Merge pull request #48 from qilei/master

完善多线程下载

group04/916758663/learn01/learn01.iml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <module org.jetbrains.idea.maven.project.MavenProjectsManager.isMavenModule="true" type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_8" inherit-compiler-output="false">
+  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_5" inherit-compiler-output="false">
     <output url="file://$MODULE_DIR$/target/classes" />
     <output-test url="file://$MODULE_DIR$/target/test-classes" />
     <content url="file://$MODULE_DIR$">

group04/916758663/learn01/src/main/java/com/coding/basic/ArrayList.java

@@ -9,23 +9,30 @@ public class ArrayList implements List {
 	private Object[] elementData = new Object[3];
 
 	public void add(Object o){
-		add(size,o);
+		ensureCapacity(size + 1);
+		elementData[size] = o;
+		size++;
 	}
+
 	public void add(int index, Object o){
 		if (index > size){
 			throw new IndexOutOfBoundsException();
 		}
+
 		// 扩容
-		if (size == elementData.length || index + 1 > elementData.length) {
-			int newLength = index + 1 > size * 2 ? index + 1 :size * 2;
-			elementData = Arrays.copyOf(elementData, newLength);
-		}
+		ensureCapacity(size + 1);
+
 		// 移动元素
 		System.arraycopy(elementData,index,elementData,index + 1 ,size-index);
 		elementData[index] = o;
 		size ++ ;
 	}
-
+
+	private void ensureCapacity(int minCapacity) {
+		int newLength = Math.max(minCapacity, size * 2);
+		elementData = Arrays.copyOf(elementData, newLength);
+	}
+
 	public Object get(int index){
 		checkIndex(index);
 		return elementData[index];
@@ -55,17 +62,17 @@ public Iterator iterator(){
 
 	private class ArrayListIterator implements Iterator {
 
-		private int currentIndex = 0;
+		private int position = 0;
 
 		@Override
 		public boolean hasNext() {
-			return currentIndex < size();
+			return position < size();
 		}
 
 		@Override
 		public Object next() {
-			Object o = get(currentIndex);
-			currentIndex ++ ;
+			Object o = get(position);
+			position++ ;
 			return o;
 		}
 	}

group04/916758663/learn03/pom.xml

@@ -0,0 +1,32 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>com.example</groupId>
+  <artifactId>download</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <name>download</name>
+  <url>http://maven.apache.org</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.12</version>
+      <scope>test</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>org.assertj</groupId>
+      <artifactId>assertj-core</artifactId>
+      <version>3.6.2</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>

group04/916758663/learn03/src/main/java/com/example/download/DownloadThread.java

@@ -0,0 +1,50 @@
+package com.example.download;
+
+
+import com.example.download.api.Connection;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.concurrent.CountDownLatch;
+
+public class DownloadThread extends Thread{
+
+	Connection conn;
+	int startPos;
+	int endPos;
+	String file;
+	CountDownLatch latch;
+
+	public DownloadThread( Connection conn, int startPos, int endPos,String file,CountDownLatch latch){
+
+		this.conn = conn;		
+		this.startPos = startPos;
+		this.endPos = endPos;
+		this.file = file;
+		this.latch = latch;
+	}
+	public void run(){
+		RandomAccessFile randomAccessFile = null;
+		try {
+			byte[] data = conn.read(startPos, endPos);
+			randomAccessFile = new RandomAccessFile(file, "rw");
+			randomAccessFile.seek(startPos);
+			randomAccessFile.write(data);
+			latch.countDown();
+		} catch (FileNotFoundException e) {
+			e.printStackTrace();
+		} catch (IOException e) {
+			e.printStackTrace();
+		}finally {
+			try {
+				if (randomAccessFile != null) {
+					randomAccessFile.close();
+				}
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+			conn.close();
+		}
+	}
+}

group04/916758663/learn03/src/main/java/com/example/download/FileDownloader.java

@@ -0,0 +1,76 @@
+package com.example.download;
+
+
+import com.example.download.api.Connection;
+import com.example.download.api.ConnectionException;
+import com.example.download.api.ConnectionManager;
+import com.example.download.api.DownloadListener;
+import java.util.concurrent.CountDownLatch;
+
+public class FileDownloader {
+
+	String url;
+
+	String localFile;
+
+	DownloadListener listener;
+
+	ConnectionManager cm;
+
+	private CountDownLatch latch = new CountDownLatch(3);
+
+
+	public FileDownloader(String _url,String localFile) {
+		this.url = _url;
+		this.localFile = localFile;
+	}
+
+	public void execute(){
+		// 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 {
+			conn = cm.open(this.url);
+			int length = conn.getContentLength();
+			int[][] array = Utils.split(length, 3);
+			for (int i = 0; i < 3; i++) {
+				new DownloadThread(conn,array[i][0],array[i][1],localFile,latch).start();
+			}
+
+			latch.await();
+
+			this.getListener().notifyFinished();
+
+		} catch (ConnectionException e) {
+			e.printStackTrace();
+		} catch (InterruptedException e) {
+			e.printStackTrace();
+		} finally{
+		}
+
+	}
+
+	public void setListener(DownloadListener listener) {
+		this.listener = listener;
+	}
+
+	public void setConnectionManager(ConnectionManager ucm){
+		this.cm = ucm;
+	}
+
+	public DownloadListener getListener(){
+		return this.listener;
+	}
+
+}

group04/916758663/learn03/src/main/java/com/example/download/Utils.java

@@ -0,0 +1,24 @@
+package com.example.download;
+
+/**
+ * Created by qilei on 17/3/26.
+ */
+public class Utils {
+
+  public static int[][] split(int len, int count) {
+    int[][] result = new int[count][2];
+    int baseLen = (int)Math.ceil(((double)len / count));
+    for (int i = 0; i < count; i++) {
+      int startPos = baseLen * i ;
+      int endPos = baseLen * (i + 1) -1;
+      if (i == count - 1) {
+        if (endPos > len - 1) {
+          endPos = len - 1;
+        }
+      }
+      result[i][0] = startPos;
+      result[i][1] = endPos;
+    }
+    return result;
+  }
+}

group04/916758663/learn03/src/main/java/com/example/download/api/Connection.java

@@ -0,0 +1,23 @@
+package com.example.download.api;
+
+import java.io.IOException;
+
+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
+	 */
+	public byte[] read(int startPos, int endPos) throws IOException;
+	/**
+	 * 得到数据内容的长度
+	 * @return
+	 */
+	public int getContentLength();
+
+	/**
+	 * 关闭连接
+	 */
+	public void close();
+}

group04/916758663/learn03/src/main/java/com/example/download/api/ConnectionException.java

@@ -0,0 +1,5 @@
+package com.example.download.api;
+
+public class ConnectionException extends Exception {
+
+}

group04/916758663/learn03/src/main/java/com/example/download/api/ConnectionManager.java

@@ -0,0 +1,10 @@
+package com.example.download.api;
+
+public interface ConnectionManager {
+	/**
+	 * 给定一个url , 打开一个连接
+	 * @param url
+	 * @return
+	 */
+	public Connection open(String url) throws ConnectionException;	
+}

group04/916758663/learn03/src/main/java/com/example/download/api/DownloadListener.java

@@ -0,0 +1,5 @@
+package com.example.download.api;
+
+public interface DownloadListener {
+	public void notifyFinished();
+}

group04/916758663/learn03/src/main/java/com/example/download/impl/ConnectionImpl.java

@@ -0,0 +1,58 @@
+package com.example.download.impl;
+
+import com.example.download.api.Connection;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLConnection;
+
+
+public class ConnectionImpl implements Connection {
+
+	private URL url;
+
+	ConnectionImpl(String urlStr){
+		try {
+			url = new URL(urlStr);
+		} catch (MalformedURLException e) {
+			e.printStackTrace();
+		}
+	}
+
+	@Override
+	public byte[] read(int startPos, int endPos) throws IOException {
+    URLConnection urlConnection = url.openConnection();
+    urlConnection.setRequestProperty("Range", "bytes=" + startPos + "-"
+        + endPos);
+    InputStream inputStream = urlConnection.getInputStream();
+    int len = endPos + 1 - startPos;
+    int bytesRead = 0;
+		byte[] buffer = new byte[len];
+    while (bytesRead < len) {
+      int result = inputStream.read(buffer, bytesRead, len - bytesRead);
+      if (result == -1){
+        break;
+      }
+      bytesRead += result;
+    }
+    inputStream.close();
+		return buffer;
+	}
+
+	@Override
+	public int getContentLength() {
+		try {
+      URLConnection urlConnection = url.openConnection();
+      return urlConnection.getContentLength();
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+    return -1;
+	}
+
+	@Override
+	public void close() {
+	}
+
+}

group04/916758663/learn03/src/main/java/com/example/download/impl/ConnectionManagerImpl.java

@@ -0,0 +1,16 @@
+package com.example.download.impl;
+
+
+import com.example.download.api.Connection;
+import com.example.download.api.ConnectionException;
+import com.example.download.api.ConnectionManager;
+
+public class ConnectionManagerImpl implements ConnectionManager {
+
+	@Override
+	public Connection open(String url) throws ConnectionException {
+		Connection conn = new ConnectionImpl(url);
+		return conn;
+	}
+
+}