(Android小应用)在Android中实现多线程断点下载（连载二）
前面已经讲了通过多线程下载网络文件的一部分核心代码，下面继续做我们的项目
当然如果我们做小一点的Android项目的时候可以先做界面，然后根据需要来扩展所需要的功能，当然有的时候我们宁愿先实现业务，业务功能做好了再实现界面，因为界面里面基本不含有技术，况且我们只是为了学习，界面不需要多美观的，能用就行，OK，继续
先做数据库这层
关于建Android项目方法的截图就省略了，我用的模拟器版本是2.3.3，至今为至最新的吧
首先建一个类DBOpenHelper继续自SQLiteOpenHelper
package com.studio.service;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBOpenHelper extends SQLiteOpenHelper {
private static final String DBNAME = "download.db";
private static final int VERSION = 1;
public DBOpenHelper(Context context) {
super(context, DBNAME, null, VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE IF NOT EXISTS filedownlog (id integer primary key autoincrement, downpath varchar(100), threadid INTEGER, downlength INTEGER)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS filedownlog");
onCreate(db);
}
}
这里定义的数据名字叫download.db,版本号为1，表名filedownlog,里面有三个字段，一个id,主键，下载路径downpath，线程ID和一个下载长度downlength
然后建一个FileService类
package com.studio.service;
import java.util.HashMap;
import java.util.Map;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
/**
* 业务bean
*
*/
public class FileService {
private DBOpenHelper openHelper;
public FileService(Context context) {
openHelper = new DBOpenHelper(context);
}
/**
* 获取每条线程已经下载的文件长度
*
* @param path
* @return
*/
public Map<Integer, Integer> getData(String path) {
SQLiteDatabase db = openHelper.getReadableDatabase();
Cursor cursor = db
.rawQuery(
"select threadid, downlength from filedownlog where downpath=?",
new String[] { path });
Map<Integer, Integer> data = new HashMap<Integer, Integer>();
while (cursor.moveToNext()) {
data.put(cursor.getInt(0), cursor.getInt(1));
}
cursor.close();
db.close();
return data;
}
/**
* 保存每条线程已经下载的文件长度
*
* @param path
* @param map
*/
public void save(String path, Map<Integer, Integer> map) {// int threadid,
// int position
SQLiteDatabase db = openHelper.getWritableDatabase();
db.beginTransaction();
try {
for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
db.execSQL(
"insert into filedownlog(downpath, threadid, downlength) values(?,?,?)",
new Object[] { path, entry.getKey(), entry.getValue() });
}
db.setTransactionSuccessful();
} finally {
db.endTransaction();
}
db.close();
}
/**
* 实时更新每条线程已经下载的文件长度
*
* @param path
* @param map
*/
public void update(String path, Map<Integer, Integer> map) {
SQLiteDatabase db = openHelper.getWritableDatabase();
db.beginTransaction();
try {
for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
db.execSQL(
"update filedownlog set downlength=? where downpath=? and threadid=?",
new Object[] { entry.getValue(), path, entry.getKey() });
}
db.setTransactionSuccessful();
} finally {
db.endTransaction();
}
db.close();
}
/**
* 当文件下载完成后，删除对应的下载记录
*
* @param path
*/
public void delete(String path) {
SQLiteDatabase db = openHelper.getWritableDatabase();
db.execSQL("delete from filedownlog where downpath=?",
new Object[] { path });
db.close();
}
}
类中都有相应的注释的，看不懂可以慢慢看……
因为要用到进度条，所以先把进度条建了
package com.studio.net.download;
public interface DownloadProgressListener {
public void onDownloadSize(int size);
}
新建一个类DownloadThread继承自Thread
package com.studio.net.download;
import java.io.File;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import android.util.Log;
public class DownloadThread extends Thread {
private static final String TAG = "DownloadThread";
private File saveFile;
private URL downUrl;
private int block;
/* 下载开始位置 */
private int threadId = -1;
private int downLength;
private boolean finish = false;
private FileDownloader downloader;
public DownloadThread(FileDownloader downloader, URL downUrl,
File saveFile, int block, int downLength, int threadId) {
this.downUrl = downUrl;
this.saveFile = saveFile;
this.block = block;
this.downloader = downloader;
this.threadId = threadId;
this.downLength = downLength;
}
@Override
public void run() {
if (downLength < block) {// 未下载完成
try {
HttpURLConnection http = (HttpURLConnection) downUrl
.openConnection();
http.setConnectTimeout(5 * 1000);
http.setRequestMethod("GET");
http.setRequestProperty(
"Accept",
"image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");
http.setRequestProperty("Accept-Language", "zh-CN");
http.setRequestProperty("Referer", downUrl.toString());
http.setRequestProperty("Charset", "UTF-8");
int startPos = block * (threadId - 1) + downLength;// 开始位置
int endPos = block * threadId - 1;// 结束位置
http.setRequestProperty("Range", "bytes=" + startPos + "-"
+ endPos);// 设置获取实体数据的范围
http.setRequestProperty(
"User-Agent",
"Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");
http.setRequestProperty("Connection", "Keep-Alive");
InputStream inStream = http.getInputStream();
byte[] buffer = new byte[1024];
int offset = 0;
print("Thread " + this.threadId
+ " start download from position " + startPos);
RandomAccessFile threadfile = new RandomAccessFile(
this.saveFile, "rwd");
threadfile.seek(startPos);
while ((offset = inStream.read(buffer, 0, 1024)) != -1) {
threadfile.write(buffer, 0, offset);
downLength += offset;
downloader.update(this.threadId, downLength);
downloader.append(offset);
}
threadfile.close();
inStream.close();
print("Thread " + this.threadId + " download finish");
this.finish = true;
} catch (Exception e) {
this.downLength = -1;
print("Thread " + this.threadId + ":" + e);
}
}
}
private static void print(String msg) {
Log.i(TAG, msg);
}
/**
* 下载是否完成
*
* @return
*/
public boolean isFinish() {
return finish;
}
/**
* 已经下载的内容大小
*
* @return 如果返回值为-1,代表下载失败
*/
public long getDownLength() {
return downLength;
}
}
再建一个文件下载器FileDownloader类
package com.studio.net.download;
import java.io.File;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import com.studio.service.FileService;
import android.content.Context;
import android.util.Log;
public class FileDownloader {
private static final String TAG = "FileDownloader";
private Context context;
private FileService fileService;
/* 已下载文件长度 */
private int downloadSize = 0;
/* 原始文件长度 */
private int fileSize = 0;
/* 线程数 */
private DownloadThread[] threads;
/* 本地保存文件 */
private File saveFile;
/* 缓存各线程下载的长度 */
private Map<Integer, Integer> data = new ConcurrentHashMap<Integer, Integer>();
/* 每条线程下载的长度 */
private int block;
/* 下载路径 */
private String downloadUrl;
/**
* 获取线程数
*/
public int getThreadSize() {
return threads.length;
}
/**
* 获取文件大小
*
* @return
*/
public int getFileSize() {
return fileSize;
}
/**
* 累计已下载大小
*
* @param size
*/
protected synchronized void append(int size) {
downloadSize += size;
}
/**
* 更新指定线程最后下载的位置
*
* @param threadId
* 线程id
* @param pos
* 最后下载的位置
*/
protected synchronized void update(int threadId, int pos) {
this.data.put(threadId, pos);
this.fileService.update(this.downloadUrl, this.data);
}
/**
* 构建文件下载器
*
* @param downloadUrl
* 下载路径
* @param fileSaveDir
* 文件保存目录
* @param threadNum
* 下载线程数
*/
public FileDownloader(Context context, String downloadUrl,
File fileSaveDir, int threadNum) {
try {
this.context = context;
this.downloadUrl = downloadUrl;
fileService = new FileService(this.context);
URL url = new URL(this.downloadUrl);
if (!fileSaveDir.exists())
fileSaveDir.mkdirs();
this.threads = new DownloadThread[threadNum];
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5 * 1000);
conn.setRequestMethod("GET");
conn.setRequestProperty(
"Accept",
"image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");
conn.setRequestProperty("Accept-Language", "zh-CN");
conn.setRequestProperty("Referer", downloadUrl);
conn.setRequestProperty("Charset", "UTF-8");
conn.setRequestProperty(
"User-Agent",
"Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.connect();
printResponseHeader(conn);
if (conn.getResponseCode() == 200) {
this.fileSize = conn.getContentLength();// 根据响应获取文件大小
if (this.fileSize <= 0)
throw new RuntimeException("Unkown file size ");
String filename = getFileName(conn);// 获取文件名称
this.saveFile = new File(fileSaveDir, filename);// 构建保存文件
Map<Integer, Integer> logdata = fileService
.getData(downloadUrl);// 获取下载记录
if (logdata.size() > 0) {// 如果存在下载记录
for (Map.Entry<Integer, Integer> entry : logdata.entrySet())
data.put(entry.getKey(), entry.getValue());// 把各条线程已经下载的数据长度放入data中
}
if (this.data.size() == this.threads.length) {// 下面计算所有线程已经下载的数据长度
for (int i = 0; i < this.threads.length; i++) {
this.downloadSize += this.data.get(i + 1);
}
print("已经下载的长度" + this.downloadSize);
}
// 计算每条线程下载的数据长度
this.block = (this.fileSize % this.threads.length) == 0 ? this.fileSize
/ this.threads.length
: this.fileSize / this.threads.length + 1;
} else {
throw new RuntimeException("server no response ");
}
} catch (Exception e) {
print(e.toString());
throw new RuntimeException("don't connection this url");
}
}
/**
* 获取文件名
*/
private String getFileName(HttpURLConnection conn) {
String filename = this.downloadUrl.substring(this.downloadUrl
.lastIndexOf('/') + 1);
if (filename == null || "".equals(filename.trim())) {// 如果获取不到文件名称
for (int i = 0;; i++) {
String mine = conn.getHeaderField(i);
if (mine == null)
break;
if ("content-disposition".equals(conn.getHeaderFieldKey(i)
.toLowerCase())) {
Matcher m = Pattern.compile(".*filename=(.*)").matcher(
mine.toLowerCase());
if (m.find())
return m.group(1);
}
}
filename = UUID.randomUUID() + ".tmp";// 默认取一个文件名
}
return filename;
}
/**
* 开始下载文件
*
* @param listener
* 监听下载数量的变化,如果不需要了解实时下载的数量,可以设置为null
* @return 已下载文件大小
* @throws Exception
*/
public int download(DownloadProgressListener listener) throws Exception {
try {
RandomAccessFile randOut = new RandomAccessFile(this.saveFile, "rw");
if (this.fileSize > 0)
randOut.setLength(this.fileSize);
randOut.close();
URL url = new URL(this.downloadUrl);
if (this.data.size() != this.threads.length) {
this.data.clear();
for (int i = 0; i < this.threads.length; i++) {
this.data.put(i + 1, 0);// 初始化每条线程已经下载的数据长度为0
}
}
for (int i = 0; i < this.threads.length; i++) {// 开启线程进行下载
int downLength = this.data.get(i + 1);
if (downLength < this.block
&& this.downloadSize < this.fileSize) {// 判断线程是否已经完成下载,否则继续下载
this.threads[i] = new DownloadThread(this, url,
this.saveFile, this.block, this.data.get(i + 1),
i + 1);
this.threads[i].setPriority(7);
this.threads[i].start();
} else {
this.threads[i] = null;
}
}
this.fileService.save(this.downloadUrl, this.data);
boolean notFinish = true;// 下载未完成
while (notFinish) {// 循环判断所有线程是否完成下载
Thread.sleep(900);
notFinish = false;// 假定全部线程下载完成
for (int i = 0; i < this.threads.length; i++) {
if (this.threads[i] != null && !this.threads[i].isFinish()) {// 如果发现线程未完成下载
notFinish = true;// 设置标志为下载没有完成
if (this.threads[i].getDownLength() == -1) {// 如果下载失败,再重新下载
this.threads[i] = new DownloadThread(this, url,
this.saveFile, this.block,
this.data.get(i + 1), i + 1);
this.threads[i].setPriority(7);
this.threads[i].start();
}
}
}
if (listener != null)
listener.onDownloadSize(this.downloadSize);// 通知目前已经下载完成的数据长度
}
fileService.delete(this.downloadUrl);
} catch (Exception e) {
print(e.toString());
throw new Exception("file download fail");
}
return this.downloadSize;
}
/**
* 获取Http响应头字段
*
* @param http
* @return
*/
public static Map<String, String> getHttpResponseHeader(
HttpURLConnection http) {
Map<String, String> header = new LinkedHashMap<String, String>();
for (int i = 0;; i++) {
String mine = http.getHeaderField(i);
if (mine == null)
break;
header.put(http.getHeaderFieldKey(i), mine);
}
return header;
}
/**
* 打印Http头字段
*
* @param http
*/
public static void printResponseHeader(HttpURLConnection http) {
Map<String, String> header = getHttpResponseHeader(http);
for (Map.Entry<String, String> entry : header.entrySet()) {
String key = entry.getKey() != null ? entry.getKey() + ":" : "";
print(key + entry.getValue());
}
}
private static void print(String msg) {
Log.i(TAG, msg);
}
}
OK至此业务写完了
现在来设计界面UI，由于要使用到String类型的字符串，所以我们先在String.xml中定义一下
添加
<string name="path">下载路径</string>
<string name="button">下载</string>
<string name="suceess">下载完成</string>
<string name="error">下载失败</string>
<string name="sdcarderror">SDCard不存在或写保护</string>
界面main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/path"
/>
<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="http://www.mp3upload.ca/upload/42981-fdt.mp3"
android:id="@+id/path"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button"
android:id="@+id/button"
/>
<ProgressBar
android:layout_width="fill_parent"
android:layout_height="20px"
style="?android:attr/progressBarStyleHorizontal"
android:id="@+id/downloadbar"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:id="@+id/result"
/>
</LinearLayout>
主类MainActivity
package com.studio.download;
import java.io.File;
import com.studio.net.download.DownloadProgressListener;
import com.studio.net.download.FileDownloader;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
private EditText pathText;
private ProgressBar downloadbar;
private TextView resultView;
// 它用于往消息队列发送消息，当Handler被创建时会自动绑定到Handler被创建时所在的线程所绑定的消息队列
private Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 1:
downloadbar.setProgress(msg.getData().getInt("size"));// 把当前已经下载的数据长度设置为进度条的当前刻度
float num = (float) downloadbar.getProgress()
/ (float) downloadbar.getMax();
int result = (int) (num * 100);
resultView.setText(result + "%");
if (downloadbar.getProgress() == downloadbar.getMax()) {
Toast.makeText(MainActivity.this, R.string.suceess, 1)
.show();
}
break;
case -1:
Toast.makeText(MainActivity.this, R.string.error, 1).show();
break;
}
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
pathText = (EditText) findViewById(R.id.path);
downloadbar = (ProgressBar) findViewById(R.id.downloadbar);
resultView = (TextView) findViewById(R.id.result);
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
String path = pathText.getText().toString();
download(path, Environment.getExternalStorageDirectory());
} else {
Toast.makeText(MainActivity.this, R.string.sdcarderror, 1)
.show();
}
}
});
}
// 对UI控件的更新只能由主线程(UI线程)负责,如果不在UI线程更新控件，更新后的值不会被重绘到屏幕上
private void download(final String path, final File saveDir) {
new Thread(new Runnable() {
@Override
public void run() {
try {
FileDownloader loader = new FileDownloader(
MainActivity.this, path, saveDir, 3);
downloadbar.setMax(loader.getFileSize());// 设置进度条的最大刻度为文件的大小
loader.download(new DownloadProgressListener() {
@Override
public void onDownloadSize(int size) {
Message msg = new Message();
msg.what = 1;
msg.getData().putInt("size", size);
handler.sendMessage(msg);
// msg.target = handler;
}
});
} catch (Exception e) {
Message msg = new Message();
msg.what = -1;
handler.sendMessage(msg);
}
}
}).start();
}
}
当然别忘了添加权限
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission>
如图所示
由于这个mp3有点大，耐心等待
OK，终于下载完成了，看看sdcard吧，上面有我们刚下载的歌曲文件了，播放一下试试，呵呵
