从我的安卓应用程序启动 pdf 查看器应用程序

Question

我正在尝试通过安卓中已安装的pdf查看器打开pdf文件。

参考链接"android：使用内置的pdf查看器从我的应用程序中打开pdf"

这是示例代码：

private void openPDF(String filePath)
{
    Intent target = new Intent(Intent.ACTION_VIEW);
    target.setDataAndType(Uri.parse(filePath),"application/pdf");
    target.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
    Intent intent = Intent.createChooser(target, "Open File");
    if(intent!=null)
    {
        try {
            startActivity(intent); // Here it giving null pointer exception 
        }
        catch (ActivityNotFoundException e) {
        // Instruct the user to install a PDF reader here, or something
        }
    }
    else
        Log.d("DEBUG","Intent is null");
} 

但是我在启动活动（意图）行上收到空指针异常。

请帮我找到问题。

堆栈跟踪 ：

01-28 16:24:48.865: W/System.err(4399): java.lang.NullPointerException
01-28 16:24:48.875: W/System.err(4399):     at android.app.Activity.startActivityForResult(Activity.java:3370)
01-28 16:24:48.875: W/System.err(4399):     at android.app.Activity.startActivityForResult(Activity.java:3331)
01-28 16:24:48.875: W/System.err(4399):     at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:819)
01-28 16:24:48.875: W/System.err(4399):     at android.app.Activity.startActivity(Activity.java:3566)
01-28 16:24:48.875: W/System.err(4399):     at android.app.Activity.startActivity(Activity.java:3534)
01-28 16:24:48.875: W/System.err(4399):     at a.MainActivity.openPDF(MainActivity.java:591)
01-28 16:24:48.875: W/System.err(4399):     at a.MainActivity.access$0(MainActivity.java:581)
01-28 16:24:48.885: W/System.err(4399):     at a.MainActivity$TestSectionFragment$1.onItemClick(MainActivity.java:480)

Answer 1

你试试吗？

 Intent intent = new Intent();                      
 intent.setClassName("com.adobe.reader", "com.adobe.reader.AdobeReader");
 intent.setAction(android.content.Intent.ACTION_VIEW);
 intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
 Uri uri = Uri.fromFile(file);
 intent.setDataAndType(uri, "application/pdf");
try {                               
    startActivity(intent);
    } catch (Exception e) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("No Application Found");
builder.setMessage("Download Application from Android Market?");
builder.setPositiveButton("Yes, Please",new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog,int which) {
        Intent marketIntent = new Intent(Intent.ACTION_VIEW);
        marketIntent.setData(Uri.parse("market://details?id=com.adobe.reader"));
        startActivity(marketIntent);
        }
    });
    builder.setNegativeButton("No, Thanks",null);
    builder.create().show();
    }

Answer 2

希望对您有所帮助，

Intent intent = new Intent(Intent.ACTION_VIEW,
        Uri.parse("path-to-document"));
intent.setType("application/pdf");
PackageManager pm = getPackageManager();
List<ResolveInfo> activities = pm.queryIntentActivities(intent, 0);
if (activities.size() > 0) {
    startActivity(intent);
} else {
    // Do something else here. Maybe pop up a Dialog or Toast
}

请尝试此link: http://stackoverflow.com/questions/10299839/how-to-read-pdf-in-my-android-application

Answer 3

替换以下行：

 startActivity(intent);

跟：

if (intent.resolveActivity(context.getPackageManager()) != null) {
    startActivity(intent);
}