向sdcard读写

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    /**
     * 定义写sdcard的方法
     * @param view
     */
    public void btnwrite(View view){
        try {
            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
                //实例化文件
                File file = new File(Environment.getExternalStorageDirectory()+"/rikao10.txt");
                //实例化输出流
                OutputStream os=new FileOutputStream(file);
                //向文件写入数据
                os.write("万薪就业，高薪就业".getBytes());
                //提交
                os.flush();
                //关闭
                os.close();
            }else{
                Toast.makeText(this, "sdcard卡没安装好", Toast.LENGTH_SHORT).show();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 定义读sdcard方法
     * @param view
     */
    public void btnread(View view){
        try {
            File file = new File(Environment.getExternalStorageDirectory()+"/rikao10.txt");
            //实例化输入流
            InputStream is=new FileInputStream(file);
            //缓冲读
            BufferedReader br=new BufferedReader(new InputStreamReader(is));
            //读一行
            String s = br.readLine();
            //关闭流
            is.close();
            br.close();
            //提示
            Toast.makeText(this, s, Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}