同樣使用網上流行的類庫
1、新增依賴（在你的module中不是project中），新增後別忘記同步

//pdf
compile 'com.github.barteksc:android-pdf-viewer:2.6.1'

2、使用在xml檔案中新增該佈局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    tools:context="com.mazhan.android_fundfriend.activitys.LoadPDFActivity">

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

3、實現

package com.mazhan.android_fundfriend.activitys;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;

import com.github.barteksc.pdfviewer.PDFView;


import
 
 com.github.barteksc.pdfviewer.listener.OnPageChangeListener;
import com.mazhan.android_fundfriend.R;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * 顯示PDF的頁面
 */
public class LoadPDFActivity extends AppCompatActivity {

    private static final String TAG = "LoadPDFActivity--TAG:";
    private PDFView pdfView;
    private String path;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_load_pdf);

        pdfView = findViewById(R.id.pdfView);
        path = getIntent().getStringExtra("url");
        if (!TextUtils.isEmpty(path)) {
            new LoadPdfThread().start();
        }
    }

    class LoadPdfThread extends Thread {

        @Override
        public void run() {
            super.run();
            try {
                URL url = new URL(path);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                if (connection.getResponseCode() == 200) {
                    final InputStream inputStream = connection.getInputStream();
                    //主執行緒更新介面
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            if (inputStream != null) {
                                pdfView.fromStream(inputStream).defaultPage(0)//預設頁面
                                        .enableDoubletap(true)
                                        .swipeHorizontal(true)//是不是橫向檢視
                                        .onPageChange(new OnPageChangeListener() {
                                            @Override
                                            public void onPageChanged(int page, int pageCount) {

                                            }
                                        })
                                        .enableSwipe(true)
                                        .load();

                            }
                        }
                    });


                }
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

我這裡沒有處理記憶體洩露，使用了內部類，而且流沒有關閉，這裡如果直接關閉流，可能導致頁面不顯示