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一定要加上权限，否则不能在sdcard中创建文件
<!--在sdcard中创建/删除文件的权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!--往sdcard中写入数据的权限 -->
直接调用 restoreDB 进行数据库恢复，调用backupDB进行数据库备份。
恢复的时候会显示出可以恢复的数据库文件列表
<!--在sdcard中创建/删除文件的权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!--往sdcard中写入数据的权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
直接调用 restoreDB 进行数据库恢复，调用backupDB进行数据库备份。
恢复的时候会显示出可以恢复的数据库文件列表
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.AsyncTask;
import android.os.Environment;
import android.view.ViewGroup.LayoutParams;
import android.view.Window;
import android.view.WindowManager;
import android.widget.ProgressBar;
import android.widget.Toast;
public class BackupAndRestore {
private Context mContext = null;
private String[] fileList = null; // 数据库文件列表
private int choicePostion = -3; // 选择数据库列表中的位置
private AlertDialog dialog = null;
private String BACK_FOLDER = "backup";
private String appName = "myApp";
public BackupAndRestore(Context context) {
mContext = context;
}
/**
* 恢复数据的Dialog
*/
public void restoreDB() {
fileList = getFileList();
AlertDialog.Builder builder = new AlertDialog.Builder(mContext);
builder.setIcon(android.R.drawable.ic_dialog_info);
builder.setTitle("恢复");
builder.setSingleChoiceItems(getFileList(), -1, new DialogClick());
builder.setPositiveButton("确定", new DialogClick());
builder.setNegativeButton("取消", new DialogClick());
builder.show();
}
/**
* 备份数据库
*/
public void backupDB() {
showDialog("是否备份数据库", 'B');
}
/**
* 显示一个Dialog
*
* @param title
* 标题 ，必须引用资源ID resource ID
* @param sign
* 根据标示调用方法 I - 恢复默认设置 D - 恢复默认设置 H -选择主机
*/
private void showDialog(String title, char sign) {
final char s = sign;
new AlertDialog.Builder(mContext).setTitle(title)
.setPositiveButton("确定", new OnClickListener() {
@Override
public void onClick(DialogInterface dialogI, int which) {
switch (s) {
case 'B': // 备份数据库
if (dialog == null) {
dialog = awaitDialog(mContext);
} else {
dialog.show();
}
new ExecuteTask().execute('B');
break;
default:
break;
}
}
}).setNegativeButton("取消", new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
}).show();
}
/**
* 备份操作
*
* @return
*/
private boolean backUp() {
boolean isOk = false;
String sp = File.separator;
File sdFile = sdCardOk();
if (sdFile != null) {
try {
String[] dbNames = { "数据库名称" };
// 创建日期文件夹
String folder_date = datePrefix();
File f = new File(sdFile.getAbsolutePath() + sp + folder_date);
if (!f.exists()) {
f.mkdirs();
}
for (int i = 0; i < dbNames.length; i++) {
String dbName = dbNames[i];
File dbFile = dbOk(dbName);
if (dbFile != null) {
File backFile = new File(f.getAbsolutePath() + sp
+ dbFile.getName());
backFile.createNewFile();
isOk = fileCopy(backFile, dbFile.getAbsoluteFile());
if (!isOk) {
break;
}
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return isOk;
}
/**
* 时间前缀
*
* @return
*/
private String datePrefix() {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss");
Date date = new Date(System.currentTimeMillis());
String str = format.format(date);
return str;
}
/**
* 文件夹列表
*
* @return
*/
private String[] getFileList() {
String[] fileList = null;
File file = sdCardOk();
if (file != null) {
File[] list = file.listFiles();
if (list != null && list.length > 0) {
fileList = new String[list.length];
for (int i = 0; i < list.length; i++) {
fileList[i] = list[i].getName();
}
}
}
return fileList;
}
/**
* sdCard是否存在 备份的文件夹是否存在
*
* @return null不能使用
*/
private File sdCardOk() {
File bkFile = null;
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
String sp = File.separator;
String backUpPath = Environment.getExternalStorageDirectory() + sp
+ appName + sp + BACK_FOLDER;
bkFile = new File(backUpPath);
if (!bkFile.exists()) {
bkFile.mkdirs();
} else
return bkFile;
} else
Toast.makeText(mContext, "Sdcard 不存在", Toast.LENGTH_SHORT).show();
return bkFile;
}
/**
* 恢复数据库
*
* @param name
* 选择的文件名称 选中的数据库名称
* @param resoreDbName
* 需要恢复的数据库名称
* @return
*/
public boolean restore(String name, File f) {
boolean isOk = false;
if (f != null) {
File dbFile = dbOk(name);
try {
// System.out.println("覆盖的名称"+dbName);
if (dbFile != null) {
isOk = fileCopy(dbFile, f.getAbsoluteFile());
} else
isOk = false;
} catch (IOException e) {
e.printStackTrace();
}
}
return isOk;
}
/**
* 数据库文件是否存在，并可以使用
*
* @return
*/
private File dbOk(String dbName) {
String sp = File.separator;
String absPath = Environment.getDataDirectory().getAbsolutePath();
String pakName = mContext.getPackageName();
String dbPath = absPath + sp + "data" + sp + pakName + sp + "databases"
+ sp + dbName;
File file = new File(dbPath);
if (file.exists()) {
return file;
} else {
return null;
}
}
/**
* 等候动画
*/
public AlertDialog awaitDialog(Context context) {
ProgressBar bar = new ProgressBar(context);
bar.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
AlertDialog dialog = new AlertDialog.Builder(context).create();
dialog.setCancelable(false);
dialog.show();
Window window = dialog.getWindow();
WindowManager.LayoutParams params = window.getAttributes();
params.width = 50;
params.height = 50;
window.setAttributes(params);
window.setContentView(bar);
return dialog;
}
/**
*
* @param outFile
* 写入
* @param inFile
* 读取
* @throws FileNotFoundException
*/
private boolean fileCopy(File outFile, File inFile) throws IOException {
if (outFile == null || inFile == null) {
return false;
}
boolean isOk = true;
FileChannel inChannel = new FileInputStream(inFile).getChannel();// 只读
FileChannel outChannel = new FileOutputStream(outFile).getChannel();// 只写
try {
long size = inChannel.transferTo(0, inChannel.size(), outChannel);
if (size <= 0) {
isOk = false;
}
} catch (IOException e) {
isOk = false;
e.printStackTrace();
} finally {
if (inChannel != null) {
inChannel.close();
}
if (outChannel != null) {
outChannel.close();
}
}
return isOk;
}
private class DialogClick implements DialogInterface.OnClickListener {
@Override
public void onClick(DialogInterface dialog, int which) {
if (which == -1) {// 确定
if (choicePostion < 0) {
Toast.makeText(mContext, "选择数据库", Toast.LENGTH_SHORT)
.show();
return;
}
String sp = File.separator;
String folderName = fileList[choicePostion];
String backUpPath = Environment.getExternalStorageDirectory()
+ sp + appName + sp + BACK_FOLDER + sp + folderName;
File file = new File(backUpPath);
if (file.isDirectory()) {
File[] files = file.listFiles();
boolean isOk = false;
for (int i = 0; i < files.length; i++) {
File f = files[i];
isOk = restore(f.getName(), f);
if (!isOk) {
String fail_msg = "恢复失败" + ":" + f.getName();
Toast.makeText(mContext, fail_msg,
Toast.LENGTH_SHORT).show();
return;
}
}
if (isOk) {
// 如果有数据体现则需要刷新出新的数据
}
}
} else if (which == -2) {// 取消
} else if (which >= 0) {
choicePostion = which;
}
}
}
/**
* 执行任务
*
* @author Administrator
*
*/
private class ExecuteTask extends AsyncTask<Character, Void, Boolean> {
@Override
protected Boolean doInBackground(Character... params) {
char c = params[0];
if (c == 'B') {
backUp();
}
return null;
}
@Override
protected void onPostExecute(Boolean result) {
super.onPostExecute(result);
if (dialog != null) {
dialog.dismiss();
}
}
}
}