多线程下载

来源：互联网发布：打电话不要钱的软件编辑：程序博客网时间：2024/05/01 01:46

Java：

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.RandomAccessFile;

import java.net.HttpURLConnection;

import java.net.URL;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import android.app.Activity;

import android.os.Bundle;

import android.os.Environment;

import android.os.Handler;

import android.os.Handler.Callback;

import android.os.Message;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.ProgressBar;

import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

private EditText weburl;

private Button btn;

private boolean flag = false;// false暂停下载true正在下载

private int total = 0;// 已下载了的

private File file;

private int end;// 文件的总长度

private List<Map<String, Integer>> list = new ArrayList<Map<String, Integer>>();

private ProgressBar progressBar0;

private Handler handler = new Handler(new Callback() {

@Override

public boolean handleMessage(Message msg) {

// TODO Auto-generated method stub

if (msg.what == 0x123) {

if (msg.arg1 >= end) {

Toast.makeText(MainActivity.this, "下载完成", 1).show();

}

progressBar0.setProgress(msg.arg1);

}

return false;

}

});

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

weburl = (EditText) findViewById(R.id.weburl1);

btn = (Button) findViewById(R.id.uploadbut1);

progressBar0 = (ProgressBar) findViewById(R.id.prog1);

btn.setOnClickListener(this);

}

@Override

public void onClick(View v) {

// TODO Auto-generated method stub

if (flag) {

flag = false;

btn.setText("下载");

return;

}

flag = true;

btn.setText("暂停");

if (total == 0) {

new Thread() {

public void run() {

try {

file = new File(

Environment.getExternalStorageDirectory()

+ "/file", getFileName(weburl.getText()

.toString()));

URL url = new URL(weburl.getText().toString());

HttpURLConnection conn = (HttpURLConnection) url

.openConnection();

conn.setConnectTimeout(5000);

end = conn.getContentLength();// 获取文件的长度

progressBar0.setMax(end);

Log.e("TAG", "length:" + end + "=====");

RandomAccessFile accessFile = new RandomAccessFile(

file, "rw");

accessFile.setLength(end);// 设置文件的长度

int addload = end / 4;

for (int i = 0; i < 4; i++) {

int start = i * addload;

int over = (i + 1) * addload;

if (i == 3) {

over = end;

}

Map<String, Integer> map = new HashMap<String, Integer>();

map.put("start", start);

map.put("over", over);

map.put("finished", 0);

list.add(map);

Thread thread = new Thread(new DownLoadd(start,

over, file, i));

thread.start();

}

} catch (IOException e) {

e.printStackTrace();

}

};

}.start();

} else {

// 续传

for (int j = 0; j < list.size(); j++) {

Thread thread = new Thread(new DownLoadd(list.get(j).get(

"start")

+ list.get(j).get("finished"), list.get(j).get("over"),

file, j));

thread.start();

}

class DownLoadd implements Runnable {

private int begin;// 请求数据的其实位置

private int end;// 请求的结束位置

private File file;

private int id;

DownLoadd(int begin, int end, File file, int id) {

this.begin = begin;

this.end = end;

this.file = file;

this.id = id;

}

public void run() {

try {

URL url = new URL(weburl.getText().toString());

HttpURLConnection conn = (HttpURLConnection) url

.openConnection();

conn.setConnectTimeout(5000);

conn.setRequestMethod("GET");

conn.setRequestProperty("Range", "bytes=" + begin + "-" + end);

RandomAccessFile accessFile = new RandomAccessFile(file, "rw");

accessFile.seek(begin);

InputStream is = conn.getInputStream();

int len;

byte[] b = new byte[1024 * 1024];

while ((len = is.read(b)) != -1 && flag) {

accessFile.write(b, 0, len);

list.get(id).put("finished",

list.get(id).get("finished") + len);

addFinshed(len);

}

accessFile.close();

is.close();

conn.disconnect();

} catch (Exception e) {

Log.e("url", "url异常");

e.printStackTrace();

}

synchronized private void addFinshed(int len) {

total += len;// 记录已下载的总长度

Log.e("TAG", "已完成：" + total);

// 发一个数据

handler.obtainMessage(0x123, total, 0).sendToTarget();

}

// 获取下载文件的文件名

private String getFileName(String url) {

int index = url.lastIndexOf("/") + 1;

return url.substring(index);

}

----------------------------------------------------------------------

xml：

<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"

tools:context=".MainActivity" >

<EditText

android:id="@+id/weburl1"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:singleLine="true"

android:text="http://192.168.43.74:8080/Download/File/Beyond.mp3" />

<Button

android:id="@+id/uploadbut1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="开始下载" />

<ProgressBar

android:id="@+id/prog1"

style="@android:style/Widget.DeviceDefault.Light.ProgressBar.Horizontal"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_marginLeft="10dp"

android:layout_marginRight="10dp"

android:progressDrawable="@drawable/layer_0" />

<TextView

android:id="@+id/jindu_1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:padding="10dp"

android:textColor="#f00" />

</LinearLayout>

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