Android 手机存储及sd卡操作--案例登录记住帐号密码
手机分为内部存储和外部存储。内部存储，即在本工程目录下。外部存储在sd卡上。手机没有sd卡也能运行程序。
判断sd是否存在
<span style="white-space:pre"> </span>//MEDIA_UNKNOWN:不能识别sd卡
//MEDIA_REMOVED:没有sd卡
//MEDIA_UNMOUNTED:sd卡存在但是没有挂载
//MEDIA_CHECKING:sd卡正在准备
//MEDIA_MOUNTED：sd卡已经挂载，可用
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
1，手机零散信息的读写方法一般用SharedPreferences方法，这个方法存储路径data/data/本包名/shared_prefs/文件名.xml。登录时，从本地获取帐号密码
package com.example.shpaerdemo01;
import java.io.File;
import android.app.Activity;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.EditText;
import android.widget.Toast;
import com.example.shpaerdemo02.R;
public class MainActivity extends Activity implements OnClickListener, OnCheckedChangeListener {
// 实现点击记住密码，用户登录时读取到密码
private EditText word;
private EditText pass;
private Button but;
private CheckBox cb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initview();
initword();
}
private void initword() {
<span style="white-space:pre"></span><pre name="code" class="html">// 获取到存储info文件
shared = getSharedPreferences("info", MODE_PRIVATE);
//1，为文件中的键.2,如果没有键默认显示为空
String names = shared.getString("word", "");
String words = shared.getString("pass", "");
if (names != null && words != null) {//当内容都不是空的时候执行
checkBox.setChecked(true);
word.setText(names);
pass.setText(words);
}
}
private void initview() {
word = (EditText) findViewById(R.id.editText1);
pass = (EditText) findViewById(R.id.editText2);
but = (Button) findViewById(R.id.button1);
cb = (CheckBox) findViewById(R.id.checkBox1);
but.setOnClickListener(this);
// 多选按钮的事件
cb.setOnCheckedChangeListener(this);
}
@Override
public void onClick(View v) {
String w = word.getText().toString().trim();
String p = pass.getText().toString().trim();
// 判断是否被选中
if (cb.isChecked()) {
// 获取到存储文件 //1.文件名,2.文件读写模式一般都为私有
// info保存为xml文件。不需要给后缀名。
SharedPreferences shared = getSharedPreferences("info",MODE_PRIVATE);
// 获取到编辑器
Editor editor = shared.edit();
// 键值对形式
editor.putString("word", w);
editor.putString("pass", p);
// 提交
editor.commit();
}
Toast.makeText(this, "登录成功", 0).show();
}
}
}
//MEDIA_UNKNOWN:不能识别sd卡
//MEDIA_REMOVED:没有sd卡
//MEDIA_UNMOUNTED:sd卡存在但是没有挂载
//MEDIA_CHECKING:sd卡正在准备
//MEDIA_MOUNTED：sd卡已经挂载，可用
package com.itheima.rwinrom;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import org.apache.http.entity.InputStreamEntity;
import com.itheima.rwinsd.R;
import android.os.Bundle;
import android.os.Environment;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity {
private EditText et_name;
private EditText et_pass;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_name = (EditText) findViewById(R.id.et_name);
et_pass = (EditText) findViewById(R.id.et_pass);
readAccount();
}
public void readAccount(){
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
File file = new File("sdcard/info.txt");
if(file.exists()){
try {
FileInputStream fis = new FileInputStream(file);
//把字节流转换成字符流
BufferedReader br = new BufferedReader(new InputStreamReader(fis));
//读取txt文件里的用户名和密码
String text = br.readLine();
String[] s = text.split("**");
et_name.setText(s[0]);
et_pass.setText(s[1]);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
public void login(View v){
String name = et_name.getText().toString();
String pass = et_pass.getText().toString();
CheckBox cb = (CheckBox) findViewById(R.id.cb);
//判断选框是否被勾选
if(cb.isChecked()){
// 获取sd卡路径，如果存在，证明已经挂载可用
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
//返回一个File对象，其路径是sd卡的真实路径
File file = new File(Environment.getExternalStorageDirectory(), "info.txt");
// File file = new File("sdcard/info.txt");
FileOutputStream fos;
try {
fos = new FileOutputStream(file);
fos.write((name + "**" + pass).getBytes());
fos.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
else{
Toast.makeText(this, "sd卡不可用", 0).show();
}
}
Toast.makeText(this, "sd", 0).show();
}
}
3，sd卡内存的内存大小的获取方法
package com.itheima.getsdavail;
import java.io.File;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.os.StatFs;
import android.app.Activity;
import android.text.format.Formatter;
import android.view.Menu;
import android.widget.TextView;
public class MainActivity extends Activity {
@SuppressWarnings("deprecation")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
File path = Environment.getExternalStorageDirectory();
StatFs stat = new StatFs(path.getPath());
long blockSize;
long totalBlocks;
long availableBlocks;
//获取当前系统版本的等级 判断是否大于4.3版本
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2){
//大于的话用新的api显示long
blockSize = stat.getBlockSizeLong();
totalBlocks = stat.getBlockCountLong();
availableBlocks = stat.getAvailableBlocksLong();
}
else{
//小于的话用旧的api显示int
blockSize = stat.getBlockSize();
totalBlocks = stat.getBlockCount();
availableBlocks = stat.getAvailableBlocks();
}
TextView tv = (TextView) findViewById(R.id.tv);
//存储卡的计算方法是，每一个单位的存储的字节数*字节
tv.setText(formatSize(availableBlocks * blockSize));
}
//调用系统
private String formatSize(long size) {
return Formatter.formatFileSize(this, size);
}
}
4，内部存储用流的读取
package com.itheima.rwinrom;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import org.apache.http.entity.InputStreamEntity;
import com.itheima.apirwinrom.R;
import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity {
private EditText et_name;
private EditText et_pass;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_name = (EditText) findViewById(R.id.et_name);
et_pass = (EditText) findViewById(R.id.et_pass);
readAccount();
}
public void readAccount(){
//FilesDir所保存的不能系统检测到删除，cachedir目录下的当系统内存不足时，会删除。
// File file = new File(getFilesDir(), "info.txt");
File file = new File(getCacheDir(), "info.txt");
//判断文件是否存在，如果存在读取
if(file.exists()){
try {
FileInputStream fis = new FileInputStream(file);
//把字节流转换成字符流
BufferedReader br = new BufferedReader(new InputStreamReader(fis));
//读取txt文件里的用户名和密码
String text = br.readLine();
String[] s = text.split("##");
et_name.setText(s[0]);
et_pass.setText(s[1]);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public void login(View v){
String name = et_name.getText().toString();
String pass = et_pass.getText().toString();
CheckBox cb = (CheckBox) findViewById(R.id.cb);
//判断选框是否被勾选,勾选保存
if(cb.isChecked()){
//返回一个File对象，其路径是data/data/com.itheima.apirwinrom/files
// File file = new File(getFilesDir(), "info.txt");
//返回值也是一个File对象，其路径是data/data/com.itheima.apirwinrom/cache
File file = new File(getCacheDir(), "info.txt");
FileOutputStream fos;
try {
fos = new FileOutputStream(file);
fos.write((name + "##" + pass).getBytes());
fos.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
5，这个可以直接复制粘贴当作判断sd卡是否存在的工具类
package com.xdl.utils;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import cn.bmob.v3.datatype.BmobFile;
import cn.bmob.v3.listener.UpdateListener;
import cn.bmob.v3.listener.UploadFileListener;
import com.xdl.bean.User;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.net.Uri;
import android.os.Environment;
import android.os.Message;
import android.provider.MediaStore;
/**
* 判断SD卡是否存在
* @author Administrator
*
*/
public class SdcardTools {
public static boolean sdcard(){
String state = Environment.getExternalStorageState();
if (state.equals(Environment.MEDIA_MOUNTED)) {
return true;
}
return false;
}
}