app实现预览功能

所花时间：2小时

代码量：如下：

博客量：本学期截至目前42篇

了解到的知识点：app预浏览

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<?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:background="@color/white"     android:padding="@dimen/box_inset_layout_padding"     tools:context=".activity.PdfActivity">     <com.github.barteksc.pdfviewer.PDFView         android:id="@+id/pdfView"         android:layout_width="match_parent"         android:layout_height="match_parent"/>       </androidx.constraintlayout.widget.ConstraintLayout>

　　

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package com.example.nucleicacid32.activity;       import android.graphics.Canvas; import android.os.Bundle; import android.os.StrictMode;    import com.example.nucleicacid32.base.BaseActivity; import com.example.nucleicacid32.databinding.ActivityPdfBinding; import com.github.barteksc.pdfviewer.listener.OnDrawListener; import com.github.barteksc.pdfviewer.listener.OnLoadCompleteListener; import com.github.barteksc.pdfviewer.listener.OnPageChangeListener; import com.github.barteksc.pdfviewer.listener.OnPageErrorListener; import com.github.barteksc.pdfviewer.scroll.DefaultScrollHandle;    public class PdfActivity extends BaseActivity<ActivityPdfBinding> implements OnPageChangeListener, OnLoadCompleteListener, OnDrawListener, OnPageErrorListener {         public static final String FILE_NAME = "ali.pdf";            @Override         public void onCreate(Bundle savedInstanceState) {             super.onCreate(savedInstanceState);             init();            }            private void init() {             if (android.os.Build.VERSION.SDK_INT > 9) {                 StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();                 StrictMode.setThreadPolicy(policy);             }             viewBinding.pdfView.fromAsset(FILE_NAME)                     .defaultPage(0)                     .onPageChange(this)                     .enableSwipe(false)                     .enableAnnotationRendering(true)                     .onLoad(this)                     .scrollHandle(new DefaultScrollHandle(this))                     .spacing(10) // in dp                     .onPageError(this)                     .load();         }               @Override         public void onPageChanged(int page, int pageCount) {            }            @Override         public void loadComplete(int nbPages) {            }            @Override         public void onLayerDrawn(Canvas canvas, float pageWidth, float pageHeight, int displayedPage) {            }            @Override         public void onPageError(int page, Throwable t) {            }           }