一、权限问题

1. 可能会遇到的问题

requires android.permission.READ_EXTERNAL_STORAGE, or grantUriPermission()

Permission Denial: reading com.android.providers.media.MediaProvider

1. 添加权限

首先在AndroidManifest.xml根节点下添加下面的权限，主要是访问网络、相机、读写权限。

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

1. 动态请求许可

再andorid新版本里面，上面申请了权限之后，还是需要动态在申请权限，所以再需要用到的界面的onCreate方法里面添加如下代码，进行申请。

 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {requestPermissions(new String[] {Manifest.permission.CAMERA}, 1);}}if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {requestPermissions(new String[] {Manifest.permission.READ_EXTERNAL_STORAGE}, 1);}}

二、调用相机

1. 声明provider

首先，我们需要在主配置文件中声明provider，与activity同级别。之所以要用到provider，是因为从Android7.0开始，就不允许在 App 间，使用 file:// 的方式，传递一个 File ，否则就会抛出异常，而provider的作用恰好就是用过 content://的模式替换掉 file://，看上去只是换了个前缀，但其实是有真实路径转为了虚拟路径。

<providerandroid:authorities="com.example.yourpackage.provider"android:name="androidx.core.content.FileProvider"android:grantUriPermissions="true"><meta-dataandroid:name="android.support.FILE_PROVIDER_PATHS"android:resource="@xml/file_paths"/></provider>

file_paths的内容

<paths><external-pathname = "photo"path = "/"/>
</paths>

1. 调用相机

首先创建一个文件，用于保存拍照图像，然后根据不同系统版本获取Uri，传递给Intent，然后调起相机（可以考虑将outputImage、imageUri设置为全局变量）。

int REQUEST_CODE = 1;  //事件请求CODE为1
outputImage = new File(getExternalFilesDir(Environment.DIRECTORY_PICTURES),"last.jpg");
if (outputImage.exists())outputImage.delete();try {outputImage.createNewFile();} catch (IOException e) {e.printStackTrace();}
//注意com.example.yourpackage.provider要和provider声明中的一致
imageUri = (Build.VERSION.SDK_INT>=Build.VERSION_CODES.N) ? FileProvider.getUriForFile(context,"com.example.yourpackage.provider",outputImage) : Uri.fromFile(outputImage);
Intent intent1 = new Intent("android.media.action.IMAGE_CAPTURE");
intent1.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intent1,REQUEST_CODE);

1. 处理回调

使用BitmapFactory读取imageUri，得到bitmap，然后进行一些压缩，然后显示。

if (resultCode == Activity.RESULT_OK) {ContentResolver contentResolver = getContentResolver();Bitmap bitmap = null;try {bitmap = BitmapFactory.decodeStream(contentResolver.openInputStream(imageUri));Log.i("TAG", "从相册回传bitmap："+bitmap.getWidth());Bitmap bitmap2 = Bitmap.createScaledBitmap(bitmap,  bitmap.getWidth()/10 ,bitmap.getHeight()/10, true);img_imgview.setImageBitmap(bitmap2);this.flag = 1;} catch (FileNotFoundException e) {e.printStackTrace();}
}

1. 获取图像绝对路径

我们使用outputImage，来获取绝对路径，用于上传或者其它操作。

outputImage.getAbsolutePath()

三、调用相册

1. 调用相册

nt REQUEST_CODE = 2;
Intent intent1 = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent1.addCategory(Intent.CATEGORY_OPENABLE);
intent1.setType("image/*");
startActivityForResult(intent1,REQUEST_CODE);

1. 处理回调

if (resultCode == Activity.RESULT_OK && data != null) {if (data.getData()!=null) {ContentResolver contentResolver = getContentResolver();Bitmap bitmap = null;try {imageUri = data.getData();bitmap = BitmapFactory.decodeStream(contentResolver.openInputStream(data.getData()));Log.i("TAG", "从相册回传bitmap："+bitmap.getWidth());Bitmap bitmap2 = Bitmap.createScaledBitmap(bitmap,  bitmap.getWidth()/10 ,bitmap.getHeight()/10, true);img_imgview.setImageBitmap(bitmap2);this.flag = 2;} catch (FileNotFoundException e) {e.printStackTrace();}}
}

1. 获取图像绝对路径

这里就要麻烦很多，详细方法见四

FileHelper.getFileAbsolutePath(context, imageUri)

四、从Uri获取文件绝对路径

这是一个完整的帮助类，可以基于Uri获取绝对路径。

public class FileHelper {/*** 根据Uri获取文件绝对路径，解决Android4.4以上版本Uri转换** @param context* @param imageUri*/public static String getFileAbsolutePath(Context context, Uri imageUri) {if (context == null || imageUri == null) {return null;}if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.KITKAT) {return getRealFilePath(context, imageUri);}if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT && android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.Q && DocumentsContract.isDocumentUri(context, imageUri)) {if (isExternalStorageDocument(imageUri)) {String docId = DocumentsContract.getDocumentId(imageUri);String[] split = docId.split(":");String type = split[0];if ("primary".equalsIgnoreCase(type)) {return Environment.getExternalStorageDirectory() + "/" + split[1];}} else if (isDownloadsDocument(imageUri)) {String id = DocumentsContract.getDocumentId(imageUri);Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));return getDataColumn(context, contentUri, null, null);} else if (isMediaDocument(imageUri)) {String docId = DocumentsContract.getDocumentId(imageUri);String[] split = docId.split(":");String type = split[0];Uri contentUri = null;if ("image".equals(type)) {contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;} else if ("video".equals(type)) {contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;} else if ("audio".equals(type)) {contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;}String selection = MediaStore.Images.Media._ID + "=?";String[] selectionArgs = new String[]{split[1]};return getDataColumn(context, contentUri, selection, selectionArgs);}} // MediaStore (and general)if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q){return uriToFileApiQ(context,imageUri);}else if ("content".equalsIgnoreCase(imageUri.getScheme())) {// Return the remote addressif (isGooglePhotosUri(imageUri)) {return imageUri.getLastPathSegment();}return getDataColumn(context, imageUri, null, null);}// Fileelse if ("file".equalsIgnoreCase(imageUri.getScheme())) {return imageUri.getPath();}return null;}//此方法 只能用于4.4以下的版本private static String getRealFilePath(final Context context, final Uri uri) {if (null == uri) {return null;}final String scheme = uri.getScheme();String data = null;if (scheme == null) {data = uri.getPath();} else if (ContentResolver.SCHEME_FILE.equals(scheme)) {data = uri.getPath();} else if (ContentResolver.SCHEME_CONTENT.equals(scheme)) {String[] projection = {MediaStore.Images.ImageColumns.DATA};Cursor cursor = context.getContentResolver().query(uri, projection, null, null, null);//            Cursor cursor = context.getContentResolver().query(uri, new String[]{MediaStore.Images.ImageColumns.DATA}, null, null, null);if (null != cursor) {if (cursor.moveToFirst()) {int index = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);if (index > -1) {data = cursor.getString(index);}}cursor.close();}}return data;}/*** @param uri The Uri to check.* @return Whether the Uri authority is ExternalStorageProvider.*/private static boolean isExternalStorageDocument(Uri uri) {return "com.android.externalstorage.documents".equals(uri.getAuthority());}/*** @param uri The Uri to check.* @return Whether the Uri authority is DownloadsProvider.*/private static boolean isDownloadsDocument(Uri uri) {return "com.android.providers.downloads.documents".equals(uri.getAuthority());}private static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {Cursor cursor = null;String column = MediaStore.Images.Media.DATA;String[] projection = {column};try {cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);if (cursor != null && cursor.moveToFirst()) {int index = cursor.getColumnIndexOrThrow(column);return cursor.getString(index);}} finally {if (cursor != null) {cursor.close();}}return null;}/*** @param uri The Uri to check.* @return Whether the Uri authority is MediaProvider.*/private static boolean isMediaDocument(Uri uri) {return "com.android.providers.media.documents".equals(uri.getAuthority());}/*** @param uri The Uri to check.* @return Whether the Uri authority is Google Photos.*/private static boolean isGooglePhotosUri(Uri uri) {return "com.google.android.apps.photos.content".equals(uri.getAuthority());}/*** Android 10 以上适配 另一种写法* @param context* @param uri* @return*/public static String getFileFromContentUri(Context context, Uri uri) {if (uri == null) {return null;}String filePath;String[] filePathColumn = {MediaStore.MediaColumns.DATA, MediaStore.MediaColumns.DISPLAY_NAME};ContentResolver contentResolver = context.getContentResolver();Cursor cursor = contentResolver.query(uri, filePathColumn, null,null, null);if (cursor != null) {cursor.moveToFirst();try {filePath = cursor.getString(cursor.getColumnIndex(filePathColumn[0]));return filePath;} catch (Exception e) {} finally {cursor.close();}}return "";}/*** Android 10 以上适配* @param context* @param uri* @return*/@RequiresApi(api = Build.VERSION_CODES.Q)private static String uriToFileApiQ(Context context, Uri uri) {File file = null;//android10以上转换if (uri.getScheme().equals(ContentResolver.SCHEME_FILE)) {file = new File(uri.getPath());} else if (uri.getScheme().equals(ContentResolver.SCHEME_CONTENT)) {//把文件复制到沙盒目录ContentResolver contentResolver = context.getContentResolver();Cursor cursor = contentResolver.query(uri, null, null, null, null);if (cursor.moveToFirst()) {String displayName = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));try {InputStream is = contentResolver.openInputStream(uri);File cache = new File(context.getExternalCacheDir().getAbsolutePath(), Math.round((Math.random() + 1) * 1000) + displayName);FileOutputStream fos = new FileOutputStream(cache);FileUtils.copy(is, fos);file = cache;fos.close();is.close();} catch (IOException e) {e.printStackTrace();}}}return file.getAbsolutePath();}
}

五、http请求并上传

1. 通过okhttp调用接口

修改模块的build.gradle 增加下面一行依赖配置

implementation 'com.squareup.okhttp3:okhttp:4.9.1

1. Get请求

OkHttpClient client = new OkHttpClient(); // 创建一个okhttp客户端对象
// 创建一个GET方式的请求结构
xRequest request = new Request.Builder()//.get() // 因为OkHttp默认采用get方式，所以这里可以不调get方法.header("Accept-Language", "zh-CN") // 给http请求添加头部信息.url("http://192.168.1.104:5291/myApi/GetList") // 指定http请求的调用地址.build();
Call call = client.newCall(request); // 根据请求结构创建调用对象
// 加入HTTP请求队列。异步调用，并设置接口应答的回调方法
call.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) { // 请求失败// 回到主线程操纵界面runOnUiThread(() -> {Toast toast= Toast.makeText(context, "默认失败的Toast" + e.getMessage().toString(), Toast.LENGTH_SHORT);toast.show();});}@Overridepublic void onResponse(Call call, final Response response) throws IOException { // 请求成功String resp = response.body().string();// 回到主线程操纵界面runOnUiThread(() -> {Toast toast= Toast.makeText(context, "默认成功的的Toast" + resp, Toast.LENGTH_SHORT);toast.show();});}
});

1. Post from表单上传文件和数据

//文件
File file = new File(picUrl);
//请求体
MultipartBody.Builder builder = new MultipartBody.Builder();
builder.setType(MultipartBody.FORM);
//数据1
builder.addFormDataPart("date", date);
//数据2
builder.addFormDataPart("banzu", banzu);
//文件，注意名称，这里是files，后台需要用这个名字接数据
builder.addFormDataPart("files", file.getName(), RequestBody.create(MediaType.parse("image/jpeg"), file));
MultipartBody body = builder.build();// 创建一个okhttp客户端对象，设置超时
OkHttpClient client = new OkHttpClient().newBuilder().connectTimeout(30, TimeUnit.SECONDS).readTimeout(60, TimeUnit.SECONDS).build();// 创建一个POST方式的请求结构
Request request = new Request.Builder().post(body).url("http://192.168.1.100:5290/upLoadFile").build();
Call call = client.newCall(request); // 根据请求结构创建调用对象
// 加入HTTP请求队列。异步调用，并设置接口应答的回调方法
call.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) { // 请求失败// 回到主线程操纵界面runOnUiThread(() -> {Toast toast= Toast.makeText(context, "默认失败的Toast" + e.getMessage().toString(), Toast.LENGTH_SHORT);toast.show();//关闭loadingdialog.dismiss();});}@Overridepublic void onResponse(Call call, final Response response) throws IOException { // 请求成功String resp = response.body().string();// 回到主线程操纵界面runOnUiThread(() -> {Toast toast= Toast.makeText(context, "默认成功的Toast", Toast.LENGTH_SHORT);toast.show();//关闭loadingdialog.dismiss();});}
});

1. Post Json数据

private void postJson() {String username = et_username.getText().toString();String password = et_password.getText().toString();String jsonString = "";try {JSONObject jsonObject = new JSONObject();jsonObject.put("username", username);jsonObject.put("password", password);jsonString = jsonObject.toString();} catch (Exception e) {e.printStackTrace();}// 创建一个POST方式的请求结构RequestBody body = RequestBody.create(jsonString, MediaType.parse("text/plain;charset=utf-8"));OkHttpClient client = new OkHttpClient(); // 创建一个okhttp客户端对象Request request = new Request.Builder().post(body).url(URL_LOGIN).build();Call call = client.newCall(request); // 根据请求结构创建调用对象// 加入HTTP请求队列。异步调用，并设置接口应答的回调方法call.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) { // 请求失败// 回到主线程操纵界面runOnUiThread(() -> tv_result.setText("调用登录接口报错："+e.getMessage()));}@Overridepublic void onResponse(Call call, final Response response) throws IOException { // 请求成功.setText("调用登录接口返回：\n"+resp));}});}

六、参考代码下载

https://download.csdn.net/download/bashendixie5/87823865