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简要介绍

本demo按照MVVM方式实现最简单的数据展示(支持自动分页加载)和删除的demo,用于展示一个完整的MVVM架构.

1. 包含:ViewModel+LiveData+Room+Paging
2. 语言:Kotlin
4. 不包含databinding(对方比较之后,觉得databinding不够灵活而且还存在一些问题,具体百度搜索.不过demo里其实也附带了一个包含databinding的例子)

代码实现(只贴出重点代码,完整代码见源代码)

1. UserActivity

class UserActivity : AppCompatActivity() {    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_user)        val viewModel =  obtainViewModel(UserViewModel::class.java)        val adapter = UserAdapter()        adapter.setOnItemClick { user ->            viewModel.delUser(user.id)        }        userRv.adapter = adapter        viewModel.userList.observe(this, Observer { adapter.submitList(it) })    }}

2. UserAdapter

class UserAdapter : PagedListAdapter
   
    (UserDiffCallback()) {    private lateinit var onItemClick: (user: User) -> Unit    override fun onBindViewHolder(holder: ViewHolder, position: Int) {        val data = getItem(position) ?: return        holder.itemView.userTv.text = data.name        holder.itemView.setOnClickListener { onItemClick(data) }    }    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {        val view = LayoutInflater.from(parent.context).inflate(R.layout.item_user, parent, false)        return ViewHolder(view)    }    infix fun setOnItemClick(onClick: (user: User) -> Unit) {        this.onItemClick = onClick    }    class ViewHolder(itemView: View?) : RecyclerView.ViewHolder(itemView!!)}private class UserDiffCallback : DiffUtil.ItemCallback
    
     () {    override fun areContentsTheSame(oldItem: User, newItem: User): Boolean {        return oldItem.id == newItem.id    }    override fun areItemsTheSame(oldItem: User, newItem: User): Boolean {        return oldItem == newItem    }}
    
   

3. UserViewModel

class UserViewModel internal constructor(private val userRepository: UserRepository) : ViewModel() {    val userList = userRepository.getUserList()    fun delUser(id: Int) {        GlobalScope.launch {            userRepository.delUser(id)        }    }}

4. UserRepository

class UserRepository private constructor(private val userDao: UserDao) {    fun getUserList() = userDao.getUserList().toLiveData(Config(            pageSize = 30,            enablePlaceholders = true))    suspend fun addUser(name: String) {        withContext(Dispatchers.IO) {            val user = User(0, name)            userDao.add(user)        }    }    suspend fun delUser(id: Int) {        withContext(Dispatchers.IO) {            val user = User(id, "")            userDao.del(user)        }    }    companion object {        @Volatile        private var instance: UserRepository? = null        fun getInstance(userDao: UserDao) =                instance ?: synchronized(this) {                    instance                            ?: UserRepository(userDao).also { instance = it }                }    }}

5. UserDao

@Daointerface UserDao {    @Query("SELECT * FROM User")    fun getUserList(): DataSource.Factory
   
        @Insert    fun add(user: User)    @Insert    fun add(users: List
    
     )    @Delete    fun del(user:User)}
    
   

Demo源代码

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