Android 数据库文件存取至储存卡的方法

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：[e-mail]");
} 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！