Android调用摄像头拍照开发教程

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package com.gyq.cameraalbumtest;

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.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.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;

public class MainActivity extends AppCompatActivity {
  public static final int TAKE_PHOTO = 1;
  public static final int CHOOSE_PHOTO = 2;
  private Button mTakePhoto, mChoosePhoto;
  private ImageView picture;
  private Uri imageUri;

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

    mTakePhoto = (Button) findViewById(R.id.btn_take_photo);
    mChoosePhoto = (Button) findViewById(R.id.choose_from_album);
    picture = (ImageView) findViewById(R.id.iv_picture);

    mTakePhoto.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 (Exception e) {
          e.printStackTrace();
        }

        if (Build.VERSION.SDK_INT >= 24) {
          imageUri = FileProvider.getUriForFile(MainActivity.this,
              "com.gyq.cameraalbumtest.fileprovider", outputImage);
        } else {
          imageUri = Uri.fromFile(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);
      }
    });

    mChoosePhoto.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        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();
        }
      }
    });
  }

  //打开相册
  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;

    }
  }

  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch (requestCode) {
      case TAKE_PHOTO:
        if (resultCode == RESULT_OK) {
          try {
            Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
            picture.setImageBitmap(bm);
          } catch (Exception e) {
            e.printStackTrace();
          }

        }
        break;
      case CHOOSE_PHOTO:
        if (resultCode == RESULT_OK) {
          if (Build.VERSION.SDK_INT >= 19) { //4.4及以上的系统使用这个方法处理图片；
            handleImageOnKitKat(data);
          } else {
            handleImageBeforeKitKat(data); //4.4及以下的系统使用这个方法处理图片
          }
        }
      default:
        break;
    }
  }

  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();
    }
  }

  /**
   * 4.4及以上的系统使用这个方法处理图片
   *
   * @param data
   */
  @TargetApi(19)
  private void handleImageOnKitKat(Intent data) {
    String imagePath = null;
    Uri uri = data.getData();
    if (DocumentsContract.isDocumentUri(this, uri)) {
      //如果document类型的Uri,则通过document来处理
      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/piblic_downloads"), Long.valueOf(docID));

        imagePath = getImagePath(contentUri, null);

      }

    } else if ("content".equalsIgnoreCase(uri.getScheme())) {
      //如果是content类型的uri，则使用普通方式使用
      imagePath = getImagePath(uri, null);
    } else if ("file".equalsIgnoreCase(uri.getScheme())) {
      //如果是file类型的uri，直接获取路径即可
      imagePath = uri.getPath();

    }

    displayImage(imagePath);
  }
}

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