diff --git a/group24/494800949/build.gradle b/group24/494800949/build.gradle
index 7930ebfca5..dd69528893 100644
--- a/group24/494800949/build.gradle
+++ b/group24/494800949/build.gradle
@@ -20,6 +20,8 @@ dependencies{
     compile group: 'junit', name: 'junit', version: '4.11'
     compile files("lib/dom4j-1.6.1.jar")
     compile files("lib/jaxen-1.1.1.jar")
+    compile group: 'org.apache.httpcomponents', name: 'httpclient', version: '4.5.2'
+
 }
 gradle.projectsEvaluated {
     tasks.withType(JavaCompile) {
diff --git a/group24/494800949/src/main/java/com/coding/week3/download/DownloadThread.java b/group24/494800949/src/main/java/com/coding/week3/download/DownloadThread.java
new file mode 100644
index 0000000000..a2a51cd583
--- /dev/null
+++ b/group24/494800949/src/main/java/com/coding/week3/download/DownloadThread.java
@@ -0,0 +1,52 @@
+package com.coding.week3.download;
+
+
+import com.coding.week3.download.api.Connection;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.RandomAccessFile;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class DownloadThread extends Thread {
+    private static final int BUFF_SIZE = 1024;
+    Connection       conn;
+    int              startPos;
+    int              endPos;
+    RandomAccessFile ras;
+    AtomicInteger    downloadBytesCount;
+
+    public DownloadThread(Connection conn, int startPos, int endPos) {
+        this.conn = conn;
+        this.startPos = startPos;
+        this.endPos = endPos;
+    }
+
+    public DownloadThread(Connection conn, int startPos, int endPos, RandomAccessFile ras, AtomicInteger atomicLong) {
+        this(conn, startPos, endPos);
+        this.ras = ras;
+        this.downloadBytesCount = atomicLong;
+    }
+
+    public void run() {
+        try {
+            InputStream is = conn.getInputStream();
+            is.skip(startPos);
+            ras.seek(startPos);
+            byte[] bytes = new byte[BUFF_SIZE];
+            int hasRead = 0;
+            int readTimes = (endPos - startPos) / BUFF_SIZE + 4;
+            for (int i = 0; i < readTimes; i++) {
+                hasRead = is.read(bytes );
+                if (hasRead == -1) {
+                    break;
+                }
+                ras.write(bytes, 0, hasRead);
+                downloadBytesCount.getAndAdd(hasRead);
+            }
+
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}
diff --git a/group24/494800949/src/main/java/com/coding/week3/download/FileDownloader.java b/group24/494800949/src/main/java/com/coding/week3/download/FileDownloader.java
new file mode 100644
index 0000000000..0e40bc38a8
--- /dev/null
+++ b/group24/494800949/src/main/java/com/coding/week3/download/FileDownloader.java
@@ -0,0 +1,133 @@
+package com.coding.week3.download;
+
+
+import com.coding.week3.download.api.Connection;
+import com.coding.week3.download.api.ConnectionException;
+import com.coding.week3.download.api.ConnectionManager;
+import com.coding.week3.download.api.DownloadListener;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class FileDownloader {
+
+	String url;
+
+	DownloadListener listener;
+
+	ConnectionManager cm;
+
+	String savePath;
+
+	int nThread;
+
+	int fileLength;
+
+	AtomicInteger downloadBytesCount;
+
+	public FileDownloader(String _url) {
+		this.url = _url;
+	}
+
+	public FileDownloader(int nThread, String savePath, String url) {
+		this.nThread = nThread;
+		this.savePath = savePath;
+		this.url = url;
+		downloadBytesCount = new AtomicInteger(0);
+	}
+
+	public void execute() throws IOException {
+		// 在这里实现你的代码， 注意： 需要用多线程实现下载
+		// 这个类依赖于其他几个接口, 你需要写这几个接口的实现代码
+		// (1) ConnectionManager , 可以打开一个连接，通过Connection可以读取其中的一段（用startPos, endPos来指定）
+		// (2) DownloadListener, 由于是多线程下载， 调用这个类的客户端不知道什么时候结束，所以你需要实现当所有
+		//     线程都执行完以后， 调用listener的notifiedFinished方法， 这样客户端就能收到通知。
+		// 具体的实现思路：
+		// 1. 需要调用ConnectionManager的open方法打开连接， 然后通过Connection.getContentLength方法获得文件的长度
+		// 2. 至少启动3个线程下载，  注意每个线程需要先调用ConnectionManager的open方法
+		// 然后调用read方法， read方法中有读取文件的开始位置和结束位置的参数， 返回值是byte[]数组
+		// 3. 把byte数组写入到文件中
+		// 4. 所有的线程都下载完成以后， 需要调用listener的notifiedFinished方法
+		
+		// 下面的代码是示例代码， 也就是说只有一个线程， 你需要改造成多线程的。
+		Connection conn = null;
+		try {
+
+			//根据文件长度为每个线程分配下载字节数量
+			conn = cm.open(this.url);
+			fileLength = conn.getContentLength();
+			//已读字节数量
+
+            int perLenOfThread ;
+            int lastLen ;
+			Thread[] threads = new Thread[nThread];
+            if ( fileLength % nThread == 0) {
+                perLenOfThread = fileLength / nThread;
+            } else {
+                lastLen = fileLength % nThread;
+                perLenOfThread = (fileLength + (nThread - lastLen)) / nThread;
+            }
+			//计算
+
+			//启动线程
+			for (int i = 0; i < nThread; i++) {
+				Connection conn1 = cm.open(this.url);
+				RandomAccessFile ras = new RandomAccessFile(savePath, "rw");
+                if ( i < nThread - 1) {
+					threads[i] = new DownloadThread(conn1, perLenOfThread * i, perLenOfThread * (i + 1)-1, ras, downloadBytesCount);
+					threads[i].start();
+				} else {
+					threads[i] =  new DownloadThread(conn1, perLenOfThread * (nThread - 1), fileLength - 1, ras, downloadBytesCount);
+					threads[i].start();
+				}
+            }
+
+			shutdown(threads);
+
+		} catch (ConnectionException e) {
+			e.printStackTrace();
+		}finally{
+			if(conn != null){
+				conn.close();
+			}
+		}
+	}
+
+	private void shutdown(Thread[] threads){
+		while (true) {
+			boolean allTerminated  = true;
+			for (int i = 0; i < nThread; i++) {
+				allTerminated = allTerminated & threads[i].getState().equals(Thread.State.TERMINATED);
+				try {
+					Thread.sleep(100);
+				} catch (InterruptedException e) {
+					e.printStackTrace();
+				}
+//				System.out.println(threads[i].getName() + "状态："+threads[i].getState().toString());
+			}
+
+			System.out.println("已下载："+(downloadBytesCount.get()/1024)+"K,百分比："+ (downloadBytesCount.get()/ (fileLength/100))+"%" );
+			if (allTerminated) {
+				listener.notifyFinished();
+				break;
+			}
+		}
+	}
+
+
+	public void setListener(DownloadListener listener) {
+		this.listener = listener;
+	}
+
+	
+	
+	public void setConnectionManager(ConnectionManager ucm){
+		this.cm = ucm;
+	}
+	
+	public DownloadListener getListener(){
+		return this.listener;
+	}
+	
+}
diff --git a/group24/494800949/src/main/java/com/coding/week3/download/api/Connection.java b/group24/494800949/src/main/java/com/coding/week3/download/api/Connection.java
new file mode 100644
index 0000000000..26261bc920
--- /dev/null
+++ b/group24/494800949/src/main/java/com/coding/week3/download/api/Connection.java
@@ -0,0 +1,26 @@
+package com.coding.week3.download.api;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+public interface Connection {
+	/**
+	 * 给定开始和结束位置， 读取数据， 返回值是字节数组
+	 * @param startPos 开始位置， 从0开始
+	 * @param endPos 结束位置
+	 * @return
+	 */
+	 byte[] read(int startPos, int endPos) throws IOException;
+	/**
+	 * 得到数据内容的长度
+	 * @return
+	 */
+	 int getContentLength();
+	
+	/**
+	 * 关闭连接
+	 */
+	 void close();
+
+	 InputStream getInputStream() throws IOException;
+}
diff --git a/group24/494800949/src/main/java/com/coding/week3/download/api/ConnectionException.java b/group24/494800949/src/main/java/com/coding/week3/download/api/ConnectionException.java
new file mode 100644
index 0000000000..1a4b6a17f2
--- /dev/null
+++ b/group24/494800949/src/main/java/com/coding/week3/download/api/ConnectionException.java
@@ -0,0 +1,10 @@
+package com.coding.week3.download.api;
+
+public class ConnectionException extends Exception {
+    public ConnectionException() {
+    }
+
+    public ConnectionException(String message) {
+        super(message);
+    }
+}
diff --git a/group24/494800949/src/main/java/com/coding/week3/download/api/ConnectionManager.java b/group24/494800949/src/main/java/com/coding/week3/download/api/ConnectionManager.java
new file mode 100644
index 0000000000..9ff27b7432
--- /dev/null
+++ b/group24/494800949/src/main/java/com/coding/week3/download/api/ConnectionManager.java
@@ -0,0 +1,10 @@
+package com.coding.week3.download.api;
+
+public interface ConnectionManager {
+	/**
+	 * 给定一个url , 打开一个连接
+	 * @param url
+	 * @return
+	 */
+	 Connection open(String url) throws ConnectionException;
+}
diff --git a/group24/494800949/src/main/java/com/coding/week3/download/api/DownloadListener.java b/group24/494800949/src/main/java/com/coding/week3/download/api/DownloadListener.java
new file mode 100644
index 0000000000..fd43497a10
--- /dev/null
+++ b/group24/494800949/src/main/java/com/coding/week3/download/api/DownloadListener.java
@@ -0,0 +1,5 @@
+package com.coding.week3.download.api;
+
+public interface DownloadListener {
+	 void notifyFinished();
+}
diff --git a/group24/494800949/src/main/java/com/coding/week3/download/impl/ConnectionImpl.java b/group24/494800949/src/main/java/com/coding/week3/download/impl/ConnectionImpl.java
new file mode 100644
index 0000000000..fe9b0a9079
--- /dev/null
+++ b/group24/494800949/src/main/java/com/coding/week3/download/impl/ConnectionImpl.java
@@ -0,0 +1,55 @@
+package com.coding.week3.download.impl;
+
+import com.coding.week3.download.api.Connection;
+
+import java.io.BufferedInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+
+
+public class ConnectionImpl implements Connection {
+
+	private HttpURLConnection httpURLConnection;
+
+	public ConnectionImpl() {
+	}
+
+	public ConnectionImpl(HttpURLConnection httpURLConnection) {
+		this.httpURLConnection = httpURLConnection;
+	}
+
+
+	@Override
+	public byte[] read(int startPos, int endPos) throws IOException {
+		if (startPos < 0 || endPos < 0 || endPos > getContentLength()) {
+			throw new IndexOutOfBoundsException();
+		}
+		if (startPos >= endPos) {
+			throw new IllegalArgumentException();
+		}
+		byte[] bytes = new byte[endPos - startPos + 1];
+
+		InputStream inputStream = httpURLConnection.getInputStream();
+		BufferedInputStream bis = new BufferedInputStream(inputStream);
+		bis.read(bytes, startPos ,bytes.length-1);
+		return bytes;
+	}
+
+
+	@Override
+	public int getContentLength() {
+		return httpURLConnection.getContentLength();
+	}
+
+	@Override
+	public void close() {
+		httpURLConnection.disconnect();
+	}
+
+	@Override
+	public InputStream getInputStream() throws IOException {
+		return httpURLConnection.getInputStream();
+	}
+
+}
diff --git a/group24/494800949/src/main/java/com/coding/week3/download/impl/ConnectionManagerImpl.java b/group24/494800949/src/main/java/com/coding/week3/download/impl/ConnectionManagerImpl.java
new file mode 100644
index 0000000000..3fd451036b
--- /dev/null
+++ b/group24/494800949/src/main/java/com/coding/week3/download/impl/ConnectionManagerImpl.java
@@ -0,0 +1,37 @@
+package com.coding.week3.download.impl;
+
+
+import com.coding.week3.download.api.Connection;
+import com.coding.week3.download.api.ConnectionException;
+import com.coding.week3.download.api.ConnectionManager;
+
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.net.URLConnection;
+
+public class ConnectionManagerImpl implements ConnectionManager {
+
+    @Override
+    public Connection open(String url) throws ConnectionException {
+        try {
+            // 统一资源
+            URL realurl = new URL(url);
+            // 连接类的父类，抽象类
+            URLConnection urlConnection = realurl.openConnection();
+            // http的连接类
+            HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
+            // 设定请求的方法，默认是GET
+            httpURLConnection.setRequestMethod("GET");
+            httpURLConnection.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
+            // 设置字符编码
+            httpURLConnection.setRequestProperty("Charset", "UTF-8");
+            // 打开到此 URL 引用的资源的通信链接（如果尚未建立这样的连接）。
+            httpURLConnection.connect();
+            return new ConnectionImpl(httpURLConnection);
+        } catch (java.io.IOException e) {
+            e.printStackTrace();
+            throw new ConnectionException(e.getMessage());
+        }
+    }
+
+}
diff --git a/group24/494800949/src/test/java/com/coding/week3/FileDownloaderTest.java b/group24/494800949/src/test/java/com/coding/week3/FileDownloaderTest.java
new file mode 100644
index 0000000000..5b423f145f
--- /dev/null
+++ b/group24/494800949/src/test/java/com/coding/week3/FileDownloaderTest.java
@@ -0,0 +1,103 @@
+package com.coding.week3;
+
+import com.coding.week3.download.FileDownloader;
+import com.coding.week3.download.api.ConnectionManager;
+import com.coding.week3.download.api.DownloadListener;
+import com.coding.week3.download.impl.ConnectionManagerImpl;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.*;
+
+
+public class FileDownloaderTest {
+	boolean downloadFinished = false;
+    static final int DEFAULT_THREADS_NUM = 5;
+
+    @Before
+	public void setUp() throws Exception {
+	}
+
+	@After
+	public void tearDown() throws Exception {
+	}
+
+	@Test
+	public void testDownload() throws IOException {
+
+//		String url =  "http://101.95.48.97:8005/res/upload/interface/apptutorials/manualstypeico/6f83ce8f-0da5-49b3-bac8-fd5fc67d2725.png";
+//		String url =  "http://download.oracle.com/otn-pub/java/jdk/8u121-b13/e9e7ea248e2c4826b92b3f075a80e441/jdk-8u121-linux-arm32-vfp-hflt.tar.gz";
+//		String url =  "https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1490808670106&di=48aa6fb7af641f0cb6f9e19120b60c7c&imgtype=0&src=http%3A%2F%2Fwww.ntjoy.com%2Fliv_loadfile%2Fhealth%2Fdzcs%2Fnvr%2Ffold1%2F1360480639_97304600.jpg";
+		String url =  "https://download.jetbrains.com/idea/ideaIU-2017.1.exe";
+		String path = new File("").getAbsolutePath();
+		String filename = url.substring(url.lastIndexOf("/"), url.length());
+		 filename = path +File.separator + filename;
+
+		FileDownloader downloader = new FileDownloader(DEFAULT_THREADS_NUM, filename, url);
+		ConnectionManager cm = new ConnectionManagerImpl();
+		downloader.setConnectionManager(cm);
+		downloader.setListener(new DownloadListener() {
+			@Override
+			public void notifyFinished() {
+				downloadFinished = true;
+			}
+
+		});
+
+		
+		downloader.execute();
+		
+		// 等待多线程下载程序执行完毕
+		while (!downloadFinished) {
+			try {
+				System.out.println("还没有下载完成，休眠五秒");
+				//休眠5秒
+				Thread.sleep(5000);
+			} catch (InterruptedException e) {				
+				e.printStackTrace();
+			}
+		}
+		System.out.println("下载完成！");
+		
+		
+
+	}
+
+
+	@Test
+	public void lenTest(){
+		int lastLen = 0;
+		int length = 10232;
+		int nThread = 10;
+		int perLenOfThread = 0;
+
+		if ( length % nThread == 0)
+			perLenOfThread = length / nThread;
+		else {
+			lastLen = length % nThread;
+			perLenOfThread = (length - lastLen) / nThread;
+		}
+		Assert.assertEquals(perLenOfThread, 1023);
+		Assert.assertEquals(lastLen, 2);
+
+		Thread[] threads = new Thread[nThread+1];
+		if ( length % nThread == 0) {
+			perLenOfThread = length / nThread;
+		}
+		else {
+			lastLen = length % nThread;
+			perLenOfThread = (length - lastLen) / nThread;
+		}
+		for (int i = 0; i <= nThread; i++) {
+			if ( i < nThread) {
+				System.out.println("startPos: " + perLenOfThread * i);
+				System.out.println("endPos: " + (perLenOfThread * (i + 1) - 1));
+			} else {
+				System.out.println("startPos: " + perLenOfThread * nThread);
+				System.out.println("endPos: " + (length - 1));
+			}
+		}
+	}
+}