MainActivity:
package top.mengmei219.multithreaddownload;
import android.content.Context;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.AttributeSet;
import android.view.View;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import top.mengmei219.multithreaddownload.util.ShareUtil;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
String sourceURL = "http://192.168.1.104:8080/itheima74/yuer.gif"; //资源链接固定
String destPath = "/sdcard/Download/"; //下载资源存放目的地
int threadCount; //线程数
int size; //分段大小
int finishThread = 0; //完成的线程数
Context mContext;
Handler mHandler = new Handler();
EditText editText; //线程数
LinearLayout progressLayout; //进度条Layout
Map progressMap = new HashMap(); //存放progress
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mContext = this;
//线程数
editText = (EditText) findViewById(R.id.et_threadCount);
int count = ShareUtil.getThreadCount(mContext); //回显线程数
if (count != -1) {
editText.setText(count);
}
//点击下载
findViewById(R.id.btn_download).setOnClickListener(this);
//进度条Layout
progressLayout = (LinearLayout) findViewById(R.id.ll_progressLayout);
}
@Override
public void onClick(View v) {
//重新下载
finishThread = 0;
//获取用户指定的线程数
threadCount = Integer.parseInt(editText.getText().toString().trim());
//开启子线程请求服务器资源总大小
new Thread(new Runnable() {
@Override
public void run() {
try {
URL url = new URL(sourceURL); //资源链接
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setConnectTimeout(1000 * 10);
int code = urlConnection.getResponseCode();
if (code == 200) {
int contentLength = urlConnection.getContentLength(); //获取资源大小
//创建一个与资源同大的文件占为
RandomAccessFile random = new RandomAccessFile(new File(destPath + getFileName(sourceURL)), "rw");
random.setLength(contentLength);
//清空进度条父控件
mHandler.post(new Runnable() {
@Override
public void run() {
progressLayout.removeAllViews();
progressMap.clear();
}
});
//计算各线程分配
for (int threadID = 0; threadID < threadCount; threadID++) {
size = contentLength / threadCount; //分段大小
int startPosition = threadID * size; //起始位置
int endPosition = (threadID + 1) * size - 1; //结束位置
if (threadID == threadCount - 1) { //最后一个线程
endPosition = contentLength - 1;
size = contentLength / threadCount + contentLength % threadCount;
}
new MyThread(mHandler, threadID, startPosition, endPosition).start(); //开启自定义线程
//去主线程加载进度条
final int finalThreadID = threadID;
mHandler.post(new Runnable() {
@Override
public void run() {
ProgressBar progress = (ProgressBar) View.inflate(mContext, R.layout.child_progress, null);
progress.setMax(size);
progressLayout.addView(progress);
progressMap.put(finalThreadID, progress);
}
});
}
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}
public String getFileName(String filePath) {
return filePath.substring(filePath.lastIndexOf("/") + 1);
}
//自定义线程
class MyThread extends Thread {
private Handler responseHandler; //结果处理
private int threadID; //线程ID
private int startPosition; //起始位置
private int endPosition; //结束位置
public MyThread(Handler responseHandler, int threadID, int startPosition, int endPosition) {
this.responseHandler = responseHandler;
this.threadID = threadID;
this.startPosition = startPosition;
this.endPosition = endPosition;
System.out.println("threadID " + threadID + ": " + startPosition + " - " + endPosition);
}
@Override
public void run() {
int lastPosition = startPosition;
try {
URL url = new URL(sourceURL); //资源链接
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setConnectTimeout(1000 * 10);
//读取最后位置
int position = ShareUtil.getLastPosition(mContext, threadID);
if (position != -1) {
if (position > endPosition) position = endPosition;
lastPosition = position;
System.out.println("实际: threadID " + threadID + ": " + lastPosition + " - " + endPosition);
}
//分段请求头
urlConnection.setRequestProperty("Range", "bytes=" + lastPosition + "-" + endPosition);
int code = urlConnection.getResponseCode();
//分段请求成功
if (code == 206) {
InputStream inputStream = urlConnection.getInputStream();
byte[] buffer = new byte[1024 * 10];
int len = 0;
RandomAccessFile random = new RandomAccessFile(destPath + getFileName(sourceURL), "rw");
random.seek(lastPosition);
while ((len = inputStream.read(buffer)) > 0) {
random.write(buffer, 0, len);
Thread.sleep(50); //睡2毫秒，使进度条缓慢前进
//更新缓存指针
lastPosition = lastPosition + len;
ShareUtil.setLastPosition(mContext, threadID, lastPosition);
//去主线程更新进度条
final int finalLastPosition1 = lastPosition;
mHandler.post(new Runnable() {
@Override
public void run() {
progressMap.get(threadID).setProgress(finalLastPosition1 - startPosition);
}
});
}
inputStream.close();
random.close();
}
synchronized (MyThread.class) {
System.out.println(threadID + " - 下载完成!");
finishThread++;
if (finishThread == threadCount) {
System.out.println("全部下载完成，删掉临时文件!");
//界面提示
responseHandler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(mContext, "全部下载完成!", Toast.LENGTH_LONG).show();
}
});
//删除临时文件
ShareUtil.setThreadCount(mContext, -1);
for (int i = 0; i < threadCount; i++) {
ShareUtil.setLastPosition(mContext, i, -1);
}
}
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
ShareUtil:
package top.mengmei219.multithreaddownload.util;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Build;
import android.preference.PreferenceManager;
import android.support.annotation.RequiresApi;
public class ShareUtil {
public static int getLastPosition(Context context, int threadID){
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
return sharedPreferences.getInt("lastPosition_thread"+threadID, -1);
}
public static boolean setLastPosition(Context context, int threadID, int position){
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
SharedPreferences.Editor editor = sharedPreferences.edit();
return editor.putInt("lastPosition_thread"+threadID, position).commit();
}
public static int getThreadCount(Context context){
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
return sharedPreferences.getInt("multiDownLoad_threadCount", -1);
}
public static boolean setThreadCount(Context context, int threadCount){
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
SharedPreferences.Editor editor = sharedPreferences.edit();
return editor.putInt("multiDownLoad_threadCount", threadCount).commit();
}
}