# android_richtext

**Repository Path**: Guguchiken/android_richtext

## Basic Information

- **Project Name**: android_richtext
- **Description**: 安卓期末作业
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 1
- **Forks**: 0
- **Created**: 2024-06-02
- **Last Updated**: 2024-11-29

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Android移动互联网开发

## 主要功能

**记笔记功能**

- 用户可以创建、编辑、删除笔记。
- 笔记可以包含富文本（可以调整文本加粗、斜体、字体大小、字体颜色...）和图片（通过摄像头拍摄或者从本地选择图片）。
- 用户可以为笔记添加标签，也可以根据标签来筛选笔记
- 用户可以置顶笔记

**待办事项功能**

- 用户可以创建、编辑、删除待办事项。

- 可以设置待办事项的提醒时间，到时通过通知提醒用户。



## 组件设计

1. **Activity**
    - 主Activity：展示主界面，管理笔记和待办事项列表两个fragment。
    - 笔记编辑Activity：展示编辑笔记的页面，用于设置笔记的标题和内容
2. **Service**
    - 用于待办定时提醒功能中，负责在特定的时间启动AlarmManager。
3. **Broadcast Receiver**
    - 用于待办定时提醒功能中，接收AlarmManager的闹钟事件，并发送通知。



## 传感器使用

1. 摄像头
    - 在笔记编辑Activity中，用户可以通过摄像头拍摄照片并添加到笔记中。



## 数据库实现

采用Room库来实现，它是Android开发中用于在SQLite数据库上进行简化操作的一种持久性库。



## 代码解释

### 富文本编辑器

采用Edit Text + Span的方式来实现，再通过HTML渲染出来。

以文本加粗为例子。

``` kotlin
btnBold.setOnClickListener {
            val start = editText.selectionStart
            val end = editText.selectionEnd

            if (start < end) {
                val spannableText = SpannableStringBuilder(editText.text)
                spannableText.setSpan(
                    StyleSpan(Typeface.BOLD),
                    start,
                    end,
                    Spannable.SPAN_EXCLUSIVE_EXCLUSIVE
                )
                editText.setText(spannableText)
                editText.setSelection(end)
            }
        }
```

```kotlin
fun toHtml(editText: EditText): String {
    val spannable = editText.text as Spannable
    val spanned: Spanned = spannable
    return Html.toHtml(spanned, Html.TO_HTML_PARAGRAPH_LINES_CONSECUTIVE)
}
```

通过使用`Spannable`类，可以方便地对文本进行各种样式的应用，如加粗、斜体、下划线等，并且可以将其转换为HTML格式。



### 数据库实现

采用room库，以待办事项数据存储（Todo）为例。

实体类

```kotlin
@Entity
data class Todo(
    var title: String?,
    var todoTime: LocalDateTime,
    var isFinished: Boolean,
) {
    @PrimaryKey(autoGenerate = true)
    var id: Long = 0
}
```

```kotlin
@Dao
interface TodoDao {

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun addTodo(todo: Todo): Long

    @Delete
    fun deleteTodo(todo: Todo)

    @Query("select * from Todo ORDER BY todoTime DESC")
    fun queryTodoAll(): MutableList<Todo>

    @Query("select * from Todo where id = :id")
    fun queryTodoById(id: Long): Todo?
}
```

```kotlin
@Database(entities = [Todo::class], version = 1, exportSchema = false)
@TypeConverters(Converters::class)
abstract class TodoDatabase : RoomDatabase() {

    companion object {
        @Volatile
        private var INSTANCE: TodoDatabase? = null

        val instance: TodoDatabase
            get() {
                return INSTANCE ?: synchronized(this) {
                    val instance = Room.databaseBuilder(
                        AppApplication.context!!,
                        TodoDatabase::class.java,
                        "todo_list_database"
                    )
                        .allowMainThreadQueries()
                        .build()
                    INSTANCE = instance
                    instance
                }
            }
    }

    abstract fun getTodoDao(): TodoDao
}

```



### 待办定时提醒功能

用户在增加/更改待办时，会启动`NotificationService`设置一个AlarmManager来在特定时间触发。`AlarmReceiver`用于接收AlarmManager的闹钟事件，并发送通知。用户在编辑待办后，会取消对应的旧Service，再启动新的Service。

```kotlin
class NotificationService : Service() {
    private var requestCode = 0
    override fun onBind(intent: Intent?): IBinder? {
        return null
    }

    @RequiresApi(Build.VERSION_CODES.O)
    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        val dateTimeString = intent?.getStringExtra("dateTime")
        val todoId = intent?.getStringExtra("todoId")

        if (dateTimeString != null) {
            val formatter = DateTimeFormatter.ISO_LOCAL_DATE_TIME
            val dateTime = LocalDateTime.parse(dateTimeString, formatter)
            
            //检查待办的提醒时间是否早于当前的时间
            if (dateTime.isBefore(LocalDateTime.now())) {
                stopSelf()
                return START_NOT_STICKY
            }

            val calendar = Calendar.getInstance().apply {
                timeInMillis = dateTime.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli()
            }

            val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
            val alarmIntent = Intent(this, AlarmReceiver::class.java).apply {
                //保证每次通知的请求码不同
                requestCode ++
                putExtra("requestCode", requestCode)
                putExtra("todoId", todoId)
            }
            val pendingIntent = PendingIntent.getBroadcast(this, requestCode, alarmIntent, PendingIntent.FLAG_UPDATE_CURRENT)

            alarmManager.setExact(AlarmManager.RTC_WAKEUP, calendar.timeInMillis, pendingIntent)
        }
        return START_STICKY
    }
}

```

```kotlin
class AlarmReceiver : BroadcastReceiver() {
    private val todoDao = TodoDatabase.instance.getTodoDao()
    @RequiresApi(Build.VERSION_CODES.O)
    override fun onReceive(context: Context, intent: Intent) {

        val notificationIntent = Intent(context, TodoActivity::class.java)
        val pendingIntent = PendingIntent.getActivity(context, 0, notificationIntent, PendingIntent.FLAG_UPDATE_CURRENT)
        
        //获取请求码，待办在数据库中的id
        val requestCode = intent.getIntExtra("requestCode", 0)
        val todoId = intent.getStringExtra("todoId")
        val todoTitle = todoId?.let { todoDao.queryTodoById(it.toLong())?.title }
        
        Log.d("AlarmReceiver code", requestCode.toString())
        
        //发送通知
        val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val channel = NotificationChannel("default", "Default Channel", NotificationManager.IMPORTANCE_DEFAULT)
            notificationManager.createNotificationChannel(channel)
        }
		
        val notification = NotificationCompat.Builder(context, "default")
            .setContentTitle("待办通知")
            .setContentText("待办" + todoTitle +"未完成")
            .setSmallIcon(R.drawable.ic_notification)
            .setContentIntent(pendingIntent)
            .setAutoCancel(true)
            .setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION))
            .build()

        notificationManager.notify(requestCode, notification)
    }
}
```



#### 笔记置顶功能

实体类有一个属性`isTop`来表示是否置顶，每次置顶或者取消置顶，就更新adapter中的数组数据，排序优先把`isTop`的元素置于前面。

````kotlin
private fun toggleTopState(id: Long) {
    val position = data.indexOfFirst { it.id == id }
    if (position != -1) {
        val item = data[position]
        item.isTop = !item.isTop

        // 更新数据库中的记录
        jobScope.launch {
            memoDao.addMemo(item)
        }

        // 重新排列列表
        val oldPosition = position
        sortData()
        val newPosition = data.indexOfFirst { it.id == id }
        notifyItemMoved(oldPosition, newPosition)
        notifyItemChanged(newPosition)
    }
}

private fun sortData() {
    data.sortWith(compareByDescending<MemoInfo> { it.isTop }.thenByDescending { it.modifiedTime })
}
````



#### 标签分类功能

标签选择窗口包含一个`RecyclerView`，创建`RecyclerView`的`Adapter`。在`Adapter`中，为`TextView`设置点击事件，并在点击事件中调用回调接口以将点击的项的标题传递给Fragment。

```kotlin
val rvClassificationList = classificationDialog.findViewById<androidx.recyclerview.widget.RecyclerView>(R.id.rv_classification_list)
rvClassificationList.layoutManager = LinearLayoutManager(activity)
classificationAdapter = ClassificationAdapter(classificationDao.queryClassificationAll()) {
    //根据tag筛选
    val filteredList : MutableList<MemoInfo> = memoDao.queryMemoAll().filter { memo -> memo.tag  == it }.toMutableList()
    //更新当前Fragment的adapter中的数据
    (binding.rvMemoList.adapter as MemoAdapter).setNewData(filteredList)
    dialog.dismiss()
}
rvClassificationList.adapter = classificationAdapter
```

```kotlin
binding.classificationTitle.setOnClickListener{
    classification.title?.let { it1 -> onItemClick.invoke(it1) }
}
```

## 第三方控件使用

侧滑菜单 https://github.com/aitsuki/SwipeMenuRecyclerView

时间选择器 https://github.com/Gredicer/datetimepicker

底部导航栏 https://github.com/akshay2211/BubbleTabBar/tree/master