簡介
複製即可用使用簡單
這是一個簡單使用的支持暫停和繼續多線程下載顯示進度條和百分比進度的多
首先添加依賴
compile 'com.loopj.android:android-async-http:1.4.9'
權限
記得如果是模擬器的話需要手動設置允許操作內存
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
佈局
<?xml version="1.0" encoding="utf-8"?>
<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="com.wyj.test.ddxc.LaoshiDDXCActivity">
<ProgressBar
android:id="@+id/pb"
style="@style/Widget.AppCompat.ProgressBar.Horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<Button
android:id="@+id/btn_start"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="download"
android:text="開始"/>
<Button
android:id="@+id/btn_stop"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="pause"
android:text="停止"/>
</LinearLayout>
以下時全部代碼
其中註釋還是挺全的
package com.wyj.test.ddxc;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import com.loopj.android.http.HttpGet;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.InputStream;
import java.io.RandomAccessFile;
import cz.msebera.android.httpclient.Header;
import cz.msebera.android.httpclient.HttpResponse;
import cz.msebera.android.httpclient.client.HttpClient;
import cz.msebera.android.httpclient.client.methods.HttpHead;
import cz.msebera.android.httpclient.impl.client.DefaultHttpClient;
public class LaoshiDDXCActivity extends AppCompatActivity {
protected static final String TAG = "OtherActivity";
//下載線程的數量
private final static int threadsize = 3;
protected static final int SET_MAX = 0;
public static final int UPDATE_VIEW = 1;
private ProgressBar pb;
private Button bt_download;
private Button bt_pause;
private TextView tv_info;
//顯示進度和更新進度
private Handler mHandler = new Handler(){
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case SET_MAX://設置進度條的最大值
int filelength = msg.arg1;
pb.setMax(filelength);
break;
case UPDATE_VIEW://更新進度條 和 下載的比率
int len = msg.arg1;//新下載的長度
pb.setProgress(pb.getProgress()+len);//設置進度條的刻度
// 進度百分比
int max = pb.getMax();//獲取進度的最大值
int progress = pb.getProgress();//獲取已經下載的數據量
// 下載:30 總:100
int result = (progress*100)/max;
tv_info.setText("下載:"+result+"%");
break;
default:
break;
}
};
};
String uri = "http://c.hiphotos.baidu.com/image/pic/item/b90e7bec54e736d1e51217c292504fc2d46269f3.jpg";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_laoshi_ddxc);
//找到控件
pb = (ProgressBar) findViewById(R.id.pb);
tv_info = (TextView) findViewById(R.id.tv);
bt_download = (Button) findViewById(R.id.btn_start);
bt_pause = (Button) findViewById(R.id.btn_stop);
//數據的回顯
//確定下載的文件
String name = getFileName(uri);
File file = new File(Environment.getExternalStorageDirectory(), name);
if (file.exists()){//文件存在回顯
//獲取文件的大小
int filelength = (int) file.length();
pb.setMax(filelength);
try {
//統計原來所有的下載量
int count = 0;
//讀取下載記錄文件
for (int threadid = 0; threadid < threadsize; threadid++) {
//獲取原來指定線程的下載記錄
int existDownloadLength = readDownloadInfo(threadid);
count = count + existDownloadLength;
}
//設置進度條的刻度
pb.setProgress(count);
//計算比率
int result = (count * 100) / filelength;
tv_info.setText("下載:" + result + "%");
} catch (Exception e) {
e.printStackTrace();
}
}
}
//暫停
private boolean flag = false;//是否在下載
public void pause(View v){
flag = false;
bt_download.setEnabled(true);
bt_pause.setEnabled(false);
}
//下載
public void download(View v){
flag = true; //是在下載
bt_download.setEnabled(false);//一點擊變成不可點擊
bt_pause.setEnabled(true);//一點擊變成可點擊
new Thread(){//子線程
public void run() {
try {
//獲取服務器上文件的大小
HttpClient client = new DefaultHttpClient();
HttpHead request = new HttpHead(uri);
HttpResponse response = client.execute(request);
//response 只有響應頭 沒有響應體
if(response.getStatusLine().getStatusCode() == 200){
Header[] headers = response.getHeaders("Content-Length");
String value = headers[0].getValue();
//文件大小
int filelength = Integer.parseInt(value);
Log.i(TAG, "filelength:"+filelength);
//設置進度條的最大值
Message msg_setmax = Message.obtain(mHandler, SET_MAX, filelength, 0);
msg_setmax.sendToTarget();
//處理下載記錄文件
for(int threadid=0;threadid<threadsize;threadid++){
//對應的下載記錄文件
File file = new File(Environment.getExternalStorageDirectory(),threadid+".txt");
//判斷文件是否存在
if(!file.exists()){
//創建文件
file.createNewFile();
}
}
//在sdcard創建和服務器大小一樣的文件
String name = getFileName(uri);
File file = new File(Environment.getExternalStorageDirectory(),name);
//隨機訪問文件
RandomAccessFile raf = new RandomAccessFile(file, "rwd");
//設置文件的大小
raf.setLength(filelength);
//關閉
raf.close();
//計算每條線程的下載量
int block = (filelength%threadsize == 0)?(filelength/threadsize):(filelength/threadsize+1);
//開啓三條線程執行下載
for(int threadid=0;threadid<threadsize;threadid++){
new DownloadThread(threadid, uri, file, block).start();
}
}
} catch (Exception e) {
e.printStackTrace();
}
};
}.start();
}
//線程下載類
private class DownloadThread extends Thread{
private int threadid;//線程的id
private String uri;//下載的地址
private File file;//下載文件
private int block;//下載的塊
private int start;
private int end;
public DownloadThread(int threadid, String uri, File file, int block) {
super();
this.threadid = threadid;
this.uri = uri;
this.file = file;
this.block = block;
//計算下載的開始位置和結束位置
start = threadid * block;
end = (threadid + 1)*block -1;
try {
//讀取該條線程原來的下載記錄
int existDownloadLength = readDownloadInfo(threadid);
//修改下載的開始位置 從新下載
start = start + existDownloadLength;
} catch (Exception e) {
e.printStackTrace();
}
}
//下載 狀態碼:200是普通的下載 206是分段下載 Range:範圍
@Override
public void run() {
super.run();
try {
RandomAccessFile raf = new RandomAccessFile(file, "rwd");
//跳轉到起始位置
raf.seek(start);
//分段下載
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(uri);
request.addHeader("Range", "bytes:"+start+"-"+end);//添加請求頭
HttpResponse response = client.execute(request);
if(response.getStatusLine().getStatusCode() == 200){
InputStream inputStream = response.getEntity().getContent();
//把流寫入到文件
byte[] buffer = new byte[1024];
int len = 0;
while((len = inputStream.read(buffer)) != -1){
//如果暫停下載 點擊暫停 false 就直接return 點擊下載true接着下載
if(!flag){
return;//標準線程結束
}
//寫數據
raf.write(buffer, 0, len);
//讀取原來下載的數據量 這裏讀取是爲了更新下載記錄
int existDownloadLength = readDownloadInfo(threadid);//原來下載的數據量
//計算最新的下載
int newDownloadLength = existDownloadLength + len;
//更新下載記錄 從新記錄最新下載位置
updateDownloadInfo(threadid, newDownloadLength);
//更新進度條的顯示 下載的百分比
Message update_msg = Message.obtain(mHandler, UPDATE_VIEW, len, 0);
update_msg.sendToTarget();
//模擬 看到進度條動的效果
SystemClock.sleep(50);
}
inputStream.close();
raf.close();
Log.i(TAG, "第"+threadid+"條線程下載完成");
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
/**
* 讀取指定線程的下載數據量
* @param threadid 線程的id
* @return
* @throws Exception
*/
public int readDownloadInfo(int threadid) throws Exception{
//下載記錄文件
File file = new File(Environment.getExternalStorageDirectory(),threadid+".txt");
BufferedReader br = new BufferedReader(new FileReader(file));
//讀取一行數據
String content = br.readLine();
int downlength = 0;
//如果該文件第一次創建去執行讀取操作 文件裏面的內容是 null
if(!TextUtils.isEmpty(content)){
downlength = Integer.parseInt(content);
}
//關閉流
br.close();
return downlength;
}
/**
* 更新下載記錄
* @param threadid
* @param newDownloadLength
*/
public void updateDownloadInfo(int threadid,int newDownloadLength) throws Exception{
//下載記錄文件
File file = new File(Environment.getExternalStorageDirectory(),threadid+".txt");
FileWriter fw = new FileWriter(file);
fw.write(newDownloadLength+"");
fw.close();
}
/**
* 獲取文件的名稱
* @param uri
* @return
*/
private String getFileName(String uri){
return uri.substring(uri.lastIndexOf("/")+1);
}
}