断点下载

最新推荐文章于 2024-12-12 19:24:03 发布

Rlingge

最新推荐文章于 2024-12-12 19:24:03 发布

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CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/Rlingge/article/details/49202867

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" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" >

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="30dp"
            android:layout_marginLeft="15dp"
            android:gravity="center_vertical"
            android:text="下载地址"
            android:textSize="15sp" />

        <EditText
            android:id="@+id/downURL"
            android:layout_width="fill_parent"
            android:layout_height="80dp"
            android:layout_marginLeft="15dp"
            android:gravity="center_vertical"
            android:text="http://img1.imgtn.bdimg.com/it/u=1212833245,963852114&fm=21&gp=0.jpg"
            android:textSize="20sp" >
        </EditText>

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="30dp"
            android:layout_marginLeft="15dp"
            android:gravity="center_vertical"
            android:text="下载文件名"
            android:textSize="15sp" />

        <EditText
            android:id="@+id/FileName"
            android:layout_width="fill_parent"
            android:layout_height="45dp"
            android:layout_marginLeft="15dp"
            android:gravity="center_vertical"
            android:textSize="20sp" />

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="30dp"
            android:layout_marginLeft="15dp"
            android:gravity="center_vertical"
            android:text="下载线程数"
            android:textSize="15sp" />

        <EditText
            android:id="@+id/ThreadNumber"
            android:layout_width="fill_parent"
            android:layout_height="45dp"
            android:layout_marginLeft="15dp"
            android:gravity="center_vertical"
            android:text="3"
            android:textSize="20sp" />

        <Button
            android:id="@+id/btn_down"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="15dp"
            android:text="开始下载"
            android:textSize="20sp" />

        <TextView
            android:id="@+id/view_downfile"
            android:layout_width="fill_parent"
            android:layout_height="30dp"
            android:layout_marginLeft="15dp"
            android:gravity="center_vertical"
            android:textSize="15sp" />
        
			<!-- 进度条 -->
        <ProgressBar
            android:id="@+id/ProgressBar"
            style="?android:attr/progressBarStyleHorizontal"
            android:layout_width="fill_parent"
            android:layout_height="5dp"
            android:layout_marginTop="15dp" />
    </LinearLayout>

</LinearLayout>

源码

package com.example.filedownload;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

import android.R.integer;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Looper;
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.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

	private EditText downURL, ThreadNumber, FileName;
	/** 显示下载状态 */
	private TextView view_downfile;
	private Button btn_down;
	private ProgressBar ProgressBar;
	/** 文件总大小 */
	public int FileSize;
	/** 当前文件下载大小 */
	public int nowDownSize;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		if(Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())){
			Toast.makeText(this, "sd卡可用", 1000).show();
		}else{
			Toast.makeText(this, "sd卡不可用", 1000).show();
		}
			

		init();
		btn_down.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				DownLoad();
			}
		});
	}

	private void init() {
		view_downfile = (TextView) findViewById(R.id.view_downfile);
		downURL = (EditText) findViewById(R.id.downURL);
		FileName = (EditText) findViewById(R.id.FileName);
		ThreadNumber = (EditText) findViewById(R.id.ThreadNumber);
		btn_down = (Button) findViewById(R.id.btn_down);
		ProgressBar = (ProgressBar) findViewById(R.id.ProgressBar);
		//进度条设置显示
		ProgressBar.setVisibility(View.VISIBLE);
		//进度条设置最大最小值
		ProgressBar.setMax(100);
		ProgressBar.setProgress(0);
	}

	/** 1、下载 */
	private void DownLoad() {
		URL url = null;
		try {
			url = new URL(downURL.getText().toString());
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		// 下载路径
		String strurl = Environment.getExternalStorageDirectory()
				+ "/MyDownload/";
		File strfile=new File(strurl);
		if(!strfile.exists()){
			strfile.mkdirs();//不存在则创建
		}
		
		// 获取文件名
		String filename = null;
		if (FileName.getText().toString().equals("") | FileName.getText().toString().equals(null)) {
			int count = downURL.getText().toString().lastIndexOf("/");
			filename = downURL.getText().toString()
					.substring(count);
		} else {
			filename = FileName.getText().toString();
		}
		Log.e(">>>>>>>>>>>>>", filename);
		File file = new File(strurl + filename);
		// 线程数
		int threadnumber = 0;
		if (ThreadNumber.getText().toString().equals("")
				| ThreadNumber.getText().toString().equals(null)) {
			ThreadNumber.setText("1");
		}
		threadnumber = Integer.valueOf(ThreadNumber.getText().toString());
		//进度条设为0
		ProgressBar.setProgress(0);
		//下载按钮不可用
		btn_down.setClickable(false);
		new DownThread(url, file, threadnumber).start();
	}

	/** 4、handler通知进度条 */
	Handler handler = new Handler() {

		@Override
		public void handleMessage(Message msg) {
			// TODO Auto-generated method stub
			super.handleMessage(msg);
			int press=Double.valueOf(nowDownSize*1.0/FileSize*100).intValue();
			if(press==100){
				btn_down.setClickable(true);
				view_downfile.setText("下载完成！");
			}else{
				view_downfile.setText(press+"%");
			}
			ProgressBar.setProgress(press);
		}
	};

	/** 3、文件下载线程 */
	public class DownThread extends Thread {

		private int locksize, downsizemore;
		private URL url;
		private File file;
		private int threadnumber;

		public DownThread(URL url, File file, int threadnumber) {
			// TODO Auto-generated constructor stub
			this.url = url;
			this.file = file;
			this.threadnumber = threadnumber;
		}

		@Override
		public void run() {
			// TODO Auto-generated method stub
			super.run();
			FileDownThread[] fdt1 = new FileDownThread[threadnumber];
			try {
				URLConnection conn = url.openConnection();
				// 获取文件长度
				FileSize = conn.getContentLength();
				// 计算每个线程的下载数据量
				locksize = FileSize / threadnumber;
				// 解决整除后百分比计算误差
				downsizemore = (FileSize % threadnumber);
				for (int i = 0; i < threadnumber; i++) {
					// 启动线程，分别下载自己需要下载的部分
					FileDownThread fdt2 = new FileDownThread(url, file, i
							* locksize, (i + 1) * locksize - 1);
					fdt2.setName("thread" + i);
					fdt2.start();
					fdt1[i] = fdt2;
				}
				boolean finished = false;
				while (!finished) {
					nowDownSize = downsizemore;
					finished = true;

					for (int i = 0; i < fdt1.length; i++) {
						nowDownSize += fdt1[i].nowDownLoad();
						if (!fdt1[i].isfinished()) {
							finished = false;
						}
					}
					//通知handler更新视图
					handler.sendEmptyMessage(0);
					sleep(1000);
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

	/** 2、文件断点下载线程 */
	public class FileDownThread extends Thread {
		private URL url;
		private File file;
		private int startwhere, nowwhere, endwhere;
		// 标示当前文件下载大小
		private boolean finshed;
		private int nowDownSize;

		public FileDownThread(URL url, File file, int startwhere, int endwhere) {
			super();
			this.url = url;
			this.file = file;
			this.startwhere = startwhere;
			this.nowwhere = startwhere;
			this.endwhere = endwhere;
		}

		@Override
		public void run() {
			// TODO Auto-generated method stub
			super.run();
			byte[] bytes = new byte[1024];
			URLConnection conn = null;
			RandomAccessFile raf = null;
			BufferedInputStream bis = null;
			try {
				conn = url.openConnection();
				// 允许用户交互
				conn.setAllowUserInteraction(true);
				// 设置当前线程下载的起点，终点
				conn.setRequestProperty("Range", "bytes=" + startwhere + "-"
						+ endwhere);
				// 使用java中的RandomAccessFile 对文件进行随机读写操作
				raf = new RandomAccessFile(file, "rw");
				// 设置文件开始位置
				raf.seek(startwhere);
				bis = new BufferedInputStream(conn.getInputStream());
				// 开始循环以流的形式读写文件
				while (nowwhere < endwhere) {
					int len = bis.read(bytes, 0, 1024);
					if (len == -1) {
						break;
					}
					raf.write(bytes, 0, 1024);
					nowwhere += len;
					if (nowwhere > endwhere) {
						nowDownSize += len - (nowwhere - endwhere) + 1;
					} else {
						nowDownSize += len;
					}
				}
				finshed = true;

			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} finally {
				if (bis != null) {
					try {
						bis.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
				if (raf != null) {
					try {
						raf.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}
		}

		public boolean isfinished() {
			return finshed;
		}

		public int nowDownLoad() {
			return nowDownSize;
		}
	}

}