Android的断点续传的下载在线文件示例
文件的结构如下:
activity_main.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/et_path"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="http://localhost:8080/gh.zip"
android:hint="请输入下载路径"
tools:ignore="HardcodedText" />
<EditText
android:id="@+id/et_threadCount"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入线程的数量" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="click"
android:text="下载" />
<LinearLayout
android:id="@+id/ll_pb"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
</LinearLayout>
</LinearLayout>
item.xml:
<?xml version="1.0" encoding="utf-8"?>
<ProgressBar xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/progressBar1"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
network_security_config.xml:
<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
<base-config cleartextTrafficPermitted="true" />
</network-security-config>
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.administrator.fdtest">
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:usesCleartextTraffic="true"
android:networkSecurityConfig="@xml/network_security_config"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
MainActivity:
package com.example.administrator.fdtest;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.support.v4.app.ActivityCompat;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
public class MainActivity extends Activity {
private EditText et_path;
private EditText et_threadCount;
private LinearLayout ll_pb_layout;
private String path;
private static int runningThread; //代表当前正在运行的线程
private int threadCount;
private List<ProgressBar> pbLists; //用来存进度条的引用
private final int REQUEST_EXTERNAL_STORAGE = 1;
private String[] PERMISSIONS_STORAGE = {
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE };
public void verifyStoragePermissions(Activity activity) {
// Check if we have write permission
int permission = ActivityCompat.checkSelfPermission(activity,
Manifest.permission.WRITE_EXTERNAL_STORAGE);
if (permission != PackageManager.PERMISSION_GRANTED) {
// We don't have permission so prompt the user
ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,
REQUEST_EXTERNAL_STORAGE);
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
verifyStoragePermissions(this);
// [1]找到我们关心的控件
et_path = (EditText) findViewById(R.id.et_path);
et_threadCount = (EditText) findViewById(R.id.et_threadCount);
ll_pb_layout = (LinearLayout) findViewById(R.id.ll_pb);
//[2]添加一个集合 用来存进度条的引用
pbLists = new ArrayList<ProgressBar>();
}
//点击按钮实现下载的逻辑
public void click(View v){
//[2]获取下载的路径
// path = et_path.getText().toString().trim();
path = "http://localhost:8080/gh.zip";
//[3]获取线程的数量
String threadCountt = et_threadCount.getText().toString().trim();
//[3.0]先移除进度条 在添加
ll_pb_layout.removeAllViews();
threadCount = Integer.parseInt(threadCountt);
pbLists.clear();
for (int i = 0; i < threadCount; i++) {
//[3.1]把我定义的item布局转换成一个view对象
ProgressBar pbView = (ProgressBar) View.inflate(getApplicationContext(), R.layout.item, null);
//[3.2]把pbView 添加到集合中
pbLists.add(pbView);
//[4]动态的添加进度条
ll_pb_layout.addView(pbView);
}
//[5]开始移植 联网 获取文件长度
new Thread(){public void run() {
//[一 ☆☆☆☆]获取服务器文件的大小 要计算每个线程下载的开始位置和结束位置
try {
//(1) 创建一个url对象 参数就是网址
URL url = new URL(path);
//(2)获取HttpURLConnection 链接对象
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
//(3)设置参数 发送get请求
conn.setRequestMethod("GET"); //默认请求 就是get 要大写
//(4)设置链接网络的超时时间
conn.setConnectTimeout(5000);
//(5)获取服务器返回的状态码
int code = conn.getResponseCode(); //200 代表获取服务器资源全部成功 206请求部分资源
if (code == 200) {
//(6)获取服务器文件的大小
int length = conn.getContentLength();
//[6.1]把线程的数量赋值给正在运行的线程
runningThread = threadCount;
System.out.println("length:"+length);
//[二☆☆☆☆ ] 创建一个大小和服务器一模一样的文件 目的提前把空间申请出来
RandomAccessFile rafAccessFile = new RandomAccessFile(getFilename(path), "rw");
rafAccessFile.setLength(length);
//(7)算出每个线程下载的大小
int blockSize = length /threadCount;
//[三☆☆☆☆ 计算每个线程下载的开始位置和结束位置 ]
for (int i = 0; i < threadCount; i++) {
int startIndex = i * blockSize; //每个线程下载的开始位置
int endIndex = (i+1)*blockSize - 1;
//特殊情况 就是最后一个线程
if (i == threadCount - 1) {
//说明是最后一个线程
endIndex = length - 1;
}
System.out.println("线程id:::"+i + "理论下载的位置"+":"+startIndex+"-----"+endIndex);
//四 开启线程去服务器下载文件
DownLoadThread downLoadThread = new DownLoadThread(startIndex, endIndex, i);
downLoadThread.start();
}
}
} catch (Exception e) {
e.printStackTrace();
}
};}.start();
}
//定义线程去服务器下载文件
private class DownLoadThread extends Thread{
//通过构造方法把每个线程下载的开始位置和结束位置传递进来
private int startIndex;
private int endIndex;
private int threadId;
private int PbMaxSize; //代表当前线程下载的最大值
//如果中断过 获取上次下载的位置
private int pblastPostion;
public DownLoadThread(int startIndex,int endIndex,int threadId){
this.startIndex = startIndex;
this.endIndex = endIndex;
this.threadId = threadId;
}
@Override
public void run() {
//四 实现去服务器下载文件的逻辑
try {
//(0)计算当前进度条的最大值
PbMaxSize = endIndex - startIndex;
//(1) 创建一个url对象 参数就是网址
URL url = new URL(path);
//(2)获取HttpURLConnection 链接对象
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();
//(3)设置参数 发送get请求
conn.setRequestMethod("GET"); //默认请求 就是get 要大写
//(4)设置链接网络的超时时间
conn.setConnectTimeout(5000);
//[4.0]如果中间断过 继续上次的位置 继续下载 从文件中读取上次下载的位置
File file =new File(getFilename(path)+threadId+".txt");
if (file.exists() && file.length()>0) {
FileInputStream fis = new FileInputStream(file);
BufferedReader bufr = new BufferedReader(new InputStreamReader(fis));
String lastPositionn = bufr.readLine(); //读取出来的内容就是上一次下载的位置
int lastPosition = Integer.parseInt(lastPositionn);
//[4.0]给我们定义的进度条条位置 赋值
pblastPostion = lastPosition - startIndex;
//[4.0.1]要改变一下 startIndex 位置
startIndex = lastPosition + 1;
System.out.println("线程id::"+threadId + "真实下载的位置"+":"+startIndex+"-----"+endIndex);
fis.close(); //关闭流
}
//[4.1]设置一个请求头Range (作用告诉服务器每个线程下载的开始位置和结束位置)
conn.setRequestProperty("Range", "bytes="+startIndex+"-"+endIndex);
//(5)获取服务器返回的状态码
int code = conn.getResponseCode(); //200 代表获取服务器资源全部成功 206请求部分资源 成功
if (code == 206) {
//[6]创建随机读写文件对象
RandomAccessFile raf = new RandomAccessFile(getFilename(path), "rw");
//[6]每个线程要从自己的位置开始写
raf.seek(startIndex);
InputStream in = conn.getInputStream(); //存的是feiq.exe
//[7]把数据写到文件中
int len = -1;
byte[] buffer = new byte[1024*1024];//1Mb
int total = 0; //代表当前线程下载的大小
while((len = in.read(buffer))!=-1){
raf.write(buffer, 0, len);
total +=len;
//[8]实现断点续传 就是把当前线程下载的位置 给存起来 下次再下载的时候 就是按照上次下载的位置继续下载 就可以了
int currentThreadPosition = startIndex + total; //比如就存到一个普通的.txt文本中
//[9]用来存当前线程下载的位置
RandomAccessFile raff = new RandomAccessFile(getFilename(path)+threadId+".txt", "rwd");
raff.write(String.valueOf(currentThreadPosition).getBytes());
raff.close();
//[10]设置一下当前进度条的最大值 和 当前进度
pbLists.get(threadId).setMax(PbMaxSize);//设置进度条的最大值
pbLists.get(threadId).setProgress(pblastPostion+total);//设置当前进度条的当前进度
}
raf.close();//关闭流 释放资源
System.out.println("线程id:"+threadId + "---下载完毕了");
//[10]把.txt文件删除 每个线程具体什么时候下载完毕了 我们不知道
synchronized (DownLoadThread.class) {
runningThread--;
if (runningThread == 0) {
//说明所有的线程都执行完毕了 就把.txt文件删除
for (int i = 0; i < threadCount; i++) {
File delteFile = new File(getFilename(path)+i+".txt");
delteFile.delete();
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
//获取文件的名字
public String getFilename(String path){
int start = path.lastIndexOf("/")+1;
String substring = path.substring(start);
String fileName = Environment.getExternalStorageDirectory().getPath()+"/"+substring;
return fileName;
}
}