Android 拍照(選擇圖片)並上傳(包含權限動態獲取)

作爲一個Android新手，想實現手機拍照並上傳的功能，經過查找資料，已實現此功能。在此記錄備忘。老鳥請忽略。

一、實現思路：

1.Android手機客戶端，拍照(或選擇圖片)，然後上傳到服務器。

2.服務器端接收手機端上傳上來的圖片。

二、實現步驟：

1.按慣例，先放效果圖：

項目結構：

2.activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="5dp">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="圖片預覽" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="400dp"
        android:background="#fff"
        android:padding="1dp"
        android:scaleType="fitXY" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btnPhoto"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="拍照" />

        <Button
            android:id="@+id/btnSelect"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="選擇" />
    </LinearLayout>
</LinearLayout>

3.MainActivity.java

package com.qingshan.note;

import androidx.annotation.NonNull;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.app.AlertDialog;
import android.content.ContentValues;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.provider.Settings;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button btnPhoto, btnSelect;
    private Intent intent;
    private final int CAMERA = 1;//事件枚舉(可以自定義)
    private final int CHOOSE = 2;//事件枚舉(可以自定義)
    private final String postUrl = "http://qingshanboke.com/Home/AndoridUploadFile";//接收上傳圖片的地址
    String photoPath = "";//要上傳的圖片路徑
    private final int permissionCode = 100;//權限請求碼

    //權限集合，對應在AndroidManifest.xml文件中添加配置
    //    <uses-permission android:name="android.permission.CAMERA" />
    //    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    //    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    //    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    //    <uses-permission android:name="android.permission.INTERNET"/>
    String[] permissions = new String[]{
            Manifest.permission.CAMERA,
            Manifest.permission.WRITE_EXTERNAL_STORAGE,
            Manifest.permission.ACCESS_NETWORK_STATE,
            Manifest.permission.ACCESS_WIFI_STATE,
            Manifest.permission.INTERNET
    };
    AlertDialog alertDialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //6.0才用動態權限
        if (Build.VERSION.SDK_INT >= 23) {
            checkPermission();
        }

        btnPhoto = findViewById(R.id.btnPhoto);
        btnSelect = findViewById(R.id.btnSelect);
        btnPhoto.setOnClickListener(this);
        btnSelect.setOnClickListener(this);
    }

    //檢查權限
    private void checkPermission() {
        List<String> permissionList = new ArrayList<>();
        for (int i = 0; i < permissions.length; i++) {
            if (ContextCompat.checkSelfPermission(this, permissions[i]) != PackageManager.PERMISSION_GRANTED) {
                permissionList.add(permissions[i]);
            }
        }
        if (permissionList.size() <= 0) {
            //說明權限都已經通過，可以做你想做的事情去

        } else {
            //存在未允許的權限
            ActivityCompat.requestPermissions(this, permissions, permissionCode);
        }
    }

    //授權後回調函數
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        boolean haspermission = false;
        if (permissionCode == requestCode) {
            for (int i = 0; i < grantResults.length; i++) {
                if (grantResults[i] == -1) {
                    haspermission = true;
                }
            }
            if (haspermission) {
                //跳轉到系統設置權限頁面，或者直接關閉頁面，不讓他繼續訪問
                permissionDialog();
            } else {
                //全部權限通過，可以進行下一步操作
            }
        }
    }

    //打開手動設置應用權限
    private void permissionDialog() {
        if (alertDialog == null) {
            alertDialog = new AlertDialog.Builder(this)
                    .setTitle("提示信息")
                    .setMessage("當前應用缺少必要權限，該功能暫時無法使用。如若需要，請單擊【確定】按鈕前往設置中心進行權限授權。")
                    .setPositiveButton("設置", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            cancelPermissionDialog();
                            Uri packageURI = Uri.parse("package:" + getPackageName());
                            Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS, packageURI);
                            startActivity(intent);
                        }
                    })
                    .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            cancelPermissionDialog();
                        }
                    })
                    .create();
        }
        alertDialog.show();
    }

    //用戶取消授權
    private void cancelPermissionDialog() {
        alertDialog.cancel();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {

            //拍照按鈕事件
            case R.id.btnPhoto:
                //方法一：這樣拍照只能取到縮略圖（不清晰）
                //intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
                //startActivityForResult(intent, CAMERA);


                //方法二：指定加載路徑圖片路徑（保存原圖，清晰）
                String SD_PATH = Environment.getExternalStorageDirectory().getPath() + "/拍照上傳示例/";
                SimpleDateFormat format = new SimpleDateFormat("yyyyMMddHHmmss");
                String fileName = format.format(new Date(System.currentTimeMillis())) + ".JPEG";
                photoPath = SD_PATH + fileName;
                File file = new File(photoPath);
                if (!file.getParentFile().exists()) {
                    file.getParentFile().mkdirs();
                }

                //兼容7.0以上的版本
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                    try {
                        ContentValues values = new ContentValues(1);
                        values.put(MediaStore.Images.Media.MIME_TYPE, "image/jpg");
                        values.put(MediaStore.Images.Media.DATA, photoPath);
                        Uri tempuri = getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
                        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
                        if (tempuri != null) {
                            intent.putExtra(MediaStore.EXTRA_OUTPUT, tempuri);
                            intent.putExtra(MediaStore.EXTRA_VIDEO_QUALITY, 1);
                        }
                        startActivityForResult(intent, CAMERA);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                } else {
                    intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                    Uri uri = Uri.fromFile(file);
                    intent.putExtra(MediaStore.EXTRA_OUTPUT, uri); //指定拍照後的存儲路徑，保存原圖
                    startActivityForResult(intent, CAMERA);
                }
                break;

            //選擇按鈕事件
            case R.id.btnSelect:
                intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
                startActivityForResult(intent, CHOOSE);
                break;
        }
    }

    @RequiresApi(api = Build.VERSION_CODES.O)
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
            // 調用照相機拍照
            case CAMERA:
                if (resultCode == RESULT_OK) {
                    //對應方法一：圖片未保存，需保存文件到本地
//                    Bundle bundle = data.getExtras();
//                    Bitmap bitmap = (Bitmap) bundle.get("data");
//                    String savePath;
//                    String SD_PATH = Environment.getExternalStorageDirectory().getPath() + "/拍照上傳示例/";
//                    SimpleDateFormat format = new SimpleDateFormat("yyyyMMddHHmmss");
//                    String fileName = format.format(new Date(System.currentTimeMillis())) + ".JPEG";
//                    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
//                        savePath = SD_PATH;
//                    } else {
//                        Toast.makeText(MainActivity.this, "保存失敗！", Toast.LENGTH_SHORT).show();
//                        return;
//                    }
//                    photoPath = savePath + fileName;
//                    File file = new File(photoPath);
//                    try {
//                        if (!file.exists()) {
//                            file.getParentFile().mkdirs();
//                            file.createNewFile();
//                        }
//                        FileOutputStream stream = new FileOutputStream(file);
//                        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);
//                        Toast.makeText(MainActivity.this, "保存成功,位置:" + file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
//                    } catch (IOException e) {
//                        e.printStackTrace();
//                    }

                    //對應方法二：圖片已保存，只需讀取就行了
                    try {
                        FileInputStream stream = new FileInputStream(photoPath);
                        Bitmap bitmap = BitmapFactory.decodeStream(stream);

                        //預覽圖片
                        ImageView image = findViewById(R.id.imageView);
                        image.setImageBitmap(bitmap);

                        //上傳圖片（Android 4.0 之後不能在主線程中請求HTTP請求）
                        File file = new File(photoPath);
                        if (file.exists()) {
                            new Thread(new Runnable() {
                                @Override
                                public void run() {
                                    //文本字段（用於驗證用戶身份）
                                    HashMap<String, String> form = new HashMap<String, String>();
                                    form.put("username", "zhangqs");
                                    form.put("password", "123456");

                                    //圖片字段
                                    HashMap<String, String> file = new HashMap<String, String>();
                                    file.put(PathHelper.getFileNameFromPath(photoPath), photoPath);
                                    formUpload(postUrl, form, file);
                                }
                            }).start();
                        }
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    }
                }
                break;
            // 選擇圖片庫的圖片
            case CHOOSE:
                if (resultCode == RESULT_OK) {
                    try {
                        Uri uri = data.getData();
                        photoPath = PathHelper.getRealPathFromUri(MainActivity.this, uri);
                        Bitmap bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), uri);

                        //壓縮圖片
                        bitmap = scaleBitmap(bitmap, (float) 0.5);

                        //預覽圖片
                        ImageView image = findViewById(R.id.imageView);
                        image.setImageBitmap(bitmap);

                        //上傳圖片（Android 4.0 之後不能在主線程中請求HTTP請求）
                        File file = new File(photoPath);
                        if (file.exists()) {
                            new Thread(new Runnable() {
                                @Override
                                public void run() {
                                    //文本字段（用於驗證用戶身份）
                                    HashMap<String, String> form = new HashMap<String, String>();
                                    form.put("username", "zhangqs");
                                    form.put("password", "123456");

                                    //圖片字段
                                    HashMap<String, String> file = new HashMap<String, String>();
                                    file.put(PathHelper.getFileNameFromPath(photoPath), photoPath);
                                    formUpload(postUrl, form, file);
                                }
                            }).start();
                        }

                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                break;
        }
    }

    //壓縮圖片
    public Bitmap scaleBitmap(Bitmap origin, float ratio) {
        if (origin == null) {
            return null;
        }
        int width = origin.getWidth();
        int height = origin.getHeight();
        Matrix matrix = new Matrix();
        matrix.preScale(ratio, ratio);
        Bitmap newBM = Bitmap.createBitmap(origin, 0, 0, width, height, matrix, false);
        return newBM;
    }

    //POST 表單提交
    @RequiresApi(api = Build.VERSION_CODES.O)
    public static String formUpload(String posturl, Map<String, String> textMap, Map<String, String> fileMap) {
        String res = "";
        HttpURLConnection conn = null;
        String BOUNDARY = "---------------------------123821742118716"; //boundary就是request頭和上傳文件內容的分隔符
        try {
            URL url = new URL(posturl);
            conn = (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(5000);
            conn.setReadTimeout(30000);
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setUseCaches(false);
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Connection", "Keep-Alive");
            conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.6)");
            conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);

            OutputStream out = new DataOutputStream(conn.getOutputStream());

            // text
            if (textMap != null) {
                StringBuffer buffer = new StringBuffer();
                Iterator iter = textMap.entrySet().iterator();
                while (iter.hasNext()) {
                    Map.Entry entry = (Map.Entry) iter.next();
                    String inputName = (String) entry.getKey();
                    String inputValue = (String) entry.getValue();
                    if (inputValue == null) {
                        continue;
                    }
                    buffer.append("\r\n").append("--").append(BOUNDARY).append("\r\n");
                    buffer.append("Content-Disposition: form-data; name=\"" + inputName + "\"\r\n\r\n");
                    buffer.append(inputValue);
                }
                out.write(buffer.toString().getBytes());
            }

            // file
            if (fileMap != null) {
                Iterator iter = fileMap.entrySet().iterator();
                while (iter.hasNext()) {
                    Map.Entry entry = (Map.Entry) iter.next();
                    String inputName = (String) entry.getKey();
                    String inputValue = (String) entry.getValue();
                    if (inputValue == null) {
                        continue;
                    }
                    File file = new File(inputValue);
                    String filename = file.getName();
                    String contentType = "";
                    if (filename.endsWith(".jpg")) {
                        contentType = "image/jpg";
                    } else if (filename.endsWith(".png")) {
                        contentType = "image/png";
                    } else if (contentType == null || contentType.equals("")) {
                        contentType = "application/octet-stream";
                    }

                    StringBuffer buffer = new StringBuffer();
                    buffer.append("\r\n").append("--").append(BOUNDARY).append("\r\n");
                    buffer.append("Content-Disposition: form-data; name=\"" + inputName + "\"; filename=\"" + filename + "\"\r\n");
                    buffer.append("Content-Type:" + contentType + "\r\n\r\n");

                    out.write(buffer.toString().getBytes());

                    DataInputStream in = new DataInputStream(new FileInputStream(file));
                    int bytes = 0;
                    byte[] bufferOut = new byte[1024];
                    while ((bytes = in.read(bufferOut)) != -1) {
                        out.write(bufferOut, 0, bytes);
                    }
                    in.close();
                }
            }

            byte[] endData = ("\r\n--" + BOUNDARY + "--\r\n").getBytes();
            out.write(endData);
            out.flush();
            out.close();

            // 讀取返回數據
            StringBuffer buffer = new StringBuffer();
            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String line = null;
            while ((line = reader.readLine()) != null) {
                buffer.append(line).append("\n");
            }
            res = buffer.toString();
            reader.close();
            reader = null;
        } catch (Exception e) {
            System.out.println("發送POST請求出錯。" + posturl);
            e.printStackTrace();
        } finally {
            if (conn != null) {
                conn.disconnect();
                conn = null;
            }
        }
        return res;
    }


}

4.輔助類 PathHelper.java

package com.qingshan.note;

import android.annotation.SuppressLint;
import android.content.ContentUris;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.provider.DocumentsContract;
import android.provider.MediaStore;

//Android 路徑輔助類
public class PathHelper {

    //適配api19以下(不包括api19),根據uri獲取圖片的絕對路徑
    public static String getRealPathFromUri(Context context, Uri uri) {
        int sdkVersion = Build.VERSION.SDK_INT;
        if (sdkVersion >= 19) { // api >= 19
            return getRealPathFromUriAboveApi19(context, uri);
        } else { // api < 19
            return getRealPathFromUriBelowAPI19(context, uri);
        }
    }

    /**
     * 適配api19以下(不包括api19),根據uri獲取圖片的絕對路徑
     *
     * @param context 上下文對象
     * @param uri     圖片的Uri
     * @return 如果Uri對應的圖片存在, 那麼返回該圖片的絕對路徑, 否則返回null
     */
    private static String getRealPathFromUriBelowAPI19(Context context, Uri uri) {
        return getDataColumn(context, uri, null, null);
    }

    /**
     * 適配api19及以上,根據uri獲取圖片的絕對路徑
     *
     * @param context 上下文對象
     * @param uri     圖片的Uri
     * @return 如果Uri對應的圖片存在, 那麼返回該圖片的絕對路徑, 否則返回null
     */
    @SuppressLint("NewApi")
    private static String getRealPathFromUriAboveApi19(Context context, Uri uri) {
        String filePath = null;
        if (DocumentsContract.isDocumentUri(context, uri)) {
            // 如果是document類型的 uri, 則通過document id來進行處理
            String documentId = DocumentsContract.getDocumentId(uri);
            if (isMediaDocument(uri)) { // MediaProvider
                // 使用':'分割
                String id = documentId.split(":")[1];
                String selection = MediaStore.Images.Media._ID + "=?";
                String[] selectionArgs = {id};
                filePath = getDataColumn(context, MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection, selectionArgs);
            } else if (isDownloadsDocument(uri)) { // DownloadsProvider
                Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(documentId));
                filePath = getDataColumn(context, contentUri, null, null);
            }
        } else if ("content".equalsIgnoreCase(uri.getScheme())) {
            // 如果是 content 類型的 Uri
            filePath = getDataColumn(context, uri, null, null);
        } else if ("file".equals(uri.getScheme())) {
            // 如果是 file 類型的 Uri,直接獲取圖片對應的路徑
            filePath = uri.getPath();
        }
        return filePath;
    }

    private static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {
        String path = null;
        String[] projection = new String[]{MediaStore.Images.Media.DATA};
        Cursor cursor = null;
        try {
            cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);
            if (cursor != null && cursor.moveToFirst()) {
                int columnIndex = cursor.getColumnIndexOrThrow(projection[0]);
                path = cursor.getString(columnIndex);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
        return path;
    }

    private static boolean isMediaDocument(Uri uri) {
        return "com.android.providers.media.documents".equals(uri.getAuthority());
    }

    private static boolean isDownloadsDocument(Uri uri) {
        return "com.android.providers.downloads.documents".equals(uri.getAuthority());
    }

    //從路徑中提取文件名
    public static String getFileNameFromPath(String path) {
        int start = path.lastIndexOf("/");
        int end = path.lastIndexOf(".");
        if (start != -1 && end != -1) {
            return path.substring(start + 1, end);
        } else {
            return null;
        }

    }
}

5.AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.qingshan.note">

    <!-- 因爲拍照需要寫入文件 所以需要申請讀取內存的權限 -->
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:networkSecurityConfig="@xml/network_security_config"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:usesCleartextTraffic="true"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

6.\res\xml\network_security_config.xml

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <base-config cleartextTrafficPermitted="true"  />
    <domain-config cleartextTrafficPermitted="true" >
        <domain includeSubdomains="true">127.0.0.1</domain>
        <domain includeSubdomains="true">192.168.100.192</domain>
        <domain includeSubdomains="true">localhost</domain>
        <domain includeSubdomains="true">qingshanboke.com</domain>
    </domain-config>
</network-security-config>

7.服務器端接收（asp.net mvc 接收）

        public ActionResult AndoridUploadFile()
        {
            var userName = Request.Params["username"];
            var password = Request.Params["password"];
            if (string.IsNullOrEmpty(userName) || string.IsNullOrEmpty(password))
            {
                return Content("抱歉，用戶名和密碼錯誤！");
            }
            //todo:身份驗證

            var dir = PathHelper.GetMapPath("~/Uploadfiles/" + DateTime.Now.ToString("yyyy-MM"));
            if (!Directory.Exists(dir))
            {
                Directory.CreateDirectory(dir);
            }
            for (int i = 0; i < Request.Files.Count; i++)
            {
                var path = Path.Combine(dir, DateTime.Now.ToString("yyyyMMddHHmmss") + ".jpg");
                if (Request.Files[i] != null)
                {
                    Request.Files[i].SaveAs(path);
                }
            }
            return Content("{\"isSuccess\":true}");
        }

三、注意事項

1.Android發起http請求時，默認請求地址需https，需要增加 network-security-config 配置來允許使用http。（詳見上面6.\res\xml\network_security_config.xml）

2.發起post提交時，往往需要做接口身份識別，需要將文本字段和圖片字段一起提交，構造表單時，需要 "Content-Type", "multipart/form-data; boundary..."。

3.拍照時，默認只能取到縮略圖，不夠清晰，若要取到原圖，需要在拍照時，傳入指定保存位置，在回調函數中只需讀取就可以了。