如何在android studio中使用资产文件夹在gridview中显示

问题描述 投票：0回答：2

我使用gridview从资产打开pdf文件我已经使用下载目录来显示pdf文件，但现在我想使用资产而我正在将主要活动和pdf活动更改为碎片伙伴帮助我使用资产文件夹

示例代码

custom adaptor.Java

package com.tutorials.hp.gridviewpdf;

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;


public class CustomAdapter extends BaseAdapter {

    Context c;
    ArrayList<PDFDoc> pdfDocs;

    public CustomAdapter(Context c, ArrayList<PDFDoc> pdfDocs) {
        this.c = c;
        this.pdfDocs = pdfDocs;
    }

    @Override
    public int getCount() {
        return pdfDocs.size();
    }

    @Override
    public Object getItem(int i) {
        return pdfDocs.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        if(view==null)
        {
            //INFLATE CUSTOM LAYOUT
            view= LayoutInflater.from(c).inflate(R.layout.model,viewGroup,false);
        }

        final PDFDoc pdfDoc= (PDFDoc) this.getItem(i);

        TextView nameTxt= (TextView) view.findViewById(R.id.nameTxt);
        ImageView img= (ImageView) view.findViewById(R.id.pdfImage);

        //BIND DATA
        nameTxt.setText(pdfDoc.getName());
        img.setImageResource(R.drawable.pdf_icon);

        //VIEW ITEM CLICK
        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               openPDFView(pdfDoc.getPath());
            }
        });
        return view;
    }

    //OPEN PDF VIEW
    private void openPDFView(String path)
    {
        Intent i=new Intent(c,PDF_Activity.class);
        i.putExtra("PATH",path);
        c.startActivity(i);
    }
}

PDF_Activity.java我将使用片段代替活动

package com.tutorials.hp.gridviewpdf;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;

import com.github.barteksc.pdfviewer.PDFView;
//import com.github.barteksc.pdfviewer.ScrollBar;
import com.github.barteksc.pdfviewer.listener.OnLoadCompleteListener;

import java.io.File;

public class PDF_Activity extends AppCompatActivity {

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

        //PDFVIEW SHALL DISPLAY OUR PDFS
        PDFView pdfView= (PDFView) findViewById(R.id.pdfView);
        //SCROLLBAR TO ENABLE SCROLLING
//        ScrollBar scrollBar = (ScrollBar) findViewById(R.id.scrollBar);
//        pdfView.setScrollBar(scrollBar);
        //VERTICAL SCROLLING
//        scrollBar.setHorizontal(false);
        //SACRIFICE MEMORY FOR QUALITY
        //pdfView.useBestQuality(true)

        //UNPACK OUR DATA FROM INTENT
        Intent i=this.getIntent();
        String path=i.getExtras().getString("PATH");

        //GET THE PDF FILE
        File file=new File(path);

            if(file.canRead())
            {
                //LOAD IT

                pdfView.fromFile(file).defaultPage(1).onLoad(new OnLoadCompleteListener() {
                    @Override
                    public void loadComplete(int nbPages) {
                        Toast.makeText(PDF_Activity.this, String.valueOf(nbPages), Toast.LENGTH_LONG).show();
                    }
                }).load();

            }


    }
}

PDF doc.Java

package com.tutorials.hp.gridviewpdf;

import android.net.Uri;

public class PDFDoc {
    String name,path;


    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }


    public String getPath() {
        return path;
    }

    public void setPath(String path) {
        this.path = path;
    }
}

MainActivity.java我将使用片段而不是活动我需要资产文件夹来显示pdf文件

package com.tutorials.hp.gridviewpdf;

import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.GridView;

import java.io.File;
import java.util.ArrayList;


public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        final GridView gv= (GridView) findViewById(R.id.gv);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                gv.setAdapter(new CustomAdapter(MainActivity.this,getPDFs()));

            }
        });
    }

    private ArrayList<PDFDoc> getPDFs()

    {
        ArrayList<PDFDoc> pdfDocs=new ArrayList<>();
        //TARGET FOLDER
        File downloadsFolder= Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);

        PDFDoc pdfDoc;

        if(downloadsFolder.exists())
        {
            //GET ALL FILES IN DOWNLOAD FOLDER
            File[] files=downloadsFolder.listFiles();

            //LOOP THRU THOSE FILES GETTING NAME AND URI
            for (int i=0;i<files.length;i++)
            {
                File file=files[i];

                if(file.getPath().endsWith("pdf"))
                {
                    pdfDoc=new PDFDoc();
                    pdfDoc.setName(file.getName());
                    pdfDoc.setPath(file.getAbsolutePath());

                    pdfDocs.add(pdfDoc);
                }

            }
        }

        return pdfDocs;
    }


}

布局

activity_main.xml我将使用片段而不是活动

    <?xml version="1.0" encoding="utf-8"?>
    <android.support.design.widget.CoordinatorLayout 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:fitsSystemWindows="true"
        tools:context="com.tutorials.hp.gridviewpdf.MainActivity">

        <android.support.design.widget.AppBarLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:theme="@style/AppTheme.AppBarOverlay">

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                android:background="?attr/colorPrimary"
                app:popupTheme="@style/AppTheme.PopupOverlay" />

        </android.support.design.widget.AppBarLayout>

        <include layout="@layout/content_main" />

        <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|end"
            android:layout_margin="@dimen/fab_margin"
            android:src="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>

activity_pdf.xml我将使用fragment而不是activity

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.tutorials.hp.gridviewpdf.PDF_Activity">

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

    <com.github.barteksc.pdfviewer.ScrollBar
        android:id="@+id/scrollBar"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />

</RelativeLayout>

content_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.tutorials.hp.gridviewpdf.MainActivity"
    tools:showIn="@layout/activity_main">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="PDF VIEWER" />

        <GridView
            android:id="@+id/gv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:numColumns="2" />
    </LinearLayout>


</RelativeLayout>

model.hml

 <?xml version="1.0" encoding="utf-8"?>
    <android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="horizontal" android:layout_width="match_parent"
        xmlns:card_view="http://schemas.android.com/apk/res-auto"
        android:layout_margin="10dp"
        card_view:cardCornerRadius="5dp"
        card_view:cardElevation="5dp"
        android:layout_height="200dp">

            <LinearLayout
                android:orientation="horizontal"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <ImageView
                    android:id="@+id/pdfImage"
                    android:src="@drawable/pdf_icon"
                    android:layout_width="150dp"
                    android:layout_height="wrap_content" />

                <LinearLayout
                    android:orientation="vertical"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:textAppearance="?android:attr/textAppearanceLarge"
                        android:text="Name"
                        android:id="@+id/nameTxt"
                        android:padding="10dp"
                        android:textColor="@color/colorAccent"
                        android:textStyle="bold"
                        android:layout_alignParentLeft="true"
                        />

                </LinearLayout>

                </LinearLayout>


    </android.support.v7.widget.CardView>
android android-studio android-fragments pdf assets
2个回答
1
投票

您可以从片段中将其作为这样的输入流打开

reader = new BufferedReader(new InputStreamReader(getActivity().getAssets().open(myfile.pdf))

当您访问应用程序的内部文件时，您不需要permisssions，但将pdf放入资源可能会增加应用程序的重量，请小心

然后你可以把它保存为那样的字符串

private StringBuilder text = new StringBuilder();
String mLine;
        while ((mLine = reader.readLine()) != null) {
            text.append(mLine);
            text.append('\n');
        }
if (reader != null) {
        try {
            reader.close();
        } catch (IOException e) {
            //log the exception
        }
2
投票

如果要将pdf存储在外部存储中，请在清单中包含此权限。像这样使用Asset文件夹

AssetManager assetManager = getAssets();
File file = new File(getFilesDir(), "xyz.pdf");
in = assetManager.open("xyz.pdf");
out = openFileOutput(file.getName(), Context.MODE_WORLD_READABLE);
copyFile(in, out);
                in.close();
                in = null;
                out.flush();
                out.close();
                out = null;
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