Android:如何用相机拍照并将位图转换为字节数组并保存到sqlite db？

Question

我对 android 还是很陌生，仍在尝试弄清楚如何将图像保存到 SQLite 数据库。因为我正在尝试使用按钮单击事件调用相机来拍摄照片，并在返回时尝试将其作为 blob 保存到数据库中。我知道这可能不是最好的方法，话虽这么说，但我不知道该怎么做。我最后需要做的是使用我的应用程序访问相机，允许它拍照，并能够将照片保存在数据库中。到目前为止，我已经看到一些论坛，人们建议获取返回的位图并将其转换为字节数组并保存它。那会很好，但我又一次不知所措，任何帮助将不胜感激。这是我目前使用的代码:

//---Pressing this button will call the built in Camera---
    Button b4 = (Button) findViewById(R.id.btn_addPhotos);
    b4.setOnClickListener(new OnClickListener()
    {

        public void onClick(View arg0){

            Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);  

            //startActivity(cameraIntent);  
            startActivityForResult(cameraIntent, CAMERA_PIC_REQUEST);  
        }

    });

这是 onActivityResult() 方法:

protected void onActivityResult(int requestCode, int resultCode, Intent data){
   if (resultCode == Activity.RESULT_CANCELED)
   {
       //handles when camera was canceled...
       Toast.makeText(this, "Camera was cancelled by user...", Toast.LENGTH_LONG).show();

   } else if (resultCode == Activity.RESULT_OK)
   {

       Bitmap imageReturned = (Bitmap) data.getExtras().get("data");

       db.open();
       boolean id = db.insertImage(AssessmentID, imageReturned, "test");
               db.close();

       //displays message, if successful...
       displayMessage(id); 

   };
};

这是我的数据库类的插入方法:

 //---insert image into the database---
    public boolean insertImage(String AssessmentID, Bitmap picture, String name)//, String sub, String parcel, String lot, String elevation, String datum) 
    {
        boolean num = false;
        try
        {
                db.execSQL("insert into storedImages values(" + AssessmentID + ", " + picture + ", " + name + ");");
                num = true;
                //getting null pointer when trying to insert....
        }catch(SQLException e)
        {
            e.printStackTrace();
            num = false;
        };

            //returns true if successful and false if not...
        return num;
    }

这是 logcat 的错误:

10-23 15:10:51.890: ERROR/NvOmxCameraSettingsparser(89): Param type 13 not supported
10-23 15:10:51.890: ERROR/NvOmxCameraSettingsparser(89): Param type 49 not supported
10-23 15:10:52.200: ERROR/ImagerODM-OV5650(89): SetParameter(): 32 not supported
10-23 15:10:57.510: ERROR/NvOmxCamera(89): Already called release()
10-23 15:11:08.020: ERROR/AndroidRuntime(10123): FATAL EXCEPTION: main
10-23 15:11:08.020: ERROR/AndroidRuntime(10123): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1337, result=-1, data=Intent { act=inline-data (has extras) }} to activity {king.chad.SDE/king.chad.SDE.NewResidentialActivity}: java.lang.NullPointerException
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.app.ActivityThread.deliverResults(ActivityThread.java:2818)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.app.ActivityThread.handleSendResult(ActivityThread.java:2861)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.app.ActivityThread.access$1000(ActivityThread.java:122)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1054)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.os.Looper.loop(Looper.java:132)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.app.ActivityThread.main(ActivityThread.java:4123)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at java.lang.reflect.Method.invokeNative(Native Method)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at java.lang.reflect.Method.invoke(Method.java:491)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at dalvik.system.NativeStart.main(Native Method)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123): Caused by: java.lang.NullPointerException
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at king.chad.SDE.DBAdapter.insertImage(DBAdapter.java:406)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at king.chad.SDE.NewResidentialActivity.onActivityResult(NewResidentialActivity.java:168)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.app.Activity.dispatchActivityResult(Activity.java:4581)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     at android.app.ActivityThread.deliverResults(ActivityThread.java:2814)
10-23 15:11:08.020: ERROR/AndroidRuntime(10123):     ... 11 more

Answer 1

您通常不会将二进制数据保存到数据库中。它被认为是错误的形式，并且由于数据最终存储在磁盘上的方式，可能会使对数据库的查询花费很长时间。您应该做的是在数据库中存储图像的文件路径，并将图像存储在 sdcard 上。

无需为您编写大量代码，下面是一个高级示例。首先，使用以下 sql 调用创建用于存储图像的表:

CREATE TABLE images (_id INTEGER PRIMARY KEY AUTOICREMENT, file_path TEXT, name TEXT);

当需要插入图像时，您必须做两件事。首先，将图像写入 SD 卡。关注instructions here要做到这一点。一旦你把它写出来并得到一个文件名，你就可以像这样做一个 sql 查询:

INSERT INTO images (file_path, name) VALUES ("your file path", "name of image");

当您真正需要显示图像时，您只需从您的 sdcard 中读取 file_path 指定的文件即可。