Android 进价5_自定义广播 通过广播更新ListView的适配器 下载管理

　　1、在处理下载管理时，服务在后台运行，下载完成后要更新listview列表的按钮，将“下载”改成“打开”这样一个功能。

　　在Activity里面写一个静态内部类，继承广播。其中属性text_button的值就是按钮显示的文字。通过mAdapter.notifyDataSetChanged()更新列表数据显示。

    public static class DownloadFinishReceiver extends BroadcastReceiver{

        public static final String DOWNLOAD_RECEIVER="com.DownloadFinishReceiver";

        @Override
        public void onReceive(Context context, Intent intent) {
            try {
                if (intent.getAction().equals(DOWNLOAD_RECEIVER)) {
                    //传递的下载地址
                    String url = intent.getStringExtra("url");
                    for(Apply apply : mApplies) {
                        if (apply.getDownload_backup().equals(url)) {
                            apply.setText_button("打开");
                        }
                    }
                    mAdapter.notifyDataSetChanged();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

　　2、在后台服务service里面注册和销毁广播

    private DownloadFinishReceiver finishReceiver;
    public void onCreate() {
        System.out.println("创建服务");
        IntentFilter intentFilter = new IntentFilter(DownloadFinishReceiver.DOWNLOAD_RECEIVER);
        finishReceiver =  new DownloadFinishReceiver();
        registerReceiver(finishReceiver, intentFilter);
        super.onCreate();
    }

    public void onDestroy() {
        unregisterReceiver(finishReceiver);
        super.onDestroy();
    }

　　3、一旦下载完成，就发送广播。

Intent intent = new Intent(DownloadFinishReceiver.DOWNLOAD_RECEIVER);
intent.putExtra("url", "http://www.baidu.com/pic/qqq.png");
sendBroadcast(intent);