diff --git a/src/main/java/lee/study/down/dispatch/DefaultHttpDownCallback.java b/src/main/java/lee/study/down/dispatch/DefaultHttpDownCallback.java
index 9a7a2384..ca0601c0 100644
--- a/src/main/java/lee/study/down/dispatch/DefaultHttpDownCallback.java
+++ b/src/main/java/lee/study/down/dispatch/DefaultHttpDownCallback.java
@@ -47,7 +47,7 @@ public void onPause(TaskInfo taskInfo) {
       taskInfo.setStatus(4);
       for (ChunkInfo chunkInfo : taskInfo.getChunkInfoList()) {
         synchronized (chunkInfo) {
-          HttpDownUtil.safeClose(chunkInfo.getChannel(), chunkInfo.getFileChannel());
+          HttpDownUtil.safeClose(chunkInfo.getChannel(), chunkInfo);
           if (chunkInfo.getStatus() != 2) {
             chunkInfo.setStatus(4);
           }
@@ -112,7 +112,7 @@ public void onDone(TaskInfo taskInfo) {
   public void onDelete(TaskInfo taskInfo) {
     for (ChunkInfo chunkInfo : taskInfo.getChunkInfoList()) {
       synchronized (chunkInfo) {
-        HttpDownUtil.safeClose(chunkInfo.getChannel(), chunkInfo.getFileChannel());
+        HttpDownUtil.safeClose(chunkInfo.getChannel(), chunkInfo);
       }
     }
     synchronized (taskInfo) {
diff --git a/src/main/java/lee/study/down/hanndle/HttpDownInitializer.java b/src/main/java/lee/study/down/hanndle/HttpDownInitializer.java
index 32a7e08b..fcc53cfc 100644
--- a/src/main/java/lee/study/down/hanndle/HttpDownInitializer.java
+++ b/src/main/java/lee/study/down/hanndle/HttpDownInitializer.java
@@ -1,6 +1,7 @@
 package lee.study.down.hanndle;
 
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.PooledByteBufAllocator;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
@@ -13,11 +14,14 @@
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.nio.ByteBuffer;
+import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel;
+import java.nio.channels.FileChannel.MapMode;
 import lee.study.down.HttpDownServer;
 import lee.study.down.dispatch.HttpDownCallback;
 import lee.study.down.model.ChunkInfo;
 import lee.study.down.model.TaskInfo;
+import lee.study.down.util.FileUtil;
 import lee.study.down.util.HttpDownUtil;
 
 public class HttpDownInitializer extends ChannelInitializer {
@@ -27,7 +31,6 @@ public class HttpDownInitializer extends ChannelInitializer {
   private ChunkInfo chunkInfo;
   private HttpDownCallback callback;
 
-  private FileChannel fileChannel;
   private long realContentSize;
 
   public HttpDownInitializer(boolean isSsl, TaskInfo taskInfo, ChunkInfo chunkInfo,
@@ -52,12 +55,12 @@ public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception
         try {
           synchronized (chunkInfo) {
             Boolean close = ctx.channel().attr(HttpDownUtil.CLOSE_ATTR).get();
-            if (close!=null&&close==true) {
+            if (close != null && close == true) {
               return;
             }
           }
           if (msg instanceof HttpContent) {
-            if (fileChannel == null || !fileChannel.isOpen()) {
+            if (chunkInfo.getFileChannel() == null || !chunkInfo.getFileChannel().isOpen()) {
               return;
             }
             HttpContent httpContent = (HttpContent) msg;
@@ -65,7 +68,7 @@ public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception
             int readableBytes = byteBuf.readableBytes();
             synchronized (chunkInfo) {
               if (chunkInfo.getStatus() == 1) {
-                fileChannel.write(byteBuf.nioBuffer());
+                chunkInfo.getMappedBuffer().put(byteBuf.nioBuffer());
                 //文件已下载大小
                 chunkInfo.setDownSize(chunkInfo.getDownSize() + readableBytes);
               } else {
@@ -78,7 +81,7 @@ public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception
             callback.onProgress(taskInfo, chunkInfo);
             //分段下载完成关闭fileChannel
             if (chunkInfo.getDownSize() == chunkInfo.getTotalSize()) {
-              HttpDownUtil.safeClose(ctx.channel(), fileChannel);
+              HttpDownUtil.safeClose(ctx.channel(), chunkInfo);
               //分段下载完成回调
               chunkInfo.setStatus(2);
               chunkInfo.setLastTime(System.currentTimeMillis());
@@ -123,10 +126,12 @@ public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception
                 "下载响应：" + chunkInfo.getIndex() + "\t" + chunkInfo.getDownSize() + "\t"
                     + httpResponse.headers().get(
                     HttpHeaderNames.CONTENT_RANGE) + "\t" + realContentSize);
-            fileChannel = new RandomAccessFile(taskInfo.buildTaskFilePath(), "rw").getChannel();
-            fileChannel.position(chunkInfo.getOriStartPosition() + chunkInfo.getDownSize());
+            FileChannel fileChannel = new RandomAccessFile(taskInfo.buildTaskFilePath(), "rw").getChannel();
+            MappedByteBuffer mappedBuffer = fileChannel.map(MapMode.READ_WRITE,
+                chunkInfo.getOriStartPosition() + chunkInfo.getDownSize(), chunkInfo.getTotalSize());
             chunkInfo.setStatus(1);
             chunkInfo.setFileChannel(fileChannel);
+            chunkInfo.setMappedBuffer(mappedBuffer);
             callback.onChunkStart(taskInfo, chunkInfo);
           }
         } catch (Exception e) {
@@ -162,31 +167,15 @@ public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws E
 
   public static void main(String[] args) throws Exception {
     String path = "f:/down/test1.txt";
-    RandomAccessFile r1 = new RandomAccessFile(path, "rw");
-    r1.setLength(1024 * 1024 * 1024 * 1L);
-    r1.close();
-    new Thread(() -> {
-      try {
-        FileChannel fileChannel = new RandomAccessFile(path, "rw").getChannel();
-        fileChannel.position(1000);
-        long time = System.currentTimeMillis();
-        fileChannel.write(ByteBuffer.wrap(new byte[1024]));
-        System.out.println("use1:" + (System.currentTimeMillis() - time));
-      } catch (Exception e) {
-        e.printStackTrace();
-      }
-    }).start();
-    new Thread(() -> {
-      try {
-        FileChannel fileChannel = new RandomAccessFile(path, "rw").getChannel();
-        fileChannel.position(4000);
-        long time = System.currentTimeMillis();
-        fileChannel.write(ByteBuffer.wrap(new byte[1024]));
-        System.out.println("use2:" + (System.currentTimeMillis() - time));
-      } catch (Exception e) {
-        e.printStackTrace();
-      }
-    }).start();
+    RandomAccessFile randomAccessFile = new RandomAccessFile(path, "rw");
+    randomAccessFile.setLength(100);
+    randomAccessFile.close();
+    FileChannel fileChannel = new RandomAccessFile(path, "rw").getChannel();
+    MappedByteBuffer mbb = fileChannel.map(MapMode.READ_WRITE, 0, 5);
+    mbb.put(new byte[]{1, 2, 3, 4, 5});
+    FileUtil.unmap(mbb);
+    fileChannel.close();
+    FileUtil.deleteIfExists(path);
   }
 
 }
diff --git a/src/main/java/lee/study/down/model/ChunkInfo.java b/src/main/java/lee/study/down/model/ChunkInfo.java
index 7fb1278a..970196fb 100644
--- a/src/main/java/lee/study/down/model/ChunkInfo.java
+++ b/src/main/java/lee/study/down/model/ChunkInfo.java
@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import io.netty.channel.Channel;
 import java.io.Serializable;
+import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel;
 import lombok.AllArgsConstructor;
 import lombok.Data;
@@ -27,6 +28,8 @@ public class ChunkInfo implements Serializable {
   private transient volatile Channel channel;
   @JsonIgnore
   private transient volatile FileChannel fileChannel;
+  @JsonIgnore
+  private transient volatile MappedByteBuffer mappedBuffer;
 
   public ChunkInfo() {
   }
diff --git a/src/main/java/lee/study/down/util/FileUtil.java b/src/main/java/lee/study/down/util/FileUtil.java
index f073b74d..8bf25d99 100644
--- a/src/main/java/lee/study/down/util/FileUtil.java
+++ b/src/main/java/lee/study/down/util/FileUtil.java
@@ -3,9 +3,12 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.RandomAccessFile;
+import java.lang.reflect.Method;
 import java.nio.ByteBuffer;
+import java.nio.MappedByteBuffer;
 import java.nio.file.Files;
 import java.util.Stack;
+import sun.nio.ch.FileChannelImpl;
 
 public class FileUtil {
 
@@ -111,7 +114,7 @@ public static File createFileSmart(String path) throws IOException {
     if (file.exists()) {
       file.delete();
       file.createNewFile();
-    }else{
+    } else {
       createDirSmart(file.getParent());
       file.createNewFile();
     }
@@ -139,8 +142,14 @@ public static File createDirSmart(String path) throws IOException {
     return file;
   }
 
+  public static void unmap(MappedByteBuffer mappedBuffer) throws Exception {
+    Method m = FileChannelImpl.class.getDeclaredMethod("unmap", MappedByteBuffer.class);
+    m.setAccessible(true);
+    m.invoke(FileChannelImpl.class, mappedBuffer);
+  }
+
   public static void main(String[] args) throws Exception {
-    RandomAccessFile raf2 = new RandomAccessFile("F:\\百度云合并下载研究\\testbbb.txt","rw");
+    RandomAccessFile raf2 = new RandomAccessFile("F:\\百度云合并下载研究\\testbbb.txt", "rw");
     raf2.setLength(10);
     raf2.getChannel().position(10).read(ByteBuffer.allocate(5));
     System.out.println(raf2.getChannel().position());
diff --git a/src/main/java/lee/study/down/util/HttpDownUtil.java b/src/main/java/lee/study/down/util/HttpDownUtil.java
index 83ea4f25..e45eb803 100644
--- a/src/main/java/lee/study/down/util/HttpDownUtil.java
+++ b/src/main/java/lee/study/down/util/HttpDownUtil.java
@@ -24,6 +24,7 @@
 import java.io.UnsupportedEncodingException;
 import java.net.InetSocketAddress;
 import java.net.URLDecoder;
+import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel;
 import java.util.Map.Entry;
 import java.util.UUID;
@@ -41,7 +42,7 @@
 
 public class HttpDownUtil {
 
-  //private static final RecvByteBufAllocator RECV_BYTE_BUF_ALLOCATOR = new AdaptiveRecvByteBufAllocator(64,8192,65536);
+//  private static final RecvByteBufAllocator RECV_BYTE_BUF_ALLOCATOR = new AdaptiveRecvByteBufAllocator(64,8192,65536);
   public static final AttributeKey<Boolean> CLOSE_ATTR = AttributeKey.newInstance("close");
 
   /**
@@ -250,7 +251,7 @@ public static void taskDown(HttpDownInfo httpDownInfo)
       for (int i = 0; i < taskInfo.getChunkInfoList().size(); i++) {
         ChunkInfo chunkInfo = taskInfo.getChunkInfoList().get(i);
         //避免分段下载速度比总的下载速度大太多的问题
-        chunkInfo.setStatus(1);
+//        chunkInfo.setStatus(1);
         chunkInfo.setStartTime(taskInfo.getStartTime());
         chunkDown(httpDownInfo, chunkInfo);
       }
@@ -267,6 +268,7 @@ public static void chunkDown(HttpDownInfo httpDownInfo, ChunkInfo chunkInfo)
     HttpDownServer.LOGGER.debug(
         "开始下载：" + chunkInfo.getIndex() + "\t" + chunkInfo.getDownSize());
     ChannelFuture cf = HttpDownServer.DOWN_BOOT
+//        .option(ChannelOption.RCVBUF_ALLOCATOR,RECV_BYTE_BUF_ALLOCATOR)
         .handler(
             new HttpDownInitializer(requestProto.getSsl(), taskInfo, chunkInfo,
                 HttpDownServer.CALLBACK))
@@ -314,7 +316,7 @@ public static void retryDown(TaskInfo taskInfo, ChunkInfo chunkInfo)
   public static void retryDown(TaskInfo taskInfo, ChunkInfo chunkInfo, long downSize)
       throws Exception {
     synchronized (chunkInfo) {
-      safeClose(chunkInfo.getChannel(), chunkInfo.getFileChannel());
+      safeClose(chunkInfo.getChannel(), chunkInfo);
       if (setStatusIfNotDone(chunkInfo, 3)) {
         if (downSize != -1) {
           chunkInfo.setDownSize(downSize);
@@ -340,7 +342,7 @@ public static void retryDown(TaskInfo taskInfo, ChunkInfo chunkInfo, long downSi
   public static void continueDown(TaskInfo taskInfo, ChunkInfo chunkInfo)
       throws Exception {
     synchronized (chunkInfo) {
-      safeClose(chunkInfo.getChannel(), chunkInfo.getFileChannel());
+      safeClose(chunkInfo.getChannel(), chunkInfo);
       //避免同时两个重新下载
       if (setStatusIfNotDone(chunkInfo, 5)) {
         //计算后续下载字节
@@ -351,7 +353,7 @@ public static void continueDown(TaskInfo taskInfo, ChunkInfo chunkInfo)
     }
   }
 
-  public static void safeClose(Channel channel, FileChannel fileChannel) {
+  public static void safeClose(Channel channel, ChunkInfo chunkInfo) {
     try {
       if (channel != null && channel.isOpen()) {
         channel.attr(CLOSE_ATTR).set(true);
@@ -362,6 +364,7 @@ public static void safeClose(Channel channel, FileChannel fileChannel) {
       HttpDownServer.LOGGER.error("safeClose netty channel", e);
     }
     try {
+      FileChannel fileChannel = chunkInfo.getFileChannel();
       if (fileChannel != null && fileChannel.isOpen()) {
         //关闭旧的下载文件连接
         fileChannel.close();
@@ -369,6 +372,15 @@ public static void safeClose(Channel channel, FileChannel fileChannel) {
     } catch (IOException e) {
       HttpDownServer.LOGGER.error("safeClose file channel", e);
     }
+    try {
+      MappedByteBuffer mappedBuffer = chunkInfo.getMappedBuffer();
+      if (mappedBuffer != null) {
+        //关闭旧的下载文件连接
+        FileUtil.unmap(mappedBuffer);
+      }
+    } catch (Exception e) {
+      HttpDownServer.LOGGER.error("safeClose file mappedBuffer", e);
+    }
   }
 
   public static boolean setStatusIfNotDone(ChunkInfo chunkInfo, int update) {