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android pdf文件预览

news 来源：原创 2024/9/19 10:00:03

首先需要项目里面有pdf文件，或者手机本地有pdf文件，如果只是测试可以直接引入pdf文件到项目的assets目录下，如果是服务器上的pdf需要先下载到手机本地然后使用文件路径

废话不多说，上方法

1.引入build.gradle中引入需要的包

implementation 'com.github.chrisbanes:PhotoView:2.0.0'

2.声明获取权限

1）AndrooidManifest.xml中声明权限

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

如果是服务器文件需要下载，还需声明网络权限

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

2）Android 6.0新特性，一些保护权限，除了要在AndroidManifest中声明权限，还需要在activity中使用代码动态获取权限

if (Build.VERSION.SDK_INT >= 23) {String[] permissions = {Manifest.permission.WRITE_EXTERNAL_STORAGE,Manifest.permission.INTERNET};//验证是否许可权限for (String str : permissions) {if (this.checkSelfPermission(str) != PackageManager.PERMISSION_GRANTED) {//申请权限this.requestPermissions(permissions, REQUEST_CODE_CONTACT);}}}

3.布局文件使用ViewPager

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"><androidx.viewpager.widget.ViewPagerandroid:id="@+id/vp_pdf"android:layout_width="match_parent"android:layout_height="match_parent"></androidx.viewpager.widget.ViewPager></LinearLayout>

4.打开pdf文件读取

 public void init() {String FILE_NAME = getIntent().getStringExtra("path");//文件路径，根据项目需求修改final File file = new File(FILE_NAME);if (!file.exists()){Toast.makeText(PdfActivity.this,"文件不存在",Toast.LENGTH_SHORT).show();}mInflater = LayoutInflater.from(this);vpPdf =findViewById(R.id.vp_pdf);try {openRender();} catch (IOException e) {e.printStackTrace();}}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)private void openRender() throws IOException {File file = new File(FILE_NAME);if (!file.exists()) {//复制文件到本地存储InputStream asset = getAssets().open(FILE_NAME);FileOutputStream fos = new FileOutputStream(file);byte[] buffer = new byte[1024];int size;while ((size = asset.read(buffer)) != -1) {fos.write(buffer, 0, size);}asset.close();fos.close();}//初始化PdfRendermDescriptor = ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);if (mDescriptor != null) {mRenderer = new PdfRenderer(mDescriptor);}//初始化ViewPager的适配器并绑定MyAdapter adapter = new MyAdapter();vpPdf.setAdapter(adapter);}class MyAdapter extends PagerAdapter {@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)@Overridepublic int getCount() {return mRenderer.getPageCount();}@Overridepublic boolean isViewFromObject(View view, Object object) {return view==object;}@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)@Overridepublic Object instantiateItem(ViewGroup container, int position) {View view = mInflater.inflate(R.layout.item_pdf, null);PhotoView pvPdf = view.findViewById(R.id.iv_pdf);pvPdf.setEnabled(true);if (getCount() <= position) {return view;}PdfRenderer.Page currentPage = mRenderer.openPage(position);Bitmap bitmap = Bitmap.createBitmap(1080, 1760, Bitmap.Config.ARGB_8888);currentPage.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);pvPdf.setImageBitmap(bitmap);//关闭当前Page对象currentPage.close();container.addView(view);return view;}@Overridepublic void destroyItem(ViewGroup container, int position, Object object) {//销毁需要销毁的视图container.removeView((View) object);}}

5.关闭pdf文件读取，一般activity销毁时需要使用

@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
private void closeRenderer() throws IOException {if (mRenderer != null){mRenderer.close();}if (mDescriptor != null){mDescriptor.close();}}

以上就是pdf文件读取的全流程