使用DownloadManager下载文件
下载文件
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
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.
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
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
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
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
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
httpURLConnection.setRequestProperty("Content-Type", "application/json");
使用JsonObject创建json字符串
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
{"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
String dirType = Environment.DIRECTORY_DOWNLOADS;//或其他
String dir = Environment.getExternalStoragePublicDirectory(dirType).getPath() + "/";
根据Url获取文件名
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
onCreate: fileName = simpleWeather.apk
判断第一次启动
//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
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
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
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
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
@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
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
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：
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
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
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
android:lineSpacingExtra="4dp"
斜体加粗
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
android:screenOrientation="landscape" //锁定横屏
android:screenOrientation="portrait" //锁定竖屏
//例如
或者在代码中添加
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
在setContentView()方法之前