Android的WebView调用本地相册

首先要知道android本身的WebView是并不支持调用手机文件并上传的，其次WebView的内核在android每次更新的时候都是不太一样的，也是够坑爹的；不过需求又不能改，H5需要调用系统相册，还好最后还是找到方法解决了，就是要重写里面的一个方法，不过这种情况也是在5.0之前有效，5.0之后就需要重写另外的一个方法，先将这些方法一个个的列出
注意在这里我们需要重写的方法是在这个WebChromeClient类里面的；

private ValueCallback<Uri> mUploadMessage;
private ValueCallback<Uri[]> mUploadCallbackAboveL;
private final static int FILECHOOSER_RESULTCODE = 101;

当我们是5.0以下的话，用的是以下三个方法：

public void openFileChooser(ValueCallback<Uri> uploadMsg) {
    Log.d(TAG, "openFileChoose(ValueCallback<Uri> uploadMsg)");
    mUploadMessage = uploadMsg;
    Intent i = new Intent(Intent.ACTION_GET_CONTENT);
    i.addCategory(Intent.CATEGORY_OPENABLE);
    i.setType("image/*");
    Html5Activity.this.startActivityForResult(Intent.createChooser(i, "File Chooser"),
            FILECHOOSER_RESULTCODE);
}

public void openFileChooser(ValueCallback uploadMsg, String acceptType) {
    Log.d(TAG, "openFileChoose( ValueCallback uploadMsg, String acceptType )");
    mUploadMessage = uploadMsg;
    Intent i = new Intent(Intent.ACTION_GET_CONTENT);
    i.addCategory(Intent.CATEGORY_OPENABLE);
    i.setType("image/*");
    Html5Activity.this.startActivityForResult(
            Intent.createChooser(i, "File Browser"),
            FILECHOOSER_RESULTCODE);
}

public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture) {
    Log.d(TAG, "openFileChoose(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/*");
    Html5Activity.this.startActivityForResult(Intent.createChooser(i, "File Browser"),
            FILECHOOSER_RESULTCODE);
}

值得注意的是这三种方法都是一样的，只是在不同版本下会分别调用，还有就是这个方法是重写这个WebChromeClient类里面的，别以为是我们随便写的，只是google不希望我们重写这个方法罢了，不过5.0之后就又不一样了，需要重写的是下面的这个方法：

@Override
public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, FileChooserParams fileChooserParams) {
    mUploadCallbackAboveL = filePathCallback;
    Intent i = new Intent(Intent.ACTION_GET_CONTENT);
    i.addCategory(Intent.CATEGORY_OPENABLE);
    i.setType("image/*");
    Html5Activity.this.startActivityForResult(
            Intent.createChooser(i, "File Browser"),
            FILECHOOSER_RESULTCODE);
    return true;
}

好了，到了这一步我们的调用已经ok了，但还有一个需要的过程；跟我们普通的回调接收是一模一样的：

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

当然还有一个是让我们在5.0的情况下用的：

private void onActivityResultAboveL(int requestCode, int resultCode, Intent data) {
    if (requestCode != FILECHOOSER_RESULTCODE
            || mUploadCallbackAboveL == null) {
        return;
    }
    Uri[] results = null;
    if (resultCode == Activity.RESULT_OK) {
        if (data == null) {
        } else {
            String dataString = data.getDataString();
            ClipData clipData = data.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();
                    Log.e(TAG, "onActivityResultAboveL: " + results[i].getPath());
                }
            }
            if (dataString != null)
                results = new Uri[]{Uri.parse(dataString)};
            Log.e(TAG, "onActivityResultAboveL: " + results.length);
        }
    }
    mUploadCallbackAboveL.onReceiveValue(results);
    mUploadCallbackAboveL = null;
    return;
}

到这一步H5基本就可以正常的调用手机的相册了。