Android获取本机图片教程

作为一名经验丰富的开发者，我将通过此篇文章教会你如何在Android应用中实现获取本机图片的功能。下面是整个流程的概览表格：

接下来，让我们逐步详细介绍每个步骤的具体操作。

步骤一：请求存储权限

在AndroidManifest.xml文件中添加以下权限：

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

在Activity中添加以下代码以请求权限：

private static final int REQUEST_STORAGE_PERMISSION = 1;

private void requestStoragePermission() {
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, REQUEST_STORAGE_PERMISSION);
    }
}

在onRequestPermissionsResult方法中处理权限请求的结果：

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (requestCode == REQUEST_STORAGE_PERMISSION) {
        if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            // 权限已授予
        } else {
            // 权限被拒绝
        }
    }
}

步骤二：打开系统相册

在需要打开相册的地方调用以下代码：

private static final int REQUEST_IMAGE_PICK = 2;

private void openGallery() {
    Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    startActivityForResult(intent, REQUEST_IMAGE_PICK);
}

步骤三：选择图片

在Activity中重写onActivityResult方法，获取选择的图片的URI：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == REQUEST_IMAGE_PICK && resultCode == RESULT_OK && data != null) {
        Uri imageUri = data.getData();
        // 将图片URI传递给下一步骤
    }
}

步骤四：获取图片路径

添加以下依赖库到app的build.gradle文件中：

implementation 'com.github.bumptech.glide:glide:4.12.0'
annotationProcessor 'com.github.bumptech.glide:compiler:4.12.0'

然后在需要获取图片路径的地方调用以下代码：

String imagePath = FileUtils.getPath(this, imageUri);

其中，FileUtils是一个自定义的工具类，用于将图片URI转换为路径。以下是FileUtils的代码：

public class FileUtils {
    public static String getPath(Context context, Uri uri) {
        String path = null;
        if (DocumentsContract.isDocumentUri(context, uri)) {
            if (isExternalStorageDocument(uri)) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];
                if ("primary".equalsIgnoreCase(type)) {
                    path = Environment.getExternalStorageDirectory() + "/" + split[1];
                }
            } else if (isDownloadsDocument(uri)) {
                final String id = DocumentsContract.getDocumentId(uri);
                final Uri contentUri = ContentUris.withAppendedId(
                        Uri.parse("content://downloads/public_downloads"), Long.parseLong(id));
                path = getDataColumn(context, contentUri, null, null);
            } else if (isMediaDocument(uri)) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final 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;
                }
                final String selection = "_id=?";
                final String[] selectionArgs = new String[]{split[1]};
                path = getDataColumn(context, contentUri, selection, selectionArgs);
            }
        } else if ("content".equalsIgnoreCase(uri.getScheme())) {
            path = getDataColumn(context, uri, null, null);
        } else if ("file".equalsIgnoreCase(uri.getScheme())) {
            path = uri.getPath();
        }
        return path;