java - Pdf 文件无法在 Android 中打开

Question

我想在点击“pdfButton”时打开一个 pdf 文件(可在 Android 手机的“下载”文件夹中找到)执行操作时，没有任何反应，没有记录错误或显示 pdf 文件。有人可以帮忙吗？

package com.mycompany.myfirstglapp;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.SurfaceView;
import android.webkit.WebView;
import android.widget.Toast;
import java.io.File;

/**
 * Created by admin on 1/11/2016.
 */

public class PdfActivity extends Activity {
    private SurfaceView surface;
    Button pdfButton;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_pdf);
        surface = (SurfaceView) findViewById(R.id.pdfSurface);
        pdfButton = (Button) findViewById(R.id.pdfView);

        pdfButton .setOnClickListener(new View.OnClickListener() {
                public void onClick(View view) {
                    // On click will call the showPdf method to display the pdf file in sd card or downloads 

                    showPdf(view);
                }
            });



    }


   public void showPdf(View view)  {

        // The pdf file [LawsofthegamewebEN_Neutral.pdf] is avaialble in Android > Downloads folder.

        File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+ "/LawsofthegamewebEN_Neutral.pdf");

        if (file.exists()) {
            Uri path = Uri.fromFile(file);
            Intent intent = new Intent(Intent.ACTION_VIEW);
            intent.setDataAndType(path, "application/pdf");
            intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

            try {
                startActivity(intent);
            }
            catch (ActivityNotFoundException e) {
                Toast.makeText(PdfActivity.this,
                        "No Application Available to View PDF",
                        Toast.LENGTH_SHORT).show();
            }
        }

    }



}

Answer 1

如果您使用调试器单步执行代码，或者放入更多日志记录语句，我怀疑您会发现 file.exists() 返回 false。而且，目前，在这种情况下您无需执行任何操作。

I would like to open a pdf file ( which is available in Downloads folder in Android phone)

那不是您的代码所寻找的地方。替换:

File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+ "/LawsofthegamewebEN_Neutral.pdf");

与:

File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "LawsofthegamewebEN_Neutral.pdf");

另请注意，您的 file.exists() 调用意味着您需要持有 READ_EXTERNAL_STORAGE 权限。