android原生实现多线程断点续传功能
本文实例为大家分享了android实现多线程断点续传功能的具体代码,供大家参考,具体内容如下
需求描述: 输入一个下载地址,和要启动的线程数量,点击下载 利用多线程将文件下载到手机端,支持 断点续传。
在前两章的java 多线程的从基础上进行
效果展示
示例代码:
布局 activity_main.xml
<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <EditText android:id="@+id/editText" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:ems="10" android:hint="下载文件地址" android:inputType="textPersonName" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <EditText android:id="@+id/editText2" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:ems="10" android:hint="开启的线程数量" android:inputType="textPersonName" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/editText" /> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:text="开始下载" app:layout_constraintStart_toStartOf="parent" android:onClick="click" app:layout_constraintTop_toBottomOf="@+id/editText2" /> <LinearLayout android:id="@+id/ll_proBox" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginBottom="8dp" android:orientation="vertical" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/button"> </LinearLayout> </android.support.constraint.ConstraintLayout>
item.xml 文件
<?xml version="1.0" encoding="utf-8"?> <ProgressBar xmlns:android="http://schemas.android.com/apk/res/android" android:layout_height="match_parent" android:layout_width="match_parent" style="@style/Widget.AppCompat.ProgressBar.Horizontal" ></ProgressBar>
MainActivity.java
package com.example.www.mutildownload; import android.Manifest; import android.os.Environment; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.LinearLayout; import android.widget.ProgressBar; 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; public class MainActivity extends AppCompatActivity { private EditText mEtUrl; private EditText mEt_thread; private Button mBtnDownload; private LinearLayout mLlProBox; private String path; private int runningThread; private int threadCount; private List<ProgressBar> mPbList; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); String[] permissions = new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}; requestPermissions(permissions, 200); mEtUrl = (EditText) findViewById(R.id.editText); mEt_thread = (EditText) findViewById(R.id.editText2); mBtnDownload = (Button) findViewById(R.id.button); mLlProBox = (LinearLayout) findViewById(R.id.ll_proBox); //添加 一个进度条的引用 mPbList = new ArrayList<>(); for (int i = 0; i < 10; i++) { String path = Environment.getExternalStorageDirectory() + "/" + i +".txt"; System.out.println(path); File file = new File(path); if(file.exists() && file.length() > 0) { file.delete(); System.out.println(file.getAbsoluteFile() + "删除成功"); } } } public void click(View v) { path = mEtUrl.getText().toString().trim(); threadCount = Integer.parseInt(mEt_thread.getText().toString().trim()); LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE); //先移除进度条 再添加 mPbList.clear(); mLlProBox.removeAllViews(); for (int i = 0; i < threadCount; i++) { ProgressBar pbView = (ProgressBar)inflater.inflate(R.layout.item, null); mPbList.add(pbView); mLlProBox.addView(pbView); } new Thread() { @Override public void run() { try { URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(5000); int responseCode = conn.getResponseCode(); if (responseCode == 200) { int contentLength = conn.getContentLength(); runningThread = threadCount; System.out.println("length" + contentLength); RandomAccessFile rafAccessFile = new RandomAccessFile(Environment.getExternalStorageDirectory() + "/" + getFileName(path), "rw"); rafAccessFile.setLength(contentLength); int blockSize = contentLength / threadCount; for (int i = 0; i < threadCount; i++) { int startIndex = i * blockSize; //每个现成下载的开始位置 int endIndex = (i + 1) * blockSize - 1;// 每个线程的结束位置 if (i == threadCount - 1) { //最后一个线程 endIndex = contentLength - 1; } new DownloadThread(startIndex, endIndex, i).start(); } } } catch (Exception e) { e.printStackTrace(); } } }.start(); } public String getFileName(String path) { int posi = path.lastIndexOf("/") + 1; return path.substring(posi); } private class DownloadThread extends Thread { private int startIndex; private int endIndex; private int threadId; private int pbMaxSize; // 当前线程下载的最大值 private int pbLastPosition; public DownloadThread(int startIndex, int endIndex, int threadId) { this.startIndex = startIndex; this.endIndex = endIndex; this.threadId = threadId; } @Override public void run() { try { pbMaxSize = endIndex - startIndex; URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(5000); File file = new File(Environment.getExternalStorageDirectory() + "/" + threadId + ".txt"); if (file.exists() && file.length() > 0) { FileInputStream fis = new FileInputStream(file); BufferedReader buff = new BufferedReader(new InputStreamReader(fis)); String lastPosition = buff.readLine();// 读取出来的内容就是上次下载的位置 int lastPos = Integer.parseInt(lastPosition); System.out.println("线程id:" + threadId + "当前线程下载的位置:-----" + lastPos); //上次进度条下载的位置 pbLastPosition = lastPos - startIndex; startIndex = lastPos; fis.close(); buff.close(); } conn.setRequestProperty("Range", "bytes=" + startIndex + "-" + endIndex); //固定写法,请求部分资源 int responseCode = conn.getResponseCode(); // 206表示请求部分资源 if (responseCode == 206) { RandomAccessFile rafAccessFile = new RandomAccessFile(Environment.getExternalStorageDirectory().getPath() + "/" +getFileName(path), "rw"); Log.v("MainActivity", Environment.getExternalStorageDirectory().getPath() + "/" +getFileName(path)); rafAccessFile.seek(startIndex); InputStream is = conn.getInputStream(); int len = -1; byte[] buffer = new byte[1024 * 1024]; int total = 0; // 代表当前线程下载的大小 while ((len = is.read(buffer)) != -1) { rafAccessFile.write(buffer, 0, len); total += len; //断点续传, 保存当前线程下载的位置 int currentThreadPosition = startIndex + total; //当前线程下载的位置 // 存储当线程的下载五位置 RandomAccessFile raff = new RandomAccessFile(Environment.getExternalStorageDirectory() + "/" + threadId + ".txt", "rwd"); raff.write(String.valueOf(currentThreadPosition).getBytes()); raff.close(); mPbList.get(threadId).setMax(pbMaxSize); mPbList.get(threadId).setProgress(pbLastPosition + total);// 设置当前进度条的当前进度 } rafAccessFile.close(); System.out.println("线程" + threadId + "下载完成"); //删除临时文件 synchronized (MainActivity.DownloadThread.class) { runningThread--; if (runningThread == 0) { for (int i = 0; i < threadCount; i++) { File deleteFile = new File(Environment.getExternalStorageDirectory() + "/" + i + ".txt"); deleteFile.delete(); } } } } } catch (Exception e) { e.printStackTrace(); } } } }
权限配置
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.www.mutildownload"> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <application 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>
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