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在本节中我们将实现后端 API 的接入及其数据展示的逻辑。
data class Movie(val id: String, val title: String, val overview: String, val posterPath: String) { override fun toString(): String { return "Movie(id='$id', title='$title', overview='$overview', posterPath='$posterPath')" }} 我们调用的 API 是
val VOTE_AVERAGE_API = "http://api.themoviedb.org//3/discover/movie?certification_country=US&certification=R&sort_by=vote_average.desc&api_key=7e55a88ece9f03408b895a96c1487979"
它的数据返回是
{ "page": 1, "total_results": 10350, "total_pages": 518, "results": [ { "vote_count": 28, "id": 138878, "video": false, "vote_average": 10, "title": "Fatal Mission", "popularity": 3.721883, "poster_path": "/u351Rsqu5nd36ZpbWxIpd3CpbJW.jpg", "original_language": "en", "original_title": "Fatal Mission", "genre_ids": [ 10752, 28, 12 ], "backdrop_path": "/wNq5uqVDT7a5G1b97ffYf4hxzYz.jpg", "adult": false, "overview": "A CIA Agent must rely on reluctant help from a female spy in the North Vietnam jungle in order to pass through enemy lines.", "release_date": "1990-07-25" }, ... ]} 我们使用 fastjson 来解析这个数据。在 app 下面的 build.gradle 中添加依赖
dependencies { ... // https://mvnrepository.com/artifact/com.alibaba/fastjson compile group: 'com.alibaba', name: 'fastjson', version: '1.2.39'} 解析代码如下
val jsonstr = URL(VOTE_AVERAGE_API).readText(Charset.defaultCharset())try { val obj = JSON.parse(jsonstr) as Map<*, *> val dataArray = obj.get("results") as JSONArray }} catch (ex: Exception) {} 然后我们把这个 dataArray 放到我们的 MovieContent 对象中
dataArray.forEachIndexed { index, it -> val title = (it as Map<*, *>).get("title") as String val overview = it.get("overview") as String val poster_path = it.get("poster_path") as String addMovie(Movie(index.toString(), title, overview, getPosterUrl(poster_path)))} 其中，addMovie 的代码是
object MovieContent {val MOVIES: MutableList = ArrayList()val MOVIE_MAP: MutableMap = HashMap()...private fun addMovie(movie: Movie) { MOVIES.add(movie) MOVIE_MAP.put(movie.id, movie)}} MovieListActivity 是电影列表页面的 Activity，代码如下
package com.easy.kotlinimport android.content.Intentimport android.os.Bundleimport android.support.v7.app.AppCompatActivityimport android.support.v7.widget.RecyclerViewimport android.view.LayoutInflaterimport android.view.Viewimport android.view.ViewGroupimport android.widget.ImageViewimport android.widget.TextViewimport com.easy.kotlin.bean.MovieContentimport com.easy.kotlin.util.HttpUtilimport kotlinx.android.synthetic.layout.activity_movie_detail.*import kotlinx.android.synthetic.layout.activity_movie_list.*import kotlinx.android.synthetic.layout.movie_list.*import kotlinx.android.synthetic.layout.movie_list_content.view.*class MovieListActivity : AppCompatActivity() { private var mTwoPane: Boolean = false override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_movie_list) setSupportActionBar(toolbar) toolbar.title = title if (movie_detail_container != null) { mTwoPane = true } setupRecyclerView(movie_list) } private fun setupRecyclerView(recyclerView: RecyclerView) { recyclerView.adapter = SimpleItemRecyclerViewAdapter(this, MovieContent.MOVIES, mTwoPane) } class SimpleItemRecyclerViewAdapter(private val mParentActivity: MovieListActivity, private val mValues: List , private val mTwoPane: Boolean) : RecyclerView.Adapter () { private val mOnClickListener: View.OnClickListener init { mOnClickListener = View.OnClickListener { v -> val item = v.tag as MovieContent.Movie if (mTwoPane) { val fragment = MovieDetailFragment().apply { arguments = Bundle() arguments.putString(MovieDetailFragment.ARG_MOVIE_ID, item.id) } mParentActivity.supportFragmentManager .beginTransaction() .replace(R.id.movie_detail_container, fragment) .commit() } else { val intent = Intent(v.context, MovieDetailActivity::class.java).apply { putExtra(MovieDetailFragment.ARG_MOVIE_ID, item.id) } v.context.startActivity(intent) } } } override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder { val view = LayoutInflater .from(parent.context) .inflate(R.layout.movie_list_content, parent, false) return ViewHolder(view) } override fun onBindViewHolder(holder: ViewHolder, position: Int) { val item = mValues[position] holder.mIdView.text = item.id holder.mTitle.text = item.title holder.mMoviePosterImageView.setImageBitmap(HttpUtil.getBitmapFromURL(item.posterPath)) with(holder.itemView) { tag = item setOnClickListener(mOnClickListener) } } override fun getItemCount(): Int { return mValues.size } inner class ViewHolder(mView: View) : RecyclerView.ViewHolder(mView) { val mIdView: TextView = mView.id_text val mTitle: TextView = mView.title val mMoviePosterImageView: ImageView = mView.movie_poster_image } }} 对应的布局文件如下
activity_movie_list.xml
movie_list.xml
movie_list_content.xml
我们在创建 MovieListActivity 过程中需要展示响应的数据，这些数据由 ViewAdapter 来承载，对应的代码如下
override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_movie_list) setSupportActionBar(toolbar) toolbar.title = title if (movie_detail_container != null) { mTwoPane = true } setupRecyclerView(movie_list) } private fun setupRecyclerView(recyclerView: RecyclerView) { recyclerView.adapter = SimpleItemRecyclerViewAdapter(this, MovieContent.MOVIES, mTwoPane) } 其中，在函数 SimpleItemRecyclerViewAdapter.onBindViewHolder 中，我们设置 View 组件与Model 数据的绑定。其中的电影海报是图片，所以我们的布局文件中使用了 ImageView，对应的布局文件是 movie_list_content.xml ，代码如下
我们这里是根据图片的 URL 来展示图片，ImageView 类有个setImageBitmap 方法，可以直接设置 Bitmap 图片数据
holder.mMoviePosterImageView.setImageBitmap(HttpUtil.getBitmapFromURL(item.posterPath))
而通过 url 获取Bitmap 图片数据的代码是
object HttpUtil { fun getBitmapFromURL(src: String): Bitmap? { try { val url = URL(src) val input = url.openStream() val myBitmap = BitmapFactory.decodeStream(input) return myBitmap } catch (e: Exception) { e.printStackTrace() return null } }} MovieDetailActivity 是电影详情页面，代码如下
package com.easy.kotlinimport android.content.Intentimport android.os.Bundleimport android.support.design.widget.Snackbarimport android.support.v7.app.AppCompatActivityimport android.view.MenuItemimport kotlinx.android.synthetic.layout.activity_movie_detail.*class MovieDetailActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_movie_detail) setSupportActionBar(detail_toolbar) fab.setOnClickListener { view -> Snackbar.make(view, "Replace with your own detail action", Snackbar.LENGTH_LONG) .setAction("Action", null).show() } supportActionBar?.setDisplayHomeAsUpEnabled(true) if (savedInstanceState == null) { val arguments = Bundle() arguments.putString(MovieDetailFragment.ARG_MOVIE_ID, intent.getStringExtra(MovieDetailFragment.ARG_MOVIE_ID)) val fragment = MovieDetailFragment() fragment.arguments = arguments supportFragmentManager.beginTransaction() .add(R.id.movie_detail_container, fragment) .commit() } } override fun onOptionsItemSelected(item: MenuItem) = when (item.itemId) { android.R.id.home -> { navigateUpTo(Intent(this, MovieListActivity::class.java)) true } else -> super.onOptionsItemSelected(item) }} 其中的详情页的布局 XML 文件是activity_item_detail.xml， 代码如下
我们把电影详情的 Fragment 的展示放到 NestedScrollView 中
电影详情的 Fragment 代码是 MovieDetailFragment
package com.easy.kotlinimport android.os.Bundleimport android.support.v4.app.Fragmentimport android.view.LayoutInflaterimport android.view.Viewimport android.view.ViewGroupimport com.easy.kotlin.bean.MovieContentimport com.easy.kotlin.util.HttpUtilimport kotlinx.android.synthetic.layout.activity_movie_detail.*import kotlinx.android.synthetic.layout.movie_detail.view.*class MovieDetailFragment : Fragment() { private var mItem: MovieContent.Movie? = null override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) if (arguments.containsKey(ARG_MOVIE_ID)) { mItem = MovieContent.MOVIE_MAP[arguments.getString(ARG_MOVIE_ID)] mItem?.let { activity.toolbar_layout?.title = it.title } } } override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? { // 绑定 movieDetailView val movieDetailView = inflater.inflate(R.layout.movie_detail, container, false) mItem?.let { movieDetailView.movie_poster_image.setImageBitmap(HttpUtil.getBitmapFromURL(it.posterPath)) movieDetailView.movie_overview.text = "影片简介： ${it.overview}" movieDetailView.movie_vote_count.text = "打分次数：${it.vote_count}" movieDetailView.movie_vote_average.text = "评分：${it.vote_average}" movieDetailView.movie_release_date.text = "发行日期：${it.release_date}" } return movieDetailView } companion object { const val ARG_MOVIE_ID = "movie_id" }} 其中的 R.layout.movie_detail 布局文件 movie_detail.xml 如下
我们定义了一个 MovieContent 对象类来存储从 API 获取到的数据，代码如下
package com.easy.kotlin.beanimport android.os.StrictModeimport com.alibaba.fastjson.JSONimport com.alibaba.fastjson.JSONArrayimport java.net.URLimport java.nio.charset.Charsetimport java.util.*object MovieContent { val MOVIES: MutableList = ArrayList() val MOVIE_MAP: MutableMap = HashMap() val VOTE_AVERAGE_API = "http://api.themoviedb.org//3/discover/movie?sort_by=popularity.desc&api_key=7e55a88ece9f03408b895a96c1487979&page=1" init { val policy = StrictMode.ThreadPolicy.Builder().permitAll().build() StrictMode.setThreadPolicy(policy) initMovieListData() } private fun initMovieListData() { val jsonstr = URL(VOTE_AVERAGE_API).readText(Charset.defaultCharset()) try { val obj = JSON.parse(jsonstr) as Map<*, *> val dataArray = obj.get("results") as JSONArray dataArray.forEachIndexed { index, it -> val title = (it as Map<*, *>).get("title") as String val overview = it.get("overview") as String val poster_path = it.get("poster_path") as String val vote_count = it.get("vote_count").toString() val vote_average = it.get("vote_average").toString() val release_date = it.get("release_date").toString() addMovie(Movie(id = index.toString(), title = title, overview = overview, vote_count = vote_count, vote_average = vote_average, release_date = release_date, posterPath = getPosterUrl(poster_path))) } } catch (ex: Exception) { ex.printStackTrace() } } private fun addMovie(movie: Movie) { MOVIES.add(movie) MOVIE_MAP.put(movie.id, movie) } fun getPosterUrl(posterPath: String): String { return "https://image.tmdb.org/t/p/w185_and_h278_bestv2$posterPath" } data class Movie(val id: String, val title: String, val overview: String, val vote_count: String, val vote_average: String, val release_date: String, val posterPath: String)} 最后，我们配置 AndroidManifest.xml文件内容如下
...
因为我们要访问网络，所以需要添加该行配置
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