试试这个 -在舱单上填写:

uses-permission android:name="android.permission.INSTALL_PACKAGES"
        tools:ignore="ProtectedPermissions"

编写代码:

File sdCard = Environment.getExternalStorageDirectory();
String fileStr = sdCard.getAbsolutePath() + "/Download";// + "app-release.apk";
File file = new File(fileStr, "app-release.apk");
Intent promptInstall = new Intent(Intent.ACTION_VIEW).setDataAndType(Uri.fromFile(file),
                        "application/vnd.android.package-archive");

startActivity(promptInstall);

在Android Oreo及以上版本中，我们必须采用不同的方法以编程方式安装apk。

 private void installApkProgramatically() {


    try {
        File path = activity.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS);

        File file = new File(path, filename);

        Uri uri;

        if (file.exists()) {

            Intent unKnownSourceIntent = new Intent(Settings.ACTION_MANAGE_UNKNOWN_APP_SOURCES).setData(Uri.parse(String.format("package:%s", activity.getPackageName())));

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {

                if (!activity.getPackageManager().canRequestPackageInstalls()) {
                    startActivityForResult(unKnownSourceIntent, Constant.UNKNOWN_RESOURCE_INTENT_REQUEST_CODE);
                } else {
                    Uri fileUri = FileProvider.getUriForFile(activity.getBaseContext(), activity.getApplicationContext().getPackageName() + ".provider", file);
                    Intent intent = new Intent(Intent.ACTION_VIEW, fileUri);
                    intent.putExtra(Intent.EXTRA_NOT_UNKNOWN_SOURCE, true);
                    intent.setDataAndType(fileUri, "application/vnd.android" + ".package-archive");
                    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK);
                    intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
                    startActivity(intent);
                    alertDialog.dismiss();
                }

            } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {

                Intent intent1 = new Intent(Intent.ACTION_INSTALL_PACKAGE);
                uri = FileProvider.getUriForFile(activity.getApplicationContext(), BuildConfig.APPLICATION_ID + ".provider", file);
                activity.grantUriPermission("com.abcd.xyz", uri, Intent.FLAG_GRANT_READ_URI_PERMISSION);
                activity.grantUriPermission("com.abcd.xyz", uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
                intent1.setDataAndType(uri,
                        "application/*");
                intent1.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                intent1.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
                intent1.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
                startActivity(intent1);

            } else {
                Intent intent = new Intent(Intent.ACTION_VIEW);

                uri = Uri.fromFile(file);

                intent.setDataAndType(uri,
                        "application/vnd.android.package-archive");
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(intent);
            }
        } else {

            Log.i(TAG, " file " + file.getPath() + " does not exist");
        }
    } catch (Exception e) {

        Log.i(TAG, "" + e.getMessage());

    }
}

在Oreo及以上版本中，我们需要未知资源安装权限。所以在活动结果中，你必须检查结果的权限

    @Override
public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    switch (requestCode) {

        case Constant.UNKNOWN_RESOURCE_INTENT_REQUEST_CODE:
            switch (resultCode) {
                case Activity.RESULT_OK:
                    installApkProgramatically();

                    break;
                case Activity.RESULT_CANCELED:
                    //unknown resouce installation cancelled

                    break;
            }
            break;
    }
}

是的，这是可能的。但要做到这一点，你需要在手机上安装未经验证的消息源。例如，slideMe就是这样做的。我认为你能做的最好的事情是检查应用程序是否存在，并向Android市场发送一个意图。你应该使用android市场的url方案。

market://details?id=package.name

我不知道如何启动这个活动但如果你用那种url启动一个活动。它应该打开android市场，给你安装应用程序的选择。

试试这个 -在舱单上填写:

uses-permission android:name="android.permission.INSTALL_PACKAGES"
        tools:ignore="ProtectedPermissions"

编写代码:

File sdCard = Environment.getExternalStorageDirectory();
String fileStr = sdCard.getAbsolutePath() + "/Download";// + "app-release.apk";
File file = new File(fileStr, "app-release.apk");
Intent promptInstall = new Intent(Intent.ACTION_VIEW).setDataAndType(Uri.fromFile(file),
                        "application/vnd.android.package-archive");

startActivity(promptInstall);

这可以帮助别人很多!

第一:

private static final String APP_DIR = Environment.getExternalStorageDirectory().getAbsolutePath() + "/MyAppFolderInStorage/";

private void install() {
    File file = new File(APP_DIR + fileName);

    if (file.exists()) {
        Intent intent = new Intent(Intent.ACTION_VIEW);
        String type = "application/vnd.android.package-archive";

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            Uri downloadedApk = FileProvider.getUriForFile(getContext(), "ir.greencode", file);
            intent.setDataAndType(downloadedApk, type);
            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        } else {
            intent.setDataAndType(Uri.fromFile(file), type);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        }

        getContext().startActivity(intent);
    } else {
        Toast.makeText(getContext(), "ّFile not found!", Toast.LENGTH_SHORT).show();
    }
}

第二:对于android 7及以上，你应该在manifest中定义一个提供商，如下所示!

    <provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="ir.greencode"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/paths" />
    </provider>

第三:在res/xml文件夹中定义path.xml，如下所示! 我使用这个路径内部存储，如果你想改变它的东西有一些方法!你可以进入这个链接: FileProvider

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-path name="your_folder_name" path="MyAppFolderInStorage/"/>
</paths>

第四:您应该在manifest中添加此权限:

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

允许应用程序请求安装包。针对api大于25的应用程序必须拥有此权限才能使用Intent.ACTION_INSTALL_PACKAGE。 请确保提供者权限相同!

您可以轻松启动市场链接或安装提示:

Intent promptInstall = new Intent(Intent.ACTION_VIEW)
    .setDataAndType(Uri.parse("file:///path/to/your.apk"), 
                    "application/vnd.android.package-archive");
startActivity(promptInstall); 

源

Intent goToMarket = new Intent(Intent.ACTION_VIEW)
    .setData(Uri.parse("market://details?id=com.package.name"));
startActivity(goToMarket);

源

但是，没有用户的明确许可，你不能安装。apks;除非设备和您的程序已经扎根。