+    public static Searcher newWithVectorIndex(Version version, String xdbPath, byte[] vectorIndex) throws IOException {
+        return new Searcher(version, new File(xdbPath), vectorIndex, null);
+    }
+
+    public static Searcher newWithVectorIndex(Version version, File xdbFile, byte[] vectorIndex) throws IOException {
+        return new Searcher(version, xdbFile, vectorIndex, null);
     }
 
     public static Searcher newWithBuffer(Version version, LongByteArray cBuff) throws IOException {
@@ -60,15 +71,15 @@ public class Searcher {
 
     // --- End of creator
 
-    public Searcher(Version version, String dbFile, byte[] vectorIndex, LongByteArray cBuff) throws IOException {
+    public Searcher(Version version, File xdbFile, byte[] vectorIndex, LongByteArray cBuff) throws IOException {
         this.version = version;
-        this.xdbPath = dbFile;
+        this.xdbFile = xdbFile;
         if (cBuff != null) {
             this.handle = null;
             this.vectorIndex = null;
             this.contentBuff = cBuff;
         } else {
-            this.handle = new RandomAccessFile(dbFile, "r");
+            this.handle = new RandomAccessFile(xdbFile, "r");
             this.vectorIndex = vectorIndex;
             this.contentBuff = null;
         }
@@ -179,13 +190,15 @@ public class Searcher {
         return String.format(
             "%s->{version:%s, xdb:%s, vIndex:%s, cBuffer:%s}", 
             super.toString(),
-            version.name, xdbPath, 
+            version.name, xdbFile == null ? "null" : xdbFile.getAbsolutePath(), 
             vectorIndex == null ? "null" : String.valueOf(vectorIndex.length),
             contentBuff == null ? "null" : String.valueOf(contentBuff.length())
         );
     }
 
+    // ---
     // --- static util function
+    // --- read xdb header
 
     public static Header loadHeader(RandomAccessFile handle) throws IOException {
         handle.seek(0);
@@ -194,13 +207,23 @@ public class Searcher {
         return new Header(buff);
     }
 
-    public static Header loadHeaderFromFile(String dbPath) throws IOException {
-        final RandomAccessFile handle = new RandomAccessFile(dbPath, "r");
+    public static Header loadHeaderFromFile(File xdbFile) throws IOException {
+        final RandomAccessFile handle = new RandomAccessFile(xdbFile, "r");
         final Header header = loadHeader(handle);
         handle.close();
         return header;
     }
 
+    public static Header loadHeaderFromFile(String xdbPath) throws IOException {
+        return loadHeaderFromFile(new File(xdbPath));
+    }
+
+    public static Header loadHeaderFromBuffer(LongByteArray cBuffer) throws IOException {
+        return new Header(cBuffer.slice(0, HeaderInfoLength));
+    }
+
+    // --- read xdb vector index
+
     public static byte[] loadVectorIndex(RandomAccessFile handle) throws IOException {
         handle.seek(HeaderInfoLength);
         int len = VectorIndexRows * VectorIndexCols * VectorIndexSize;
@@ -213,13 +236,24 @@ public class Searcher {
         return buff;
     }
 
-    public static byte[] loadVectorIndexFromFile(String dbPath) throws IOException {
-        final RandomAccessFile handle = new RandomAccessFile(dbPath, "r");
+    public static byte[] loadVectorIndexFromFile(File xdbFile) throws IOException {
+        final RandomAccessFile handle = new RandomAccessFile(xdbFile, "r");
         final byte[] vIndex = loadVectorIndex(handle);
         handle.close();
         return vIndex;
     }
 
+    public static byte[] loadVectorIndexFromFile(String xdbPath) throws IOException {
+        return loadVectorIndexFromFile(new File(xdbPath));
+    }
+
+    public static byte[] loadVectorIndexFromBuffer(LongByteArray cBuffer) throws IOException {
+        final int len = VectorIndexRows * VectorIndexCols * VectorIndexSize;
+        return cBuffer.slice(HeaderInfoLength, len);
+    }
+
+    // --- read xdb content
+
     public static LongByteArray loadContent(RandomAccessFile handle) throws IOException {
         handle.seek(0);
         // check the length and do the buff load
@@ -239,13 +273,56 @@ public class Searcher {
         return byteArray;
     }
 
-    public static LongByteArray loadContentFromFile(String dbPath) throws IOException {
-        final RandomAccessFile handle = new RandomAccessFile(dbPath, "r");
+    public static LongByteArray loadContentFromFile(File xdbFile) throws IOException {
+        final RandomAccessFile handle = new RandomAccessFile(xdbFile, "r");
         final LongByteArray content = loadContent(handle);
         handle.close();
         return content;
     }
 
+    public static LongByteArray loadContentFromFile(String xdbPath) throws IOException {
+        return loadContentFromFile(new File(xdbPath));
+    }
+
+    public static LongByteArray loadContentFromInputStream(InputStream is) throws IOException {
+        final LongByteArray byteArray = new LongByteArray();
+        while (true) {
+            boolean done = false;
+
+            // read at most MAX_WRITE_BYTES bytes
+            int rLen, tBytes = 0;
+            final byte[] buff = new byte[MAX_WRITE_BYTES];
+            while (true) {
+                rLen = is.read(buff, tBytes, buff.length - tBytes);
+                if (rLen == -1) {
+                    // reach the end of the stream
+                    done = true;
+                    break;
+                } else if (rLen == 0) {
+                    // the entire buff was filled
+                    break;
+                }
+
+                tBytes += rLen;
+            }
+
+            // check and copy the buffer with its actual filled bytes
+            if (tBytes == buff.length) {
+                byteArray.append(buff);
+            } else {
+                final byte[] nBuff = new byte[tBytes];
+                System.arraycopy(buff, 0, nBuff, 0, tBytes);
+                byteArray.append(nBuff);
+            }
+
+            if (done) {
+                break;
+            }
+        }
+
+        return byteArray;
+    }
+
     // --- verify util function
 
     // Verify if the current Searcher could be used to search the specified xdb file.
@@ -254,9 +331,7 @@ public class Searcher {
     //
     // @Note: You Just need to check this ONCE when the service starts
     // Or use another process (eg, A command) to check once Just to confirm the suitability.
-    public static void verify(RandomAccessFile handle) throws IOException, XdbException {
-        final Header header = loadHeader(handle);
-
+    public static void verify(Header header, long fileBytes) throws IOException, XdbException {
         // get the runtime ptr bytes
         int runtimePtrBytes = 0;
         if (header.version == STRUCTURE_20) {
@@ -270,15 +345,23 @@ public class Searcher {
         // 1, confirm the xdb file size
         // to ensure that the maximum file pointer does not overflow
         final long maxFilePtr = (1L << (runtimePtrBytes * 8)) - 1;
-        if (handle.length() > maxFilePtr) {
+        if (fileBytes > maxFilePtr) {
             throw new XdbException("xdb file exceeds the maximum supported bytes: "+maxFilePtr+"");
         }
     }
 
-    public static void verifyFromFile(String dbFile) throws IOException, XdbException {
-        final RandomAccessFile handle = new RandomAccessFile(dbFile, "r");
+    public static void verify(RandomAccessFile handle) throws IOException, XdbException {
+        verify(loadHeader(handle), handle.length());
+    }
+
+    public static void verifyFromFile(File xdbFile) throws IOException, XdbException {
+        final RandomAccessFile handle = new RandomAccessFile(xdbFile, "r");
         verify(handle);
         handle.close();
     }
 
+    public static void verifyFromFile(String xdbPath) throws IOException, XdbException {
+        verifyFromFile(new File(xdbPath));
+    }
+
 }
\ No newline at end of file
diff --git a/binding/java/src/test/java/org/lionsoul/ip2region/service/ConfigTest.java b/binding/java/src/test/java/org/lionsoul/ip2region/service/ConfigTest.java
index 56a5b66..ef26581 100644
--- a/binding/java/src/test/java/org/lionsoul/ip2region/service/ConfigTest.java
+++ b/binding/java/src/test/java/org/lionsoul/ip2region/service/ConfigTest.java
@@ -1,4 +1,6 @@
 package org.lionsoul.ip2region.service;
+import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
 import java.security.CodeSource;
 
@@ -21,9 +23,9 @@ public class ConfigTest {
     }
 
     @Test
-    public void testBuildV4Config() throws IOException, XdbException {
+    public void testBuildV4Config() throws IOException, XdbException, InvalidConfigException {
         final Config v4Config = Config.custom()
-            .setCachePolicy(Config.BufferCache)
+            .setCachePolicy(Config.VIndexCache)
             .setXdbPath(getDataPath("ip2region_v4.xdb"))
             .setSearchers(20)
             .asV4();
@@ -31,7 +33,29 @@ public class ConfigTest {
     }
 
     @Test
-    public void testBuildV6Config() throws IOException, XdbException {
+    public void testBuildV4ConfigFromFile() throws IOException, XdbException, InvalidConfigException {
+        final Config v4Config = Config.custom()
+            .setCachePolicy(Config.BufferCache)
+            .setXdbFile(new File(getDataPath("ip2region_v4.xdb")))
+            .setSearchers(20)
+            .asV4();
+        log.debugf("builded config: %s", v4Config);
+    }
+
+    @Test
+    public void testBuildV4ConfigFromInputStream() throws IOException, XdbException, InvalidConfigException {
+        final Config v4Config = Config.custom()
+            .setCachePolicy(Config.BufferCache)
+            .setXdbInputStream(new FileInputStream(getDataPath("ip2region_v4.xdb")))
+            .setSearchers(20)
+            .asV4();
+        log.debugf("builded config: %s", v4Config);
+    }
+
+    // --- IPv6
+
+    @Test
+    public void testBuildV6Config() throws IOException, XdbException, InvalidConfigException {
         final Config v4Config = Config.custom()
             .setCachePolicy(Config.VIndexCache)
             .setXdbPath(getDataPath("ip2region_v6.xdb"))
@@ -39,4 +63,25 @@ public class ConfigTest {
             .asV6();
         log.debugf("builded config: %s", v4Config);
     }
+
+    @Test
+    public void testBuildV6ConfigFromFile() throws IOException, XdbException, InvalidConfigException {
+        final Config v4Config = Config.custom()
+            .setCachePolicy(Config.BufferCache)
+            .setXdbFile(new File(getDataPath("ip2region_v6.xdb")))
+            .setSearchers(20)
+            .asV6();
+        log.debugf("builded config: %s", v4Config);
+    }
+
+    @Test
+    public void testBuildV6ConfigFromInputStream() throws IOException, XdbException, InvalidConfigException {
+        final Config v4Config = Config.custom()
+            .setCachePolicy(Config.BufferCache)
+            .setXdbInputStream(new FileInputStream(getDataPath("ip2region_v6.xdb")))
+            .setSearchers(20)
+            .asV6();
+        log.debugf("builded config: %s", v4Config);
+    }
+
 }
diff --git a/binding/java/src/test/java/org/lionsoul/ip2region/service/Ip2RegionTest.java b/binding/java/src/test/java/org/lionsoul/ip2region/service/Ip2RegionTest.java
index d0fcab7..d78829d 100644
--- a/binding/java/src/test/java/org/lionsoul/ip2region/service/Ip2RegionTest.java
+++ b/binding/java/src/test/java/org/lionsoul/ip2region/service/Ip2RegionTest.java
@@ -17,7 +17,7 @@ public class Ip2RegionTest {
     private static final Log log = Log.getLogger(Ip2RegionTest.class).setLevel(Log.DEBUG);
 
     @Test
-    public void TestConfigCreate() throws IOException, XdbException, InetAddressException, InterruptedException {
+    public void TestConfigCreate() throws IOException, XdbException, InetAddressException, InterruptedException, InvalidConfigException {
         final Config v4Config = Config.custom()
             .setCachePolicy(Config.NoCache)
             .setSearchers(10)
@@ -46,7 +46,7 @@ public class Ip2RegionTest {
     }
 
     @Test
-    public void TestPathCreate() throws InetAddressException, IOException, XdbException, InterruptedException {
+    public void TestPathCreate() throws InetAddressException, IOException, XdbException, InterruptedException, InvalidConfigException {
         byte[] v4Bytes = Util.parseIP("113.92.157.29");
         byte[] v6Bytes = Util.parseIP("240e:3b7:3272:d8d0:db09:c067:8d59:539e");
         final Ip2Region ip2Region = Ip2Region.create(ConfigTest.getDataPath("ip2region_v4.xdb"), ConfigTest.getDataPath("ip2region_v6.xdb"));
@@ -63,7 +63,7 @@ public class Ip2RegionTest {
     }
 
     @Test
-    public void TestInMemSearch() throws IOException, XdbException, InetAddressException, InterruptedException {
+    public void TestInMemSearch() throws IOException, XdbException, InetAddressException, InterruptedException, InvalidConfigException {
         final Config v4Config = Config.custom()
             .setCachePolicy(Config.BufferCache)
             .setXdbPath(ConfigTest.getDataPath("ip2region_v4.xdb"))
@@ -90,7 +90,7 @@ public class Ip2RegionTest {
     }
 
     @Test
-    public void TestConcurrentCall() throws IOException, XdbException, InetAddressException, InterruptedException {
+    public void TestConcurrentCall() throws IOException, XdbException, InetAddressException, InterruptedException, InvalidConfigException {
         final Config v4Config = Config.custom()
             .setCachePolicy(Config.VIndexCache)
             .setSearchers(15)
@@ -144,7 +144,7 @@ public class Ip2RegionTest {
     }
 
     @Test
-    public void TestV4Only() throws IOException, XdbException, InetAddressException, InterruptedException {
+    public void TestV4Only() throws IOException, XdbException, InetAddressException, InterruptedException, InvalidConfigException {
         final Config v4Config = Config.custom()
             .setCachePolicy(Config.NoCache)
             .setXdbPath(ConfigTest.getDataPath("ip2region_v4.xdb"))
diff --git a/binding/java/src/test/java/org/lionsoul/ip2region/service/SearcherPoolTest.java b/binding/java/src/test/java/org/lionsoul/ip2region/service/SearcherPoolTest.java
index 5d07761..5c32f63 100644
--- a/binding/java/src/test/java/org/lionsoul/ip2region/service/SearcherPoolTest.java
+++ b/binding/java/src/test/java/org/lionsoul/ip2region/service/SearcherPoolTest.java
@@ -32,6 +32,30 @@ public class SearcherPoolTest {
         log.debugf("v4 searcher pool closed gracefully");
     }
 
+    @Test
+    public void testInMemV4SearcherPool() throws Exception {
+        final Config v4Config = Config.custom()
+            .setCachePolicy(Config.FullCache)
+            .setSearchers(5)
+            .setXdbPath(ConfigTest.getDataPath("ip2region_v4.xdb"))
+            .asV4();
+
+
+        final String ipStr = "58.250.36.41";
+        final SearcherPool v4Pool = SearcherPool.create(v4Config);
+        for (int i = 0; i < 20; i++) {
+            final Searcher searcher = v4Pool.borrowSearcher();
+            log.debugf("borrowed searcher %d: %s", i, searcher.toString());
+            final String region = searcher.search(ipStr);
+            log.debugf("search(%s)=%s", ipStr, region);
+            v4Pool.returnSearcher(searcher);
+            log.debugf("return searcher %d", i);
+        }
+
+        v4Pool.close();
+        log.debugf("v4 searcher pool closed gracefully");
+    }
+
     @Test
     public void testV6SearcherPool() throws Exception {
         final Config v6Config = Config.custom()