Android(安卓)studio 43 文件存储到sdcard download文件夹下

第一步在模拟器或手机中 应用管理设置手机存储权限打开。第二步 AndroidManifest.xml    <uses-permission android:name="android.permission.INTERNET" />    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>第三步activity——main.xml    <Button        android:id="@+id/button"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="Button" />第四步MainActivity.javapackage com.example.filewr02;import androidx.appcompat.app.AppCompatActivity;import android.os.Bundle;import android.os.Environment;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.Toast;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStreamWriter;public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button btn = findViewById(R.id.button);        btn.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                // 响应事件                //Toast.makeText(MainActivity.this,"测试按钮",Toast.LENGTH_SHORT).show();                Log.i("MainActivity", "===========================================================================");                Log.i("MainActivity", Environment.getExternalStorageState());                if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){                    Log.i("MainActivity", "SD not found..............................................");                    return;//若SD卡不可用 直接返回。                }                //获取SD卡根目录                File file = Environment.getExternalStorageDirectory();                Log.i("MainActivity", "============================file weizhi =====================================================");                Log.i("MainActivity", Environment.getExternalStorageDirectory().toString());                try{                    FileOutputStream outStream = new FileOutputStream("/sdcard/Download/"+"xxxd222"+".txt",true);                    OutputStreamWriter writer = new OutputStreamWriter(outStream,"gb2312");                    writer.write("sssssssssssssdddddddddddddddddddddddddddd");                    writer.write("/n");                    writer.flush();                    writer.close();//记得关闭                    outStream.close();                }                catch (Exception e)                {                    Log.e("m", "file write error");                }            }        });    }}
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