Android：让WebView支持<input type=”file”…>元素

在Android中，当我们通过WebView打开一个页面时，如果里面有元素是<input type=”file”…>类型的，WebView只能正常的显示样式，但是是无法点击的。要解决这个问题，我们需要重写WebChromeClient。

下面直接给出Demo代码：

Activity文件：

public class MainActivity extends Activity {

    private final String host = "demo.com";
    private final String urlAddress = "http://" + host;

    private WebView web;
    private ProgressBar progressBar;

    private ValueCallback<Uri> mUploadMessage;
    private final static int FILECHOOSER_RESULTCODE = 1;

    @Override
    protected void onActivityResult(int requestCode, int resultCode,
                                    Intent intent) {
        if (requestCode == FILECHOOSER_RESULTCODE) {
            if (null == mUploadMessage) return;
            Uri result = intent == null || resultCode != RESULT_OK ? null
                    : intent.getData();
            mUploadMessage.onReceiveValue(result);
            mUploadMessage = null;
        }
    }

    /**
     * Called when the activity is first created.
     */
    @SuppressLint("SetJavaScriptEnabled")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        web = (WebView) findViewById(R.id.webView1);
        progressBar = (ProgressBar) findViewById(R.id.progressBar1);

        WebSettings settings = web.getSettings();
        settings.setJavaScriptEnabled(true);
        web.loadUrl(urlAddress);
        web.setWebViewClient(new MyWebViewClient());

        web.setWebChromeClient(new WebChromeClient() {
            //关键代码，以下函数是没有API文档的，所以在Eclipse中会报错，如果添加了@Override关键字在这里的话。

            // For Android 3.0+
            public void openFileChooser(ValueCallback<Uri> uploadMsg) {

                mUploadMessage = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("image/*");
                MainActivity.this.startActivityForResult(Intent.createChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE);

            }

            // For Android 3.0+
            public void openFileChooser(ValueCallback uploadMsg, String acceptType) {
                mUploadMessage = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("*/*");
                MainActivity.this.startActivityForResult(
                        Intent.createChooser(i, "File Browser"),
                        FILECHOOSER_RESULTCODE);
            }

            //For Android 4.1
            public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture) {
                mUploadMessage = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("image/*");
                MainActivity.this.startActivityForResult(Intent.createChooser(i, "File Chooser"), MainActivity.FILECHOOSER_RESULTCODE);

            }
        });

//        setContentView(web);
    }

    private class MyWebViewClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (Uri.parse(url).getHost().equals(host)) {
                // This is my web site, so do not override; let my WebView load the page
                return false;
            }
            // Otherwise, the link is not for a page on my site, so launch another Activity that handles URLs
            Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
            startActivity(intent);
            return true;
        }

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            // TODO Auto-generated method stub
            super.onPageStarted(view, url, favicon);
        }

        @Override
        public void onPageFinished(WebView view, String url) {
            // TODO Auto-generated method stub
            super.onPageFinished(view, url);

            progressBar.setVisibility(View.GONE);
        }
    }

    //flipscreen not loading again
    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
    }

    // 捕捉“回退”按键，让WebView能回退到上一页，而不是直接关闭Activity。
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_BACK) && web.canGoBack()) {
            web.goBack();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
}

Layout代码就不贴出来了，就是很简单的一个WebView和一个Progress。通过以上代码，我们就能够在WebView中上传文件了。

PS: 和iOS比起来，这不是一个完美的解决方案，因为它不支持直接拍照上传文件，如果需要这个功能的话，那么还需要做进一步的开发才行。

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