Android开发工程师文集-提示框，菜单，数据存储，组件篇

Posted 2020-12-03 程序员哆啦A梦

提示框，菜单，数据存储，组件篇

Toast

Toast.makeText(context, text, 时间).show();

setDuration();//设置时间
setGravity();//位置

获取：

添加toast.getView();
imageView添加到toast中，addView();

LayoutInflater inflater = LayoutInflater.from(this);
View toast_view=inflater.inflate(R.id.,null);
Toast.
Toast.setView(toast_view);

AlertDialog

AlertDialog.Builder

setTitle();
setIcon();
setView();
setItems();

setMultiChoiceItems(); 复选
setSingleChoiceItems(); 单选
setNeutralButton();

setPositiveButton();
setNegativeButton();

AlertDialog dialog = builder.create(); .show();

消失
dialog.dismiss();

Notification通知栏，如接收短信

属性
Notification 
setTicker();//手机状态栏的提示
setWhen();//设置时间
setContentTitle();
setContentText();
setContentIntent();

Notification notification = builder.build();

OptionsMenu

onCreateOptionsMenu();
动态：menu.add();
监听：onOptionsItemSelected();

public boolean onCreateOptionsMenu(Menu menu){
    getMenuInflater().inflate(R.menu.main,menu);
    return true;
}

监听：onOptionsItemSelected

public boolean onOptionsItemSelected(MenuItem item){
    switch(item.getItemId()){
        case R.id..:
        ...
    }
}

ContextMenu上下文菜单

public boolean onCreateItemSelected(MenuItem item){

}

public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo){
    super.onCreateContextMenu(menu, v, menuIfo);
}

SubMenu 子菜单

protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

public boolean onCreateOptionsMenu(Menu menu){
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
    //return super.onOptionsItemSelected(item);
}

xml

<menu ...>
 <item
  android:showAsAction="never"
  android:title="文件">
  <menu>
   <item
    android:id="@+id/.."
    android:showAsAction="never"
    android:title="打开"/>
</menu>

MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);

数据存储方式

四种：

1. SharedPreferences
2. SQLite
3. Content Provider
4. File

SharedPreferences是一种比较轻型的数据存储，基于xml的键值对存储，存储一些简单的信息。

SharedPreferences只能获取数据不能存储和修改，但能通过Editor实现存储修改。

步骤：

1. 获取SharedPreferences对象
2. SharedPreferences.Editor
3. Editor的putXXX的方法
4. Editor.commit()

SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);

SharedPreferences sharedPreferences = getSharedPreferences("sharedPreferences", MODE_PRIVATE);
Editor editor = sharedPreferences.edit();
editor.putXXX();
editor.commit();

用户名和密码的存储

sharedPreferences = getSharedPreferences("UserInfo", MODE_PRIVATE);
Editor editor = sharedPreferences.editor();

登录
String name = etName.getText().toString().trim();
String pass = etPass.getText().toString().trim();

SQLite的形式，以单个文件的存储，存储2T内存，以B-Tree形式。

SQLite的数据类型，null,integer,real,text,blob。

1. SQLiteDatabase
2. SQLiteOpenHelper

SQLiteDatabase db = openOrCreateDatabase("table.db", MODE_PRIVATE, null);

SQLiteOpenHelper

DBOpenHelper helper = new DBOpenHelper(MainActivity.this, "user.db");
SQLiteDatabase db = helper.getWritableDatabase();
Cursor c = db.rawQuery("select * from user", null);

public DBOpenHelper(Context context, String name, CursorFactory factory, int version){
    super(context, name, factory, version);
}

public void onCreate(SQLiteDatabase db){

}

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){

}

File file = this.getFilesDir();
File file = this.getCacheDir();//重要文件就不要放在这里

MODE_PRIVATE

默认操作

MODE_APPEND

文件是否存在

public void WriteFiles(String content){
    try{
        FileOutputStream fileOutputStream = openFileOutput("super.txt", MODE_PRIVATE);
        fileOutputStream.write(content.getBytes());
        fileOutputStream.close();
    }catch(){

    }catch(){

    }
}

ContentProvider

<provider
 android:name=""
 android:authorities=""/>

public class MyContentProvider extends ContentProvider{
    public int delete(Uri uri,String selection, String[] selectionArgs){

    }
}

Uri 通用资源标志符

Broadcast广播

BroadcastReceiver 广播接收器

使用：需要Intent对象，sendBroadcast(),sendOrderBroadcast(),sendStickyBroadcast()。

Service

注册：

<service android:name=""/>

public void onClick(View v){
    switch(v.getId()){
        case R.id.:
        Intent intent = new Intent(MainActivity.this, MyService.class);
        startService(intent);
        break;
    }
}

public class MyService extends Service{
    public void onCreate(){
        super.onCreate();
    }
    public int onStartCommand(Intent intent,int flags,int startId){
        return super.onStartCommand(intent,flags,startId);
    }
    public void onDestroy(){
        super.onDestroy();
    }
    public IBinder onBind(Intent intent){
        return null;
    }
}

Bind

public void onCreate(){

}
public IBinder onBind(Intent intent){

}
public void unbindService(ServiceConnection conn){

}

ServiceConnection conn = new ServiceConnection(){
    public void onServiceDisconnected(ComponentName name){

    }
    public void onServiceConnected(ComponentName name, IBinder binder){

    }
}

系统服务

MountService,ClipboardService,getSystemService().

public Object getSystemService(String name){

}

POWER_SERVICE,PowerManger电源服务
ALARM_SERVICE,AlarmManager闹钟服务

LayoutInflater inflater = MainActivity.this.getSystemService(LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout. , null);
setContentView(view);

getSystemService

GestureDetector

MotionEvent,GestureDetector,onGestureListener.

GestureOverlayView

Android:eventsInterceptionEnabled
Android:fadeDuration
Android:fadeEnabled
Android:gestureColor

<android.gesture.GestureOverlayView 
 android:id=""
 android:layout_width=""
 android:layout_height="">
 <ImageView
  android:id=""
  android:layout_width=""
  android:layout_height=""
</android.gesture.GestureOverlayView>  

定位：分享 Android&Java 知识点
完结！