多线程并发断点续传下载器
2015-06-03 16:50
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利用文件存储上次暂停时的下载量
大家可以改用sqlite3数据库来存储暂停时的数据量来完成断点下载，我就把我自己写的代码附上，大家共同学习，代码里面有大量的注释，如有逻辑不够清晰的地方，还请指点~~~~~~下面是简图：
下面是主程序：
public class MainActivity extends Activity {
public static final int UPDATE = 5;
public static final int DOWM_FIN = 4;
private EditText et_path;
private ProgressBar pb;
private Button btn;
private TextView tv_process;
public static int runningThread = 5;
public static int threadcount = 5;
public static final int DOWN_LOAD_ERROR = 1;
public static final int SERVICE_ERROR = 2;
public int currentProcess = 0;// 当前进度条的进度
private Handler hander = new Handler() {
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
switch (msg.what) {
case DOWN_LOAD_ERROR:
Toast.makeText(getApplicationContext(), "下载失败", 0).show();
break;
case SERVICE_ERROR:
Toast.makeText(getApplicationContext(), "服务失败", 0).show();
break;
case DOWM_FIN:
Toast.makeText(getApplicationContext(), "下载完毕", 0).show();
break;
case UPDATE:
//pb.setProgress(currentProcess);
tv_process.setText("当前进度：" + pb.getProgress() * 100
/ pb.getMax());
break;
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_path = (EditText) findViewById(R.id.editText1);
pb = (ProgressBar) findViewById(R.id.progressBar1);
tv_process = (TextView) findViewById(R.id.textView1);
btn = (Button) findViewById(R.id.button1);
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
new Thread() {
@Override
public void run() {
// TODO Auto-generated method stub
super.run();
download();
}
}.start();
}
});
}
public void download() {
final String path = et_path.getText().toString().trim();
if (TextUtils.isEmpty(path)) {
Toast.makeText(this, "下载路径错误", 0).show();
return;
}
new Thread() {
@Override
public void run() {
try {
// 链接服务器，获取文件和长度；在本地创建一个大小跟服务器文件大小一样的额临时文件
// String path =
// "http://192.168.191.1:9011/wireshark-win32-1.2.4.exe";
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
int code = conn.getResponseCode();
if (code == 200) {
// 服务器返回的长度就是文件的长度
int length = conn.getContentLength();
System.out.println("文件长度" + length);
pb.setMax(length);
// 创建临时文件
RandomAccessFile raf = new RandomAccessFile(
"/storage/sdcard/stup.exe", "rwd");
raf.setLength(length);
raf.close();
// 假设3个线程去下载资源
// 平均每个线程下载的大小
int blocksize = length / threadcount;
for (int threadid = 1; threadid <= threadcount; threadid++) {
int startIndex = (threadid - 1) * blocksize;
int endIndex = threadid * blocksize - 1;
if (threadid == threadcount) {
endIndex = length;
}
System.out.println("线程" + threadid + "下载："
+ startIndex + "----->" + endIndex);
new DownloadThread(path, threadid, startIndex,
endIndex).start();
}
} else {
System.out.println("服务器错误 ");
Message msg = new Message();
msg.what = SERVICE_ERROR;
hander.sendMessage(msg);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Message msg = new Message();
msg.what = DOWN_LOAD_ERROR;
hander.sendMessage(msg);
}
}
}.start();
}
public class DownloadThread extends Thread {
private int threadid;
private int startIndex;
private int endIndex;
private String path;
public DownloadThread(String path, int threadid, int startIndex,
int endIndex) {
this.threadid = threadid;
this.endIndex = endIndex;
this.startIndex = startIndex;
this.path = path;
}
@Override
public void run() {
// TODO Auto-generated method stub
try {
// 把下面的代码转换为数据库存储
// ---------------sqlite3------------------------------
// 检查是否纯在记录下载长度的文件，如果存在读取这个文件的数据
File tempFile = new File("/storage/sdcard/" + threadid + ".txt");
if (tempFile.exists() && tempFile.length() > 0) {
FileInputStream fis = new FileInputStream(tempFile);
byte[] temp = new byte[1024];
int leng = fis.read(temp);
String download = new String(temp, 0, leng);
int downloadInt = Integer.parseInt(download);
System.out.println("从已存文件读取的数据：" + threadid+":"+downloadInt);
int alreadyDownload = downloadInt - startIndex;
currentProcess += alreadyDownload;// 计算上次断点已经下载的 长度
startIndex = downloadInt;// 修改下载真是的开始位置
System.out.println("线程" + threadid+"下载的真实位置：" + startIndex);
fis.close();
}
// ---------------------------------------------------
// ---------------------------------------------------
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Range", "bytes=" + startIndex + "-"
+ endIndex);
System.out.println("线程真实下载：" + threadid + "下载：" + startIndex
+ "----->" + endIndex);
conn.setConnectTimeout(5000);
int code = conn.getResponseCode();// 从服务器返回全部资源200，部分206；300资源不存在或重定向；400资源没有找到；500服务为武器内部出现错误
// System.out.println(code);
if (code == 206) {
InputStream is = conn.getInputStream();
RandomAccessFile raf = new RandomAccessFile(
"/storage/sdcard/stup.exe", "rwd");
raf.seek(startIndex);
int len = 0;
byte[] buffer = new byte[1024];
int total = 0;// 已经下载de数据的长度
while ((len = is.read(buffer)) != -1) {
// 记录当前线程下咋的数据长度
RandomAccessFile file = new RandomAccessFile(
"/storage/sdcard/" + threadid + ".txt", "rwd");
raf.write(buffer, 0, len);
total += len;// 已经下载的数据长度
//System.out.println(threadid + "已下载数据长度："+ total);
file.write((startIndex + total + "").getBytes());// 记录下载的位置，并不是进度
file.close();
// 更新进度条
synchronized (MainActivity.this) {
currentProcess += len;// 获取所有线程的总进度
pb.setProgress(currentProcess);// 更改界面进度//特殊
Message msg = Message.obtain();
msg.what = UPDATE;
hander.sendMessage(msg);
}
}
is.close();
raf.close();
System.out.println("线程" + threadid + "下载完毕");
} else {
System.out.println("线程" + threadid + "下载失败");
}
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
thread_finish();
}
}
private synchronized void thread_finish() {
runningThread--;
if (runningThread == 0) {
for (int i = 1; i <= 5; i++) {
// 判断几个线程全部都执行完
File delete = new File("/storage/sdcard/" + i + ".txt");
delete.delete();
}
System.out.println("文件下载完毕，删除所有记录");
Message msg = new Message();
msg.what = DOWM_FIN;
hander.sendMessage(msg);
}
}
}
}下面是xml的简单布局
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<EditText
android:id="@+id/editText1"
android:hint="请输入下载路径"
android:text="http://192.168.191.1:9011/wireshark-win32-1.2.4.exe"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10" >
<requestFocus />
</EditText>
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下载" />
<ProgressBar
android:id="@+id/progressBar1"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下载进度" />
</LinearLayout>下面要注意对sdcard进行读写操作要加权限，如下：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.INTERNET"/>好了，所有代码已附录，新手上路多多关照，有繁琐逻辑的话，还请提出，下载应用程序，我已经试过了，没有问题，完全可以断点续传，对了，暂停的按钮没有添加，可以在eclipse里面进行暂停操作。
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