android 操作SD卡上的檔案

標籤：android   style   blog   class   code   java   

（1）說明:操作SD卡上的檔案需要加入以下許可權

 在SD卡上建立和刪除檔案許可權

 <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

在SD卡上寫入資料的許可權
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

在sd卡上的檔案操作和我上一篇文章差不多，如果有不懂的可以看我的上一篇文章

 

android 讀寫檔案樣本

http://blog.csdn.net/liuzuyi200/article/details/25049183

只不過多加了判斷SD卡是否存在的方法

Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)

（2）布局檔案

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <RelativeLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:orientation="vertical" >        <TextView            android:id="@+id/label_01"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@string/name"            android:textSize="20dp" />        <EditText            android:id="@+id/filename"            android:layout_width="160dp"            android:layout_height="wrap_content"            android:layout_alignTop="@id/label_01"            android:layout_toRightOf="@id/label_01" />    </RelativeLayout>    <TextView        android:id="@+id/label_02"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/neirong" />    <EditText        android:id="@+id/content"        android:layout_width="fill_parent"        android:layout_height="120px"        android:ems="10" >        <requestFocus />    </EditText>    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <Button            android:id="@+id/savebutton"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:gravity="right"            android:text="@string/save" />        <Button            android:id="@+id/readbutton"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:gravity="right"            android:text="@string/read" />    </LinearLayout>    <TextView        android:id="@+id/textcontent"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="0.10" /></LinearLayout>

（3）代碼

package com.liuzuyi.file;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;import android.support.v7.app.ActionBarActivity;import android.support.v7.app.ActionBar;import android.support.v4.app.Fragment;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.os.Environment;import android.util.Log;import android.view.LayoutInflater;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;import android.os.Build;public class MainActivity extends Activity {private  EditText filename;private  EditText context;private TextView textcontent;private static final String TAG="simplefile";protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);filename=(EditText)this.findViewById(R.id.filename);context=(EditText)this.findViewById(R.id.content);textcontent=(TextView)this.findViewById(R.id.textcontent);Button savebtn=(Button)this.findViewById(R.id.savebutton);Button viewbtn=(Button)this.findViewById(R.id.readbutton);savebtn.setOnClickListener(l);viewbtn.setOnClickListener(l);}   private View.OnClickListener l =new OnClickListener() {public void onClick(View v) { Button button =(Button)v; //過濾掉開頭結尾的空格 String namestr = filename.getText().toString().trim(); String contentstr =context.getText().toString();  switch ( button.getId() ) {case R.id.savebutton:String resid_s ="success";OutputStream fileos = null;try {if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))  {FileOutputStream outstream = new FileOutputStream("/sdcard/"+namestr+".txt");outstream.write(contentstr.getBytes() );outstream.close();  }elsereturn ;} catch (Exception e) { resid_s = "faile"; e.printStackTrace();}Toast.makeText(MainActivity.this,  resid_s,Toast.LENGTH_LONG).show();Log.i(TAG, namestr);Log.i(TAG, contentstr);break;case R.id.readbutton:String resid_v ="success";InputStream filsIs= null;String contentst = null;try {if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))  {File SDCardDir=Environment.getExternalStorageDirectory();File saveFile = new File(SDCardDir,namestr+".txt");FileInputStream instream = new FileInputStream(saveFile);ByteArrayOutputStream Ostream = new ByteArrayOutputStream();byte[] buffer = new byte[1024];int len = -1;  while( (len = instream.read(buffer)) != -1 )    {  Ostream.write(buffer,0,len);  }  contentst = Ostream.toString();  Ostream.close();  instream.close();   }else{Toast.makeText(MainActivity.this, "SD卡不存在", Toast.LENGTH_LONG).show();}} catch (Exception e) { resid_v ="faile"; e.printStackTrace();}textcontent.setText( contentst);Log.i(TAG, contentst);Toast.makeText(MainActivity.this, resid_v,Toast.LENGTH_LONG).show();Log.i(TAG,namestr);break;}  }    };}