TypeError：无法读取undefined的属性'fileOpener'

Question

我正在为android做phonegap项目，我正在使用插件fileOpener打开本地pdf文件，并收到错误。

我的FileOpener.java代码如下：

package com.phonegap.plugins.fileopener;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import org.json.JSONArray;
import org.json.JSONException;

import android.content.Context;
import android.content.Intent;
import android.net.Uri;

import org.apache.cordova.api.Plugin;
import org.apache.cordova.api.PluginResult;

public class FileOpener extends Plugin {

@Override
public PluginResult execute(String action, JSONArray args, String callbackId) {
    PluginResult.Status status = PluginResult.Status.OK;
    String result = "";

    try {
        if (action.equals("openFile")) {
            openFile(args.getString(0));
        }
        else {
            status = PluginResult.Status.INVALID_ACTION;
        }
        return new PluginResult(status, result);
    } catch (JSONException e) {
        return new PluginResult(PluginResult.Status.JSON_EXCEPTION);
    } catch (IOException e) {
        return new PluginResult(PluginResult.Status.IO_EXCEPTION);
    }
}

private void openFile(String url) throws IOException {
    // Create URI
    Uri uri = Uri.parse(url);

    Intent intent = null;
    // Check what kind of file you are trying to open, by comparing the url with extensions.
    // When the if condition is matched, plugin sets the correct intent (mime) type, 
    // so Android knew what application to use to open the file

    if (url.contains(".doc") || url.contains(".docx")) {
        // Word document
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "application/msword");
    } else if(url.contains(".pdf")) {
        // PDF file
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "application/pdf");
    } else if(url.contains(".ppt") || url.contains(".pptx")) {
        // Powerpoint file
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "application/vnd.ms-powerpoint");
    } else if(url.contains(".xls") || url.contains(".xlsx")) {
        // Excel file
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "application/vnd.ms-excel");
    } else if(url.contains(".rtf")) {
        // RTF file
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "application/rtf");
    } else if(url.contains(".wav")) {
        // WAV audio file
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "audio/x-wav");
    } else if(url.contains(".gif")) {
        // GIF file
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "image/gif");
    } else if(url.contains(".jpg") || url.contains(".jpeg")) {
        // JPG file
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "image/jpeg");
    } else if(url.contains(".txt")) {
        // Text file
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "text/plain");
    } else if(url.contains(".mpg") || url.contains(".mpeg") || url.contains(".mpe") || url.contains(".mp4") || url.contains(".avi")) {
        // Video files
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "video/*");
    }         

    //if you want you can also define the intent type for any other file

    //additionally use else clause below, to manage other unknown extensions
    //in this case, Android will show all applications installed on the device
    //so you can choose which application to use

    else {
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "*/*");
    }

    this.cordova.getActivity().startActivity(intent);
}

}

我在config.xml中添加了条目：

<plugin name="FileOpener" value="com.phonegap.plugins.fileopener.FileOpener"/>

在我的JavaScript中，我调用了函数：

window.plugins.fileOpener.open(file); 

哪里出错？