android 展示PDF文件

•  注:此方式展示pdf文件会增加apk大小3-4m左右 建议使用x5的webview进行加载pdf文件(可扩展)
  

1. 加入此依赖

implementation 'com.github.barteksc:android-pdf-viewer:3.2.0-beta.1'

2. 简单介绍

此篇文章主要还是将pdf文件进行下载到本sd目录下，之后转为file文件，交给pdfview进行展示，具体的展示pdf文件可进入pdfview源码中进行查看

https://github.com/barteksc/AndroidPdfViewer

3. 开始操作

public class PDF2Activity extends AppCompatActivity {


    private PDFView pdfView;


    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_p_d_f2);

        pdfView = findViewById(R.id.pdfView);


        download("xxx.pdf");


    }


    private void download(String url) {

        DownloadUtil.download(url, getCacheDir() + "/temp.pdf", new DownloadUtil.OnDownloadListener() {

            @Override

            public void onDownloadSuccess(final String path) {

                Log.d("MainActivity", "onDownloadSuccess: " + path);

                runOnUiThread(new Runnable() {

                    @Override

                    public void run() {

                        preView(path);

                    }

                });

            }


            @Override

            public void onDownloading(int progress) {

                Log.d("MainActivity", "onDownloading: " + progress);

            }


            @Override

            public void onDownloadFailed(String msg) {

                Log.d("MainActivity", "onDownloadFailed: " + msg);

            }

        });

    }


    private void preView(String path) {

        File file = new File(path);

        //这里只是作为一个file文件进行展示 还有其他的办法进行展示

        pdfView.fromFile(file)

                .enableSwipe(true) // allows to block changing pages using swipe

                .swipeHorizontal(false)

                .enableDoubletap(true)

                .defaultPage(0)

                // allows to draw something on the current page, usually visible in the middle of the screen

                .enableAnnotationRendering(false) // render annotations (such as comments, colors or forms)

                .password(null)

                .scrollHandle(null)

                .enableAntialiasing(true) // improve rendering a little bit on low-res screens

                // spacing between pages in dp. To define spacing color, set view background

                .spacing(0)

                .load();

    }

3.1 okhttp

implementation("com.squareup.okhttp3:okhttp:4.6.0")

4.DownLoadUtils

public class DownloadUtil {


    public static void download(final String url, final String saveFile, final OnDownloadListener listener) {

        Request request = new Request.Builder().url(url).build();

        new OkHttpClient().newCall(request).enqueue(new Callback() {

            @Override

            public void onFailure(Call call, IOException e) {

                listener.onDownloadFailed(e.getMessage());

            }


            @Override

            public void onResponse(Call call, Response response) throws IOException {

                InputStream is = null;

                byte[] buf = new byte[2048];

                int len;

                FileOutputStream fos = null;

                try {

                    is = response.body().byteStream();

                    long total = response.body().contentLength();

                    File file = new File(saveFile);

                    fos = new FileOutputStream(file);

                    long sum = 0;

                    while ((len = is.read(buf)) != -1) {

                        fos.write(buf, 0, len);

                        sum += len;

                        int progress = (int) (sum * 1.0f / total * 100);

                        listener.onDownloading(progress);

                    }

                    fos.flush();

                    listener.onDownloadSuccess(file.getAbsolutePath());

                } catch (Exception e) {

                    listener.onDownloadFailed(e.getMessage());

                } finally {

                    try {

                        if (is != null)

                            is.close();

                    } catch (IOException e) {

                        e.printStackTrace();

                    }

                    try {

                        if (fos != null)

                            fos.close();

                    } catch (IOException e) {

                        e.printStackTrace();

                    }

                }

            }

        });

    }


    public interface OnDownloadListener {

        void onDownloadSuccess(String path);


        void onDownloading(int progress);


        void onDownloadFailed(String msg);

    }

}