Android显示PDF文件之PDFviewer

Android显示PDF文件

最近由于项目需要，大致了解了一下关于如何在Android端显示PDF文件的内容，因此在这里进行一下小小的总结，方便今后开发。我目前了解到并成功实现的有三种开源框架分别是：Android PdfViewer、MUpdf以及iText,

• Android PdfViewer

• MUpdf

• iText

---

其中Android PdfViewer、MUpdf是显示PDF文件中所有文件，而iText则主要是方便用于解析PDF文件中的文本信息，这里主要介绍Android PdfViewer的使用方法：
Android PdfViewer的使用方法最是简单，直接添加依赖即可，而且显示效果也相当好，但功能没有MUpdf全面，且解析速度比MUpdf稍稍慢一点点，特别是在解析大文件的时候更加明显，但就普通的PDF文件显示的话还是完全能够胜任的。

GitHub地址：https://github.com/barteksc/AndroidPdfViewer

其实在这个GitHub地址里已经有详细的说明了，不必下载直接添加依赖

compile 'com.github.barteksc:android-pdf-viewer:2.7.0-beta.1'

添加完依赖后就可以直接使用了，简直不要太方便，下面是布局文件。

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="www.alphamap.cn.test02.MainActivity">

    <com.github.barteksc.pdfviewer.PDFView
        android:id="@+id/pdfView"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </com.github.barteksc.pdfviewer.PDFView>

    <Button
        android:onClick="button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="打开pdf" />
</RelativeLayout>

然后是MainActivity里的，记得要.load()：

pdfView.fromFile(new File("文件路径")).load();

或者按照GitHub里介绍的：

pdfView.fromUri(Uri)
or
pdfView.fromFile(File)
or
pdfView.fromBytes(byte[])
or
pdfView.fromStream(InputStream) // stream is written to bytearray - native code cannot use Java Streams
or
pdfView.fromSource(DocumentSource)
or
pdfView.fromAsset(String)
    .pages(0, 2, 1, 3, 3, 3) // all pages are displayed by default
    .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
    .onDraw(onDrawListener)
    // allows to draw something on all pages, separately for every page. Called only for visible pages
    .onDrawAll(onDrawListener)
    .onLoad(onLoadCompleteListener) // called after document is loaded and starts to be rendered
    .onPageChange(onPageChangeListener)
    .onPageScroll(onPageScrollListener)
    .onError(onErrorListener)
    .onRender(onRenderListener) // called after document is rendered for the first time
    .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();

记得添加权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

如果系统是Android6.0版本以上的话不要忘了获取动态权限，附带获取动态权限代码：

package www.alphamap.cn.test02;

import android.Manifest;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.os.Environment;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import com.github.barteksc.pdfviewer.PDFView;
import java.io.File;

public class MainActivity extends Activity {

    private PDFView pdfView;
    private static final int REQUEST_EXTERNAL_STORAGE = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取动态权限
        getPermission();
    }

    public void button(View view){
        pdfView = (PDFView) findViewById(R.id.pdfView);
        pdfView.fromFile(new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/AlphaMap/58号文.pdf")).load();
    }

    private static String[] PERMISSIONS_STORAGE = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };

    /**
     * 获取动态权限
     */
    public void getPermission(){
        int hasWriteContactsPermission = ContextCompat.checkSelfPermission(MainActivity.this,
                Manifest.permission.READ_EXTERNAL_STORAGE);
        if (hasWriteContactsPermission != PackageManager.PERMISSION_GRANTED) {
            if (!ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this,
                    Manifest.permission.READ_EXTERNAL_STORAGE)) {
                Log.d("yx","get permission");
                ActivityCompat.requestPermissions(MainActivity.this,
                        PERMISSIONS_STORAGE,REQUEST_EXTERNAL_STORAGE);
            }
            Log.d("yx","get permission2");
            ActivityCompat.requestPermissions(MainActivity.this,
                    PERMISSIONS_STORAGE,REQUEST_EXTERNAL_STORAGE);
        }
        Log.d("yx","wait for PERMISSION_GRANTED");
        while (( ContextCompat.checkSelfPermission(MainActivity.this,
                Manifest.permission.READ_EXTERNAL_STORAGE))!= PackageManager.PERMISSION_GRANTED) {
        }
        Log.d("yx","wait for PERMISSION_GRANTED finish");
    }

}