这里有新鲜出炉的精品教程,程序狗速度看过来!
Android是一种基于Linux的自由及开放源代码的操作系统,主要使用于移动设备,如智能手机和平板电脑,由Google公司和开放手机联盟领导及开发。尚未有统一中文名称,中国大陆地区较多人使用“安卓”或“安致”。
这篇文章主要介绍了Android 数据库文件存取至储存卡的方法的相关资料,需要的朋友可以参考下
废话不多说了,直接给大家贴代码了,具体代码如下
- <?xml version="1.0" encoding="utf-8"?>
- <LinearLayout
- xmlns:android="http://schemas.android.com/apk/res/android"
- android:layout_width="match_parent"
- android:layout_height="match_parent"
- android:orientation="vertical" >
- <Button
- android:id="@+id/save"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="保存数据(File)" />
- <Button
- android:id="@+id/read"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="读取数据(File)" />
- </LinearLayout>
- package com.example.yanlei.wifi;
- import android.os.Bundle;
- import android.os.Environment;
- import android.support.v7.app.AppCompatActivity;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.widget.Button;
- import android.widget.Toast;
- import java.io.File;
- import java.io.FileInputStream;
- import java.io.FileNotFoundException;
- import java.io.FileOutputStream;
- import java.io.PrintStream;
- import java.util.Scanner;
- public class MainActivity extends AppCompatActivity {
- private Button btnSave=null;
- private Button btnRead=null;
- private File file=null;
- private static final String FILENAME="data.txt";
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- btnSave=(Button)super.findViewById(R.id.save);
- btnRead=(Button)super.findViewById(R.id.read);
- btnSave.setOnClickListener(new OnClickListener(){
- public void onClick(View v)
- {
- PrintStream ps=null;
- //判断外部存储卡是否存在
- if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
- Toast.makeText(getApplicationContext(), "读取失败,SD存储卡不存在!", Toast.LENGTH_LONG).show();
- return;
- }
- //初始化File
- String path=Environment.getExternalStorageDirectory().toString()
- +File.separator
- +"genwoxue"
- +File.separator
- +FILENAME;
- file=new File(path);
- //如果当前文件的父文件夹不存在,则创建genwoxue文件夹
- if(!file.getParentFile().exists())
- file.getParentFile().mkdirs();
- //写文件
- try {
- ps = new PrintStream(new FileOutputStream(file));
- ps.println("跟我学网址:www.genwoxue.com");
- ps.println("");
- ps.println("电子邮件:hello@genwoxue.com");
- } catch (FileNotFoundException e) {
- e.printStackTrace();
- }finally{
- ps.close();
- }
- Toast.makeText(getApplicationContext(), "保存成功!", Toast.LENGTH_LONG).show();
- }
- });
- btnRead.setOnClickListener(new OnClickListener(){
- public void onClick(View v)
- {
- StringBuffer info=new StringBuffer();
- //判断外部存储卡是否存在
- if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
- Toast.makeText(getApplicationContext(), "读取失败,SD存储卡不存在!", Toast.LENGTH_LONG).show();
- return;
- }
- //初始化File
- String path=Environment.getExternalStorageDirectory().toString()
- +File.separator
- +"genwoxue"
- +File.separator
- +FILENAME;
- file=new File(path);
- if(!file.exists()){
- Toast.makeText(getApplicationContext(), "文件不存在!", Toast.LENGTH_LONG).show();
- return;
- }
- //读取文件内容
- Scanner scan=null;
- try {
- scan=new Scanner(new FileInputStream(file));
- while(scan.hasNext()){
- info.append(scan.next()).append("☆☆☆\n");
- }
- Toast.makeText(getApplicationContext(), info.toString(), Toast.LENGTH_LONG).show();
- } catch (FileNotFoundException e) {
- e.printStackTrace();
- }finally{
- scan.close();
- }
- }
- });
- }
- }
权限
- <?xml version="1.0" encoding="utf-8" ?>
- <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.yanlei.wifi">
- <!-- 在SDCard中创建与删除文件权限 -->
- <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"
- />
- <!-- 往SDCard写入数据权限 -->
- <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"
- />
- <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
- />
- <application android:allowBackup="true" android:icon="@mipmap/ic_launcher"
- android:label="@string/app_name" android:theme="@style/AppTheme">
- <activity android:name=".MainActivity" android:label="@string/app_name">
- <intent-filter>
- <action android:name="android.intent.action.MAIN" />
- <category android:name="android.intent.category.LAUNCHER" />
- </intent-filter>
- </activity>
- </application>
- </manifest>
- <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"
- />
- <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
- />
以上所述是小编给大家介绍的Android 数据库文件存取至储存卡的方法,希望对大家有所帮助,本文写的不好还请各位大侠见谅!
来源: http://www.phperz.com/article/17/0916/348804.html