Android开发--FileInputStream/OutStream/Sdcard写入

╰半夏微凉° 2022-03-20 03:50 366阅读 0赞

首先，需要向Android模拟器的SD卡写入文件，就需要获得权限，所以需要在AndroidManifest.xml文件中注册权限，使用的方法是：

<uses-permission android:name="android.permission.WRITE\_EXTERNAL\_STORAGE"/>

这个例子的作用是点击第一个按钮把图像文件存储到SD卡中，点击第二个按钮利用下面的ImageView显示Sd卡中的内容，本示例的截图如下：

![1358649448_4932.png][]

使用的源代码如下：

public class Sdcard_FileInOutput_Activty extends Activity { private Button button; private Button button2; private ImageView imageView; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_sdcard__file_in_output__activty);  button=(Button)findViewById(R.id.buttonsave);  button2=(Button)findViewById(R.id.buttonread);  imageView=(ImageView)findViewById(R.id.image);  button.setOnClickListener(new OnClickListener() {      @Override   public void onClick(View v) {    // TODO Auto-generated method stub   try {    FileOutputStream fos=new FileOutputStream(android.os.Environment.getExternalStorageDirectory()+"/b.jpg");    InputStream is=getResources().getAssets().open("b.jpg");    byte[] buffer=new byte[8192];    int count=0;    while ((count=is.read(buffer))>=0) {     fos.write(buffer,0,count);    }    fos.close();    is.close();    Toast.makeText(Sdcard_FileInOutput_Activty.this, "成功将文件写入到SD卡上", Toast.LENGTH_SHORT).show();   } catch (Exception e) {    // TODO: handle exception    e.printStackTrace();   }    }  });  button2.setOnClickListener(new OnClickListener() {      @Override   public void onClick(View v) {    // TODO Auto-generated method stub   String filename=android.os.Environment.getExternalStorageDirectory()+"/b.jpg";   if(!new File(filename).exists()){    Toast.makeText(Sdcard_FileInOutput_Activty.this, "还没有将文件写入到SD卡上", Toast.LENGTH_SHORT).show();    return;   }   try {    FileInputStream fis=new FileInputStream(filename);    Bitmap bitmap=BitmapFactory.decodeStream(fis);    imageView.setImageBitmap(bitmap);    fis.close();   } catch (Exception e) {    // TODO: handle exception    e.printStackTrace();   }   }  }); }}

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[1358649448_4932.png]: https://img-my.csdn.net/uploads/201301/20/1358649448_4932.png
[https_blog.csdn.net_jiangjunshow]: https://blog.csdn.net/jiangjunshow/article/details/77338485