Merge pull request #37 from Jayzyyzyy/master

3.12作业

group15/1511_714512544/out/production/1511_714512544/com/coding/basic/平衡二叉树AVL.md

@@ -0,0 +1,5 @@
+
+1. 每个结点的平衡因子就是该结点的左子树的高度减去右子树的高度，平衡二叉树的每个结点的平衡因子的绝对值不会超过2。
+2. 右旋口诀：左子作父，父为右子，右孙变左孙
+   左旋口诀：右子作父，父为左子，左孙变右孙
+

group15/1511_714512544/src/com/coderising/array/ArrayUtil.java

@@ -12,6 +12,7 @@ public class ArrayUtil {
      * @return
      */
     public void reverseArray(int[] origin){
+        if(origin == null) return ; //边界条件
         int len = origin.length;
         int temp = 0;
         for (int i = 0; i < len/2; i++) {
@@ -30,6 +31,7 @@ public void reverseArray(int[] origin){
      */
 
     public int[] removeZero(int[] oldArray){
+        if(oldArray == null) return null; //边界条件
         int[] temp = new int[oldArray.length];
         int index = 0;
         for (int i : oldArray) {
@@ -52,6 +54,10 @@ public int[] removeZero(int[] oldArray){
      */
 
     public int[] merge(int[] array1, int[] array2){
+        if(array1 == null && array2 == null ) return null;
+        if(array1 == null) return array2;
+        if(array2 == null) return array1;
+
         int[] array3 = new int[array1.length+array2.length];
         for (int i = 0; i < array1.length; i++) {
             array3[i] = array1[i];

group15/1511_714512544/src/com/coderising/download/Demo.java

@@ -0,0 +1,99 @@
+package com.coderising.download;
+
+import java.io.InputStream;
+import java.io.RandomAccessFile;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+public class Demo {
+    public static String path = "https://ss0.bdstatic.com/5aV1bjqh_Q23odCf/static/superman/img/logo/logo_white_fe6da1ec.png";
+    public static int threadCount = 3;
+    public static void main(String[] args) throws Exception{
+        //1.连接服务器，获取一个文件，获取文件的长度，在本地创建一个跟服务器一样大小的临时文件
+        URL url = new URL(path);
+        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
+        conn.setConnectTimeout(5000);
+        conn.setRequestMethod("GET");
+        int code = conn.getResponseCode();
+        if (code == 200) {
+            //服务器端返回的数据的长度，实际上就是文件的长度
+            int length = conn.getContentLength();
+            System.out.println("文件总长度："+length);
+            //在客户端本地创建出来一个大小跟服务器端一样大小的临时文件
+            RandomAccessFile raf = new RandomAccessFile("d:/1.png", "rwd");
+            //指定创建的这个文件的长度
+            raf.setLength(length);
+            raf.close();
+            //假设是3个线程去下载资源。
+            //平均每一个线程下载的文件大小.
+            int blockSize = length / threadCount;
+            for (int threadId = 1; threadId <= threadCount; threadId++) {
+                //第一个线程下载的开始位置
+                int startIndex = (threadId - 1) * blockSize;
+                int endIndex = threadId * blockSize - 1;
+                if (threadId == threadCount) {//最后一个线程下载的长度要稍微长一点
+                    endIndex = length;
+                }
+                System.out.println("线程："+threadId+"下载:---"+startIndex+"--->"+endIndex);
+                new DownLoadThread(path, threadId, startIndex, endIndex).start();
+            }
+
+        }else {
+            System.out.printf("服务器错误!");
+        }
+    }
+
+    /**
+     * 下载文件的子线程  每一个线程下载对应位置的文件
+     * @author jie
+     *
+     */
+    public static class DownLoadThread extends Thread{
+        private int threadId;
+        private int startIndex;
+        private int endIndex;
+        /**
+         * @param path 下载文件在服务器上的路径
+         * @param threadId 线程Id
+         * @param startIndex 线程下载的开始位置
+         * @param endIndex    线程下载的结束位置
+         */
+        public DownLoadThread(String path, int threadId, int startIndex, int endIndex) {
+            super();
+            this.threadId = threadId;
+            this.startIndex = startIndex;
+            this.endIndex = endIndex;
+        }
+
+        @Override
+        public void run() {
+            try {
+                URL url = new URL(path);
+                HttpURLConnection conn = (HttpURLConnection)url.openConnection();
+                conn.setConnectTimeout(5000);
+                conn.setRequestMethod("GET");
+                //重要:请求服务器下载部分文件 指定文件的位置
+                conn.setRequestProperty("Range", "bytes="+startIndex+"-"+endIndex);
+                //从服务器请求全部资源返回200 ok如果从服务器请求部分资源 返回 206 ok
+                int code = conn.getResponseCode();
+                System.out.println("code:"+code);
+                InputStream is = conn.getInputStream();//已经设置了请求的位置，返回的是当前位置对应的文件的输入流
+                RandomAccessFile raf = new RandomAccessFile("d:/1.png", "rwd");
+                //随机写文件的时候从哪个位置开始写
+                raf.seek(startIndex);//定位文件
+
+                int len = 0;
+                byte[] buffer = new byte[1024];
+                while ((len = is.read(buffer)) != -1) {
+                    raf.write(buffer, 0, len);
+                }
+                is.close();
+                raf.close();
+                System.out.println("线程："+threadId+"下载完毕");
+            } catch (Exception e) {
+                e.printStackTrace();
+            }
+        }
+
+    }
+}

group15/1511_714512544/src/com/coderising/download/DownloadThread.java

@@ -0,0 +1,58 @@
+package com.coderising.download;
+
+import com.coderising.download.api.Connection;
+import com.coderising.download.api.DownloadListener;
+import com.coderising.download.impl.ConnectionImpl;
+import com.coderising.download.impl.ConnectionManagerImpl;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.net.URL;
+
+public class DownloadThread extends Thread{
+	int startPos;
+	int endPos;
+	String url;
+	String savePath;
+	DownloadListener listener;
+	private static int count = 0;
+	private Object lock = new Object();  //对象锁
+
+	public DownloadThread(String url, String savePath, DownloadListener listener, int startPos, int endPos){
+		this.startPos = startPos;
+		this.endPos = endPos;
+		this.url = url;
+		this.savePath = savePath;
+		this.listener = listener;
+	}
+	public void run(){
+		RandomAccessFile raf = null;
+		//实现
+		try {
+			Connection conn = new ConnectionManagerImpl().open(url);
+			raf = new RandomAccessFile(savePath,"rwd");
+
+			byte[] data= conn.read(startPos,endPos);
+
+			raf.seek(startPos);
+			raf.write(data);
+			synchronized (lock){  //加对象锁
+				count ++;
+				if(count == 3){
+					listener.notifyFinished();
+				}
+			}
+
+		} catch (Exception e) {
+			throw new RuntimeException("读取错误");
+		}finally {
+			try {
+				if(raf != null){
+					raf.close();
+				}
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		}
+	}
+}

group15/1511_714512544/src/com/coderising/download/FileDownloader.java

@@ -0,0 +1,81 @@
+package com.coderising.download;
+
+import com.coderising.download.api.Connection;
+import com.coderising.download.api.ConnectionException;
+import com.coderising.download.api.ConnectionManager;
+import com.coderising.download.api.DownloadListener;
+import com.coderising.download.impl.ConnectionManagerImpl;
+
+import java.io.RandomAccessFile;
+
+/**
+ * 文件下载器
+ */
+public class FileDownloader {
+	String url;  //下载路径
+	String savePath = "d:/1.png"; //保存路径
+	DownloadListener listener ; //下载监听器
+	ConnectionManager cm ; //连接管理
+
+	public FileDownloader(String _url) {
+		this.url = _url;
+
+	}
+
+	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;
+		RandomAccessFile raf = null;
+		try {
+			cm = new ConnectionManagerImpl();
+			conn = cm.open(this.url);
+			int length = conn.getContentLength();
+
+			raf = new RandomAccessFile(savePath,"rwd");
+			if(raf.length() == 0){
+				raf.setLength(length);
+			}
+			raf.close();
+
+			for (int i = 0; i <= 2; i++) {
+				int startPos = i*length/3;
+				int endPos = length*(i+1)/3-1;
+				if(i == 2) {
+					endPos = length-1;
+				}
+				new DownloadThread(url, savePath,listener ,startPos, endPos).start();
+			}
+
+		} catch (Exception e) {
+			e.printStackTrace();
+		}
+
+	}
+
+	public void setListener(DownloadListener listener) {
+		this.listener = listener;
+	}
+
+
+
+	public void setConnectionManager(ConnectionManager ucm){
+		this.cm = ucm;
+	}
+
+	public DownloadListener getListener(){
+		return this.listener;
+	}
+
+}

group15/1511_714512544/src/com/coderising/download/FileDownloaderTest.java

@@ -0,0 +1,58 @@
+package com.coderising.download;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.coderising.download.api.ConnectionManager;
+import com.coderising.download.api.DownloadListener;
+import com.coderising.download.impl.ConnectionManagerImpl;
+
+public class FileDownloaderTest {
+	boolean downloadFinished = false; //是否下载完
+	@Before
+	public void setUp() throws Exception {
+	}
+
+	@After
+	public void tearDown() throws Exception {
+	}
+
+	@Test
+	public void testDownload() {
+
+		String url = "https://www.baidu.com/img/bd_logo1.png";
+
+		FileDownloader downloader = new FileDownloader(url);
+
+		ConnectionManager cm = new ConnectionManagerImpl();
+		downloader.setConnectionManager(cm);  //设置连接管理器
+
+		downloader.setListener(new DownloadListener() {  //设置监听器
+			@Override
+			public void notifyFinished() {
+				downloadFinished = true;
+			}
+
+		});
+
+
+		downloader.execute(); //执行下载
+
+		// 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("Down!!!");
+
+
+
+	}
+
+}

group15/1511_714512544/src/com/coderising/download/api/Connection.java

@@ -0,0 +1,24 @@
+package com.coderising.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();
+
+}

group15/1511_714512544/src/com/coderising/download/api/ConnectionException.java

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

group15/1511_714512544/src/com/coderising/download/api/ConnectionManager.java

@@ -0,0 +1,10 @@
+package com.coderising.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;	
+}

group15/1511_714512544/src/com/coderising/download/api/DownloadListener.java

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