diff --git a/agents-flex-core/src/main/java/com/agentsflex/core/document/parser/DefaultTextDocumentParser.java b/agents-flex-core/src/main/java/com/agentsflex/core/document/parser/DefaultTextDocumentParser.java
index 08d527f..0641bdb 100644
--- a/agents-flex-core/src/main/java/com/agentsflex/core/document/parser/DefaultTextDocumentParser.java
+++ b/agents-flex-core/src/main/java/com/agentsflex/core/document/parser/DefaultTextDocumentParser.java
@@ -17,26 +17,18 @@ package com.agentsflex.core.document.parser;
 
 import com.agentsflex.core.document.Document;
 import com.agentsflex.core.document.DocumentParser;
+import com.agentsflex.core.util.IOUtil;
 
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.nio.charset.StandardCharsets;
 
 public class DefaultTextDocumentParser implements DocumentParser {
     @Override
     public Document parse(InputStream stream) {
         try {
-            ByteArrayOutputStream baos = new ByteArrayOutputStream();
-            byte[] buffer = new byte[1024];
-            int len;
-            while ((len = stream.read(buffer)) != -1) {
-                baos.write(buffer, 0, len);
-            }
-            return new Document(new String(baos.toByteArray(), StandardCharsets.UTF_8));
+            return Document.of(IOUtil.readUtf8(stream));
         } catch (IOException e) {
-            e.printStackTrace();
+            throw new RuntimeException(e);
         }
-        return null;
     }
 }
diff --git a/agents-flex-core/src/main/java/com/agentsflex/core/image/Image.java b/agents-flex-core/src/main/java/com/agentsflex/core/image/Image.java
index 22ee6a4..775c4ff 100644
--- a/agents-flex-core/src/main/java/com/agentsflex/core/image/Image.java
+++ b/agents-flex-core/src/main/java/com/agentsflex/core/image/Image.java
@@ -15,9 +15,9 @@
  */
 package com.agentsflex.core.image;
 
+import com.agentsflex.core.util.IOUtil;
+
 import java.io.File;
-import java.io.FileOutputStream;
-import java.io.IOException;
 import java.util.Arrays;
 
 public class Image {
@@ -78,11 +78,7 @@ public class Image {
     }
 
     public void writeBytesToFile(File file) {
-        try (FileOutputStream stream = new FileOutputStream(file)) {
-            stream.write(bytes);
-        } catch (IOException e) {
-            throw new RuntimeException(e);
-        }
+        IOUtil.writeBytes(this.bytes, file);
     }
 
     @Override
diff --git a/agents-flex-core/src/main/java/com/agentsflex/core/llm/client/HttpClient.java b/agents-flex-core/src/main/java/com/agentsflex/core/llm/client/HttpClient.java
index 932b60c..6ee5b84 100644
--- a/agents-flex-core/src/main/java/com/agentsflex/core/llm/client/HttpClient.java
+++ b/agents-flex-core/src/main/java/com/agentsflex/core/llm/client/HttpClient.java
@@ -15,8 +15,10 @@
  */
 package com.agentsflex.core.llm.client;
 
+import com.agentsflex.core.util.IOUtil;
 import okhttp3.*;
 import okio.BufferedSink;
+import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -191,11 +193,8 @@ public class HttpClient {
         }
 
         @Override
-        public void writeTo(BufferedSink sink) throws IOException {
-            byte[] buffer = new byte[1024];
-            for (int len; (len = inputStream.read(buffer)) != -1; ) {
-                sink.write(buffer, 0, len);
-            }
+        public void writeTo(@NotNull BufferedSink sink) throws IOException {
+            IOUtil.copy(inputStream, sink);
         }
     }
 }
diff --git a/agents-flex-core/src/main/java/com/agentsflex/core/util/IOUtil.java b/agents-flex-core/src/main/java/com/agentsflex/core/util/IOUtil.java
new file mode 100644
index 0000000..e213a0a
--- /dev/null
+++ b/agents-flex-core/src/main/java/com/agentsflex/core/util/IOUtil.java
@@ -0,0 +1,52 @@
+/*
+ *  Copyright (c) 2023-2025, Agents-Flex (fuhai999@gmail.com).
+ *  <p>
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  <p>
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *  <p>
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package com.agentsflex.core.util;
+
+import okio.BufferedSink;
+
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+
+public class IOUtil {
+
+    public static void writeBytes(byte[] bytes, File toFile) {
+        try (FileOutputStream stream = new FileOutputStream(toFile)) {
+            stream.write(bytes);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static void copy(InputStream inputStream, BufferedSink sink) throws IOException {
+        byte[] buffer = new byte[1024];
+        for (int len; (len = inputStream.read(buffer)) != -1; ) {
+            sink.write(buffer, 0, len);
+        }
+    }
+
+    public static void copy(InputStream inputStream, OutputStream outStream) throws IOException {
+        byte[] buffer = new byte[1024];
+        for (int len; (len = inputStream.read(buffer)) != -1; ) {
+            outStream.write(buffer, 0, len);
+        }
+    }
+
+    public static String readUtf8(InputStream inputStream) throws IOException {
+        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
+        copy(inputStream, outStream);
+        return new String(outStream.toByteArray(), StandardCharsets.UTF_8);
+    }
+}