Android多線程+單線程+斷點續(xù)傳+進度條顯示下載功能
更新時間：2017年06月01日 14:34:54 作者：cmazxiaoma
這篇文章主要介紹了Android多線程+單線程+斷點續(xù)傳+進度條顯示下載功能,需要的朋友可以參考下
效果圖
白話分析:
多線程:肯定是多個線程咯
斷點:線程停止下載的位置
續(xù)傳:線程從停止下載的位置上繼續(xù)下載，直到完成任務為止。
核心分析:
斷點:
當前線程已經(jīng)下載的數(shù)據(jù)長度
續(xù)傳:
向服務器請求上次線程停止下載位置的數(shù)據(jù)
con.setRequestProperty("Range", "bytes=" + start + "-" + end);
分配線程:
int currentPartSize = fileSize / mThreadNum;
定義位置
定義線程開始下載的位置和結(jié)束的位置
for (int i = 0; i < mThreadNum; i++) {
int start = i * currentPartSize;//計算每條線程下載的開始位置
int end = start + currentPartSize-1;//線程結(jié)束的位置
if(i==mThreadNum-1){
end=fileSize;
}}
創(chuàng)建數(shù)據(jù)庫:
由于每一個文件要分成多個部分，要被不同的線程同時進行下載。當然要創(chuàng)建線程表，保存當前線程下載開始的位置和結(jié)束的位置，還有完成進度等。創(chuàng)建file表，保存當前下載的文件信息，比如：文件名，url，下載進度等信息
線程表:
public static final String CREATE_TABLE_SQL="create table "+TABLE_NAME+"(_id integer primary "
+"key autoincrement, threadId, start , end, completed, url)";
file表：
public static final String CREATE_TABLE_SQL="create table "+TABLE_NAME+"(_id integer primary" +
" key autoincrement ,fileName, url, length, finished)";
創(chuàng)建線程類
無非就2個類，一個是線程管理類DownLoadManager.Java，核心方法：start(),stop(),restart(),addTask().clear()。另一個是線程任務類
DownLoadTask.java，就是一個線程類，用于下載線程分配好的任務。后面會貼出具體代碼。
創(chuàng)建數(shù)據(jù)庫方法類
無非就是單例模式，封裝一些增刪改查等基礎數(shù)據(jù)庫方法，后面會貼出具體代碼。
創(chuàng)建實體類
也就是創(chuàng)建ThreadInfo和FileInfo這2個實體類，把下載文件信息和線程信息暫時存儲起來。
引入的第三方開源庫
NumberProgressBar是一個關(guān)于進度條的開源庫，挺不錯的。直達鏈接
代碼具體分析
1.首先是創(chuàng)建實體類，文件的實體類FileInfo，肯定有fileName,url,length,finised,isStop,isDownloading這些屬性。線程的實體類ThreadInfo肯定有threadId,start,end,completed,url這些屬性。這些都很簡單
//ThredInfo.java
public class FileInfo {
private String fileName; //文件名
private String url; //下載地址
private int length; //文件大小
private int finished; //下載已完成進度
private boolean isStop=false; //是否暫停下載
private boolean isDownloading=false; //是否正在下載
public FileInfo(){
}
public FileInfo(String fileName,String url){
this.fileName=fileName;
this.url=url;
}
public String getFileName() {
return fileName;
}
public void setFileName(String fileName) {
this.fileName = fileName;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public int getLength() {
return length;
}
public void setLength(int length) {
this.length = length;
}
public int getFinished() {
return finished;
}
public void setFinished(int finished) {
this.finished = finished;
}
public boolean isStop() {
return isStop;
}
public void setStop(boolean stop) {
isStop = stop;
}
public boolean isDownloading() {
return isDownloading;
}
public void setDownloading(boolean downloading) {
isDownloading = downloading;
}
@Override
public String toString() {
return "FileInfo{" +
"fileName='" + fileName + '\'' +
", url='" + url + '\'' +
", length=" + length +
", finished=" + finished +
", isStop=" + isStop +
", isDownloading=" + isDownloading +
'}';
}}
//FileInfo.java
public class FileInfo {
private String fileName; //文件名
private String url; //下載地址
private int length; //文件大小
private int finished; //下載已完成進度
private boolean isStop=false; //是否暫停下載
private boolean isDownloading=false; //是否正在下載
public FileInfo(){
}
public FileInfo(String fileName,String url){
this.fileName=fileName;
this.url=url;
}
public String getFileName() {
return fileName;
}
public void setFileName(String fileName) {
this.fileName = fileName;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public int getLength() {
return length;
}
public void setLength(int length) {
this.length = length;
}
public int getFinished() {
return finished;
}
public void setFinished(int finished) {
this.finished = finished;
}
public boolean isStop() {
return isStop;
}
public void setStop(boolean stop) {
isStop = stop;
}
public boolean isDownloading() {
return isDownloading;
}
public void setDownloading(boolean downloading) {
isDownloading = downloading;
}
@Override
public String toString() {
return "FileInfo{" +
"fileName='" + fileName + '\'' +
", url='" + url + '\'' +
", length=" + length +
", finished=" + finished +
", isStop=" + isStop +
", isDownloading=" + isDownloading +
'}';
}}
2.實體類寫完了，那么接下來寫創(chuàng)建一個類，繼承SQLiteOpenHelper類，來管理數(shù)據(jù)庫連接，主要作用：管理數(shù)據(jù)庫的初始化，并允許應用程序通過該類獲取SQLiteDatabase對象。
public class ThreadHelper extends SQLiteOpenHelper{
public static final String TABLE_NAME="downthread";
public static final String CREATE_TABLE_SQL="create table "+TABLE_NAME+"(_id integer primary "
+"key autoincrement, threadId, start , end, completed, url)";
public ThreadHelper(Context context, String name, int version) {
super(context, name, null, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE_SQL);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}}
3.接下來封裝一些數(shù)據(jù)庫的增刪改查操作，用的單例模式，用雙重檢驗鎖實現(xiàn)單例。好處:既能很大程度上確保線程安全，又能實現(xiàn)延遲加載。 缺點:使用volatile關(guān)鍵字會使JVM對該代碼的優(yōu)化喪失，影響性能。并且在一些高并發(fā)的情況，仍然可能會創(chuàng)建多個實例，這稱為雙重檢驗鎖定失效。單例模式
public class Thread {
private SQLiteDatabase db;
public static final String DB_NAME="downthread.db3";
public static final int VERSION=1;
private Context mContext;
private volatile static Thread t=null;
private Thread(){
mContext= BaseApplication.getContext();
db=new ThreadHelper(mContext,DB_NAME,VERSION).getReadableDatabase();
}
public static Thread getInstance(){
if(t==null){
synchronized (Thread.class){
if(t==null){
t=new Thread();
}
}
}
return t;
}
public SQLiteDatabase getDb(){
return db;
}
//保存當前線程下載進度
public synchronized void insert(ThreadInfo threadInfo){
ContentValues values=new ContentValues();
values.put("threadId",threadInfo.getThreadId());
values.put("start",threadInfo.getStart());
values.put("end",threadInfo.getEnd());
values.put("completed",threadInfo.getCompeleted());
values.put("url",threadInfo.getUrl());
long rowId=db.insert(ThreadHelper.TABLE_NAME,null,values);
if(rowId!=-1){
UtilsLog.i("插入線程記錄成功");
}else{
UtilsLog.i("插入線程記錄失敗");
}
}
//查詢當前線程 下載的進度
public synchronized ThreadInfo query(String threadId,String queryUrl){
Cursor cursor=db.query(ThreadHelper.TABLE_NAME,null,"threadId= ? and url= ?",new String[]{threadId,queryUrl},null,null,null);
ThreadInfo info=new ThreadInfo();
if(cursor!=null){
while (cursor.moveToNext()){
int start=cursor.getInt(2);
int end=cursor.getInt(3);
int completed=cursor.getInt(4);
String url=cursor.getString(5);
info.setThreadId(threadId);
info.setStart(start);
info.setEnd(end);
info.setCompeleted(completed);
info.setUrl(url);
}
cursor.close();
}
return info;
}
//更新當前線程下載進度
public synchronized void update(ThreadInfo info){
ContentValues values=new ContentValues();
values.put("start",info.getStart());
values.put("completed",info.getCompeleted());
db.update(ThreadHelper.TABLE_NAME,values,"threadId= ? and url= ?",new String[]{info.getThreadId(),info.getUrl()});
}
//關(guān)閉db
public void close(){
db.close();
}
//判斷多線程任務下載 是否第一次創(chuàng)建線程
public boolean isExist(String url){
Cursor cursor=db.query(ThreadHelper.TABLE_NAME,null,"url= ?",new String[]{url},null,null,null);
boolean isExist=cursor.moveToNext();
cursor.close();
return isExist;
}
public synchronized void delete(ThreadInfo info){
long rowId=db.delete(ThreadHelper.TABLE_NAME,"url =? and threadId= ?",new String[]{info.getUrl(),info.getThreadId()});
if(rowId!=-1){
UtilsLog.i("刪除下載線程記錄成功");
}else{
UtilsLog.i("刪除下載線程記錄失敗");
}
}
public synchronized void delete(String url){
long rowId=db.delete(ThreadHelper.TABLE_NAME,"url =? ",new String[]{url});
if(rowId!=-1){
UtilsLog.i("刪除下載線程記錄成功");
}else{
UtilsLog.i("刪除下載線程記錄失敗");
}
}}
4.基本的準備操作我們已經(jīng)完成了，那么開始寫關(guān)于下載的類吧。首先寫的肯定是DownLoadManager類，就是管理任務下載的類。不多說，直接看代碼。
public class DownLoadManager {
private Map<String, FileInfo> map = new HashMap<>();
private static int mThreadNum;
private int fileSize;
private boolean flag = false; //true第一次下載 false不是第一次下載
private List<DownLoadTask> threads;
private static FileInfo mInfo;
private static ResultListener mlistener;
public static ExecutorService executorService = Executors.newCachedThreadPool();
public static File file;
private int totalComleted;
private DownLoadManager() {
threads = new ArrayList<>();
}
public static DownLoadManager getInstance(FileInfo info, int threadNum,ResultListener listener) {
mlistener = listener;
mThreadNum = threadNum;
mInfo = info;
return DownLoadManagerHolder.dlm;
}
private static class DownLoadManagerHolder {
private static final DownLoadManager dlm = new DownLoadManager();
}
public void start() {
totalComleted=0;
clear();
final FileInfo newInfo = DownLoad.getInstance().queryData(mInfo.getUrl());
newInfo.setDownloading(true);
map.put(mInfo.getUrl(),newInfo);
prepare(newInfo);
}
//停止下載任務
public void stop() {
map.get(mInfo.getUrl()).setDownloading(false);
map.get(mInfo.getUrl()).setStop(true);
}
public void clear(){
if(threads.size()>0){
threads.clear();
}
}
//重新下載任務
public void restart() {
stop();
try {
File file = new File(com.cmazxiaoma.downloader.download.DownLoadManager.FILE_PATH, map.get(mInfo.getUrl()).getFileName());
if (file.exists()) {
file.delete();
}
java.lang.Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
DownLoad.getInstance().resetData(mInfo.getUrl());
start();
}
//獲取當前任務狀態(tài), 是否在下載
public boolean getCurrentState() {
return map.get(mInfo.getUrl()).isDownloading();
}
//添加下載任務
public void addTask(FileInfo info) {
//判斷數(shù)據(jù)庫是否已經(jīng)存在此下載信息
if (!DownLoad.getInstance().isExist(info)) {
DownLoad.getInstance().insertData(info);
map.put(info.getUrl(), info);
} else {
DownLoad.getInstance().delete(info);
DownLoad.getInstance().insertData(info);
UtilsLog.i("map已經(jīng)更新");
map.remove(info.getUrl());
map.put(info.getUrl(), info);
}
}
private void prepare(final FileInfo newInfo) {
new java.lang.Thread(){
@Override
public void run() {
HttpURLConnection con = null;
RandomAccessFile raf=null;
try {
//連接資源
URL url = new URL(newInfo.getUrl());
UtilsLog.i("url=" + url);
con = (HttpURLConnection) url.openConnection();
con.setConnectTimeout(2 * 1000);
con.setRequestMethod("GET");
int length = -1;
UtilsLog.i("responseCode=" + con.getResponseCode());
if (con.getResponseCode() == 200) {
length = con.getContentLength();
UtilsLog.i("文件大小=" + length);
}
if (length <= 0) {
return;
}
//創(chuàng)建文件保存路徑
File dir = new File(com.cmazxiaoma.downloader.download.DownLoadManager.FILE_PATH);
if (!dir.exists()) {
dir.mkdirs();//建立多級文件夾
}
newInfo.setLength(length);
fileSize = length;
UtilsLog.i("當前線程Id=" + java.lang.Thread.currentThread().getId() + ",name=" + java.lang.Thread.currentThread().getName());
int currentPartSize = fileSize / mThreadNum;
file = new File(com.cmazxiaoma.downloader.download.DownLoadManager.FILE_PATH, newInfo.getFileName());
raf = new RandomAccessFile(file, "rwd");
raf.setLength(fileSize);
if (Thread.getInstance().isExist(newInfo.getUrl())) {
flag = false;
} else {
flag = true;
}
for (int i = 0; i < mThreadNum; i++) {
if (flag) {
UtilsLog.i("第一次多線程下載");
int start = i * currentPartSize;//計算每條線程下載的開始位置
int end = start + currentPartSize-1;//線程結(jié)束的位置
if(i==mThreadNum-1){
end=fileSize;
}
String threadId = "xiaoma" + i;
ThreadInfo threadInfo = new ThreadInfo(threadId, start, end, 0,newInfo.getUrl());
Thread.getInstance().insert(threadInfo);
DownLoadTask thread = new DownLoadTask(threadInfo,newInfo, threadId, start, end, 0);
DownLoadManager.executorService.execute(thread);
threads.add(thread);
} else {
UtilsLog.i("不是第一次多線程下載");
ThreadInfo threadInfo = Thread.getInstance().query("xiaoma" + i, newInfo.getUrl());
DownLoadTask thread = new DownLoadTask(threadInfo,newInfo,threadInfo.getThreadId(),threadInfo.getStart(),threadInfo.getEnd(),threadInfo.getCompeleted());//這里出現(xiàn)過問題
DownLoadManager.executorService.execute(thread);
threads.add(thread);
}
}
boolean isCompleted=false;
while(!isCompleted){
isCompleted=true;
for(DownLoadTask thread:threads){
totalComleted+=thread.completed;
if(!thread.isCompleted){
isCompleted=false;
}
}
if(newInfo.isStop()){
totalComleted=0;
return;
}
Message message=new Message();
message.what=0x555;
message.arg1=fileSize;
message.arg2=totalComleted;
handler.sendMessage(message);
if(isCompleted){
totalComleted=0;
//任務線程全部完成，清空集合
clear();
handler.sendEmptyMessage(0x666);
return;
}
totalComleted=0;
java.lang.Thread.sleep(1000);
}
}catch (Exception e) {
e.printStackTrace();
}finally {
try {
if (con != null) {
con.disconnect();
}
if(raf!=null){
raf.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}.start();
}
private Handler handler=new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what){
case 0x555:
if(mlistener!=null){
mlistener.progress(msg.arg1,msg.arg2);
}
break;
case 0x666:
if(mlistener!=null){
mlistener.comleted();
}
break;
}
}
};}
5.接下來呢，就是DownLoadTask類了，就是一個線程下載類。
public class DownLoadTask extends java.lang.Thread{
private int start;//當前線程的開始下載位置
private int end;//當前線程結(jié)束下載的位置
private RandomAccessFile raf;//當前線程負責下載的文件大小
public int completed=0;//當前線程已下載的字節(jié)數(shù)
private String threadId;//自己定義的線程Id
private FileInfo info;
private ThreadInfo threadInfo;
public boolean isCompleted=false; //true為當前線程完成任務,false為當前線程未完成任務
//保存新的start
public int finshed=0;
public int newStart=0;
public DownLoadTask(ThreadInfo threadInfo,FileInfo info,String threadId, int start, int end,int completed){
this.threadInfo=threadInfo;
this.info=info;
this.threadId=threadId;
this.start=start;
this.end=end;
this.completed=completed;
}
@Override
public void run() {
HttpURLConnection con = null;
try {
UtilsLog.i("start="+start+",end="+end+",completed="+completed+",threadId="+getThreadId());
URL url = new URL(info.getUrl());
con = (HttpURLConnection) url.openConnection();
con.setConnectTimeout(2 * 1000);
con.setRequestMethod("GET");
con.setRequestProperty("Range", "bytes=" + start + "-"+end);//重點
raf=new RandomAccessFile(DownLoadManager.file,"rwd");
//從文件的某一位置寫入
raf.seek(start);
if (con.getResponseCode() == 206) { //文件部分下載 返回碼是206
InputStream is = con.getInputStream();
byte[] buffer = new byte[4096];
int hasRead = 0;
while ((hasRead = is.read(buffer)) != -1) {
//寫入文件
raf.write(buffer, 0, hasRead);
//單個文件的完成程度
completed += hasRead;
threadInfo.setCompeleted(completed);
//保存新的start
finshed=finshed+hasRead;//這里出現(xiàn)過問題，嘻嘻
newStart=start+finshed;
threadInfo.setStart(newStart);
//UtilsLog.i("Thread:"+getThreadId()+",completed=" + completed);
//停止下載
if (info.isStop()) {
UtilsLog.i("isStop="+info.isStop());
//保存下載進度
UtilsLog.i("現(xiàn)在Thread:"+getThreadId()+",completed=" + completed);
Thread.getInstance().update(threadInfo);
return;
}
}
//刪除該線程下載記錄
Thread.getInstance().delete(threadInfo);
isCompleted=true;
Thread.getInstance().update(threadInfo);
UtilsLog.i("thread:"+getThreadId()+"已經(jīng)完成任務!--"+"completed="+completed);
}
} catch (Exception e) {
if (con != null) {
con.disconnect();
}
try {
if (raf != null) {
raf.close();
}
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
public String getThreadId() {
return threadId;
}}
6.接口，就是一個監(jiān)聽下載進度的接口，也是很簡單。
public interface ResultListener{
void progress(int max, int progress);
void comleted();}
結(jié)束
大致操作就是這樣，其實多線程也挺簡單的。
以上所述是小編給大家介紹的Android多線程+單線程+斷點續(xù)傳+進度條顯示下載功能，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復大家的。在此也非常感謝大家對腳本之家網(wǎng)站的支持！
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