使用前提

手機(jī)必須支持OTG協(xié)議

USB硬盤(pán)格式必須是FAT32（libaums庫(kù)只支持FAT32，若其他格式請(qǐng)使用原生讀取方式）

集成libaums庫(kù)

Github地址

在app/build.gradle文件導(dǎo)入library

dependencies {
    implementation 'com.github.mjdev:libaums:0.7.1'
}

使用

查出USB設(shè)備

UsbMassStorageDevice[] devices = UsbMassStorageDevice.getMassStorageDevices(this);

獲取原生USB管理對(duì)象

UsbManager mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);

動(dòng)態(tài)獲取權(quán)限

PendingIntent permissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
for (UsbMassStorageDevice device : devices) {
    mUsbManager.requestPermission(device.getUsbDevice(), permissionIntent);
}

這時(shí)候，系統(tǒng)就會(huì)彈出提示框，“允許應(yīng)用“XXX”訪問(wèn)該USB設(shè)備嗎？”（不同廠商ROM可能有不同的提示），選擇確定即可接收到回執(zhí)廣播。

這里寫(xiě)一個(gè)廣播接收器來(lái)接收回執(zhí)

private BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (action == null) {
            return;
        }
        switch (action) {
            case ACTION_USB_PERMISSION:
        }
    }
};

然后就可以執(zhí)行文件的讀寫(xiě)操作了，這里先展示一下根目錄

for (UsbMassStorageDevice device : devices) {
    // before interacting with a device you need to call init()!
    try {
        device.init();
    } catch (IOException e) {
        e.printStackTrace();
    }
    // Only uses the first partition on the device
    FileSystem currentFs = device.getPartitions().get(0).getFileSystem();
    try {
        UsbFile root = currentFs.getRootDirectory();
        UsbFile[] files = root.listFiles();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

讀取文件, root/計(jì)價(jià)器原始記錄/9-1

InputStream is = null;
try {
    UsbFile file = root.search("計(jì)價(jià)器原始記錄").search("9-1");

    // read from a file
    is = new UsbFileInputStream(file);
    InputStreamReader inputStreamReader = new InputStreamReader(is, "GBK");
    BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
    String tempLine;
    StringBuilder resultSb = new StringBuilder();
    while ((tempLine = bufferedReader.readLine()) != null) {
        System.out.println(tempLine);
        resultSb.append(tempLine).append("\n");
    }
    System.out.println("讀取記錄數(shù)據(jù)" + resultSb);
} catch (IOException e) {
    e.printStackTrace();
} finally {
    try {
        if (is != null) {
            is.close();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

創(chuàng)建文件并寫(xiě)入 root/foo/bar.txt

OutputStream os = null;
try {
    UsbFile newDir = root.createDirectory("foo");
    UsbFile file = newDir.createFile("bar.txt");
    // write to a file
    os = new UsbFileOutputStream(file);
    os.write("hello".getBytes());
    os.close();
} catch (IOException e) {
    e.printStackTrace();
} finally {
    try {
        os.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}