可以直接滑动到页面底部复制可以正常编译运行的 Kotlin 代码。
我们一个新的 Android 项目是用 Kotlin 来开发，因使用到了 Webview，不可避免地会遇到 Webview 中上传图片的问题，如果不做处理的话，在 web 中点击是没有任何反应的，需要写一堆方法。
我直接拿这篇文章「Android WebView那些坑之上传文件」的 Java 代码，然后用 Android Studio的自动转换，转换为 Kotlin 代码，但有两处报错。
首先把 Java 代码贴出来：
public class MainActivity extends AppCompatActivity {
private ValueCallback uploadMessage;
private ValueCallback uploadMessageAboveL;
private final static int FILE_CHOOSER_RESULT_CODE = 10000;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
WebView webview = (WebView) findViewById(R.id.web_view);
assert webview != null;
WebSettings settings = webview.getSettings();
settings.setUseWideViewPort(true);
settings.setLoadWithOverviewMode(true);
settings.setJavaScriptEnabled(true);
webview.setWebChromeClient(new WebChromeClient() {
// For Android < 3.0
public void openFileChooser(ValueCallback valueCallback) {
uploadMessage = valueCallback;
openImageChooserActivity();
}
// For Android >= 3.0
public void openFileChooser(ValueCallback valueCallback, String acceptType) {
uploadMessage = valueCallback;
openImageChooserActivity();
}
//For Android >= 4.1
public void openFileChooser(ValueCallback valueCallback, String acceptType, String capture) {
uploadMessage = valueCallback;
openImageChooserActivity();
}
// For Android >= 5.0
@Override
public boolean onShowFileChooser(WebView webView, ValueCallback filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) {
uploadMessageAboveL = filePathCallback;
openImageChooserActivity();
return true;
}
});
String targetUrl = "file:///android_asset/up.html";
webview.loadUrl(targetUrl);
}
private void openImageChooserActivity() {
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILE_CHOOSER_RESULT_CODE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == FILE_CHOOSER_RESULT_CODE) {
if (null == uploadMessage && null == uploadMessageAboveL) return;
Uri result = data == null || resultCode != RESULT_OK ? null : data.getData();
if (uploadMessageAboveL != null) {
onActivityResultAboveL(requestCode, resultCode, data);
} else if (uploadMessage != null) {
uploadMessage.onReceiveValue(result);
uploadMessage = null;
}
}
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private void onActivityResultAboveL(int requestCode, int resultCode, Intent intent) {
if (requestCode != FILE_CHOOSER_RESULT_CODE || uploadMessageAboveL == null)
return;
Uri[] results = null;
if (resultCode == Activity.RESULT_OK) {
if (intent != null) {
String dataString = intent.getDataString();
ClipData clipData = intent.getClipData();
if (clipData != null) {
results = new Uri[clipData.getItemCount()];
for (int i = 0; i < clipData.getItemCount(); i++) {
ClipData.Item item = clipData.getItemAt(i);
results[i] = item.getUri();
}
}
if (dataString != null)
results = new Uri[]{Uri.parse(dataString)};
}
}
uploadMessageAboveL.onReceiveValue(results);
uploadMessageAboveL = null;
}
}
转换后的 Kotlin 代码：
class MainActivity : AppCompatActivity() {
private var uploadMessage: ValueCallback? = null
private var uploadMessageAboveL: ValueCallback>? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val webview = findViewById(R.id.web_view) as WebView
val settings = webview.settings
settings.useWideViewPort = true
settings.loadWithOverviewMode = true
settings.javaScriptEnabled = true
webview.webChromeClient = object : WebChromeClient() {
// For Android < 3.0
fun openFileChooser(valueCallback: ValueCallback) {
uploadMessage = valueCallback
openImageChooserActivity()
}
// For Android >= 3.0
fun openFileChooser(valueCallback: ValueCallback<*>, acceptType: String) {
uploadMessage = valueCallback
openImageChooserActivity()
}
//For Android >= 4.1
fun openFileChooser(
valueCallback: ValueCallback,
acceptType: String,
capture: String
) {
uploadMessage = valueCallback
openImageChooserActivity()
}
// For Android >= 5.0
override fun onShowFileChooser(
webView: WebView,
filePathCallback: ValueCallback>,
fileChooserParams: WebChromeClient.FileChooserParams
): Boolean {
uploadMessageAboveL = filePathCallback
openImageChooserActivity()
return true
}
}
val targetUrl = "file:///android_asset/up.html"
webview.loadUrl(targetUrl)
}
private fun openImageChooserActivity() {
val i = Intent(Intent.ACTION_GET_CONTENT)
i.addCategory(Intent.CATEGORY_OPENABLE)
i.type = "image/*"
startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILE_CHOOSER_RESULT_CODE)
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
if (requestCode == FILE_CHOOSER_RESULT_CODE) {
if (null == uploadMessage && null == uploadMessageAboveL) return
val result = if (data == null || resultCode != Activity.RESULT_OK) null else data.data
if (uploadMessageAboveL != null) {
onActivityResultAboveL(requestCode, resultCode, data)
} else if (uploadMessage != null) {
uploadMessage!!.onReceiveValue(result)
uploadMessage = null
}
}
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private fun onActivityResultAboveL(requestCode: Int, resultCode: Int, intent: Intent?) {
if (requestCode != FILE_CHOOSER_RESULT_CODE || uploadMessageAboveL == null)
return
var results: Array? = null
if (resultCode == Activity.RESULT_OK) {
if (intent != null) {
val dataString = intent.dataString
val clipData = intent.clipData
if (clipData != null) {
results = arrayOfNulls(clipData.itemCount)
for (i in 0 until clipData.itemCount) {
val item = clipData.getItemAt(i)
results[i] = item.uri
}
}
if (dataString != null)
results = arrayOf(Uri.parse(dataString))
}
}
uploadMessageAboveL!!.onReceiveValue(results)
uploadMessageAboveL = null
}
companion object {
private val FILE_CHOOSER_RESULT_CODE = 10000
}
}
两处报错如下。
第 1 处：
image.png
修改后：
// For Android >= 3.0
fun openFileChooser(valueCallback: ValueCallback, acceptType: String) {
uploadMessage = valueCallback
openImageChooserActivity()
}
第 2 处：
image.png
修改后：
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private fun onActivityResultAboveL(requestCode: Int, resultCode: Int, intent: Intent?) {
if (requestCode != FILE_CHOOSER_RESULT_CODE || uploadMessageAboveL == null)
return
var results: Array? = null
if (resultCode == Activity.RESULT_OK) {
if (intent != null) {
val dataString = intent.dataString
val clipData = intent.clipData
if (clipData != null) {
results = Array(clipData.itemCount){
i -> clipData.getItemAt(i).uri
}
}
if (dataString != null)
results = arrayOf(Uri.parse(dataString))
}
}
uploadMessageAboveL!!.onReceiveValue(results)
uploadMessageAboveL = null
}
修改后就可以正常编译运行了。
最后把完整的 Kotlin 代码贴上来：
class MainActivity : AppCompatActivity() {
private var uploadMessage: ValueCallback? = null
private var uploadMessageAboveL: ValueCallback>? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val webview = findViewById(R.id.web_view) as WebView
val settings = webview.settings
settings.useWideViewPort = true
settings.loadWithOverviewMode = true
settings.javaScriptEnabled = true
webview.webChromeClient = object : WebChromeClient() {
// For Android < 3.0
fun openFileChooser(valueCallback: ValueCallback) {
uploadMessage = valueCallback
openImageChooserActivity()
}
// For Android >= 3.0
fun openFileChooser(valueCallback: ValueCallback, acceptType: String) {
uploadMessage = valueCallback
openImageChooserActivity()
}
//For Android >= 4.1
fun openFileChooser(
valueCallback: ValueCallback,
acceptType: String,
capture: String
) {
uploadMessage = valueCallback
openImageChooserActivity()
}
// For Android >= 5.0
override fun onShowFileChooser(
webView: WebView,
filePathCallback: ValueCallback>,
fileChooserParams: WebChromeClient.FileChooserParams
): Boolean {
uploadMessageAboveL = filePathCallback
openImageChooserActivity()
return true
}
}
val targetUrl = "file:///android_asset/up.html"
webview.loadUrl(targetUrl)
}
private fun openImageChooserActivity() {
val i = Intent(Intent.ACTION_GET_CONTENT)
i.addCategory(Intent.CATEGORY_OPENABLE)
i.type = "image/*"
startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILE_CHOOSER_RESULT_CODE)
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
if (requestCode == FILE_CHOOSER_RESULT_CODE) {
if (null == uploadMessage && null == uploadMessageAboveL) return
val result = if (data == null || resultCode != Activity.RESULT_OK) null else data.data
if (uploadMessageAboveL != null) {
onActivityResultAboveL(requestCode, resultCode, data)
} else if (uploadMessage != null) {
uploadMessage!!.onReceiveValue(result)
uploadMessage = null
}
}
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private fun onActivityResultAboveL(requestCode: Int, resultCode: Int, intent: Intent?) {
if (requestCode != FILE_CHOOSER_RESULT_CODE || uploadMessageAboveL == null)
return
var results: Array? = null
if (resultCode == Activity.RESULT_OK) {
if (intent != null) {
val dataString = intent.dataString
val clipData = intent.clipData
if (clipData != null) {
results = Array(clipData.itemCount){
i -> clipData.getItemAt(i).uri
}
}
if (dataString != null)
results = arrayOf(Uri.parse(dataString))
}
}
uploadMessageAboveL!!.onReceiveValue(results)
uploadMessageAboveL = null
}
companion object {
private val FILE_CHOOSER_RESULT_CODE = 10000
}
}