Android实现调用摄像头和相册的方法

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package com.example.luoxn28.activity; 
 
import android.annotation.TargetApi; 
import android.content.ContentUris; 
import android.content.Intent; 
import android.database.Cursor; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.net.Uri; 
import android.os.Bundle; 
import android.os.Environment; 
import android.provider.DocumentsContract; 
import android.provider.MediaStore; 
import android.support.v7.app.ActionBarActivity; 
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 ActionBarActivity { 
  private static final String TAG = "hdu"; 
 
  public static final int TAKE_PHOTO = 1; 
  public static final int CROP_PHOTO = 2; 
  public static final int CHOOSE_PHOTO = 3; 
 
  private Button takePhoto; 
  private ImageView picture; 
  private Uri imageUri; 
 
  private Button chooseFromAlbum; 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    //requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.activity_main); 
 
    takePhoto = (Button) findViewById(R.id.take_photo); 
    picture = (ImageView) findViewById(R.id.picture); 
    chooseFromAlbum = (Button) findViewById(R.id.choose_from_album); 
 
    takePhoto.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
        // 创建File对象，用于存储拍摄后照片 
        File saveImage = new File(Environment.getExternalStorageDirectory(), "saveImage.jpg"); 
        try { 
          if (saveImage.exists()) { 
            saveImage.delete(); 
          } 
          saveImage.createNewFile(); 
        } 
        catch (IOException ex) { 
          ex.printStackTrace(); 
        } 
 
        imageUri = Uri.fromFile(saveImage); 
        Intent intent = new Intent("android.media.action.IMAGE_CAPTURE"); 
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri); 
        // 启动相机 
        startActivityForResult(intent, TAKE_PHOTO); 
      } 
    }); 
 
    chooseFromAlbum.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
        Intent intent = new Intent("android.intent.action.GET_CONTENT"); 
        intent.setType("image/*"); 
        // 打开相册 
        startActivityForResult(intent, CHOOSE_PHOTO); 
      } 
    }); 
  } 
 
  @Override 
  protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    switch (requestCode) { 
      case TAKE_PHOTO: 
        if (resultCode == RESULT_OK) { 
          Intent intent = new Intent("com.android.camera.action.CROP"); 
          intent.setDataAndType(imageUri, "image/*"); 
          intent.putExtra("scale", true); 
          intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri); 
          // 启动裁剪程序 
          startActivityForResult(intent, CROP_PHOTO); 
        } 
        break; 
 
      case CROP_PHOTO: 
        if (resultCode == RESULT_OK) { 
          try { 
            Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri)); 
            // 显示裁剪后的图片 
            picture.setImageBitmap(bitmap); 
          } 
          catch (FileNotFoundException ex) { 
            ex.printStackTrace(); 
          } 
        } 
        break; 
 
      case CHOOSE_PHOTO: 
        if (resultCode == RESULT_OK) { 
          handleImage(data); 
        } 
        break; 
 
      default: 
        break; 
    } 
  } 
 
  // 只在Android4.4及以上版本使用 
  @TargetApi(19) 
  private void handleImage(Intent data) { 
    String imagePath = null; 
    Uri uri = data.getData(); 
 
    if (DocumentsContract.isDocumentUri(this, uri)) { 
      // 通过document id来处理 
      String docId = DocumentsContract.getDocumentId(uri); 
      if ("com.android.providers.media.documents".equals(uri.getAuthority())) { 
        // 解析出数字id 
        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".equals(uri.getScheme())) { 
      // 如果不是document类型的Uri，则使用普通方式处理 
      imagePath = getImagePath(uri, null); 
    } 
 
    // 根据图片路径显示图片 
    displayImage(imagePath); 
  } 
 
  private String getImagePath(Uri uri, String selection) { 
    String path = null; 
    // 通过Uri和selection来获取真实图片路径 
    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(); 
    } 
  } 
}