文件多线程下载实现

布局文件

 1 - <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".MainActivity"> 2 - <LinearLayout android:id="@+id/ll" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> 3 - <EditText android:id="@+id/pathET" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:inputType="textUri" android:text="http://192.168.1.251:8080/WebServer/FeiQ.exe"> 4   <requestFocus />  5   </EditText> 6   <ImageButton android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="download" android:src="@android:drawable/ic_media_play" />  7   </LinearLayout> 8   <ProgressBar android:id="@+id/downloadPB" style="?android:attr/progressBarStyleHorizontal" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@id/ll" android:layout_marginTop="20dp" />  9   <TextView android:id="@+id/percentTV" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@id/downloadPB" android:text="0%" /> 10   <TextView android:id="@+id/progressTV" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_below="@id/downloadPB" android:text="0/0" /> 11   </RelativeLayout>

View Code

MyHandler.java

 1 package com.itheima.download; 2  3 import java.io.File; 4 import java.io.FileOutputStream; 5 import java.io.IOException; 6 import java.io.InputStream; 7  8 import org.apache.http.HttpEntity; 9 10 import android.content.Context;11 12 import com.loopj.android.http.FileAsyncHttpResponseHandler;13 14 public abstract class MyFileHandler extends FileAsyncHttpResponseHandler {15     private boolean isCancel;16 17     public MyFileHandler(Context context) {18         super(context);19     }20 21     public MyFileHandler(File file) {22         super(file);23     }24 25     @Override26     protected byte[] getResponseData(HttpEntity entity) throws IOException {27         if (entity != null) {28             InputStream instream = entity.getContent();29             long contentLength = entity.getContentLength();30             FileOutputStream buffer = new FileOutputStream(getTargetFile(), true);31             if (instream != null) {32                 try {33                     byte[] tmp = new byte[BUFFER_SIZE];34                     int l, count = 0;35                     // do not send messages if request has been cancelled36                     while ((l = instream.read(tmp)) != -1 && !Thread.currentThread().isInterrupted()) {37                         if (isCancel)38                             break;39                         count += l;40                         buffer.write(tmp, 0, l);41                         sendProgressMessage(count, (int) contentLength);42                     }43                 } finally {44                     instream.close();45                     buffer.flush();46                     buffer.close();47                 }48             }49         }50         return null;51     }52     53     public void cancel() {54         isCancel = true;55     }56 57 }

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MainActivity.java

 1 package com.itheima.download; 2  3 import java.io.File; 4  5 import android.app.Activity; 6 import android.os.Bundle; 7 import android.os.Environment; 8 import android.view.View; 9 import android.widget.EditText;10 import android.widget.ImageButton;11 import android.widget.ProgressBar;12 import android.widget.TextView;13 14 public class MainActivity extends Activity {15 16 //    private AsyncHttpClient client;17     18     private EditText pathET;19     private ProgressBar downloadPB;20     private TextView percentTV;21     private TextView progressTV;22     private DownloadTask task;23 24     @Override25     protected void onCreate(Bundle savedInstanceState) {26         super.onCreate(savedInstanceState);27         setContentView(R.layout.activity_main);28         29         pathET = (EditText) findViewById(R.id.pathET);30         downloadPB = (ProgressBar) findViewById(R.id.downloadPB);31         percentTV = (TextView) findViewById(R.id.percentTV);32         progressTV = (TextView) findViewById(R.id.progressTV);33         34 //        client = new AsyncHttpClient();35     }36     37     public void download(View v) {38         ImageButton ib = (ImageButton) v;39         40         if (task == null) {41             String targetUrl = pathET.getText().toString().trim();42             File localFile = new File(Environment.getExternalStorageDirectory(), targetUrl.substring(targetUrl.lastIndexOf("/") + 1));43             task = new DownloadTask(targetUrl, localFile, 3, this, downloadPB, percentTV, progressTV);44             task.execute();45             ib.setImageResource(android.R.drawable.ic_media_pause);46         } else {47             task.stop();48             task = null;49             ib.setImageResource(android.R.drawable.ic_media_play);50         }51     }52 53     /*54     public void classicDownload(View v) {55         String path = pathET.getText().toString().trim();56         File file = new File("/mnt/sdcard/", path.substring(path.lastIndexOf("/") + 1));57         58         client.get(path, new FileAsyncHttpResponseHandler(file) {        // 处理文件传输的处理器59             public void onSuccess(int statusCode, Header[] headers, File file) {60                 Toast.makeText(getApplicationContext(), "下载成功", Toast.LENGTH_SHORT).show();61             }62             public void onFailure(int statusCode, Header[] headers, Throwable throwable, File file) {63                 Toast.makeText(getApplicationContext(), "下载失败 " + statusCode, Toast.LENGTH_SHORT).show();64                 throwable.printStackTrace();65             }66             public void onProgress(int bytesWritten, int totalSize) {    // 下载或上传的进度67                 System.out.println(bytesWritten + " / " + totalSize + " (" + bytesWritten * 100 / totalSize + "%)");68             }69         });70     }71     */72 73 }

View Code

DownloadTask.java

  1 package com.itheima.download;  2   3 import java.io.File;  4 import java.io.FileInputStream;  5 import java.io.FileOutputStream;  6 import java.io.IOException;  7 import java.util.ArrayList;  8   9 import org.apache.http.Header; 10  11 import android.content.Context; 12 import android.widget.ProgressBar; 13 import android.widget.TextView; 14  15 import com.loopj.android.http.AsyncHttpClient; 16 import com.loopj.android.http.AsyncHttpResponseHandler; 17  18 public class DownloadTask { 19     private String targetUrl; 20     private File localFile; 21     private int threadAmount; 22     private Context context; 23     private ProgressBar downloadPB; 24     private TextView percentTV; 25     private TextView progressTV; 26  27     private long contentLength; 28     private long threadLength; 29     private ArrayList<File> cacheList = new ArrayList<File>(); 30     private ArrayList<MyFileHandler> handlerList = new ArrayList<MyFileHandler>(); 31      32     /** 33      * 创建下载任务 34      * @param targetUrl        目标地址 35      * @param localFile        本地路径 36      * @param threadAmount    线程数量 37      * @param context        应用环境 38      * @param downloadPB  39      * @param progressTV  40      * @param percentTV  41      */ 42     public DownloadTask(String targetUrl, File localFile, int threadAmount, Context context, ProgressBar downloadPB, TextView percentTV, TextView progressTV) { 43         super(); 44         this.targetUrl = targetUrl; 45         this.localFile = localFile; 46         this.threadAmount = threadAmount; 47         this.context = context; 48         this.downloadPB = downloadPB; 49         this.percentTV = percentTV; 50         this.progressTV = progressTV; 51     } 52  53     public void execute() { 54         new AsyncHttpClient().head(targetUrl, new AsyncHttpResponseHandler() {        // 根据URL向服务器发起一个请求, 获取响应头 55             public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) { 56                 caculateLength(headers);    // 获取文件总长度, 计算每个线程负责的长度 57                 beginDownload();            // 开启多个线程下载 58             } 59             public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error) { 60             } 61         }); 62     } 63      64     private void caculateLength(Header[] headers) {         65         for (Header header : headers)  66             if ("Content-Length".equals(header.getName()))  67                 contentLength = Long.parseLong(header.getValue());            // 从相应头中获取文件总大小 68         threadLength = (contentLength + threadAmount - 1) / threadAmount;    // 计算每个线程负责多少 69         downloadPB.setMax((int) contentLength);        // 设置进度条的最大刻度为文件总大小 70     } 71      72     private void beginDownload() { 73         for (int i = 0; i < threadAmount; i++) {    // 定义循环, 每次循环启动1个线程下载 74             File cacheFile = new File(context.getCacheDir(), localFile.getName() + ".temp" + i);    // 定义临时文件的路径 75             cacheList.add(cacheFile);                // 把文件装入集合 76              77             long begin = i * threadLength + cacheFile.length();        // 计算开始位置 78             long end = i * threadLength + threadLength - 1;            // 计算结束位置 79             System.out.println(i + ": " + begin + " - " + end); 80             if (begin > end) 81                 continue; 82              83             MyFileHandler fileHandler = new MyFileHandler(cacheFile) {            // 发送请求, 下载数据, 存储到临时文件 84                 private long ms; 85                 public void onSuccess(int statusCode, Header[] headers, File file) { 86                     System.out.println(Thread.currentThread().getName() + ": " + file + " 下载完成"); 87                     checkOtherThread();                // 检查其他线程是否下载完毕, 如果都完了, 合并文件 88                 } 89                 public void onFailure(int statusCode, Header[] headers, Throwable throwable, File file) { 90                 } 91                 public void onProgress(int bytesWritten, int totalSize) {    // 运行频率非常高 92                     if (System.currentTimeMillis() - ms > 100) { 93                         ms = System.currentTimeMillis(); 94                         updateProgress(); 95                     } 96                 } 97             }; 98             handlerList.add(fileHandler); 99             100             AsyncHttpClient client = new AsyncHttpClient();101             client.addHeader("Range", "bytes=" + begin + "-" + end);        // 设置请求数据的范围102             client.get(targetUrl, fileHandler);103         }104     }105     106     private void updateProgress() {107         long finishLength = getFinishLength();108         if (finishLength == 0)109             return;110         downloadPB.setProgress((int) finishLength);111         percentTV.setText(finishLength * 1000 / contentLength / 10f + "%"); 112         progressTV.setText(finishLength + "/" + contentLength);113     }114     115     private long getFinishLength() {116         long finishLength = 0;117         for (File cacheFile : cacheList)             // 遍历所有临时文件118             finishLength += cacheFile.length();        // 统计总长度119         return finishLength;120     }121 122     private void checkOtherThread() {123         if (getFinishLength() == contentLength) {     // 如果文件长度和ContentLength相等, 代表下载完成124             updateProgress();125             merge();                                // 合并所有的临时文件126         }127     }128 129     private void merge() {130         try {131             FileOutputStream out = new FileOutputStream(localFile);        132             for (File cacheFile : cacheList) {                                // 遍历所有临时文件133                 FileInputStream in = new FileInputStream(cacheFile);        134                 byte[] buffer = new byte[8192];135                 int length;136                 while ((length = in.read(buffer)) != -1)    // 读取每个文件137                     out.write(buffer, 0, length);            // 把每个文件的数据都写出到localFile138                 in.close();139                 cacheFile.delete();140             }141             out.close();142         } catch (IOException e) {143             throw new RuntimeException(e);144         }145     }146     147     public void stop() {148         for (MyFileHandler fileHandler : handlerList) {149             fileHandler.cancel();150         }151     }152 }

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