时间戳

时间戳的编写包括记事本编辑区域的时间展示和记事本列表的时间展示

编辑框的时间戳

获取系统时间并转换格式

        Date date = new Date();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Log.v("时间：",sdf.format(date));tv_now.setText(sdf.format(date));

把时间保存到数据库，每次修改都更新一次时间

private void saveNote(){NoteDataBaseHelper dbHelper = MainActivity.getDbHelper();ContentValues values = new ContentValues();values.put(Note.title,et_title.getText().toString());values.put(Note.content,et_content.getText().toString());values.put(Note.time,tv_now.getText().toString());if (insertFlag){Note.insertNote(dbHelper,values);}else{Note.updateNote(dbHelper,Integer.parseInt(currentNote.getId()),values);}}

关于时间的布局

<TextViewandroid:id="@+id/tv_now"android:layout_width="match_parent"android:layout_height="30dp"android:background="#A5BECE"android:textAlignment="textEnd"android:gravity="end|center_vertical"android:paddingRight="8dp"/>

初始化视图

private void initView(){btn_save = findViewById(R.id.btn_save);btn_return = findViewById(R.id.btn_return);tv_now = findViewById(R.id.tv_now);et_content = findViewById(R.id.edit_content);et_title = findViewById(R.id.edit_title);//以下为测试代码Date date = new Date();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Log.v("时间：",sdf.format(date));tv_now.setText(sdf.format(date));}

记事本列表的时间戳

从数据库获取每个笔记的时间

//从数据库中读取所有笔记 封装成List<NoteInfo>private void getNoteList(){noteList.clear();Cursor allNotes = Note.getAllNotes(dbHelper);for (allNotes.moveToFirst(); !allNotes.isAfterLast(); allNotes.moveToNext()){NoteInfo noteInfo = new NoteInfo();noteInfo.setId(allNotes.getString(allNotes.getColumnIndex(Note._id)));noteInfo.setTitle(allNotes.getString(allNotes.getColumnIndex(Note.title)));noteInfo.setContent(allNotes.getString(allNotes.getColumnIndex(Note.content)));noteInfo.setDate(allNotes.getString(allNotes.getColumnIndex(Note.time)));noteList.add(noteInfo);}}

初始化试图

public ViewHolder(View itemView) {if (itemView == null){throw new IllegalArgumentException("item View can not be null!");}this.itemView = itemView;itemIcon = itemView.findViewById(R.id.rand_icon);itemNoteTitle = itemView.findViewById(R.id.item_note_title);itemNoteDate = itemView.findViewById(R.id.item_note_date);}

时间布局

<TextViewandroid:id="@+id/item_note_date"android:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="1"android:textSize="16sp"android:gravity="center_vertical"android:singleLine="true"/>

查询功能

通过EditText内容的动态变化来实现查询

通过标题来模糊查询数据库的数据

private void getSelectNoteList(String title){noteList.clear();Cursor allNotes = Note.selectNotes(dbHelper,title);for (allNotes.moveToFirst(); !allNotes.isAfterLast(); allNotes.moveToNext()){NoteInfo noteInfo = new NoteInfo();noteInfo.setId(allNotes.getString(allNotes.getColumnIndex(Note._id)));noteInfo.setTitle(allNotes.getString(allNotes.getColumnIndex(Note.title)));noteInfo.setContent(allNotes.getString(allNotes.getColumnIndex(Note.content)));noteInfo.setDate(allNotes.getString(allNotes.getColumnIndex(Note.time)));noteList.add(noteInfo);}}

当EditText内容发生变化时会调用此方法，根据内容变化动态来查询数据库的数据，然后把数据装配到适配器中，从而把列表显示出来

et_title.addTextChangedListener(new TextWatcher() {@Overridepublic void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {}//当EditText内容发生变化时会调用此方法@Overridepublic void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {if (charSequence.toString().equals("")){search_del.setVisibility(View.GONE);}else{search_del.setVisibility(View.VISIBLE);}String titleChange=et_title.getText().toString();Log.v("改变数据：",titleChange);getSelectNoteList(titleChange);mListAdapter.notifyDataSetChanged();}@Overridepublic void afterTextChanged(Editable editable) {}});

通过按钮来实现查询

这个方法没有第一种方法人性化，用户体验较差

给查询按钮添加一个监听器

private void setListener(){addBtn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {Intent intent = new Intent(MainActivity.this,EditActivity.class);startActivity(intent);}});selectBtn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {String edit_title=et_title.getText().toString();HashMap<Integer,HashMap<String,Object>> map1=new HashMap<Integer,HashMap<String,Object>>();;map1=Note.getNote(dbHelper,edit_title);Log.v("查询",map1.toString());Intent intent = new Intent(MainActivity.this,SelectActivity.class);intent.putExtra("edit_title",edit_title );startActivity(intent);//getSelectNoteList(edit_title);}});

清空文本框

把EditTtext的内容置为空

search_del.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {getNoteList();;//初始化数据et_title.setText("");mListAdapter.notifyDataSetChanged();//更新RecycleView}});

插入本地图片和拍照插入图片

插入图片有多种方式，这里简单介绍两种，分别是从本地获取图片以及拍照直接插入图片。

首先要申请权限

在AndroidManifest.xml中设置权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

如果是Android7.0以上的版本需要在onCreate()这个方法中加入以下代码，不然启动拍照功能的时候会出现路径不对的问题：

// android 7.0系统解决拍照的问题
StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
StrictMode.setVmPolicy(builder.build());
builder.detectFileUriExposure();

插入本地图片

通过设置intent的类型来启动图片相关的intent

//从相册取图片public void getPhoto() {Intent intent = new Intent();intent.setType("image/*");intent.setAction(Intent.ACTION_OPEN_DOCUMENT);startActivityForResult(intent, PHOTO_FROM_GALLERY);}

通过使用正则表达式来提取图片路径

private static final String regex="content://com.android.providers.media.documents/"+"document/image%\\w{4}";
private static final String reg="file:///storage/emulated/0/\\d+.jpg";

拍照插入图片

获取权限并且启动拍照相关的intent

//拍照取照片public void takeCamera() {if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {ActivityCompat.requestPermissions( this, new String[] { Manifest.permission.CAMERA }, PHOTO_FROM_CAMERA);}else {File file=new File(Environment.getExternalStorageDirectory(),System.currentTimeMillis()+".jpg");try {if(file.exists()){file.delete();}file.createNewFile();}catch (IOException e){e.printStackTrace();}imageUri=Uri.fromFile(file);Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);startActivityForResult(intent, PHOTO_FROM_CAMERA);}}

图片处理

把图片转换形式并加入文本框，执行保存时把图片存进数据库

@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {ContentResolver resolver = getContentResolver();super.onActivityResult(requestCode, resultCode, data);//第一层switchswitch (requestCode) {case PHOTO_FROM_GALLERY://第二层switchswitch (resultCode) {case RESULT_OK:if (data != null) {Uri uri = data.getData();//获取Intent uriBitmap bitmap = null;//判断该路径是否存在try {Bitmap originalBitmap = BitmapFactory.decodeStream(resolver.openInputStream(uri));bitmap = resizeImage(originalBitmap, 200, 200);//图片缩放} catch (FileNotFoundException e) {e.printStackTrace();}if(bitmap != null){//如果图片存在//将选择的图片追加到EditText中光标所在位置int index = mText.getSelectionStart(); //获取光标所在位置Editable edit_text = mText.getEditableText();//编辑文本框if(index <0 || index >= edit_text.length()){edit_text.append(uri.toString());updateNoteText(mText.getText().toString());//更新到数据库}else{edit_text.insert(index,uri.toString());updateNoteText(mText.getText().toString());//更新到数据库}}else{Toast.makeText(NoteEditor.this, "获取图片失败", Toast.LENGTH_SHORT).show();}}break;case RESULT_CANCELED:break;}break;case PHOTO_FROM_CAMERA:if (resultCode == RESULT_OK) {Bitmap originalBitmap1=null;//判断图片是否存在try{originalBitmap1=BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));}catch (FileNotFoundException e){e.printStackTrace();}if(originalBitmap1 != null){//如果图片存在保存URI//将选择的图片追加到EditText中光标所在位置int index = mText.getSelectionStart(); //获取光标所在位置Editable edit_text = mText.getEditableText();//编辑文本框if(index <0 || index >= edit_text.length()){edit_text.append(imageUri.toString());updateNoteText(mText.getText().toString());//更新到数据库}else{edit_text.insert(index, imageUri.toString());updateNoteText(mText.getText().toString());//更新到数据库}}else{Toast.makeText(NoteEditor.this, "获取图片失败", Toast.LENGTH_SHORT).show();}} else {Log.e("result", "is not ok" + resultCode);}break;default:break;}}

图片缩放

/*** 图片缩放* @param originalBitmap 原始的Bitmap* @param newWidth 自定义宽度* @return 缩放后的Bitmap*/private Bitmap resizeImage(Bitmap originalBitmap, int newWidth, int newHeight){int width = originalBitmap.getWidth();int height = originalBitmap.getHeight();//定义欲转换成的宽、高
//            int newWidth = 200;
//            int newHeight = 200;//计算宽、高缩放率float scanleWidth = (float)newWidth/width;float scanleHeight = (float)newHeight/height;//创建操作图片用的matrix对象 MatrixMatrix matrix = new Matrix();// 缩放图片动作matrix.postScale(scanleWidth,scanleHeight);//旋转图片 动作//matrix.postRotate(45);// 创建新的图片BitmapBitmap resizedBitmap = Bitmap.createBitmap(originalBitmap,0,0,width,height,matrix,true);return resizedBitmap;}

运行效果截图

作者：肖斌宇
原文链接