Android 开发之 Webview 上传图片代码（Kotlin版）

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<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;
    }
}

转换后的 Kotlin 代码：

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
    }
}

两处报错如下。

第 1 处：

修改后：

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

第 2 处：

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
    }

修改后就可以正常编译运行了。

最后把完整的 Kotlin 代码贴上来：

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
    }
}