Question

首先，我知道这个问题需要很多时间，你可以肯定我会阅读并尝试所有这些问题，但我无法悲伤地成功。我需要再次询问为android开发中的所有新手。顺便说一句，我正在学习udacity。我正在尝试从资产中打开pdf文件。我找到了这个（cw-omnibus ContentProvider），这非常有用，但它不是动态的，我无法弄清楚如何为所有pdf制作动态。基本上，每当我想通过按钮，cardview等打开pdf时，它应该使用fileprovider打开。简单地说，我可以使用其他名称复制和粘贴FileProvider，我可以使用它。但如果我有20个pdfs，我会有很多java文件。这就像走路而不是乘公共汽车去另一个城市。我只想学习如何做到这一点。我不太了解java。我尝试了很多东西乘坐公共汽车，但我仍然找不到公共汽车。我想要一些帮助。在github示例中，如您所见，“test.pdf”是静态的。当意图被称为“test.pdf”打开时。我厌倦了为test.pdf配置变量并尝试使用cardview的开关盒（如按钮）但我无法从FileProvider.java调用变量而且我累了很多事情。：（（我知道我可以使用recyclerview进行cardview，但我很难理解并自定义，以便我手动创建卡片视图。我在下面分享我的所有代码。

XML

<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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:background="@color/colorBg"
    android:fillViewport="true"
    tools:context="com.example.tk.buzebv2.Hizmetlerimiz">

    <LinearLayout xmlns:card_view="http://schemas.android.com/apk/res-auto"
        android:id="@+id/activity_kilavuzlar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin">

        <android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:id="@+id/card_clicked1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_marginBottom="@dimen/card_view_bottom"
            android:clickable="true"
            android:foreground="?android:attr/selectableItemBackground"
            android:onClick="onClick"
            card_view:cardCornerRadius="4dp">

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

                <ImageView
                    android:id="@+id/imageView2"
                    android:layout_width="match_parent"
                    android:layout_height="150dp"
                    android:scaleType="centerCrop"
                    android:src="@drawable/hizmetlerimiz1" />

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:paddingLeft="16dp"
                    android:paddingTop="16dp"
                    android:text="Uzaktan Öğretim Sınıfı"
                    android:textColor="@color/colorDefaultText"
                    android:textSize="24sp" />

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@android:color/white"
                    android:gravity="left"
                    android:lineSpacingMultiplier="1.3"
                    android:padding="@dimen/activity_horizontal_margin"
                    android:text="@string/hakkimizda_aciklama1"
                    android:textColor="@color/colorDefaultText"
                    android:textSize="16sp" />


            </LinearLayout>
        </android.support.v7.widget.CardView>

        <android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:id="@+id/card_clicked2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_marginBottom="@dimen/card_view_bottom"
            android:clickable="true"
            android:foreground="?android:attr/selectableItemBackground"
            android:onClick="onClick"
            card_view:cardCornerRadius="4dp">

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

                <ImageView
                    android:layout_width="match_parent"
                    android:layout_height="150dp"
                    android:scaleType="centerCrop"
                    android:src="@drawable/hizmetlerimiz2" />

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:paddingLeft="16dp"
                    android:paddingTop="16dp"
                    android:text="Uzaktan Öğretim Hizmetleri"
                    android:textColor="@color/colorDefaultText"
                    android:textSize="24sp" />

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@android:color/white"
                    android:gravity="left"
                    android:lineSpacingMultiplier="1.3"
                    android:padding="@dimen/activity_horizontal_margin"
                    android:text="@string/hakkimizda_aciklama3"
                    android:textColor="@color/colorDefaultText"
                    android:textSize="16sp" />


            </LinearLayout>
        </android.support.v7.widget.CardView>

        <android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:id="@+id/card_clicked3"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_marginBottom="@dimen/card_view_bottom"
            android:clickable="true"
            android:foreground="?android:attr/selectableItemBackground"
            android:onClick="onClick"
            card_view:cardCornerRadius="4dp">

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

                <ImageView
                    android:layout_width="match_parent"
                    android:layout_height="150dp"
                    android:scaleType="centerCrop"
                    android:src="@drawable/hizmetlerimiz3" />

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:paddingLeft="16dp"
                    android:paddingTop="16dp"
                    android:text="Online Sınav Hizmetleri"
                    android:textColor="@color/colorDefaultText"
                    android:textSize="24sp" />

                <TextView
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@android:color/white"
                    android:gravity="left"
                    android:lineSpacingMultiplier="1.3"
                    android:padding="@dimen/activity_horizontal_margin"
                    android:text="@string/hakkimizda_aciklama3"
                    android:textColor="@color/colorDefaultText"
                    android:textSize="16sp" />


            </LinearLayout>
        </android.support.v7.widget.CardView>


    </LinearLayout>
</ScrollView>

JAVA

package com.example.tk.buzebv2;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.CardView;
import android.util.Log;
import android.view.View;


public class Hizmetlerimiz extends AppCompatActivity implements View.OnClickListener  {

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


        CardView b1= (CardView) findViewById(R.id.card_clicked1);
        CardView b2= (CardView) findViewById(R.id.card_clicked2);
        CardView b3= (CardView) findViewById(R.id.card_clicked3);
        b1.setOnClickListener(this);
        b2.setOnClickListener(this);
        b3.setOnClickListener(this);

    }


    public void onClick(View v) {

        int i = v.getId();
        if (i == R.id.card_toast) {
            String hizmet_01 = "hizmet_01_a201.pdf";
            startActivity(new Intent(Intent.ACTION_VIEW,
                    Uri.parse(FileProvider.CONTENT_URI
                            + hizmet_01)));

        } else if (i == R.id.card_toast1) {
            String hizmet_02 = "hizmet_02_distance.pdf";
            startActivity(new Intent(Intent.ACTION_VIEW,
                    Uri.parse(FileProvider.CONTENT_URI
                            + hizmet_02)));


        } else if (i == R.id.card_toast2) {
            String hizmet_03 = "hizmet_03_online_sinav.pdf";
            startActivity(new Intent(Intent.ACTION_VIEW,
                    Uri.parse(FileProvider.CONTENT_URI
                            + hizmet_03)));


        }

    }
}

FileProvider.java

/***
  Copyright (c) 2008-2014 CommonsWare, LLC
  Licensed under the Apache License, Version 2.0 (the "License"); you may not
  use this file except in compliance with the License. You may obtain a copy
  of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
  by applicable law or agreed to in writing, software distributed under the
  License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
  OF ANY KIND, either express or implied. See the License for the specific
  language governing permissions and limitations under the License.

  From _The Busy Coder's Guide to Android Development_
    https://commonsware.com/Android
 */

package com.commonsware.android.cp.files;

import android.content.res.AssetManager;
import android.net.Uri;
import android.os.ParcelFileDescriptor;
import android.util.Log;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;

public class FileProvider extends AbstractFileProvider {
  public static final Uri CONTENT_URI=
      Uri.parse("content://com.commonsware.android.cp.files/");

  @Override
  public boolean onCreate() {
    File f=new File(getContext().getFilesDir(), "test.pdf");

    if (!f.exists()) {
      AssetManager assets=getContext().getResources().getAssets();

      try {
        copy(assets.open("test.pdf"), f);
      }
      catch (IOException e) {
        Log.e("FileProvider", "Exception copying from assets", e);

        return(false);
      }
    }

    return(true);
  }

  @Override
  public ParcelFileDescriptor openFile(Uri uri, String mode)
    throws FileNotFoundException {
    File root=getContext().getFilesDir();
    File f=new File(root, uri.getPath()).getAbsoluteFile();

    if (!f.getPath().startsWith(root.getPath())) {
      throw new
        SecurityException("Resolved path jumped beyond root");
    }

    if (f.exists()) {
      return(ParcelFileDescriptor.open(f, parseMode(mode)));
    }

    throw new FileNotFoundException(uri.getPath());
  }

  @Override
  protected long getDataLength(Uri uri) {
    File f=new File(getContext().getFilesDir(), uri.getPath());

    return(f.length());
  }

  // following is from ParcelFileDescriptor source code
  // Copyright (C) 2006 The Android Open Source Project
  // (even though this method was added much after 2006...)

  private static int parseMode(String mode) {
    final int modeBits;
    if ("r".equals(mode)) {
      modeBits=ParcelFileDescriptor.MODE_READ_ONLY;
    }
    else if ("w".equals(mode) || "wt".equals(mode)) {
      modeBits=
          ParcelFileDescriptor.MODE_WRITE_ONLY
              | ParcelFileDescriptor.MODE_CREATE
              | ParcelFileDescriptor.MODE_TRUNCATE;
    }
    else if ("wa".equals(mode)) {
      modeBits=
          ParcelFileDescriptor.MODE_WRITE_ONLY
              | ParcelFileDescriptor.MODE_CREATE
              | ParcelFileDescriptor.MODE_APPEND;
    }
    else if ("rw".equals(mode)) {
      modeBits=
          ParcelFileDescriptor.MODE_READ_WRITE
              | ParcelFileDescriptor.MODE_CREATE;
    }
    else if ("rwt".equals(mode)) {
      modeBits=
          ParcelFileDescriptor.MODE_READ_WRITE
              | ParcelFileDescriptor.MODE_CREATE
              | ParcelFileDescriptor.MODE_TRUNCATE;
    }
    else {
      throw new IllegalArgumentException("Bad mode '" + mode + "'");
    }
    return modeBits;
  }
}

Answer 1

最简单的方法是使用my StreamProvider，它为您处理所有这些“开箱即用”。它基于Android支持库提供的FileProvider，但它直接提供资源外的文件服务，而不需要您查看的特定样本应用程序的干预副本。

否则，您在那里的样本将处理任意数量的PDF。它碰巧只在onCreate()中设置了一个。您可以改为onCreate()分叉后台线程，并根据需要设置多个PDF。 ContentProvider中的其余代码不需要更改，因为它只根据getFilesDir()上提供的文件名查找Uri中的文件。

如何使用ContentProvider

1 个答案: