Android 从SD卡上读取文本信息

从SD卡上读取文本信息

 代码实现：

        String fileName = "/sdcard/y.txt";//文件路径

        // 也可以用String fileName = "mnt/sdcard/Y.txt";

        String res = "";

        try {

            FileInputStream fin = new FileInputStream(fileName);

            // FileInputStream fin = openFileInput(fileName);

            // 用这个就不行了，必须用FileInputStream

            int length = fin.available();

            byte[] buffer = new byte[length];

            fin.read(buffer);

            res = EncodingUtils.getString(buffer, "GBK");//依Y.txt的编码类型选择合适的编码，如果不调整会乱码

            fin.close();//关闭资源

            System.out.println("res--->"+res);

            int a=Integer.parseInt(res.substring(3, 5));

            int b=Integer.parseInt(res.substring(8, 10));

            System.out.println(a+"res--->"+b);//获取的a.b

        } catch (Exception e) {

            e.printStackTrace();

        }

res = EncodingUtils.getString(buffer, "GBK");

这儿charset="GBK"

charset还可以等于"UTF-8"、"BIG-5"

从SD卡上读取图片信息（这儿读取已知路径下的jpeg格式的图片）

public class MainActivity extends Activity {

 @Override

 public void onCreate(Bundle savedInstanceState) {

  super.onCreate(savedInstanceState);

  setContentView(R.layout.imageview);

  ImageView imageView=(ImageView)findViewById(R.id.imageView);

  String location="";

  if (isSdcard() != null) {

   File file = new File(isSdcard());

   File[] files = file.listFiles();

   for (int i = 0; i < files.length; i++) {

    if (files[i].getName().equals("13.jpeg")) {

     Bitmap bitmap = BitmapFactory.decodeFile(files[i].getName());

     location = isSdcard() + "/" + files[i].getName();

     imageView.setImageDrawable(Drawable.createFromPath(location));

     System.out.println("13.jpeg的位置："+location);

    }

   }

  }

 }

 private String isSdcard() {

  File sdcardDir = null;

  boolean isSDExist = Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);

  // 判断ＳＤ卡是否存在

  if (isSDExist) {

   // 如果存在SDcard 就找到跟目录

   sdcardDir = Environment.getExternalStorageDirectory();

   return sdcardDir.toString();

  } else {

   return null;

  }

 }

}

xml布局文件

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout

 xmlns:android="http://schemas.android.com/apk/res/android"

    android:orientation="vertical"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:layout_marginTop="5dp"

 >

    <ImageView

     android:id="@+id/imageView"

     android:layout_width="fill_parent"

        android:layout_height="fill_parent"

        android:layout_gravity="center"

 />

</LinearLayout>