android第三更（下载附件，通知栏显示进度）

我们在开发中经常需要从服务器下载文件，下载的内容可能有交换的信息，缓存的图片，程序更新包等。我们使用URLConnection来实现下载。先看几行代码：

  URL url=new URL(urls);             HttpURLConnection conn=(HttpURLConnection) url.openConnection();//建立连接             conn.setConnectTimeout(5000);//设置等待时间             fileSize =conn.getContentLength();//获取文件的长度             InputStream is=conn.getInputStream();//获取输入流              FileOutputStream fos=new FileOutputStream(file);             byte[] buffer =new byte[1024];             int len=0;             while((len=is.read(buffer))!=-1){//将文件下载到指定目录中                 fos.write(buffer,0,len);                 downloadSize += len;//获取当前下载的长度                 Message msg=new Message();                 Log.i(TAG,downloadSize+"    "+fileSize);//               msg.what=1;                 msg.what= downloadSize * 100 / fileSize;                 Log.i("downloadSize",msg.what+"");                 handler.sendMessage(msg);//向handle进行传值             }             fos.flush();             fos.close();             is.close();

下载文件很简单，主要是和通知栏建立联系 这就需要用到Handle 通过Handle可以对通知栏进行刷新，并且还可以传递下载进度。
DownActivity.java 主程序
DownUtil .java 设置、刷新通知栏进度
FileDownloadThread .java 下载附件

在DownActivity中我们只需要设置下载文件的文件名、存储地址和下载地址就可以

DownActivity.java

public class DownActivity extends Activity {    Button btn;    public String downloadDir;//文件的存储路径    public String downloadUrl;//文件的下载地址    private String fileName;//下载文件名    Down down;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);         //从网上随便找的一个APK下载地址        downloadUrl = "http://activitymo.homelink.com.cn/download/homelink/android/Android_homelinkfanstong1.apk";         down = new Down(DownActivity.this);        btn = (Button) findViewById(R.id.btn);        btn.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                download();            }        });    }    /**     * 下载附件     */    public void download(){        downloadDir= Environment.getExternalStorageDirectory()+"/taotao/attach";        File file=new File(downloadDir);        //如果文件夹不存在 则重建        if(!file.exists()){            file.mkdirs();        }        //返回最后一个“/”后一个字符的位置int值        int filestart=downloadUrl.lastIndexOf("/");        //截取（）之后的字符        fileName=downloadUrl.substring(filestart+1);//        downloadProgressBar.setVisibility(View.VISIBLE);//        downloadProgressBar.setProgress(0);        down.downloadTask(downloadUrl,  downloadDir, fileName);    }}

接下来就是通知栏下载进度条、通知栏刷新这个放在一个工具类中
DownUtil .java

public class DownUtil {    private String fileName;//下载文件名    private String paths;//文件地址    private Context context;    public DownUtil(Context context){        this.context = context;    }    Handler handler=new Handler(){        public void handleMessage(android.os.Message msg) {            //当收到更新视图消息时，计算以完成下载百分比，同时个in关心进度条信息            //通知栏功能的实现            String ns = Context.NOTIFICATION_SERVICE;            //初始化通知管理            NotificationManager mNotificationManager = (NotificationManager)context.getSystemService(ns);            //创建Notification对象            Notification notification = new Notification();            int progress = msg.what;            if (progress == -1) {                notification.contentView = new RemoteViews(context.getPackageName(), R.layout.notification);                notification.contentView.setProgressBar(R.id.ProgressBar01, 100, progress, false);                notification.contentView.setTextViewText(R.id.TextView01, "下载失败");                notification.contentView.setTextViewText(R.id.TextView03, progress + "%");                notification.contentView.setTextViewText(R.id.TextView02, fileName+"下载");                notification.icon = R.mipmap.ic_launcher;                mNotificationManager.notify(1, notification);            } else {                if (progress <= 100) {                    notification.contentView = new RemoteViews(context.getPackageName(), R.layout.notification);                    notification.contentView.setProgressBar(R.id.ProgressBar01, 100, progress, false);                    notification.contentView.setTextViewText(R.id.TextView03, progress + "%");                    notification.contentView.setTextViewText(R.id.TextView02, fileName+"下载");                    notification.icon = R.mipmap.ic_launcher_icon;                    mNotificationManager.notify(1, notification);                }                if (progress == 100) {                    //定义通知栏展现的内容信息                    notification.icon = R.mipmap.ic_launcher_icon;                    notification.tickerText = fileName+"下载完成";                    notification.defaults = Notification.DEFAULT_VIBRATE;                    //定义下拉通知栏时要展现的内容信息//                    Context context = getApplicationContext();                    CharSequence contentTitle = fileName+"下载完成";                    CharSequence contentText = "淘淘:" + fileName;                    notification.flags |= Notification.FLAG_AUTO_CANCEL;                    Intent notificationIntent = AndroidFileUtil.openFile(new File(paths));                    PendingIntent contentIntent = PendingIntent.getActivity(context, 0, notificationIntent, 0);                    notification.setLatestEventInfo(context, contentTitle, contentText, contentIntent);                    //用mNotificationManager的notify方法通知用户生成标题栏消息通知                    mNotificationManager.notify(1, notification);                }            }        }    };    /**     * 线程下载开始     *     * **/        public void downloadTask(String urlStr,String dirPath,String fileName){            this.fileName = fileName;            Message msg = new Message();            msg.what = 0;            handler.sendMessage(msg);                paths=dirPath+fileName;                File file=new File(dirPath + fileName);            //如果文件已存在 则先删除 后下载            if(file.exists()){                file.delete();            }            //启动线程，文件                    FileDownloadThread fdt=new FileDownloadThread(urlStr,file,handler);                    fdt.setName("thread");                    fdt.start();        }    }

最后就是下载文件的工具类
FileDownloadThread .java
/**
* 下载文件
* @author Administrator
*
*/
public class FileDownloadThread extends Thread {

private static final int BUFFER_SIZE = 1024;private static final String TAG = "FileDownloadThread";private String urls;private File file;private int curPosition;private int fileSize; //用于标识当前线程是否下载完成  private boolean finished=false;  private int downloadSize=0;private Handler handler;/** *  * @param url 下载地址 * @param file  */public FileDownloadThread(String urls,File file,Handler handler){    this.urls=urls;    this.file=file;      this.handler = handler;}@Overridepublic void run() {    // TODO Auto-generated method stub     try {         URL url=new URL(urls);         HttpURLConnection conn=(HttpURLConnection) url.openConnection();         conn.setConnectTimeout(5000);         fileSize =conn.getContentLength();         InputStream is=conn.getInputStream();//获取输入流         Log.i("file",file+"");         FileOutputStream fos=new FileOutputStream(file);         byte[] buffer =new byte[1024];         int len=0;         while((len=is.read(buffer))!=-1){             fos.write(buffer,0,len);             downloadSize += len;             Message msg=new Message();             Log.i(TAG,downloadSize+"    "+fileSize);

// msg.what=1;
msg.what= downloadSize * 100 / fileSize;
Log.i(“downloadSize”,msg.what+”“);
handler.sendMessage(msg);
}
fos.flush();
fos.close();
is.close();
} catch (FileNotFoundException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}

    }  

}
xml文件我就写通知栏的布局
notification.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:orientation="horizontal" >    <RelativeLayout        android:id="@+id/relayout"        android:layout_width="wrap_content"        android:layout_height="wrap_content" >        <ImageView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_centerInParent="true"            android:paddingTop="10dp"            android:paddingBottom="10dp"            android:paddingRight="10dp"            android:src="@mipmap/ic_launcher" />    </RelativeLayout>    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_alignBottom="@+id/relayout"        android:layout_alignTop="@+id/relayout"        android:layout_marginRight="10dp"        android:paddingBottom="10dp"        android:paddingTop="10dp"        android:layout_toRightOf="@+id/relayout"        android:orientation="vertical" >        <TextView            android:id="@+id/TextView01"            android:layout_width="fill_parent"            android:layout_height="wrap_content"            android:text="正在下载 ..."            android:textSize="18sp" >        </TextView>        <RelativeLayout            android:layout_width="fill_parent"            android:layout_height="wrap_content" >            <TextView                android:id="@+id/TextView02"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="文件名。。。。" >            </TextView>            <TextView                android:id="@+id/TextView03"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:layout_alignParentRight="true"                android:text="0%" >            </TextView>        </RelativeLayout>        <ProgressBar            android:id="@+id/ProgressBar01"            style="?android:attr/progressBarStyleHorizontal"            android:layout_width="fill_parent"            android:layout_height="wrap_content" >        </ProgressBar>    </LinearLayout></RelativeLayout>