android自定义camera以及uri和文件路径之间的转换
相对直接调用系统的camera,这种方法使用得相对还少一些。根据api文档,步骤如下:
定义一个预览类
可以参照《android高薪之路》这本书上面,有这种方法的一种完整实现
而对应的activity如下:
package com.bobo.mycamara; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.text.SimpleDateFormat; import java.util.Date; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Bitmap.CompressFormat; import android.hardware.Camera; import android.hardware.Camera.PictureCallback; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.view.View; import android.widget.Button; import android.widget.FrameLayout; public class MyCameraActivity extends Activity { private Camera mCamera; private Button btn_capture; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(R.layout.mycamera_layout); btn_capture = (Button) this.findViewById(R.id.button_capture); mCamera = getCameraInstance(); MyCameraPreview mPreview = new MyCameraPreview(this, mCamera); FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview); preview.addView(mPreview); btn_capture.setOnClickListener(new CaptureListener()); } class CaptureListener implements View.OnClickListener { @Override public void onClick(View v) { // 这里进行拍照操作 mCamera.takePicture(null, null, mPicture); } } // 拍照结束之后的回调接口 private PictureCallback mPicture = new PictureCallback() { @Override public void onPictureTaken(byte[] data, Camera camera) { // 将文件进行存储 System.out.println(new String(data)); File mediaFile = getMediaFile(); try { FileOutputStream fos = new FileOutputStream(mediaFile); // 这样保存出来的也是图像格式 fos.write(data); // 不过如果使用下面的方法,可以在保存之前利用bitmap的相关方法,对相应的bitmap进行进一步的调整,如借助matrix // Bitmap bitmap=BitmapFactory.decodeByteArray(data, 0, // data.length); // bitmap.compress(CompressFormat.JPEG, 100, fos); } catch (Exception e) { e.printStackTrace(); } } }; // 当activity暂停的时候一定要记得将camera资源release掉 @Override protected void onPause() { super.onPause(); if (this.mCamera != null) { this.mCamera.release(); this.mCamera = null; } } protected Uri getFileUri(File file) { return Uri.fromFile(file); } protected File getMediaFile() { File mediaDir = new File( Environment .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "myCamera"); if (!mediaDir.exists()) { if (!mediaDir.mkdirs()) { return null; } } String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss") .format(new Date()); File mediaFile; mediaFile = new File(mediaDir.getPath() + File.separator + "IMG_" + timeStamp + ".jpg"); return mediaFile; } // 获得系统的相机 public Camera getCameraInstance() { Camera c = null; try { c = Camera.open(); // attempt to get a Camera instance } catch (Exception e) { } return c; } }
private String getRealPath(Uri fileUrl) { String fileName = null; Uri filePathUri = fileUrl; if (fileUrl != null) { if (fileUrl.getScheme().toString().compareTo("content") == 0) { // content://开头的uri Cursor cursor = getContentResolver().query(fileUrl, null, null, null, null); if (cursor != null && cursor.moveToFirst()) { int column_index = cursor.getColumnIndexOrThrow("_data"); fileName = cursor.getString(column_index); // 取出文件路径 if (!fileName.startsWith("/mnt")) { // 检查是否有”/mnt“前缀 fileName = "/mnt" + fileName; } cursor.close(); } } else if (fileUrl.getScheme().compareTo("file") == 0) { // file:///开头的uri fileName = filePathUri.toString(); fileName = filePathUri.toString().replace("file://", ""); // 替换file:// if (!fileName.startsWith("/mnt")) { // 加上"/mnt"头 fileName += "/mnt"; } } } return fileName; }
同时别忘了增添了相应的权限。这里有将文件路径转换为uri的方法,反过来如何通过uri查看文件路径呢?