Android(安卓)学习之《第一行代码》第二版 笔记（十九）从相册中选取图片
16lz
2021-01-26
单击按钮从相册中选取图片并展示出来
在此基础代码上修改：调用摄像头拍照
1. 效果图
2. MainActivity.java
import android.Manifest;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.os.Bundle;import android.provider.DocumentsContract;import android.provider.MediaStore;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.util.Log;import android.view.View;import android.widget.Button;import android.widget.ImageView;import android.widget.Toast;import java.io.File;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); //获取控件实例 takePhoto = (Button) findViewById(R.id.take_photo); chooseFromAlbum = (Button) findViewById(R.id.choose_from_album); picture = (ImageView) findViewById(R.id.picture); //设置takePhoto按钮点击事件 takePhoto.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // 创建File对象，用于存储拍照后的图片 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 = Uri.fromFile(outputImage); } else { imageUri = FileProvider.getUriForFile(MainActivity.this, "com.example.cameraalbumtest.fileprovider", outputImage); } // 启动相机程序 Intent intent = new Intent("android.media.action.IMAGE_CAPTURE"); intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri); startActivityForResult(intent, TAKE_PHOTO); } }); //设置chooseFromAlbum按钮点击事件 chooseFromAlbum.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { //处理运行时权限 //WRITE_EXTERNAL_STORAGE表示同时授予程序对SD卡读和写的能力 if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) { ActivityCompat.requestPermissions(MainActivity.this, new String[]{ 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); // 打开相册 } @Override public void onRequestPermissionsResult(int requestCode, String[] permissions, 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 { // 将拍摄的照片显示出来 Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri)); picture.setImageBitmap(bitmap); } catch (Exception e) { e.printStackTrace(); } } break; case CHOOSE_PHOTO: if (resultCode == RESULT_OK) { // 判断手机系统版本号 if (Build.VERSION.SDK_INT >= 19) { // 4.4及以上系统使用这个方法处理图片 // 从4.4版本开始，选取相册中的图片不再返回图片真实的Uri了，而是一个封装过的Uri handleImageOnKitKat(data); } else { // 4.4以下系统使用这个方法处理图片 handleImageBeforeKitKat(data); } } break; default: break; } } @TargetApi(19) private void handleImageOnKitKat(Intent data) { String imagePath = null; Uri uri = data.getData(); Log.d("TAG", "handleImageOnKitKat: uri is " + uri); if (DocumentsContract.isDocumentUri(this, uri)) { // 如果是document类型的Uri，则通过document id处理 String docId = DocumentsContract.getDocumentId(uri); if("com.android.providers.media.documents".equals(uri.getAuthority())) { String id = docId.split(":")[1]; // 解析出数字格式的id 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())) { // 如果是content类型的Uri，则使用普通方式处理 imagePath = getImagePath(uri, null); } else if ("file".equalsIgnoreCase(uri.getScheme())) { // 如果是file类型的Uri，直接获取图片路径即可 imagePath = uri.getPath(); } displayImage(imagePath); // 根据图片路径显示图片 } 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; // 通过Uri和selection来获取真实的图片路径 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(); } }}3. activity_main.xml
<?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.thinkpad.cameraalbumtest.MainActivity"> <Button android:id="@+id/take_photo" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="点击拍照"/> <Button android:id="@+id/choose_from_album" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="从相册中选取照片"/> <ImageView android:id="@+id/picture" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center_horizontal"/>LinearLayout>整理学习自郭霖大佬的《第一行代码》
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