Android应用内在线查看PDF文件

下面介绍几种可行性较高的方案

一.PDFView

这个比较早，有几年没更新了，但可以满足一般的需求，手势放大缩小，左右滑动，体积也较小，对于Android版本可以兼容到较低版本，缺点也比较明显，不能查看带有水印和超链接的PDF

1.添加依赖 compile 'com.joanzapata.pdfview:android-pdfview:1.0.4@aar'

2.适用场景：加载本地asserts中的资源；加载内存中的文件（其实在线预览也就是先下载，然后查看）

3.show code

public class PdfReadActivity extends AppCompatActivity implements OnPageChangeListener {public static final String APP_NAME = "my/pdf";public static final String IS_LOAD_COMPLETE = "is_load_complete";public static final int LOAD_CANCEL = 0;public static final int LOAD_ERROR = 1;private MyHandler myHandler;private PDFView pdf;private TextView tvPage;private AsyncTask task;private String pdfName;@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_pdf_read);pdf = (PDFView) findViewById(R.id.pdf);tvPage = (TextView) findViewById(R.id.tv_page);//Asserts资源查看
//        pdf.fromAsset("sample.pdf")
//                .defaultPage(1)
//                .showMinimap(false)
//                .enableSwipe(true)
//                .onPageChange(this)
//                .load();
//String path = getIntent().getStringExtra("path");myHandler = new MyHandler(this);if (TextUtils.isEmpty(path)) {Toast.makeText(this, "文件不存在", Toast.LENGTH_SHORT).show();finish();}startOpenPdf(path);}private void startOpenPdf(String path) {getPdfName(path);boolean isLoadComplete = SharedPreferencesUtils.getBooleanParam(this, IS_LOAD_COMPLETE, false);String pdfPath = checkApkExist();//若存在pdf文件...不存在则直接下载if (!TextUtils.isEmpty(pdfPath)) {if (isLoadComplete) {showPdf(pdfPath);} else {File file = new File(FileUtils.getRootFilePath() + APP_NAME, pdfName);FileUtils.deleteFile(file);task = new DownPdfFileTask().execute(path);}} else {task = new DownPdfFileTask().execute(path);}}private void getPdfName(String path) {try {URL url = new URL(path);String urlPath = url.getPath();pdfName = urlPath.substring(urlPath.lastIndexOf("/") + 1);} catch (Exception e) {e.printStackTrace();}}private String checkApkExist() {String path = FileUtils.getRootFilePath() + APP_NAME;File file = new File(path, pdfName);return file.exists() ? path + "/" + pdfName : "";}private class DownPdfFileTask extends AsyncTask {private File pdfFile;String result = null;@Overrideprotected String doInBackground(String... params) {InputStream input = null;FileOutputStream fos = null;try {URL url = new URL(params[0]);String urlPath = url.getPath();pdfName = urlPath.substring(urlPath.lastIndexOf("/") + 1);url = new URL("http://resourcetest.com/" + URLEncoder.encode(pdfName));HttpURLConnection connection = (HttpURLConnection) url.openConnection();connection.setConnectTimeout(10000);connection.setRequestMethod("GET");if (HttpURLConnection.HTTP_OK != connection.getResponseCode()) {return null;}String pdkDir = FileUtils.getRootFilePath() + APP_NAME;FileUtils.createDirectory(pdkDir);pdfFile = new File(pdkDir, pdfName);input = new BufferedInputStream(connection.getInputStream());fos = new FileOutputStream(pdfFile);int count;byte buf[] = new byte[1024];while ((count = input.read(buf)) != -1) {if (isCancelled()) {break;}fos.write(buf, 0, count);}result = pdkDir + "/" + pdfName;} catch (IOException e) {e.printStackTrace();if (pdfFile != null && pdfFile.exists()) {pdfFile.delete();result = null;}myHandler.sendEmptyMessage(LOAD_ERROR);} finally {if (null != fos) {try {fos.flush();fos.close();} catch (IOException e) {e.printStackTrace();}}if (null != input) {try {input.close();} catch (IOException e) {e.printStackTrace();}}}return result;}@Overrideprotected void onPostExecute(String s) {super.onPostExecute(s);if (!TextUtils.isEmpty(s)) {Message message = new Message();Bundle bundle = new Bundle();bundle.putString("path", s);message.setData(bundle);myHandler.sendMessage(message);}}}private void showPdf(String fileName) {if (TextUtils.isEmpty(fileName)) {Toast.makeText(this, "文件不存在", Toast.LENGTH_SHORT).show();} else {try {pdf.fromFile(new File(fileName)).defaultPage(1).showMinimap(false).enableSwipe(true).onLoad(new OnLoadCompleteListener() {@Overridepublic void loadComplete(int nbPages) {float pageWidth = pdf.getOptimalPageWidth();float viewWidth = pdf.getWidth();pdf.zoomTo(viewWidth / pageWidth);pdf.loadPages();}}).onPageChange(this).load();} catch (FileNotFoundException e) {Toast.makeText(this, "文件不存在", Toast.LENGTH_SHORT).show();File file = new File(fileName);FileUtils.deleteFile(file);}}}@Overridepublic void onPageChanged(int page, int pageCount) {tvPage.setText(getString(R.string.page_count, page, pageCount));}static class MyHandler extends Handler {private WeakReference weakReference;MyHandler(PdfReadActivity activity) {weakReference = new WeakReference<>(activity);}@Overridepublic void handleMessage(Message msg) {super.handleMessage(msg);PdfReadActivity activity = weakReference.get();int what = msg.what;if (null != activity) {if (LOAD_ERROR == what) {Toast.makeText(activity, "文件读取失败，请重试", Toast.LENGTH_SHORT).show();} else if (LOAD_CANCEL == what) {SharedPreferencesUtils.saveBooleanParam(activity, IS_LOAD_COMPLETE, false);}Bundle data = msg.getData();if (null != data) {String path = (String) data.get("path");SharedPreferencesUtils.saveBooleanParam(activity, IS_LOAD_COMPLETE, true);activity.showPdf(path);}}}}@Overrideprotected void onDestroy() {if (task != null && task.getStatus() == AsyncTask.Status.RUNNING) {SharedPreferencesUtils.saveBooleanParam(this, IS_LOAD_COMPLETE, false);task.cancel(true);}super.onDestroy();}
}

//文件工具类

public class FileUtils { public static boolean hasSDCard() { return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);  }

public static String getRootFilePath() { if (hasSDCard()) { // filePath:/sdcard/  return Environment.getExternalStorageDirectory().getAbsolutePath() + "/";  } else { // filePath: /data/data/  return Environment.getDataDirectory().getAbsolutePath() + "/data/";  } }

补充：compile 'com.lidong.pdf:android_pdf:1.0.1'

这个是也算是上者的升级版，内部封装好了Retrofit 网络下载，也做了缓存，一次只能缓存一个，主要是通过文件名是否一致来判断，所以喜欢简单的，也可以试试，毕竟一行代码解决很吸引人。

二.Android自带PdfRenderer

这个是Google的，对于apk不会增加体积为0，乍看很有诱惑，但是可惜的是最低支持5.0系统，核心是转换成图片然后显示

1.适用场景：同上

2.show code

@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) public class AndroidPdfViewActivity extends AppCompatActivity implements View.OnClickListener { /**  * Key string for saving the state of current page index.  */  private static final String STATE_CURRENT_PAGE_INDEX = "current_page_index";   /**  * The filename of the PDF.  */  private static final String FILENAME = "sample.pdf";    /**  * File descriptor of the PDF.  */  private ParcelFileDescriptor mFileDescriptor;   /**  * Page that is currently shown on the screen.  */  private PdfRenderer.Page mCurrentPage;   /**  * PDF page index  */  private int mPageIndex;   /**  * {@link android.graphics.pdf.PdfRenderer} to render the PDF.  */  private PdfRenderer mPdfRenderer;  private ImageView mImageView;  private Button btnPrevious;  private Button btnNext;   @Override  protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState);  if (null != mCurrentPage) { outState.putInt(STATE_CURRENT_PAGE_INDEX, mCurrentPage.getIndex());  } } @Override  protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState);  setContentView(R.layout.activity_third_pdf_view);  mImageView = (ImageView) findViewById(R.id.iv);  btnPrevious = (Button) findViewById(R.id.btn_previous);  btnNext = (Button) findViewById(R.id.btn_next);   btnPrevious.setOnClickListener(this);  btnNext.setOnClickListener(this);  mPageIndex = 0;  // If there is a savedInstanceState (screen orientations, etc.), we restore the page index.  if (null != savedInstanceState) { mPageIndex = savedInstanceState.getInt(STATE_CURRENT_PAGE_INDEX, 0);  } } @Override  protected void onStart() { super.onStart();  try { openRenderer(this);  showPage(mPageIndex);  } catch (IOException e) { e.printStackTrace();  Toast.makeText(this, "Error! " + e.getMessage(), Toast.LENGTH_SHORT).show();  } } /**  * Sets up a {@link android.graphics.pdf.PdfRenderer} and related resources.  */  private void openRenderer(Context context) throws IOException { // In this sample, we read a PDF from the assets directory.  File file = new File(context.getCacheDir(), FILENAME);  if (!file.exists()) { // Since PdfRenderer cannot handle the compressed asset file directly, we copy it into  // the cache directory.  InputStream asset = getAssets().open(FILENAME);  FileOutputStream output = new FileOutputStream(file);  final byte[] buffer = new byte[1024];  int size;  while ((size = asset.read(buffer)) != -1) { output.write(buffer, 0, size);  } asset.close();  output.close();  } mFileDescriptor = ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);  // This is the PdfRenderer we use to render the PDF.  if (mFileDescriptor != null) { mPdfRenderer = new PdfRenderer(mFileDescriptor);  } } /**  * Shows the specified page of PDF to the screen.  *  * @param index The page index.  */  private void showPage(int index) { if (mPdfRenderer.getPageCount() <= index) { return;  } // Make sure to close the current page before opening another one.  if (null != mCurrentPage) { mCurrentPage.close();  } // Use `openPage` to open a specific page in PDF.  mCurrentPage = mPdfRenderer.openPage(index);  // Important: the destination bitmap must be ARGB (not RGB).  Bitmap bitmap = Bitmap.createBitmap(mCurrentPage.getWidth(), mCurrentPage.getHeight(),  Bitmap.Config.ARGB_8888);  // Here, we render the page onto the Bitmap.  // To render a portion of the page, use the second and third parameter. Pass nulls to get  // the default result.  // Pass either RENDER_MODE_FOR_DISPLAY or RENDER_MODE_FOR_PRINT for the last parameter.  mCurrentPage.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);  // We are ready to show the Bitmap to user.  mImageView.setImageBitmap(bitmap);  updateUi();  } /**  * Closes the {@link android.graphics.pdf.PdfRenderer} and related resources.  *  * @throws java.io.IOException When the PDF file cannot be closed.  */  private void closeRenderer() throws IOException { if (null != mCurrentPage) { mCurrentPage.close();  } mPdfRenderer.close();  mFileDescriptor.close();  } @Override  protected void onDestroy() { try { closeRenderer();  } catch (IOException e) { e.printStackTrace();  } super.onDestroy();  } @Override  protected void onPause() { try { closeRenderer();  } catch (IOException e) { e.printStackTrace();  } super.onPause();  } /**  * Updates the state of 2 control buttons in response to the current page index.  */  private void updateUi() { int index = mCurrentPage.getIndex();  int pageCount = mPdfRenderer.getPageCount();  btnPrevious.setEnabled(0 != index);  btnNext.setEnabled(index + 1 < pageCount); // setTitle(getString(R.string.app_name_with_index, index + 1, pageCount));  } /**  * Gets the number of pages in the PDF. This method is marked as public for testing.  *  * @return The number of pages.  */  public int getPageCount() { return mPdfRenderer.getPageCount();  } @Override  public void onClick(View v) { switch (v.getId()) { case R.id.btn_previous: { // Move to the previous page  showPage(mCurrentPage.getIndex() - 1);  break;  } case R.id.btn_next: { // Move to the next page  showPage(mCurrentPage.getIndex() + 1);  break;  } } } }

三.Android PdfViewer

它是基于PdfiumAndroid解码PDF文件

compile 'com.github.barteksc:android-pdf-viewer:2.8.1'

1.适用场景很广，使用简单，唯一缺陷就是会明显增大包体积，所以就不多介绍了

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