Android——数据存储:手机外部存储 SD卡存储
xml
<EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/et_5" android:hint="要存储的的内容"/> <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/et_6" android:hint="从文件中读取的内容" /> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:layout_width="0dp" android:layout_height="wrap_content" android:text="保存到带包名的目录" android:layout_weight="1" android:onClick="onclick7"/> <Button android:layout_width="0dp" android:layout_height="wrap_content" android:text="从带包名的目录中获取" android:layout_weight="1" android:onClick="onclick8"/> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:layout_width="0dp" android:layout_height="wrap_content" android:text="保存到自定义的目录" android:layout_weight="1" android:onClick="onclick9"/> <Button android:layout_width="0dp" android:layout_height="wrap_content" android:text="从自定义的目录中获取" android:layout_weight="1" android:onClick="onclick10"/> </LinearLayout>
java
需要权限
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
//向外部空间存储文件 保存到带包名的目录 public void onclick7(View view) { // if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { //1.获取要存储的内容 String content = et_5.getText().toString(); //2.获取外部存储带包名的目录 ——只到根目录 // String sdpath = Environment.getExternalStorageDirectory().getAbsolutePath(); //Toast.makeText(Activitydata.this, "sdpath= "+sdpath, Toast.LENGTH_LONG).show(); //参数 代表不同文件类型的子目录 如果没有就传null 获取到根目录下的带包名的目录 String sdpath = getExternalFilesDir(null).getAbsolutePath(); Toast.makeText(Activitydata.this, "sdpath= "+sdpath, Toast.LENGTH_LONG).show(); //3.构造输出流 sdpath += "/" +FILENAME; try { FileOutputStream fos = new FileOutputStream(sdpath,true); //传统方式 字节数组方式 fos.write(content.getBytes("utf-8")); fos.close(); Toast.makeText(Activitydata.this, "保存成功", Toast.LENGTH_SHORT).show(); } catch (Exception e) { e.printStackTrace(); Toast.makeText(Activitydata.this, "保存失败", Toast.LENGTH_SHORT).show(); } } else { Toast.makeText(Activitydata.this, "sd卡没有挂载", Toast.LENGTH_SHORT).show(); } } //从外部存储空间中读取带包名文件 //判断是否挂载 public void onclick8(View view) { if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { //1.获取要存储的内容 //String content = et_5.getText().toString(); //2.获取外部存储带包名的目录 ——只到根目录 // String sdpath = Environment.getExternalStorageDirectory().getAbsolutePath(); //Toast.makeText(Activitydata.this, "sdpath= "+sdpath, Toast.LENGTH_LONG).show(); //参数 代表不同文件类型的子目录 如果没有就传null 获取到根目录下的带包名的目录 String sdpath = getExternalFilesDir(null).getAbsolutePath(); // Toast.makeText(Activitydata.this, "sdpath= "+sdpath, Toast.LENGTH_LONG).show(); //3.构造输入流 sdpath += "/" +FILENAME; try { FileInputStream fis = new FileInputStream(sdpath); byte[] b = new byte[1024]; int i = 0; StringBuilder sbr = new StringBuilder(); while ((i = fis.read(b))>0) { sbr.append(new String(b,0,i)); et_6.setText(sbr); } fis.close(); Toast.makeText(Activitydata.this, "获取成功", Toast.LENGTH_SHORT).show(); } catch (Exception e) { e.printStackTrace(); Toast.makeText(Activitydata.this, "获取失败", Toast.LENGTH_SHORT).show(); } } else { Toast.makeText(Activitydata.this, "sd卡没有挂载", Toast.LENGTH_SHORT).show(); } } //保存文件到自定义目录 public void onclick9(View view) { if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { //1.获取要存储的内容 String content = et_5.getText().toString(); //2.获取外部存储的根目录 String sdpath = Environment.getExternalStorageDirectory().getAbsolutePath(); //在sd卡的根目录下创建子目录 sdpath += "/hanqi"; //实例化File,指向一个目录 File file = new File(sdpath); //如果不存在创建一个 if (!file.exists()) { //创建目录 file.mkdirs(); } Toast.makeText(Activitydata.this, "path= " + sdpath, Toast.LENGTH_SHORT).show(); //3.创建输出流 sdpath += "/" + FILENAME; try { FileOutputStream fos = new FileOutputStream(sdpath, true); //传统方式 字节数组方式 fos.write(content.getBytes("utf-8")); fos.close(); Toast.makeText(Activitydata.this, "保存成功", Toast.LENGTH_SHORT).show(); } catch (Exception e) { e.printStackTrace(); Toast.makeText(Activitydata.this, "保存失败", Toast.LENGTH_SHORT).show(); } } else { Toast.makeText(Activitydata.this, "sd卡没有挂载", Toast.LENGTH_SHORT).show(); } } public void onclick10(View view){ if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { //1.获取要存储的内容 //String content = et_5.getText().toString(); //2.获取外部存储带包名的目录 ——只到根目录 String sdpath = Environment.getExternalStorageDirectory().getAbsolutePath(); //Toast.makeText(Activitydata.this, "sdpath= "+sdpath, Toast.LENGTH_LONG).show(); //参数 代表不同文件类型的子目录 如果没有就传null 获取到根目录下的带包名的目录 //String sdpath = getExternalFilesDir(null).getAbsolutePath(); // Toast.makeText(Activitydata.this, "sdpath= "+sdpath, Toast.LENGTH_LONG).show(); //3.构造输入流 sdpath += "/hanqi/" +FILENAME; Toast.makeText(Activitydata.this, ""+sdpath, Toast.LENGTH_SHORT).show(); try { FileInputStream fis = new FileInputStream(sdpath); byte[] b = new byte[1024]; int i = 0; StringBuilder sbr = new StringBuilder(); while ((i = fis.read(b))>0) { sbr.append(new String(b,0,i)); et_6.setText(sbr); } fis.close(); Toast.makeText(Activitydata.this, "获取成功", Toast.LENGTH_SHORT).show(); } catch (Exception e) { e.printStackTrace(); Toast.makeText(Activitydata.this, "获取失败", Toast.LENGTH_SHORT).show(); } } else { Toast.makeText(Activitydata.this, "sd卡没有挂载", Toast.LENGTH_SHORT).show(); } }