Android实现选择相册图片并显示功能

package com.example.www.mutilmedia;import android.Manifest;import android.app.Activity;import android.content.Intent;import android.content.pm.PackageManager;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Build;import android.os.Bundle;import android.support.annotation.NonNull;import android.support.v4.app.ActivityCompat;import android.support.v7.app.AppCompatActivity;import android.util.Log;import android.view.View;import android.widget.ImageView;import android.widget.Toast;import java.util.Arrays;public class MainActivity extends AppCompatActivity {  String[] mPermissionList = new String[]{      Manifest.permission.WRITE_EXTERNAL_STORAGE,      Manifest.permission.READ_EXTERNAL_STORAGE};  public static final int REQUEST_PICK_IMAGE = 11101;  private ImageView mShowImg;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    mShowImg = (ImageView) findViewById(R.id.imageView);  }  @Override  public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {    super.onRequestPermissionsResult(requestCode, permissions, grantResults);    switch (requestCode) {      case 100:        boolean writeExternalStorage = grantResults[0] == PackageManager.PERMISSION_GRANTED;        boolean readExternalStorage = grantResults[1] == PackageManager.PERMISSION_GRANTED;        Log.e("MainActivity", Arrays.toString(grantResults));        if (grantResults.length > 0 && writeExternalStorage && readExternalStorage) {          getImage();        } else {          Toast.makeText(this, "请设置必要权限", Toast.LENGTH_SHORT).show();        }        break;    }  }  private void getImage() {    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {      startActivityForResult(new Intent(Intent.ACTION_GET_CONTENT).setType("image/*"),          REQUEST_PICK_IMAGE);    } else {      Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);      intent.addCategory(Intent.CATEGORY_OPENABLE);      intent.setType("image/*");      startActivityForResult(intent, REQUEST_PICK_IMAGE);    }  }  @Override  protected void onActivityResult(int requestCode, int resultCode, Intent data) {    super.onActivityResult(requestCode, resultCode, data);    if (resultCode == Activity.RESULT_OK) {      switch (requestCode) {        case REQUEST_PICK_IMAGE:          if (data != null) {            String realPathFromUri = RealPathFromUriUtils.getRealPathFromUri(this, data.getData());            Log.e("MainActivity", realPathFromUri);            showImg(realPathFromUri);          } else {            Toast.makeText(this, "图片损坏，请重新选择", Toast.LENGTH_SHORT).show();          }          break;      }    }  }  public void openCamera(View view) {    ActivityCompat.requestPermissions(MainActivity.this, mPermissionList, 100);  }  public void showImg(String path){    Bitmap bitmap = BitmapFactory.decodeFile(path);    mShowImg.setImageBitmap(bitmap);  }}

package com.example.www.mutilmedia;import android.annotation.SuppressLint;import android.content.ContentUris;import android.content.Context;import android.database.Cursor;import android.net.Uri;import android.os.Build;import android.provider.DocumentsContract;import android.provider.MediaStore;public class RealPathFromUriUtils {  /**   * 根据Uri获取图片的绝对路径   *   * @param context 上下文对象   * @param uri   图片的Uri   * @return 如果Uri对应的图片存在, 那么返回该图片的绝对路径, 否则返回null   */  public static String getRealPathFromUri(Context context, Uri uri) {    int sdkVersion = Build.VERSION.SDK_INT;    if (sdkVersion >= 19) { // api >= 19      return getRealPathFromUriAboveApi19(context, uri);    } else { // api < 19      return getRealPathFromUriBelowAPI19(context, uri);    }  }  /**   * 适配api19以下(不包括api19),根据uri获取图片的绝对路径   *   * @param context 上下文对象   * @param uri   图片的Uri   * @return 如果Uri对应的图片存在, 那么返回该图片的绝对路径, 否则返回null   */  private static String getRealPathFromUriBelowAPI19(Context context, Uri uri) {    return getDataColumn(context, uri, null, null);  }  /**   * 适配api19及以上,根据uri获取图片的绝对路径   *   * @param context 上下文对象   * @param uri   图片的Uri   * @return 如果Uri对应的图片存在, 那么返回该图片的绝对路径, 否则返回null   */  @SuppressLint("NewApi")  private static String getRealPathFromUriAboveApi19(Context context, Uri uri) {    String filePath = null;    if (DocumentsContract.isDocumentUri(context, uri)) {      // 如果是document类型的 uri, 则通过document id来进行处理      String documentId = DocumentsContract.getDocumentId(uri);      if (isMediaDocument(uri)) { // MediaProvider        // 使用':'分割        String id = documentId.split(":")[1];        String selection = MediaStore.Images.Media._ID + "=?";        String[] selectionArgs = {id};        filePath = getDataColumn(context, MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection, selectionArgs);      } else if (isDownloadsDocument(uri)) { // DownloadsProvider        Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(documentId));        filePath = getDataColumn(context, contentUri, null, null);      }    } else if ("content".equalsIgnoreCase(uri.getScheme())) {      // 如果是 content 类型的 Uri      filePath = getDataColumn(context, uri, null, null);    } else if ("file".equals(uri.getScheme())) {      // 如果是 file 类型的 Uri,直接获取图片对应的路径      filePath = uri.getPath();    }    return filePath;  }  /**   * 获取数据库表中的 _data 列，即返回Uri对应的文件路径   *   * @return   */  private static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {    String path = null;    String[] projection = new String[]{MediaStore.Images.Media.DATA};    Cursor cursor = null;    try {      cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);      if (cursor != null && cursor.moveToFirst()) {        int columnIndex = cursor.getColumnIndexOrThrow(projection[0]);        path = cursor.getString(columnIndex);      }    } catch (Exception e) {      if (cursor != null) {        cursor.close();      }    }    return path;  }  /**   * @param uri the Uri to check   * @return Whether the Uri authority is MediaProvider   */  private static boolean isMediaDocument(Uri uri) {    return "com.android.providers.media.documents".equals(uri.getAuthority());  }  /**   * @param uri the Uri to check   * @return Whether the Uri authority is DownloadsProvider   */  private static boolean isDownloadsDocument(Uri uri) {    return "com.android.providers.downloads.documents".equals(uri.getAuthority());  }}

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout 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=".MainActivity">  <ImageView    android:id="@+id/imageView"    android:layout_width="0dp"    android:layout_height="0dp"    android:layout_marginStart="8dp"    android:layout_marginTop="8dp"    android:layout_marginEnd="8dp"    android:layout_marginBottom="8dp"    app:layout_constraintBottom_toBottomOf="parent"    app:layout_constraintEnd_toEndOf="parent"    app:layout_constraintStart_toStartOf="parent"    app:layout_constraintTop_toBottomOf="@+id/button3"    app:srcCompat="@android:color/white" />  <Button    android:id="@+id/button3"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_marginStart="8dp"    android:layout_marginTop="16dp"    android:layout_marginEnd="8dp"    android:onClick="openCamera"    android:text="camera"    app:layout_constraintEnd_toEndOf="parent"    app:layout_constraintHorizontal_bias="0.048"    app:layout_constraintStart_toStartOf="parent"    app:layout_constraintTop_toTopOf="parent" /></android.support.constraint.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"  package="com.example.www.mutilmedia">  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />  <application    android:allowBackup="true"    android:icon="@mipmap/ic_launcher"    android:label="@string/app_name"    android:roundIcon="@mipmap/ic_launcher_round"    android:supportsRtl="true"    android:theme="@style/AppTheme">    <activity android:name=".MainActivity">      <intent-filter>        <action android:name="android.intent.action.MAIN" />        <category android:name="android.intent.category.LAUNCHER" />      </intent-filter>    </activity>  </application></manifest>