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1. 引言

最近工作有解析外部xml文件在App中显示的需求，特来写篇文章记录一下，方便下次使用。

2. 准备工作

首先，在项目的AndroidManifest.xml文件中添加读取外部存储的权限声明。

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

3. XML示例文件

<?xml version="1.0" encoding="UTF-8"?>
<items><item><number>1</number><description>First item description</description></item><item><number>2</number><description>Second item description</description></item>
</items>

4. 请求运行时权限

在你的Activity中，需要处理运行时权限请求。

private val requestPermissionLauncher =registerForActivityResult(ActivityResultContracts.RequestPermission()) { isGranted: Boolean ->if (isGranted) {readAndParseXmlFile()} else {Toast.makeText(this, "读取外部存储权限被拒绝", Toast.LENGTH_SHORT).show()}}override fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)when {ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) ==PackageManager.PERMISSION_GRANTED -> {readAndParseXmlFile()}else -> {requestPermissionLauncher.launch(Manifest.permission.READ_EXTERNAL_STORAGE)}}
}

5. 定义数据模型和适配器

定义一个数据类Item和一个RecyclerView的适配器ItemAdapter。

Item.kt

data class Item(val number: Int, val description: String)

ItemAdapter.kt

class ItemAdapter(private val items: MutableList<Item>) :RecyclerView.Adapter<ItemAdapter.ItemViewHolder>() {class ItemViewHolder(val textView: TextView) : RecyclerView.ViewHolder(textView)override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ItemViewHolder {val textView = LayoutInflater.from(parent.context).inflate(android.R.layout.simple_list_item_2, parent, false) as TextViewreturn ItemViewHolder(textView)}override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {val (number, description) = items[position]holder.textView.text = "$number - $description"}override fun getItemCount() = items.sizefun addItem(item: Item) {items.add(item)notifyItemInserted(items.size - 1)}
}

6. 解析XML文件

义一个方法来解析XML文件，并在解析出新数据时即时更新RecyclerView。

private fun parseXmlAndUpdateRecyclerView(inputStream: InputStream) {try {val factory = XmlPullParserFactory.newInstance()factory.isNamespaceAware = trueval parser = factory.newPullParser()parser.setInput(inputStream, null)var eventType = parser.eventTypevar currentNumber: Int? = nullvar currentDescription: String? = nullwhile (eventType != XmlPullParser.END_DOCUMENT) {when (eventType) {XmlPullParser.START_TAG -> {when (parser.name) {"number" -> currentNumber = parser.nextText().toIntOrNull()"description" -> currentDescription = parser.nextText()}}XmlPullParser.END_TAG -> {if (parser.name == "item" && currentNumber != null && currentDescription != null) {val newItem = Item(currentNumber, currentDescription)runOnUiThread {adapter.addItem(newItem)}currentNumber = nullcurrentDescription = null}}}eventType = parser.next()}} catch (e: Exception) {Log.e("XMLParser", "Error parsing XML", e)Toast.makeText(this, "解析XML文件失败: ${e.message}", Toast.LENGTH_SHORT).show()} finally {try {inputStream.close()} catch (e: Exception) {e.printStackTrace()}}
}

7. 使用

在你的代码中直接调用readAndParseXmlFile方法，我是把xml文件直接放到了 sdcard目录下了，你也可以随意修改目录，注意不同安卓版本的权限问题，

    private fun readAndParseXmlFile() {try {// 修改为从SD卡根目录获取XML文件val xmlFile = File(Environment.getExternalStorageDirectory(), "data.xml")if (!xmlFile.exists()) {Log.e("XMLParser", "File does not exist.")Toast.makeText(this, "XML文件不存在", Toast.LENGTH_SHORT).show()return}FileInputStream(xmlFile).use { fis ->parseXmlAndUpdateRecyclerView(fis)}} catch (e: Exception) {Log.e("XMLParser", "Error reading XML file", e)Toast.makeText(this, "读取XML文件失败: ${e.message}", Toast.LENGTH_SHORT).show()}}

8.效果图

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THE END