Android 断点续传

packagecom.example.downloaderstopsart;

importjava.util.ArrayList;
importjava.util.HashMap;
importjava.util.List;
importjava.util.Map;

importandroid.os.Bundle;
importandroid.os.Handler;
importandroid.os.Message;
importandroid.os.StrictMode;
importandroid.app.ListActivity;
importandroid.view.View;
importandroid.widget.LinearLayout;
importandroid.widget.LinearLayout.LayoutParams;
importandroid.widget.ProgressBar;
importandroid.widget.SimpleAdapter;
importandroid.widget.TextView;
importandroid.widget.Toast;

publicclassMainActivityextendsListActivity{

//固定下载的资源路径，这里可以设置网络上的地址
privatestaticfinalStringURL="http://10.81.36.193:8080/";
//固定存放下载的音乐的路径：SD卡目录下
privatestaticfinalStringSD_PATH="/mnt/sdcard/";
//存放各个下载器
privateMap<String,Downloader>downloaders=newHashMap<String,Downloader>();
//存放与下载器对应的进度条
privateMap<String,ProgressBar>ProgressBars=newHashMap<String,ProgressBar>();
/**
*利用消息处理机制适时更新进度条
*/
privateHandlermHandler=newHandler(){
publicvoidhandleMessage(Messagemsg){
if(msg.what==1){
Stringurl=(String)msg.obj;
intlength=msg.arg1;
ProgressBarbar=ProgressBars.get(url);
if(bar!=null){
//设置进度条按读取的length长度更新
bar.incrementProgressBy(length);
if(bar.getProgress()==bar.getMax()){
Toast.makeText(MainActivity.this,"下载完成！",0).show();
//下载完成后清除进度条并将map中的数据清空
LinearLayoutlayout=(LinearLayout)bar.getParent();
layout.removeView(bar);
ProgressBars.remove(url);
downloaders.get(url).delete(url);
downloaders.get(url).reset();
downloaders.remove(url);
}
}
}
}
};
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
showListView();
StrictMode.setThreadPolicy(newStrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());
StrictMode.setVmPolicy(newStrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());
}
//显示listView，这里可以随便添加音乐
privatevoidshowListView(){
List<Map<String,String>>data=newArrayList<Map<String,String>>();
Map<String,String>map=newHashMap<String,String>();
map.put("name","mm.mp3");
data.add(map);
map=newHashMap<String,String>();
map.put("name","pp.mp3");
data.add(map);
map=newHashMap<String,String>();
map.put("name","tt.mp3");
data.add(map);
map=newHashMap<String,String>();
map.put("name","ou.mp3");
data.add(map);
SimpleAdapteradapter=newSimpleAdapter(this,data,R.layout.list_item,newString[]{"name"},
newint[]{R.id.tv_resouce_name});
setListAdapter(adapter);
}
/**
*响应开始下载按钮的点击事件
*/
publicvoidstartDownload(Viewv){
//得到textView的内容
LinearLayoutlayout=(LinearLayout)v.getParent();
StringmusicName=((TextView)layout.findViewById(R.id.tv_resouce_name)).getText().toString();
Stringurlstr=URL+musicName;
Stringlocalfile=SD_PATH+musicName;
//设置下载线程数为4，这里是我为了方便随便固定的
intthreadcount=4;
//初始化一个downloader下载器
Downloaderdownloader=downloaders.get(urlstr);
if(downloader==null){
downloader=newDownloader(urlstr,localfile,threadcount,this,mHandler);
downloaders.put(urlstr,downloader);
}
if(downloader.isdownloading())
return;
//得到下载信息类的个数组成集合
LoadInfoloadInfo=downloader.getDownloaderInfors();
//显示进度条
showProgress(loadInfo,urlstr,v);
//调用方法开始下载
downloader.download();
}

/**
*显示进度条
*/
privatevoidshowProgress(LoadInfoloadInfo,Stringurl,Viewv){
ProgressBarbar=ProgressBars.get(url);
if(bar==null){
bar=newProgressBar(this,null,android.R.attr.progressBarStyleHorizontal);
bar.setMax(loadInfo.getFileSize());
bar.setProgress(loadInfo.getComplete());
ProgressBars.put(url,bar);
LinearLayout.LayoutParamsparams=newLayoutParams(LayoutParams.FILL_PARENT,5);
((LinearLayout)((LinearLayout)v.getParent()).getParent()).addView(bar,params);
}
}
/**
*响应暂停下载按钮的点击事件
*/
publicvoidpauseDownload(Viewv){
LinearLayoutlayout=(LinearLayout)v.getParent();
StringmusicName=((TextView)layout.findViewById(R.id.tv_resouce_name)).getText().toString();
Stringurlstr=URL+musicName;
downloaders.get(urlstr).pause();
}
}

DBHelper：

packagecom.example.downloaderstopsart;

importandroid.content.Context;
importandroid.database.sqlite.SQLiteDatabase;
importandroid.database.sqlite.SQLiteOpenHelper;

/**
*建立一个数据库帮助类
*/
publicclassDBHelperextendsSQLiteOpenHelper{
//download.db-->数据库名
publicDBHelper(Contextcontext){
super(context,"download.db",null,1);
}

/**
*在download.db数据库下创建一个download_info表存储下载信息
*/
@Override
publicvoidonCreate(SQLiteDatabasedb){
db.execSQL("createtabledownload_info(_idintegerPRIMARYKEYAUTOINCREMENT,thread_idinteger,"
+"start_posinteger,end_posinteger,compelete_sizeinteger,urlchar)");
}

@Override
publicvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion){

}

}

DownloadInfo：

packagecom.example.downloaderstopsart;

publicclassDownloadInfo{
privateintthreadId;//下载器id
privateintstartPos;//开始点
privateintendPos;//结束点
privateintcompeleteSize;//完成度
privateStringurl;//下载器网络标识

publicDownloadInfo(intthreadId,intstartPos,intendPos,
intcompeleteSize,Stringurl){
this.threadId=threadId;
this.startPos=startPos;
this.endPos=endPos;
this.compeleteSize=compeleteSize;
this.url=url;
}

publicDownloadInfo(){
}

publicStringgetUrl(){
returnurl;
}

publicvoidsetUrl(Stringurl){
this.url=url;
}

publicintgetThreadId(){
returnthreadId;
}

publicvoidsetThreadId(intthreadId){
this.threadId=threadId;
}

publicintgetStartPos(){
returnstartPos;
}

publicvoidsetStartPos(intstartPos){
this.startPos=startPos;
}

publicintgetEndPos(){
returnendPos;
}

publicvoidsetEndPos(intendPos){
this.endPos=endPos;
}

publicintgetCompeleteSize(){
returncompeleteSize;
}

publicvoidsetCompeleteSize(intcompeleteSize){
this.compeleteSize=compeleteSize;
}

@Override
publicStringtoString(){
return"DownloadInfo[threadId="+threadId+",startPos="+startPos
+",endPos="+endPos+",compeleteSize="+compeleteSize
+"]";
}
}

LoadInfo：

packagecom.example.downloaderstopsart;

publicclassLoadInfo{
publicintfileSize;//文件大小
privateintcomplete;//完成度
privateStringurlstring;//下载器标识

publicLoadInfo(intfileSize,intcomplete,Stringurlstring){
this.fileSize=fileSize;
this.complete=complete;
this.urlstring=urlstring;
}

publicLoadInfo(){
}

publicintgetFileSize(){
returnfileSize;
}

publicvoidsetFileSize(intfileSize){
this.fileSize=fileSize;
}

publicintgetComplete(){
returncomplete;
}

publicvoidsetComplete(intcomplete){
this.complete=complete;
}

publicStringgetUrlstring(){
returnurlstring;
}

publicvoidsetUrlstring(Stringurlstring){
this.urlstring=urlstring;
}

@Override
publicStringtoString(){
return"LoadInfo[fileSize="+fileSize+",complete="+complete
+",urlstring="+urlstring+"]";
}
}

Downloader：

packagecom.example.downloaderstopsart;
importjava.io.File;
importjava.io.InputStream;
importjava.io.RandomAccessFile;
importjava.net.HttpURLConnection;
importjava.net.URL;
importjava.util.ArrayList;
importjava.util.List;
importandroid.content.Context;
importandroid.os.Handler;
importandroid.os.Message;
importandroid.util.Log;

publicclassDownloader{
privateStringurlstr;//下载的地址
privateStringlocalfile;//保存路径
privateintthreadcount;//线程数
privateHandlermHandler;//消息处理器
privateDaodao;//工具类
privateintfileSize;//所要下载的文件的大小
privateList<DownloadInfo>infos;//存放下载信息类的集合
privatestaticfinalintINIT=1;//定义三种下载的状态：初始化状态，正在下载状态，暂停状态
privatestaticfinalintDOWNLOADING=2;
privatestaticfinalintPAUSE=3;
privateintstate=INIT;

publicDownloader(Stringurlstr,Stringlocalfile,intthreadcount,
Contextcontext,HandlermHandler){
this.urlstr=urlstr;
this.localfile=localfile;
this.threadcount=threadcount;
this.mHandler=mHandler;
dao=newDao(context);
}
/**
*判断是否正在下载
*/
publicbooleanisdownloading(){
returnstate==DOWNLOADING;
}
/**
*得到downloader里的信息
*首先进行判断是否是第一次下载，如果是第一次就要进行初始化，并将下载器的信息保存到数据库中
*如果不是第一次下载，那就要从数据库中读出之前下载的信息（起始位置，结束为止，文件大小等），并将下载信息返回给下载器
*/
publicLoadInfogetDownloaderInfors(){
if(isFirst(urlstr)){
Log.v("TAG","isFirst");
init();
intrange=fileSize/threadcount;
infos=newArrayList<DownloadInfo>();
for(inti=0;i<threadcount-1;i++){
DownloadInfoinfo=newDownloadInfo(i,i*range,(i+1)*range-1,0,urlstr);
infos.add(info);
}
DownloadInfoinfo=newDownloadInfo(threadcount-1,(threadcount-1)*range,fileSize-1,0,urlstr);
infos.add(info);
//保存infos中的数据到数据库
dao.saveInfos(infos);
//创建一个LoadInfo对象记载下载器的具体信息
LoadInfoloadInfo=newLoadInfo(fileSize,0,urlstr);
returnloadInfo;
}else{
//得到数据库中已有的urlstr的下载器的具体信息
infos=dao.getInfos(urlstr);
Log.v("TAG","notisFirstsize="+infos.size());
intsize=0;
intcompeleteSize=0;
for(DownloadInfoinfo:infos){
compeleteSize+=info.getCompeleteSize();
size+=info.getEndPos()-info.getStartPos()+1;
}
returnnewLoadInfo(size,compeleteSize,urlstr);
}
}

/**
*初始化
*/
privatevoidinit(){
try{
URLurl=newURL(urlstr);
HttpURLConnectionconnection=(HttpURLConnection)url.openConnection();
connection.setConnectTimeout(5000);
connection.setRequestMethod("GET");
fileSize=connection.getContentLength();

Filefile=newFile(localfile);
if(!file.exists()){
file.createNewFile();
}
//本地访问文件
RandomAccessFileaccessFile=newRandomAccessFile(file,"rwd");
accessFile.setLength(fileSize);
accessFile.close();
connection.disconnect();
}catch(Exceptione){
e.printStackTrace();
}
}

/**
*判断是否是第一次下载
*/
privatebooleanisFirst(Stringurlstr){
returndao.isHasInfors(urlstr);
}

/**
*利用线程开始下载数据
*/
publicvoiddownload(){
if(infos!=null){
if(state==DOWNLOADING)
return;
state=DOWNLOADING;
for(DownloadInfoinfo:infos){
newMyThread(info.getThreadId(),info.getStartPos(),
info.getEndPos(),info.getCompeleteSize(),
info.getUrl()).start();
}
}
}

publicclassMyThreadextendsThread{
privateintthreadId;
privateintstartPos;
privateintendPos;
privateintcompeleteSize;
privateStringurlstr;

publicMyThread(intthreadId,intstartPos,intendPos,
intcompeleteSize,Stringurlstr){
this.threadId=threadId;
this.startPos=startPos;
this.endPos=endPos;
this.compeleteSize=compeleteSize;
this.urlstr=urlstr;
}
@Override
publicvoidrun(){
HttpURLConnectionconnection=null;
RandomAccessFilerandomAccessFile=null;
InputStreamis=null;
try{

URLurl=newURL(urlstr);
connection=(HttpURLConnection)url.openConnection();
connection.setConnectTimeout(5000);
connection.setRequestMethod("GET");
//设置范围，格式为Range：bytesx-y;
connection.setRequestProperty("Range","bytes="+(startPos+compeleteSize)+"-"+endPos);

randomAccessFile=newRandomAccessFile(localfile,"rwd");
randomAccessFile.seek(startPos+compeleteSize);
Log.i("RG","connection--->>>"+connection);
//将要下载的文件写到保存在保存路径下的文件中
is=connection.getInputStream();
byte[]buffer=newbyte[4096];
intlength=-1;
while((length=is.read(buffer))!=-1){
randomAccessFile.write(buffer,0,length);
compeleteSize+=length;
//更新数据库中的下载信息
dao.updataInfos(threadId,compeleteSize,urlstr);
//用消息将下载信息传给进度条，对进度条进行更新
Messagemessage=Message.obtain();
message.what=1;
message.obj=urlstr;
message.arg1=length;
mHandler.sendMessage(message);
if(state==PAUSE){
return;
}
}
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
is.close();
randomAccessFile.close();
connection.disconnect();
dao.closeDb();
}catch(Exceptione){
e.printStackTrace();
}
}

}
}
//删除数据库中urlstr对应的下载器信息
publicvoiddelete(Stringurlstr){
dao.delete(urlstr);
}
//设置暂停
publicvoidpause(){
state=PAUSE;
}
//重置下载状态
publicvoidreset(){
state=INIT;
}
}

Dao:

packagecom.example.downloaderstopsart;

importjava.util.ArrayList;
importjava.util.List;
importandroid.content.Context;
importandroid.database.Cursor;
importandroid.database.sqlite.SQLiteDatabase;

publicclassDao{
privateDBHelperdbHelper;

publicDao(Contextcontext){
dbHelper=newDBHelper(context);
}

/**
*查看数据库中是否有数据
*/
publicbooleanisHasInfors(Stringurlstr){
SQLiteDatabasedatabase=dbHelper.getReadableDatabase();
Stringsql="selectcount(*)fromdownload_infowhereurl=?";
Cursorcursor=database.rawQuery(sql,newString[]{urlstr});
cursor.moveToFirst();
intcount=cursor.getInt(0);
cursor.close();
returncount==0;
}

/**
*36*保存下载的具体信息37
*/
publicvoidsaveInfos(List<DownloadInfo>infos){
SQLiteDatabasedatabase=dbHelper.getWritableDatabase();
for(DownloadInfoinfo:infos){
Stringsql="insertintodownload_info(thread_id,start_pos,end_pos,compelete_size,url)values(?,?,?,?,?)";
Object[]bindArgs={info.getThreadId(),info.getStartPos(),
info.getEndPos(),info.getCompeleteSize(),info.getUrl()};
database.execSQL(sql,bindArgs);
}
}

/**
*得到下载具体信息
*/
publicList<DownloadInfo>getInfos(Stringurlstr){
List<DownloadInfo>list=newArrayList<DownloadInfo>();
SQLiteDatabasedatabase=dbHelper.getReadableDatabase();
Stringsql="selectthread_id,start_pos,end_pos,compelete_size,urlfromdownload_infowhereurl=?";
Cursorcursor=database.rawQuery(sql,newString[]{urlstr});
while(cursor.moveToNext()){
DownloadInfoinfo=newDownloadInfo(cursor.getInt(0),
cursor.getInt(1),cursor.getInt(2),cursor.getInt(3),
cursor.getString(4));
list.add(info);
}
cursor.close();
returnlist;
}

/**
*更新数据库中的下载信息
*/
publicvoidupdataInfos(intthreadId,intcompeleteSize,Stringurlstr){
SQLiteDatabasedatabase=dbHelper.getReadableDatabase();
Stringsql="updatedownload_infosetcompelete_size=?wherethread_id=?andurl=?";
Object[]bindArgs={compeleteSize,threadId,urlstr};
database.execSQL(sql,bindArgs);
}

/**
*关闭数据库
*/
publicvoidcloseDb(){
dbHelper.close();
}

/**
*下载完成后删除数据库中的数据
*/
publicvoiddelete(Stringurl){
SQLiteDatabasedatabase=dbHelper.getReadableDatabase();
database.delete("download_info","url=?",newString[]{url});
database.close();
}
}

xml如下：

<?xmlversion="1.0"encoding="utf-8"?>
<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/llRoot">
<ListViewandroid:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
</ListView>
</LinearLayout>

item_list.xml：

<?xmlversion="1.0"encoding="utf-8"?>
<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical">

<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="5dip"
android:orientation="horizontal">

<TextView
android:id="@+id/tv_resouce_name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>

<Button
android:id="@+id/btn_start"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:onClick="startDownload"
android:text="下载"/>

<Button
android:id="@+id/btn_pause"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:onClick="pauseDownload"
android:text="暂停"/>
</LinearLayout>

</LinearLayout>

记得加权限：

<uses-permissionandroid:name="android.permission.INTERNET"/>
　<uses-permissionandroid:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

还有在3.0以上的版本记得加上这句话：

StrictMode.setThreadPolicy(newStrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());
StrictMode.setVmPolicy(newStrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());

效果图如下：