Android 開發之 Webview 上傳圖片代碼(Kotlin版)

可以直接滑動到頁面底部復制可以正常編譯運行的 Kotlin 代碼。

我們一個新的 Android 項目是用 Kotlin 來開發,因使用到了 Webview,不可避免地會遇到 Webview 中上傳圖片的問題,如果不做處理的話,在 web 中點擊是沒有任何反應的,需要寫一堆方法。

我直接拿這篇文章「Android WebView那些坑之上傳文件」的 Java 代碼,然后用 Android Studio的自動轉換,轉換為 Kotlin 代碼,但有兩處報錯。

首先把 Java 代碼貼出來:

public class MainActivity extends AppCompatActivity {

    private ValueCallback<Uri> uploadMessage;
    private ValueCallback<Uri[]> 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<Uri> 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<Uri> valueCallback, String acceptType, String capture) {
                uploadMessage = valueCallback;
                openImageChooserActivity();
            }

            // For Android >= 5.0
            @Override
            public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> 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;
    }
}

轉換后的 Kotlin 代碼:

class MainActivity : AppCompatActivity() {

    private var uploadMessage: ValueCallback<Uri>? = null
    private var uploadMessageAboveL: ValueCallback<Array<Uri>>? = 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<Uri>) {
                uploadMessage = valueCallback
                openImageChooserActivity()
            }

            // For Android  >= 3.0
            fun openFileChooser(valueCallback: ValueCallback<*>, acceptType: String) {
                uploadMessage = valueCallback
                openImageChooserActivity()
            }

            //For Android  >= 4.1
            fun openFileChooser(
                valueCallback: ValueCallback<Uri>,
                acceptType: String,
                capture: String
            ) {
                uploadMessage = valueCallback
                openImageChooserActivity()
            }

            // For Android >= 5.0
            override fun onShowFileChooser(
                webView: WebView,
                filePathCallback: ValueCallback<Array<Uri>>,
                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<Uri>? = 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
    }
}

兩處報錯如下。

第 1 處:

image.png

修改后:

// For Android  >= 3.0
fun openFileChooser(valueCallback: ValueCallback<Uri>, acceptType: String) {
     uploadMessage = valueCallback
     openImageChooserActivity()
}

第 2 處:

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<Uri>? = 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
    }

修改后就可以正常編譯運行了。

最后把完整的 Kotlin 代碼貼上來:

class MainActivity : AppCompatActivity() {

    private var uploadMessage: ValueCallback<Uri>? = null
    private var uploadMessageAboveL: ValueCallback<Array<Uri>>? = 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<Uri>) {
                uploadMessage = valueCallback
                openImageChooserActivity()
            }

            // For Android  >= 3.0
            fun openFileChooser(valueCallback: ValueCallback<Uri>, acceptType: String) {
                uploadMessage = valueCallback
                openImageChooserActivity()
            }

            //For Android  >= 4.1
            fun openFileChooser(
                valueCallback: ValueCallback<Uri>,
                acceptType: String,
                capture: String
            ) {
                uploadMessage = valueCallback
                openImageChooserActivity()
            }

            // For Android >= 5.0
            override fun onShowFileChooser(
                webView: WebView,
                filePathCallback: ValueCallback<Array<Uri>>,
                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<Uri>? = 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
    }
}
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