本文参考：
http://blog.csdn.net/inter_native/article/details/78603256
首先要引入GreenDao，具体引用请参考本人的前面的博客，这里就不再写了；
废话完就要开始写了
首先要写一个User类：
@Entity
public class User { @Id
private Long id;
private Integer thread_id;
private Integer start_pos;
private Integer end_pos;
private Integer compelete_size;
private String url;
}
到这一步之后不要急不要慌，深呼吸然后运行一下子，看这个类和你的gen包都好了没，方方面面好了之后就开始粘贴下面的代码；
然后就先粘贴布局（这是本人多年粘贴代码的经验，先粘贴布局）
这个布局就非常简单了，在MainActivity的布局中粘贴
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="23dp"
android:layout_marginStart="23dp"
android:layout_marginTop="18dp"
android:text="TextView" />
<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="fill_parent"
android:layout_height="7.5dp"
android:layout_below="@+id/textView"
android:layout_marginRight="8dp"
android:max="100"
android:progress="100"
android:visibility="visible" />
<Button
android:id="@+id/start"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_toEndOf="@+id/textView"
android:layout_toRightOf="@+id/textView"
android:text="下载" />
<Button
android:id="@+id/delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_marginLeft="48dp"
android:layout_marginStart="48dp"
android:layout_toEndOf="@+id/start"
android:layout_toRightOf="@+id/start"
android:text="暂停" />
App
public class App extends Application {
public static UserDao userDao;
@Override
public void onCreate() {
super.onCreate();
DaoMaster.DevOpenHelper devOpenHelper = new DaoMaster.DevOpenHelper(this, "lenvess.db", null);
DaoMaster daoMaster = new DaoMaster(devOpenHelper.getWritableDb());
DaoSession daoSession = daoMaster.newSession();
userDao = daoSession.getUserDao();
}
}
DownlaodSqlTool
public class DownlaodSqlTool {
/**
* 创建下载的具体信息
*/
public void insertInfos(List<DownloadInfo> infos) {
for (DownloadInfo info : infos) {
User user = new User(null, info.getThreadId(), info.getStartPos(), info.getEndPos(), info.getCompeleteSize(), info.getUrl());
userDao.insert(user);
}
}
/**
* 得到下载具体信息
*/
public List<DownloadInfo> getInfos(String urlstr) {
List<DownloadInfo> list = new ArrayList<DownloadInfo>();
List<User> list1 = userDao.queryBuilder().where(UserDao.Properties.Url.eq(urlstr)).build().list();
for (User user : list1) {
DownloadInfo infoss = new DownloadInfo(
user.getThread_id(), user.getStart_pos(), user.getEnd_pos(),
user.getCompelete_size(), user.getUrl());
Log.d("main-----", infoss.toString());
list.add(infoss);
}
return list;
}
/**
* 更新数据库中的下载信息
*/
public void updataInfos(int threadId, int compeleteSize, String urlstr) {
User user = userDao.queryBuilder()
.where(UserDao.Properties.Thread_id.eq(threadId), UserDao.Properties.Url.eq(urlstr)).build().unique();
user.setCompelete_size(compeleteSize);
userDao.update(user);
}
/**
* 下载完成后删除数据库中的数据
*/
public void delete(String url) {
userDao.deleteAll();
}
}
DownloadHttpTool
public class DownloadHttpTool {
/**
* 利用Http协议进行多线程下载具体实践类
*/
private static final String TAG = DownloadHttpTool.class.getSimpleName();
private int threadCount;//线程数量
private String urlstr;//URL地址
private Context mContext;
private Handler mHandler;
private List<DownloadInfo> downloadInfos;//保存下载信息的类
private String localPath;//目录
private String fileName;//文件名
private int fileSize;
private DownlaodSqlTool sqlTool;//文件信息保存的数据库操作类
private enum Download_State {
Downloading, Pause, Ready;//利用枚举表示下载的三种状态
}
private Download_State state = Download_State.Ready;//当前下载状态
private int globalCompelete = 0;//所有线程下载的总数
public DownloadHttpTool(int threadCount, String urlString,
String localPath, String fileName, Context context, Handler handler) {
super();
this.threadCount = threadCount;
this.urlstr = urlString;
this.localPath = localPath;
this.mContext = context;
this.mHandler = handler;
this.fileName = fileName;
sqlTool = new DownlaodSqlTool();
}
//在开始下载之前需要调用ready方法进行配置
public void ready() {
Log.w(TAG, "ready");
globalCompelete = 0;
downloadInfos = sqlTool.getInfos(urlstr);
if (downloadInfos.size() == 0) {
initFirst();
} else {
File file = new File(localPath + "/" + fileName);
if (!file.exists()) {
sqlTool.delete(urlstr);
initFirst();
} else {
fileSize = downloadInfos.get(downloadInfos.size() - 1)
.getEndPos();
for (DownloadInfo info : downloadInfos) {
globalCompelete += info.getCompeleteSize();
}
Log.w(TAG, "globalCompelete:::" + globalCompelete);
}
}
}
public void start() {
Log.w(TAG, "start");
if (downloadInfos != null) {
if (state == Download_State.Downloading) {
return;
}
state = Download_State.Downloading;
for (DownloadInfo info : downloadInfos) {
Log.v(TAG, "startThread");
new DownloadThread(info.getThreadId(), info.getStartPos(),
info.getEndPos(), info.getCompeleteSize(),
info.getUrl()).start();
}
}
}
public void pause() {
state = Download_State.Pause;
}
public void delete() {
compelete();
File file = new File(localPath + "/" + fileName);
file.delete();
}
public void compelete() {
sqlTool.delete(urlstr);
}
public int getFileSize() {
return fileSize;
}
public int getCompeleteSize() {
return globalCompelete;
}
//第一次下载初始化
private void initFirst() {
Log.w(TAG, "initFirst");
try {
URL url = new URL(urlstr);
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();
connection.setConnectTimeout(5000);
connection.setRequestMethod("GET");
fileSize = connection.getContentLength();
Log.w(TAG, "fileSize::" + fileSize);
File fileParent = new File(localPath);
if (!fileParent.exists()) {
fileParent.mkdir();
}
File file = new File(fileParent, fileName);
if (!file.exists()) {
file.createNewFile();
}
// 本地访问文件
RandomAccessFile accessFile = new RandomAccessFile(file, "rwd");
accessFile.setLength(fileSize);
accessFile.close();
connection.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
int range = fileSize / threadCount;
downloadInfos = new ArrayList<DownloadInfo>();
for (int i = 0; i < threadCount - 1; i++) {
DownloadInfo info = new DownloadInfo(i, i * range, (i + 1) * range
- 1, 0, urlstr);
downloadInfos.add(info);
}
DownloadInfo info = new DownloadInfo(threadCount - 1, (threadCount - 1)
* range, fileSize - 1, 0, urlstr);
downloadInfos.add(info);
sqlTool.insertInfos(downloadInfos);
}
//自定义下载线程
private class DownloadThread extends Thread {
private int threadId;
private int startPos;
private int endPos;
private int compeleteSize;
private String urlstr;
private int totalThreadSize;
public DownloadThread(int threadId, int startPos, int endPos,
int compeleteSize, String urlstr) {
this.threadId = threadId;
this.startPos = startPos;
this.endPos = endPos;
totalThreadSize = endPos - startPos + 1;
this.urlstr = urlstr;
this.compeleteSize = compeleteSize;
}
@Override
public void run() {
HttpURLConnection connection = null;
RandomAccessFile randomAccessFile = null;
InputStream is = null;
try {
randomAccessFile = new RandomAccessFile(localPath + "/"
+ fileName, "rwd");
randomAccessFile.seek(startPos + compeleteSize);
URL url = new URL(urlstr);
connection = (HttpURLConnection) url.openConnection();
connection.setConnectTimeout(5000);
connection.setRequestMethod("GET");
connection.setRequestProperty("Range", "bytes="
+ (startPos + compeleteSize) + "-" + endPos);
is = connection.getInputStream();
byte[] buffer = new byte[1024];
int length = -1;
while ((length = is.read(buffer)) != -1) {
randomAccessFile.write(buffer, 0, length);
compeleteSize += length;
Message message = Message.obtain();
message.what = threadId;
message.obj = urlstr;
message.arg1 = length;
mHandler.sendMessage(message);
sqlTool.updataInfos(threadId, compeleteSize, urlstr);
Log.w(TAG, "Threadid::" + threadId + " compelete::"
+ compeleteSize + " total::" + totalThreadSize);
if (compeleteSize >= totalThreadSize) {
break;
}
if (state != Download_State.Downloading) {
break;
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (is != null) {
is.close();
}
randomAccessFile.close();
connection.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
}
DownloadInfo
public class DownloadInfo {
/**
* 保存每个下载线程下载信息类
*
*/
private int threadId;// 下载器id
private int startPos;// 开始点
private int endPos;// 结束点
private int compeleteSize;// 完成度
private String url;// 下载文件的URL地址
public DownloadInfo(int threadId, int startPos, int endPos,
int compeleteSize, String url) {
this.threadId = threadId;
this.startPos = startPos;
this.endPos = endPos;
this.compeleteSize = compeleteSize;
this.url = url;
}
public DownloadInfo() {
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public int getThreadId() {
return threadId;
}
public void setThreadId(int threadId) {
this.threadId = threadId;
}
public int getStartPos() {
return startPos;
}
public void setStartPos(int startPos) {
this.startPos = startPos;
}
public int getEndPos() {
return endPos;
}
public void setEndPos(int endPos) {
this.endPos = endPos;
}
public int getCompeleteSize() {
return compeleteSize;
}
public void setCompeleteSize(int compeleteSize) {
this.compeleteSize = compeleteSize;
}
@Override
public String toString() {
return "DownloadInfo [threadId=" + threadId + ", startPos=" + startPos
+ ", endPos=" + endPos + ", compeleteSize=" + compeleteSize
+ "]";
}
}
DownloadUtil
public class DownloadUtil {
private DownloadHttpTool mDownloadHttpTool;
private OnDownloadListener onDownloadListener;
private int fileSize;
private int downloadedSize = 0;
@SuppressLint("HandlerLeak")
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
int length = msg.arg1;
synchronized (this) {//加锁保证已下载的正确性
downloadedSize += length;
}
if (onDownloadListener != null) {
onDownloadListener.downloadProgress(downloadedSize);
}
if (downloadedSize >= fileSize) {
mDownloadHttpTool.compelete();
if (onDownloadListener != null) {
onDownloadListener.downloadEnd();
}
}
}
};
public DownloadUtil(int threadCount, String filePath, String filename,
String urlString, Context context) {
mDownloadHttpTool = new DownloadHttpTool(threadCount, urlString,
filePath, filename, context, mHandler);
}
//下载之前首先异步线程调用ready方法获得文件大小信息，之后调用开始方法
public void start() {
new AsyncTask<Void,Void,Void>() {
@Override
protected Void doInBackground(Void... arg0) {
// TODO Auto-generated method stub
mDownloadHttpTool.ready();
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
fileSize = mDownloadHttpTool.getFileSize();
downloadedSize = mDownloadHttpTool.getCompeleteSize();
Log.w("Tag", "downloadedSize::" + downloadedSize);
if (onDownloadListener != null) {
onDownloadListener.downloadStart(fileSize);
}
mDownloadHttpTool.start();
}
}.execute();
}
public void pause() {
mDownloadHttpTool.pause();
}
public void delete(){
mDownloadHttpTool.delete();
}
public void reset(){
mDownloadHttpTool.delete();
start();
}
public void setOnDownloadListener(OnDownloadListener onDownloadListener) {
this.onDownloadListener = onDownloadListener;
}
//下载回调接口
public interface OnDownloadListener {
public void downloadStart(int fileSize);
public void downloadProgress(int downloadedSize);//记录当前所有线程下总和
public void downloadEnd();
}
}
MainActivity（！！注意，注意这是MainActivity不是自己创的类，不要粘贴错了）
public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getSimpleName();
private ProgressBar mProgressBar;
private Button start;
private Button pause;
private TextView total;
private int max;
private DownloadUtil mDownloadUtil;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
total = (TextView) findViewById(R.id.textView);
start = (Button) findViewById(R.id.start);
pause = (Button) findViewById(R.id.delete);
mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
String urlString = "http://2449.vod.myqcloud.com/2449_22ca37a6ea9011e5acaaf51d105342e3.f20.mp4";
String localPath = Environment.getExternalStorageDirectory()
.getAbsolutePath() + "/local2";
mDownloadUtil = new DownloadUtil(2, localPath, "adc.mp4", urlString,
this);
mDownloadUtil.setOnDownloadListener(new DownloadUtil.OnDownloadListener() {
@Override
public void downloadStart(int fileSize) {
// TODO Auto-generated method stub
Log.w(TAG, "fileSize::" + fileSize);
max = fileSize;
mProgressBar.setMax(fileSize);
}
@Override
public void downloadProgress(int downloadedSize) {
// TODO Auto-generated method stub
Log.w(TAG, "Compelete::" + downloadedSize);
mProgressBar.setProgress(downloadedSize);
total.setText((int) downloadedSize * 100 / max + "%");
}
@Override
public void downloadEnd() {
// TODO Auto-generated method stub
Log.w(TAG, "ENd");
}
});
start.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
mDownloadUtil.start();
}
});
pause.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
mDownloadUtil.pause();
}
});
}
}
这样代码方面就完事了；如果有报错一般是Handler的事这个千万记的倒OS那个包
然后就是权限：
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
如果运行了还报错，可能是你的App没有配，不要慌，仔细检查