當我們從Internet中下載一個文件時，有的文件比較大，比如音樂或視頻文件，下載的話需要比較長的時間，當我們在下載過程中，如果手機沒電了或者其它原因，使當前的下載中斷了，按照一般的程序，當下次下載又需要從新開始，這裏我們來實現多純程斷點下載，當下載中斷了，下次啓動的時候還會接着下載，有點像我們的迅雷了……
首先呢，我們先不急着建Android應用，先建一個Java項目，測試一下下
然後在這個項目裏面建一個測試用例
包都可以不填，因爲只是測試，不是真正的應用，偷懶了……
OK，接着寫代碼
package junit.test;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import org.junit.Test;
public class InternetTest {
/**
* 讀取輸入流並返回數據
* @param input
* @return
* @throws Exception
*/
public byte[] readStream(InputStream input) throws Exception{
byte[] buffer = new byte[1024];
ByteArrayOutputStream output = new ByteArrayOutputStream();
int len = -1;
while((len=input.read(buffer))!=-1){
output.write(buffer, 0, len);
}
input.close();
output.close();
return output.toByteArray();
}
/**
* 從網絡上下載圖片
* @throws Exception
*/
@Test
public void getImage()throws Exception{
String urlPath = "http://photocdn.sohu.com/20110401/Img280097999.jpg";//在網絡上隨便找一張圖片的鏈接
URL url = new URL(urlPath);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();//返回一個連接對象
conn.setRequestMethod("GET");//設置請求方式
conn.setConnectTimeout(6*1000);//設置連接超時，這裏可以不用設置，但是在android應用中應該設置超時時間
if (conn.getResponseCode()==200) {
InputStream input = conn.getInputStream();
byte[] data = readStream(input);
File file = new File("test.jpg");
FileOutputStream output = new FileOutputStream(file);
output.write(data);
output.close();
}
}
/**
* 得到網頁html
* @throws Exception
*/
@Test
public void getHtml()throws Exception{
String urlPath = "http://www.baidu.com";
URL url = new URL(urlPath);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(6*1000);
if (conn.getResponseCode()==200) {
InputStream input = conn.getInputStream();
byte[] data = readStream(input);
System.out.println(new String(data));//直接輸出到控制檯
}
}
}
然後測試，是否有預期的結果，如果有，繼續下面，如果沒有，再看看是不是哪兒錯了
然後再建一個測試類，實現多線程下載，以下載一首mp3爲例
package junit.test;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import org.junit.Test;
public class DownloaderTest {
/**
* 讀取輸入流並返回數據
* @param input
* @return
* @throws Exception
*/
public byte[] readStream(InputStream input) throws Exception {
ByteArrayOutputStream output = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = -1;
while ((len = input.read(buffer)) != -1) {
output.write(buffer, 0, len);
}
input.close();
output.close();
return output.toByteArray();
}
@Test
public void downloader() throws Exception {
String urlPath = "http://dl.toofiles.com/vaaoje/audios/qbd.mp3";
URL url = new URL(urlPath);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
int threadsize = 3;//定義線程數
int filesize = conn.getContentLength();// 獲取文件大小
int block = filesize / threadsize + 1;// 每條線程下載的數量
conn.disconnect();
File file = new File("千百度.mp3");
RandomAccessFile randfile = new RandomAccessFile(file, "rw");//RandomAccessFile可以指定從文件的什麼位置寫入數據
for(int i=0;i<threadsize;i++){
int startposition = i * block;//記錄每條線程的開始位置
RandomAccessFile threadfile = new RandomAccessFile(file, "rw");
threadfile.seek(startposition);//從文件的什麼位置開始寫入
new Thread(new DownloadThread(i,url,startposition,threadfile,block)).start();
}
/*
* 設置一個標誌，當輸入q的時候停止主線程
*/
byte b[] = new byte[1];
System.in.read(b);
while(!('q'==b[0])){
Thread.sleep(3*1000);
}
}
private class DownloadThread implements Runnable{
private int id ;
private URL url;
private int startposition;
private RandomAccessFile threadfile;
private int block;
public DownloadThread(int id ,URL url,int startposition,RandomAccessFile threadfile,int block){
this.id=id;
this.url=url;
this.startposition=startposition;
this.threadfile=threadfile;
this.block=block;
}
@Override
public void run() {
// TODO Auto-generated method stub
try {
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Range", "bytes="+startposition+"-");
conn.setConnectTimeout(6 * 1000);
InputStream input = conn.getInputStream();
byte[] buffer = new byte[1024];
int len = -1;
int readfilesize = 0;//記錄下載的文件大小
while (readfilesize<block && ((len = input.read(buffer)) != -1)) {
threadfile.write(buffer, 0, len);
readfilesize += len;//累計下載的文件大小
}
threadfile.close();
conn.disconnect();
System.out.println((this.id+1)+"線程下載完成");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}運行此測試類，如果沒有異常拋出的話就成功了……
多線程下載的核心代碼已經完成，下面結合到android應用中，我們還得用到SQLite知識，要實現多線程下載，當中斷的時候，我們系統會記錄一個下載位置，我們把它保存在數據庫中，第二次運行的時候再從數據庫中讀取出來，假設大家都有SQLite方面的知識……
接下來應該建Android項目了
當然如果我們做小一點的Android項目的時候可以先做界面，然後根據需要來擴展所需要的功能，當然有的時候我們寧願先實現業務，業務功能做好了再實現界面，因爲界面裏面基本不含有技術，況且我們只是爲了學習，界面不需要多美觀的，能用就行，OK，繼續
先做數據庫這層
關於建Android項目方法的截圖就省略了，我用的模擬器版本是2.3.3，至今爲至最新的吧
首先建一個類DBOpenHelper繼續自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);
}
}這裏定義的數據名字叫download.db,版本號爲1，表名filedownlog,裏面有三個字段，一個id,主鍵，下載路徑downpath，線程ID和一個下載長度downlength
然後建一個FileService類
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;
/**
* 業務bean
*
*/
public class FileService {
private DBOpenHelper openHelper;
public FileService(Context context) {
openHelper = new DBOpenHelper(context);
}
/**
* 獲取每條線程已經下載的文件長度
*
* @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;
}
/**
* 保存每條線程已經下載的文件長度
*
* @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();
}
/**
* 實時更新每條線程已經下載的文件長度
*
* @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();
}
/**
* 當文件下載完成後，刪除對應的下載記錄
*
* @param path
*/
public void delete(String path) {
SQLiteDatabase db = openHelper.getWritableDatabase();
db.execSQL("delete from filedownlog where downpath=?",
new Object[] { path });
db.close();
}
}類中都有相應的註釋的，看不懂可以慢慢看……
因爲要用到進度條，所以先把進度條建了
package com.studio.net.download;
public interface DownloadProgressListener {
public void onDownloadSize(int size);
}這裏我們定義了一個進度條監聽接口，由實現此接口的類來調用onDownloadSize()方法新建一個類DownloadThread繼承自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;
/* 下載開始位置 */
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) {// 未下載完成
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;// 開始位置
int endPos = block * threadId - 1;// 結束位置
http.setRequestProperty("Range", "bytes=" + startPos + "-"
+ endPos);// 設置獲取實體數據的範圍
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);
}
/**
* 下載是否完成
*
* @return
*/
public boolean isFinish() {
return finish;
}
/**
* 已經下載的內容大小
*
* @return 如果返回值爲-1,代表下載失敗
*/
public long getDownLength() {
return downLength;
}
}再建一個文件下載器FileDownloader類
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;
/* 已下載文件長度 */
private int downloadSize = 0;
/* 原始文件長度 */
private int fileSize = 0;
/* 線程數 */
private DownloadThread[] threads;
/* 本地保存文件 */
private File saveFile;
/* 緩存各線程下載的長度 */
private Map<Integer, Integer> data = new ConcurrentHashMap<Integer, Integer>();
/* 每條線程下載的長度 */
private int block;
/* 下載路徑 */
private String downloadUrl;
/**
* 獲取線程數
*/
public int getThreadSize() {
return threads.length;
}
/**
* 獲取文件大小
*
* @return
*/
public int getFileSize() {
return fileSize;
}
/**
* 累計已下載大小
*
* @param size
*/
protected synchronized void append(int size) {
downloadSize += size;
}
/**
* 更新指定線程最後下載的位置
*
* @param threadId
* 線程id
* @param pos
* 最後下載的位置
*/
protected synchronized void update(int threadId, int pos) {
this.data.put(threadId, pos);
this.fileService.update(this.downloadUrl, this.data);
}
/**
* 構建文件下載器
*
* @param downloadUrl
* 下載路徑
* @param fileSaveDir
* 文件保存目錄
* @param threadNum
* 下載線程數
*/
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();// 根據響應獲取文件大小
if (this.fileSize <= 0)
throw new RuntimeException("Unkown file size ");
String filename = getFileName(conn);// 獲取文件名稱
this.saveFile = new File(fileSaveDir, filename);// 構建保存文件
Map<Integer, Integer> logdata = fileService
.getData(downloadUrl);// 獲取下載記錄
if (logdata.size() > 0) {// 如果存在下載記錄
for (Map.Entry<Integer, Integer> entry : logdata.entrySet())
data.put(entry.getKey(), entry.getValue());// 把各條線程已經下載的數據長度放入data中
}
if (this.data.size() == this.threads.length) {// 下面計算所有線程已經下載的數據長度
for (int i = 0; i < this.threads.length; i++) {
this.downloadSize += this.data.get(i + 1);
}
print("已經下載的長度" + this.downloadSize);
}
// 計算每條線程下載的數據長度
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");
}
}
/**
* 獲取文件名
*/
private String getFileName(HttpURLConnection conn) {
String filename = this.downloadUrl.substring(this.downloadUrl
.lastIndexOf('/') + 1);
if (filename == null || "".equals(filename.trim())) {// 如果獲取不到文件名稱
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";// 默認取一個文件名
}
return filename;
}
/**
* 開始下載文件
*
* @param listener
* 監聽下載數量的變化,如果不需要了解實時下載的數量,可以設置爲null
* @return 已下載文件大小
* @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);// 初始化每條線程已經下載的數據長度爲0
}
}
for (int i = 0; i < this.threads.length; i++) {// 開啓線程進行下載
int downLength = this.data.get(i + 1);
if (downLength < this.block
&& this.downloadSize < this.fileSize) {// 判斷線程是否已經完成下載,否則繼續下載
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;// 下載未完成
while (notFinish) {// 循環判斷所有線程是否完成下載
Thread.sleep(900);
notFinish = false;// 假定全部線程下載完成
for (int i = 0; i < this.threads.length; i++) {
if (this.threads[i] != null && !this.threads[i].isFinish()) {// 如果發現線程未完成下載
notFinish = true;// 設置標誌爲下載沒有完成
if (this.threads[i].getDownLength() == -1) {// 如果下載失敗,再重新下載
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);// 通知目前已經下載完成的數據長度
}
fileService.delete(this.downloadUrl);
} catch (Exception e) {
print(e.toString());
throw new Exception("file download fail");
}
return this.downloadSize;
}
/**
* 獲取Http響應頭字段
*
* @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頭字段
*
* @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至此業務寫完了
現在來設計界面UI，由於要使用到String類型的字符串，所以我們先在String.xml中定義一下
添加
<string name="path">下載路徑</string>
<string name="button">下載</string>
<string name="suceess">下載完成</string>
<string name="error">下載失敗</string>
<string name="sdcarderror">SDCard不存在或寫保護</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>主類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;
// 它用於往消息隊列發送消息，當Handler被創建時會自動綁定到Handler被創建時所在的線程所綁定的消息隊列
private Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 1:
downloadbar.setProgress(msg.getData().getInt("size"));// 把當前已經下載的數據長度設置爲進度條的當前刻度
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();
}
}
});
}
// 對UI控件的更新只能由主線程(UI線程)負責,如果不在UI線程更新控件，更新後的值不會被重繪到屏幕上
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());// 設置進度條的最大刻度爲文件的大小
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();
}
}
當然別忘了添加權限
<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>OK，搞定，運行一下
如圖所示
由於這個mp3有點大，耐心等待
OK，終於下載完成了，看看sdcard吧，上面有我們剛下載的歌曲文件了，播放一下試試