安卓实训第七天---多线程下载实现（进度条）

packagecom.example.download;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

// 定义正在执行的线程
private int threadRunning = 3;
// 线程开启的数量
private int threadNum = 3;

private EditText et_url;
// 进度条
private ProgressBar progressBar;

private TextView tv_pb;

private int currentProgress = 0;

private boolean flag = true;
// 记录进度条的值
public static int pb_count = 0;
public static Handler handler;
public static final int TEXTVALUE = 1;
public static int pb_num = 0;
public static int size = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 获取控件对象
et_url = (EditText) findViewById(R.id.et_url);
progressBar = (ProgressBar) findViewById(R.id.tv_jindu);
tv_pb = (TextView) findViewById(R.id.tv_pb);
File sdDir = Environment.getExternalStorageDirectory();
File pdFile = new File(sdDir, "pb.txt");
InputStream is = null;
try {
if (pdFile.exists()) {
is = new FileInputStream(pdFile);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
if (is != null) {
String value = StreamTools.streamTostr(is);
String arr[] = value.split(";");
progressBar.setMax(Integer.valueOf(arr[0]));// 最大值
currentProgress = Integer.valueOf(arr[1]);// 当前值
progressBar.setProgress(currentProgress);
;
tv_pb.setText("当前的进度是" + arr[2] + "%");
}
}

public void downLoadFile(View v) {
// 訪问地址：
final String spec = et_url.getText().toString();// "http://172.16.237.144:8080/Login/football.jpg";
if (TextUtils.isEmpty(spec)) {
Toast.makeText(this, "下载地址不能为空", Toast.LENGTH_LONG).show();
} else {
new Thread() {
public void run() {
try {
URL url = new URL(spec);
HttpURLConnection httpURLConnection = (HttpURLConnection) url
.openConnection();
// 设置请求的头文件信息还有时间
httpURLConnection.setRequestMethod("GET");
httpURLConnection.setConnectTimeout(5000);
httpURLConnection.setReadTimeout(5000);
if (httpURLConnection.getResponseCode() == 200) {
int fileLength = httpURLConnection
.getContentLength();
// 设置进度条的最大值
progressBar.setMax(fileLength);
// 推断你的设备SDCard是否可用
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
// 外部存储设备的路径
File sdfile = Environment
.getExternalStorageDirectory();
// 获取文件的名称
String fileName = spec.substring(spec
.lastIndexOf("/") + 1);
// 创建保存的文件
File file = new File(sdfile, fileName);
// 创建随机能够訪问的文件对象
RandomAccessFile accessFile = new RandomAccessFile(
file, "rwd");
// 设置文件大小
accessFile.setLength(fileLength);
// 关闭操作
accessFile.close();
// 首先计算出每一个线程下载的大小 開始位置 结束位置
int threadSize = fileLength / threadNum;
// for循环开启线程处理
for (int threadId = 1; threadId <= 3; threadId++) {
int startIndex = (threadId - 1)
* threadSize;// 開始位置
int endIndex = threadId * threadSize - 1;
if (threadId == threadNum) {// 最后一个线程
endIndex = fileLength - 1;
}
System.out.println("当前线程--" + threadId
+ "開始位置---" + startIndex
+ "结束位置---" + endIndex + "线程大小---");
// 开启线程下载要用Start方法
new DownLoadThread(threadId, startIndex,
endIndex, spec, fileName).start();
}
} else {
MainActivity.this.runOnUiThread(new Runnable() {

@Override
public void run() {
Toast.makeText(MainActivity.this,
"设备的SD卡不可用", Toast.LENGTH_LONG)
.show();
}
});
}
} else {
// 这里用这个能够让它在主线程中执行
MainActivity.this.runOnUiThread(new Runnable() {

@Override
public void run() {
Toast.makeText(MainActivity.this,
"server端返回错误", Toast.LENGTH_LONG)
.show();
}
});
}
} catch (Exception e) {
e.printStackTrace();
}
};
}.start();
}
}

class DownLoadThread extends Thread {
private int threadId;
private int startIndex;
private int endIndex;
private String path;
private String fileName;

public DownLoadThread(int threadId, int startIndex, int endIndex,
String path, String fileName) {
super();
this.threadId = threadId;
this.startIndex = startIndex;
this.endIndex = endIndex;
this.path = path;
this.fileName = fileName;
}
@Override
public void run() {
// 能够通过每一个线程去下载文件了。
try {
File sdfile = Environment.getExternalStorageDirectory();
// 获取每一个线程下载的记录文件
File recordFile = new File(sdfile, threadId + ".txt");
// 推断记录文件是否存在
if (recordFile.exists()) {
// 读取文件的内容
InputStream is = new FileInputStream(recordFile);
// 利用工具类转换
String value = StreamTools.streamTostr(is);
// 获取记录位置
int recordIndex = Integer.parseInt(value);
// 记录的位置复制给開始的位置就可以
startIndex = recordIndex;
}
// 通过path路径构建URL对象
URL url = new URL(path);
// 通过URL对象的打开连接，返回对象
HttpURLConnection httpURLConnection = (HttpURLConnection) url
.openConnection();
// 设置请求头
httpURLConnection.setRequestMethod("GET");
httpURLConnection.setConnectTimeout(5000);
// 设置下载文件的開始位置和结束位置
httpURLConnection.setRequestProperty("Range", "bytes="
+ startIndex + "-" + endIndex);
// 获取的状态吗
int code = httpURLConnection.getResponseCode();
if (code == 206) {
// 获取每一个线程返回的流对象：
InputStream inputStream = httpURLConnection
.getInputStream();

// 获取文件名 由于已经通过那边传过来了
// String fileName =
// path.substring(path.lastIndexOf("/")+1);
// 外部存储设备的路径

File file = new File(sdfile, fileName);
// 依据文件创建她RandomAccessFile对象
RandomAccessFile raf = new RandomAccessFile(file, "rwd");
raf.seek(startIndex);
// 定义读取的长度
int len = 0;
byte buffer[] = new byte[50];
int total = 0;
// 循环读取
while ((len = inputStream.read(buffer)) != -1) {
System.out.println("当前线程--" + threadId + "--已经下载了"
+ (startIndex + total));
// 创建线程下载记录的文件
RandomAccessFile threadfile = new RandomAccessFile(
new File(sdfile, threadId + ".txt"), "rwd");
threadfile.writeBytes((startIndex + total) + "");
threadfile.close();
raf.write(buffer, 0, len);
total += len;

synchronized (MainActivity.this) {
currentProgress += len;
progressBar.setProgress(currentProgress);
// 计算百分比的操作 int
final String percent = currentProgress * 100L
/ progressBar.getMax() + "";
MainActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
tv_pb.setText("当前的进度是：" + percent + "%");
}
});
RandomAccessFile pbfile = new RandomAccessFile(
new File(sdfile, "pb.txt"), "rwd");
pbfile.writeBytes(progressBar.getMax() + ";"
+ currentProgress + ";" + percent);
pbfile.close();
}

}
raf.close();
inputStream.close();
MainActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
// System.out.println("当前线程----"+threadId+"完成下载");
Toast.makeText(MainActivity.this,
"当前线程----" + threadId + "完成下载",
Toast.LENGTH_LONG).show();
}
});
deleteRecordFiles();
} else {
MainActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(MainActivity.this, "server端下载错误",
Toast.LENGTH_LONG).show();
}
});
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

public synchronized void deleteRecordFiles() {
File sdfile = Environment.getExternalStorageDirectory();
System.out.println("-------------------------");
threadRunning--;
if (threadRunning == 0) {
for (int i = 1; i <= 3; i++) {
File recordFile = new File(sdfile, i + ".txt");
if (recordFile.exists()) {
boolean flag1 = recordFile.delete();// 删除掉文件
System.out.println("下载记录" + i + "文件已" + flag1 + "删除");
}
File pdFile = new File(sdfile, "pb.txt");
if (pdFile.exists()) {
boolean flag2 = pdFile.delete();
System.out.println("进度条记录文件已" + flag2 + "删除");
}
}
}
}

public void displayMsg() {

}
}

BUG注意事项：

1、继续线程下载的文件一定要运行threadfile.close(),不然就无法运行后面的删除TXT文件部分。

2、一定要注意下载速度的设置，不能太快。超过传输文件的大小。不然会导致模拟器死掉。;