Android 6.0以上动态申请文件读写权限

自Android 6.0开始，Google开始对系统权限做出严格的要求，有些权限必须用户同意才能调用相应功能，所以开发者需要调用权限申请的代码，弹出一个小窗口，向用户动态申请权限。
以下是动态申请文件读写权限的过程：
1.读与写的权限先定义到静态字符数组中： private static String[] PERMISSIONS_STORAGE = {
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE};
2.首先判断当前系统是否是Android6.0(对应API 23)以及以上，如果是则判断是否含有了写文件的权限，如果没有则调用动态申请权限的代码，ActivityCompat.requestPermission方法的第一个参数是目标Activity,填写this即可，第二个参数是String[]字符数组类型的权限集，第三个即请求码：if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP) {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, PERMISSIONS_STORAGE, REQUEST_PERMISSION_CODE);
}
}3.回调函数，申请权限后回调onRequestPermissionResult函数，第一个参数为请求码，第二个参数是刚刚请求的权限集，第三个参数是请求结果，0表示授权成功，-1表示授权失败：@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == REQUEST_PERMISSION_CODE) {
for (int i = 0; i < permissions.length; i++) {
Log.i("MainActivity", "申请的权限为：" + permissions[i] + ",申请结果：" + grantResults[i]);
}
}
}4.完整代码：public class MainActivity extends AppCompatActivity {
//读写权限
private static String[] PERMISSIONS_STORAGE = {
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE};
//请求状态码
private static int REQUEST_PERMISSION_CODE = 1;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP) {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, PERMISSIONS_STORAGE, REQUEST_PERMISSION_CODE);
}
}
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == REQUEST_PERMISSION_CODE) {
for (int i = 0; i < permissions.length; i++) {

4000
Log.i("MainActivity", "申请的权限为：" + permissions[i] + ",申请结果：" + grantResults[i]);
}
}
}
}