Oreo ViewPager 显示来自外部存储文件路径的图像
Oreo ViewPager to display images from external storage filepaths
所以我对 Java 和 Android 都很陌生,正在为一个项目开发应用程序。在该应用程序中,我希望拥有自己的图片库/查看器,专门用于我们将使用该应用程序保存的图像。因此,我想使用 ViewPager 来滑动图像,并创建了一个自定义寻呼机适配器。以下是相关文件:
CustomSwipeAdapter.java
package app.rpass;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;
import android.support.v4.view.PagerAdapter;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.io.File;
import java.util.ArrayList;
public class CustomSwipeAdapter extends PagerAdapter {
ArrayList<String> f = new ArrayList<String>();// list of file paths
File[] listFile;
private Context ctx;
private LayoutInflater layoutInflater;
ArrayList<Bitmap> images = new ArrayList<Bitmap>(); //list of bitmaps
public CustomSwipeAdapter(Context ctx){
this.ctx = ctx;
}
@Override
public int getCount() {
return images.size();
}
@Override
public boolean isViewFromObject(View view, Object object) {
return (view == (LinearLayout)object);
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
layoutInflater = (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View item_view = layoutInflater.inflate(R.layout.swipe_layout,container,false);
TextView textView = (TextView) item_view.findViewById(R.id.image_count);
String[] output = f.get(position).split("/");
textView.setText(output[output.length-1]);
ImageView imageView = (ImageView) item_view.findViewById(R.id.imageView2);
imageView.setImageBitmap(images.get(position));
container.addView(item_view);
return item_view;
}
@Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((LinearLayout)object);
}
public void getFromSdcard()
{
File file= new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),"pictures");
if (file.isDirectory()) {
try{
listFile = file.listFiles();
for (int i = 0; i < listFile.length; i++) {
f.add(listFile[i].getAbsolutePath());
}
}
catch(Exception e){
Log.i("File Error","No File Could be Created");
}
}
else{
Log.i("File Error","Filepath was not a directory");
}
}
public void makeBitmaps(ArrayList<String> files){
final BitmapFactory.Options options = new BitmapFactory.Options();
for (int i = 0; i < files.size(); i ++){
File imgFile = new File(files.get(i));
if (imgFile.exists() && imgFile.canRead()){
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(imgFile.getAbsolutePath());
options.inSampleSize = calculateInSampleSize(options,50,50);
options.inJustDecodeBounds = false;
images.add(BitmapFactory.decodeFile(imgFile.getAbsolutePath(),options));
}
}
}
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
// Calculate the largest inSampleSize value that is a power of 2 and keeps both
// height and width larger than the requested height and width.
while ((halfHeight / inSampleSize) >= reqHeight
&& (halfWidth / inSampleSize) >= reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
}
SlideActivity.java
package app.rpass;
import android.Manifest;
import android.app.ProgressDialog;
import android.content.pm.PackageManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.PersistableBundle;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
public class SlideActivity extends AppCompatActivity {
ViewPager viewPager;
CustomSwipeAdapter adapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.swipe);
viewPager = (ViewPager)findViewById(R.id.view_pager);
int MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE =1;
if (ContextCompat.checkSelfPermission(SlideActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
!= PackageManager.PERMISSION_GRANTED) {
Log.i("Permissions Error","No permission inside of SlideActivity");
ActivityCompat.requestPermissions(SlideActivity.this,
new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE);
}
adapter = new CustomSwipeAdapter(this);
new AsyncTask<Void,Void,Void>(){
ProgressDialog dialog = new ProgressDialog(SlideActivity.this);
@Override
protected void onPreExecute() {
dialog.setMessage("Loading Data...");
dialog.show();
}
@Override
protected Void doInBackground(Void... voids) {
adapter.getFromSdcard();
adapter.makeBitmaps(adapter.f);
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
if (dialog.isShowing()){
dialog.dismiss();
}
viewPager.setAdapter(adapter);
viewPager.getAdapter().notifyDataSetChanged();
}
}.execute();
//adapter.getFromSdcard();
//adapter.makeBitmaps(adapter.f);
//viewPager.setAdapter(adapter);
//viewPager.getAdapter().notifyDataSetChanged();
}
}
Swipe.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:tools="http://schemas.android.com/tools">
<android.support.v4.view.ViewPager
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v4.view.ViewPager>
</RelativeLayout>
swipe_layout.xml
<?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">
<TextView
android:id="@+id/image_count"
android:text=""
android:textSize="25dp"
android:textStyle="bold"
android:gravity="center"
android:layout_marginTop="25dp"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<ImageView
android:layout_marginTop="25dp"
android:scaleType="fitXY"
android:id="@+id/imageView2"
android:layout_width="50dp"
android:layout_height="50dp" />
</LinearLayout>
我的问题是 textView 创建得很好,并提供了适当的文件路径,但图像没有出现。我已经搜索了许多其他示例,但仍然无法弄清楚我做错了什么。我确信我一直在努力,以至于我只是忽略了一些东西。任何输入将不胜感激。谢谢!
所以我对 Java 和 Android 都很陌生,正在为一个项目开发应用程序。在该应用程序中,我希望拥有自己的图片库/查看器,专门用于我们将使用该应用程序保存的图像。因此,我想使用 ViewPager 来滑动图像,并创建了一个自定义寻呼机适配器。以下是相关文件:
CustomSwipeAdapter.java
package app.rpass;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;
import android.support.v4.view.PagerAdapter;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.io.File;
import java.util.ArrayList;
public class CustomSwipeAdapter extends PagerAdapter {
ArrayList<String> f = new ArrayList<String>();// list of file paths
File[] listFile;
private Context ctx;
private LayoutInflater layoutInflater;
ArrayList<Bitmap> images = new ArrayList<Bitmap>(); //list of bitmaps
public CustomSwipeAdapter(Context ctx){
this.ctx = ctx;
}
@Override
public int getCount() {
return images.size();
}
@Override
public boolean isViewFromObject(View view, Object object) {
return (view == (LinearLayout)object);
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
layoutInflater = (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View item_view = layoutInflater.inflate(R.layout.swipe_layout,container,false);
TextView textView = (TextView) item_view.findViewById(R.id.image_count);
String[] output = f.get(position).split("/");
textView.setText(output[output.length-1]);
ImageView imageView = (ImageView) item_view.findViewById(R.id.imageView2);
imageView.setImageBitmap(images.get(position));
container.addView(item_view);
return item_view;
}
@Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((LinearLayout)object);
}
public void getFromSdcard()
{
File file= new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),"pictures");
if (file.isDirectory()) {
try{
listFile = file.listFiles();
for (int i = 0; i < listFile.length; i++) {
f.add(listFile[i].getAbsolutePath());
}
}
catch(Exception e){
Log.i("File Error","No File Could be Created");
}
}
else{
Log.i("File Error","Filepath was not a directory");
}
}
public void makeBitmaps(ArrayList<String> files){
final BitmapFactory.Options options = new BitmapFactory.Options();
for (int i = 0; i < files.size(); i ++){
File imgFile = new File(files.get(i));
if (imgFile.exists() && imgFile.canRead()){
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(imgFile.getAbsolutePath());
options.inSampleSize = calculateInSampleSize(options,50,50);
options.inJustDecodeBounds = false;
images.add(BitmapFactory.decodeFile(imgFile.getAbsolutePath(),options));
}
}
}
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
// Calculate the largest inSampleSize value that is a power of 2 and keeps both
// height and width larger than the requested height and width.
while ((halfHeight / inSampleSize) >= reqHeight
&& (halfWidth / inSampleSize) >= reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
}
SlideActivity.java
package app.rpass;
import android.Manifest;
import android.app.ProgressDialog;
import android.content.pm.PackageManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.PersistableBundle;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
public class SlideActivity extends AppCompatActivity {
ViewPager viewPager;
CustomSwipeAdapter adapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.swipe);
viewPager = (ViewPager)findViewById(R.id.view_pager);
int MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE =1;
if (ContextCompat.checkSelfPermission(SlideActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
!= PackageManager.PERMISSION_GRANTED) {
Log.i("Permissions Error","No permission inside of SlideActivity");
ActivityCompat.requestPermissions(SlideActivity.this,
new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
MY_PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE);
}
adapter = new CustomSwipeAdapter(this);
new AsyncTask<Void,Void,Void>(){
ProgressDialog dialog = new ProgressDialog(SlideActivity.this);
@Override
protected void onPreExecute() {
dialog.setMessage("Loading Data...");
dialog.show();
}
@Override
protected Void doInBackground(Void... voids) {
adapter.getFromSdcard();
adapter.makeBitmaps(adapter.f);
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
if (dialog.isShowing()){
dialog.dismiss();
}
viewPager.setAdapter(adapter);
viewPager.getAdapter().notifyDataSetChanged();
}
}.execute();
//adapter.getFromSdcard();
//adapter.makeBitmaps(adapter.f);
//viewPager.setAdapter(adapter);
//viewPager.getAdapter().notifyDataSetChanged();
}
}
Swipe.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:tools="http://schemas.android.com/tools">
<android.support.v4.view.ViewPager
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v4.view.ViewPager>
</RelativeLayout>
swipe_layout.xml
<?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">
<TextView
android:id="@+id/image_count"
android:text=""
android:textSize="25dp"
android:textStyle="bold"
android:gravity="center"
android:layout_marginTop="25dp"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<ImageView
android:layout_marginTop="25dp"
android:scaleType="fitXY"
android:id="@+id/imageView2"
android:layout_width="50dp"
android:layout_height="50dp" />
</LinearLayout>
我的问题是 textView 创建得很好,并提供了适当的文件路径,但图像没有出现。我已经搜索了许多其他示例,但仍然无法弄清楚我做错了什么。我确信我一直在努力,以至于我只是忽略了一些东西。任何输入将不胜感激。谢谢!