从相册选择照片不显示

[GalleyF]

package com.example.yrc.cameraalbumtest;

import android.annotation.TargetApi;
import android.content.ContentUris;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Build;
import android.provider.DocumentsContract;
import android.provider.MediaStore;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v4.content.FileProvider;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

public static final int TAKE_PHOTO=1;
public static final int CHOOSE_PHOTO=2;

private ImageView picture;
private Button TakePhoto;
private Button chooseFromAlbum;
private Uri imageUri;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
picture = (ImageView) findViewById(R.id.picture);
TakePhoto = (Button) findViewById(R.id.button);
TakePhoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
File outputImage = new File(getExternalCacheDir(), "output_image.jpg");
try {
if (outputImage.exists()) {
outputImage.delete();
}
outputImage.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
if (Build.VERSION.SDK_INT >= 24) {
imageUri = FileProvider.getUriForFile(MainActivity.this, "com.example.yrc.cameraalbumtest.fileprovider", outputImage);
} else {
imageUri = Uri.fromFile(outputImage);
}
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intent, TAKE_PHOTO);
}
});
chooseFromAlbum = (Button) findViewById(R.id.choose_from_album);
chooseFromAlbum.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (ContextCompat.checkSelfPermission(MainActivity.this,
android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(MainActivity.this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
} else {
openAlbum();
}
}
});

}

private void openAlbum(){
Intent intent=new Intent("android.intent.action.GET_CONTENT");
intent.setType("image/*");
startActivityForResult(intent,CHOOSE_PHOTO);
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode){
case 1:
if (grantResults.length>0&&grantResults[0]==PackageManager.PERMISSION_GRANTED){
openAlbum();
}else {
Toast.makeText(this,"You denied the permission",Toast.LENGTH_SHORT).show();
}
break;
default:
}
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode){
case TAKE_PHOTO:
if (resultCode==RESULT_OK){
try{
Bitmap bitmap= BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
picture.setImageBitmap(bitmap);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
case CHOOSE_PHOTO:
if (requestCode==RESULT_OK){
if (Build.VERSION.SDK_INT>=19){
handleImageOnKitKat(data);
}else {
handleImageBeforeKitKat(data);
}
}
break;
default:
break;
}
}

@TargetApi(19)
private void handleImageOnKitKat(Intent data) {
String imagePath = null;
Uri uri = data.getData();
if (DocumentsContract.isDocumentUri(this, uri)) {
String docId = DocumentsContract.getDocumentId(uri);
if ("com.android.providers.media.documents".equals(uri.getAuthority())) {
String id = docId.split(":")[1];
String selection = MediaStore.Images.Media._ID + "=" + id;
imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);
} else if ("com.android.providers.downloads.documents".equals(uri.getAuthority())) {
Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(docId));
imagePath = getImagePath(contentUri, null);
} else if ("content".equalsIgnoreCase(uri.getScheme())) {
imagePath = getImagePath(uri, null);
} else if ("file".equalsIgnoreCase(uri.getScheme())) {
imagePath = uri.getPath();
}
displayImage(imagePath);
}
}
private void handleImageBeforeKitKat(Intent data ){
Uri uri=data.getData();
String imagePath = getImagePath(uri,null);
displayImage(imagePath);
}
private String getImagePath(Uri uri , String selection){
String path=null;
Cursor cursor=getContentResolver().query(uri,null,selection,null,null);
if (cursor!=null){
if (cursor.moveToFirst()){
path=cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
}
cursor.close();
}
return path;

}

private void displayImage(String imagePath){
if (imagePath!=null){
Bitmap bitmap=BitmapFactory.decodeFile(imagePath);
picture.setImageBitmap(bitmap);
}else {
Toast.makeText(this,"failed to get image",Toast.LENGTH_SHORT).show();
}
}


}

xml文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.yrc.cameraalbumtest.MainActivity">

<Button
android:text="Take Photo"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/button" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Choose From Album"
android:id="@+id/choose_from_album"/>

<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/picture"
android:layout_gravity="center_horizontal"/>

</LinearLayout>


在学习第一行代码第二版的时候，不知道为什么发生这种问题，请各位帮忙解答下

[寒冰大神]

你这里写错了， if (requestCode==RESULT_OK){} requestCode 应该是 resultCode 请求码和返回码不一样的 case CHOOSE_PHOTO: if (resultCode == RESULT_OK) { if (Build.VERSION.SDK_INT >= 19) { handleImageOnKitKat(data); } else { handleImageBeforeKitKat(data); } } break;