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;
@Override
protected 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;
@Override
protected 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;
}
@Override
protected 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() {
@Override
public 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);
}
}
}
@Override
public 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);
}
@Override
public 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);
}
}
}
}
@Override
protected 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