使用DownloadManager下载文件

下载文件

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DownloadManager.Request req = new DownloadManager.Request(Uri.parse("urlString"));
// 通过setAllowedNetworkTypes方法可以设置允许在何种网络下下载，
// 也可以使用setAllowedOverRoaming方法，它更加灵活
//req.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI);
//req.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_MOBILE);
//req.setAllowedNetworkTypes(DownloadManager.Request.NET)
// 此方法表示在下载过程中通知栏会一直显示该下载，在下载完成后仍然会显示，
// 直到用户点击该通知或者消除该通知。还有其他参数可供选择
req.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
// 设置下载文件存放的路径，同样你可以选择以下方法存放在你想要的位置。
// setDestinationUri
// setDestinationInExternalPublicDir
req.setDestinationInExternalFilesDir(context, "dirPath", "fileName");
// 设置一些基本显示信息
req.setTitle(mVideoData.getName());
//req.setDescription("Title");
req.setMimeType("video/mpeg4");
mDownloadId = mDownloadManager.enqueue(req);

监听下载结果

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public class DownloadReceiver extends BroadcastReceiver {
	private static final String TAG = "DownloadReceiver";
	@Override
	public void onReceive(Context context, Intent intent) {
		DownloadManager dm = (DownloadManager)
			context.getSystemService(context.DOWNLOAD_SERVICE);
		if (intent.getAction().equals(DownloadManager.ACTION_DOWNLOAD_COMPLETE)) {
		long downId = intent.getLongExtra(
			DownloadManager.EXTRA_DOWNLOAD_ID, -1);
	Cursor c = dm.query(new DownloadManager.Query().setFilterById(downId));
			if (c.moveToFirst()) {
				int status = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
				if (status == DownloadManager.STATUS_SUCCESSFUL) {
				//downComplete(Uri.decode(c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI)))) ;
					//downComplete( c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_FILENAME))) ;
					Log.d(TAG, "onReceive: fileName = " + c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_FILENAME)));
				} else {
					int reason = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_REASON));
				}
			}
		}
	}
}

文件下载断点续传

1.获取已下载的文件长度.

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long downloadedLength = 0;  //已下载文件长度
if (file.exists()){
downloadedLength = file.length();
}

2.获取服务器文件长度

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OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
	.url(url)
	.build();
Response response = client.newCall(request).execute();
long contentLength = response.body().contentLength();

3.设置请求，跳过已下载长度

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OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
	//断点下载
	.addHeader("RANGE", "bytes=" + downloadedLength + "-")
	.url(url)
	.build();
Response response = client.newCall(request).execute();
if (response != null){
	inputStream = response.body().byteStream();
	saveFile = new RandomAccessFile(file, "rw");
	saveFile.seek(downloadedLength); //跳过已下载的字节
	byte[] b = new byte[1024];
	int total = 0;
	int len;
	while ((len = inputStream.read(b)) != -1){
		total += len;
		saveFile.write(b,0,len);
		int progress = (int)((total + downloadedLength) * 100 / contentLength);
		publishProgress(progress);
	}
	response.body().close();
	return TYPE_SUCCESS;
}

判断网络类型

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private int getNetWorkType(){
    ConnectivityManager connectivityManager = (ConnectivityManager)  getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
    if (networkInfo != null && networkInfo.isConnected()) {
        int type = networkInfo.getType();
        if (type == ConnectivityManager.TYPE_WIFI) {
            return NET_WORK_WIFI;
        } else if (type == ConnectivityManager.TYPE_MOBILE) {
            return NET_WORK_MOBILE;
        }
    }
    return -1;
}

HttpUrlConnection传递数据

关键代码

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URL url = new URL("http://119.23.30.121:80/JFitness/userController/getUserInfo");
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
//设置每次传输的流大小
httpURLConnection.setChunkedStreamingMode(128 * 1024); //128K
//允许输入输出流
httpURLConnection.setDoInput(true);
httpURLConnection.setDoOutput(true);
httpURLConnection.setUseCaches(false);
httpURLConnection.setRequestProperty("Content-Type", "application/json");
httpURLConnection.connect();
// POST请求
DataOutputStream out = new DataOutputStream(httpURLConnection.getOutputStream());
//JSONObject obj = new JSONObject();
//String json = java.net.URLEncoder.encode(obj.toString(), "utf-8");
String json = "{\n" +
        "\t\"xid\":\"9875642\"\n" +
        "}";
out.writeBytes(json);
out.flush();
out.close();
// 读取响应
BufferedReader reader = new BufferedReader(new InputStreamReader(httpURLConnection.getInputStream()));
String lines;
StringBuffer sb = new StringBuffer("");
while ((lines = reader.readLine()) != null) {
    lines = URLDecoder.decode(lines, "utf-8");
    sb.append(lines);
}
System.out.println(sb);
Log.d(TAG, "get user info = " + sb);
reader.close();
// 断开连接
httpURLConnection.disconnect();

注意设置请求头数据格式为json

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httpURLConnection.setRequestProperty("Content-Type", "application/json");

使用JsonObject创建json字符串

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private void createJson(){
    JSONObject jsonObj = new JSONObject();
    try {
        jsonObj.put("key_1",1);
        jsonObj.put("key_2","value");
        jsonObj.put("key_3",false);
        jsonObj.put("key_4",0.3f);
        jsonObj.put("key_5",3L);
        jsonObj.put("key_6",new Object());
        jsonObj.put("key_7",new ArrayList<>());
        Log.d(TAG, "createJson:  = \n" + jsonObj.toString());
    }catch (Exception e){
        e.printStackTrace();
    }
}

打印结果

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{"key_1":1,"key_2":"value","key_3":false,"key_4":0.30000001192092896,"key_5":3,"key_6":"java.lang.Object@f94f4ed","key_7":"[]"}

获取外部存储路径

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String dirType = Environment.DIRECTORY_DOWNLOADS;//或其他
String dir = Environment.getExternalStoragePublicDirectory(dirType).getPath() + "/";

根据Url获取文件名

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String url = "https://github.com/devallever/MyCoolWeather/blob/master/app/simpleWeather.apk";
String fileName = url.substring(url.lastIndexOf("/")).split("/")[1];//不带"/"

打印结果

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onCreate: fileName = simpleWeather.apk

判断第一次启动

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//第一次启动
SharedPreferences sharedPreferences = getSharedPreferences("setting",MODE_PRIVATE);
boolean first_lanch = sharedPreferences.getBoolean("first_lanch",true);
if(first_lanch){
	Toast.makeText(this,"第一次启动",Toast.LENGTH_LONG).show();
	sharedPreferences.edit().putBoolean("first_lanch", false).commit
}else {
	Toast.makeText(this,"不是第一次启动",Toast.LENGTH_LONG).show();
}

ViewPager设置手势监听和页面触摸监听

创建个手势监听器

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private int verticalMinistance = 100;            //水平最小识别距离
private int minVelocity = 10;            //最小识别速度
private GestureDetector.OnGestureListener onGestureListener = new GestureDetector.SimpleOnGestureListener() {
    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        if (e1.getX() - e2.getX() > verticalMinistance && Math.abs(velocityX) > minVelocity) {
            showToast("left");
        } else if (e2.getX() - e1.getX() > verticalMinistance && Math.abs(velocityX) > minVelocity) {
            showToast("right");
        } else if (e1.getY() - e2.getY() > verticalMinistance && Math.abs(velocityY) > minVelocity) {
            showToast("up");
        } else if (e2.getY() - e1.getY() > verticalMinistance && Math.abs(velocityY) > minVelocity) {
            showToast("down");
        }
        return false;
    }
    @Override
    public boolean onDown(MotionEvent e) {
        return  true;
    }
};

其中,onDown()必须返回true, 否则onFling()不起效
然后创建GestureDetector对象

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mGestureDetector = new GestureDetector(this,onGestureListener);

最后设置触摸监听,把事件交给手势监听器处理

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mViewPager.setOnTouchListener(new View.OnTouchListener() {
	@Override
	public boolean onTouch(View view, MotionEvent motionEvent) {
		//把触摸事件交给手势
		mGestureDetector.onTouchEvent(motionEvent);
		return false;
	}
});

LinearLayout从右到左排列

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android:gravity="right"

使用较高API的方法

例如canvas.drawRoundRect()是minSDK21以上的方法要使用的话在方法上添加标注，然后在代码中判断当前sdk版本，进行不同的处理

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@TargetApi(Build.VERSION_CODES.LOLLIPOP)
@Override
protected void onDraw(Canvas canvas) {
	super.onDraw(canvas);
	if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
		canvas.drawRoundRect();
	}else{
		canvas.drawRect();
	}
}

ListView(RecyclerView)的单选效果

在Adapter中公开一个方法,传入选中的position,然后刷新

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public void setSelected(int selectedPosition){
	mSelectedPosition = selectedPosition;
	notifyDataSetChanged();
}

listView设置选项监听,在监听回调方法中,记录选中的position,调用上面方法setSelected()

在getView方法中判断position是否为mSelectedPosition,然后进行相应操作

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if (mSelectedPosition == position){
	deviceListViewHolder.iv_select.setVisibility(View.VISIBLE);
	deviceListViewHolder.tv_device_name.setTextColor(context.getResources().getColor(R.color.code_blue));
}else {
	deviceListViewHolder.iv_select.setVisibility(View.INVISIBLE);
	deviceListViewHolder.tv_device_name.setTextColor(context.getResources().getColor(R.color.gray));
}

EditText相关

光标颜色

在使用EditText的XML 文件中加入一个属性：

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android:textCursorDrawable="@null"

android:textCursorDrawable 这个属性是用来控制光标颜色的，”@null” 是作用是让光标颜色和text color一样
比如

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android:textCursorDrawable="@color/black_color"

就可以设置成黑色。pad上面很多光标颜色和背景色一样。

TextView相关

##　更改字体

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textView.setTypeface(Typeface.createFromAsset(context.getAssets(), "font/Shket-Regular_0.016.otf"));

字体文件放在/asset/font目录下

设置行距

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android:lineSpacingExtra="4dp"

斜体加粗

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android:textStyle="bold|italic"

修改语言

全屏显示

强制横屏

在AndroidManifest.xml中设置,在Activity节点中添加

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android:screenOrientation="landscape" //锁定横屏
android:screenOrientation="portrait"	//锁定竖屏
//例如
<activity android:name=".BaseActivity"
	android:screenOrientation="landscape">
</activity>

或者在代码中添加

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setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

在setContentView()方法之前

透明状态栏