导出SQLite数据库到csv文件在android [英] Exporting SQLite Database to csv file in android
本文介绍了导出SQLite数据库到csv文件在android的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我试图导出SQLite数据到SD卡在Android中作为一个目录上的CSV文件。
所以我试过这个方法下面，显然它只显示此文字列印出来：
数据库的第一个表
日期，项目，金额，货币
在我的DBHelper.java中，我定义了如下函数：
public boolean exportDatabase（）{
DateFormat df = DateFormat.getDateInstance（DateFormat.SHORT，Locale.getDefault（））;
/ **首先我们检查设备的外部存储设备是否可用于写入。
*请记住，外部存储不一定是sd卡。通常是
*设备存储。
* /
String state = Environment.getExternalStorageState（）;
if（！Environment.MEDIA_MOUNTED.equals（state））{
return false;
}
else {
//我们使用下载目录保存我们的.csv文件。
文件exportDir = Environment.getExternalStoragePublicDirectory（Environment.DIRECTORY_DOWNLOADS）;
if（！exportDir.exists（））
{
exportDir.mkdirs（）;
}
文件文件;
PrintWriter printWriter = null;
try
{
file = new File（exportDir，MyCSVFile.csv）;
file.createNewFile（）;
printWriter = new PrintWriter（new FileWriter（file））;
/ **这是我们的数据库连接器类，它从数据库读取数据。
*为简洁起见，省略了这个类的代码。
* /
SQLiteDatabase db = this.getReadableDatabase（）; //打开读取数据库
/ **让我们读取数据库的第一个表。
* getFirstTable（）是我们的DBCOurDatabaseConnector类中的一个方法，它检索包含表的所有记录（所有字段）的游标
*。
*为简洁起见，省略了这个类的代码。
* /
Cursor curCSV = db.rawQuery（select * from contacts，null）;
//在.csv文件中写入表的名称和列的名称（逗号分隔值）。
printWriter.println（FIRST TABLE OF THE DATABASE）;
printWriter.println（DATE，ITEM，AMOUNT，CURRENCY）;
while（curCSV.moveToNext（））
{
Long date = curCSV.getLong（curCSV.getColumnIndex（date））;
String title = curCSV.getString（curCSV.getColumnIndex（title））;
Float amount = curCSV.getFloat（curCSV.getColumnIndex（amount））;
String description = curCSV.getString（curCSV.getColumnIndex（description））;
/ **创建要在.csv文件中写入的行。
*我们需要一个字符串，其中的值以逗号分隔。
*字段日期（Long）以可读文本格式化。金额字段
*转换为字符串。
* /
String record = df.format（new Date（date））+，+ title +，+ amount +，+ description;
printWriter.println（record）; //在.csv文件中写入记录
}
curCSV.close（）;
db.close（）;
}
catch（Exception exc）{
//如果有任何异常，返回false
return false;
}
finally {
if（printWriter！= null）printWriter.close（）;
}
//如果没有错误，返回true。
return true;
}
}
}
/ p>
public static final String DATABASE_NAME =MyDBName.db;
public static final String CONTACTS_TABLE_NAME =contacts;
public static final String CONTACTS_COLUMN_ID =id;
public static final String CONTACTS_COLUMN_TITLE =title;
public static final String CONTACTS_COLUMN_AMOUNT =amount;
public static final String CONTACTS_COLUMN_DESC =description;如果您需要更多代码，请告诉我。
解决方案感谢您的建议。 =jsdata-hide =false>
private void exportDB ）{File dbFile = getDatabasePath（MyDBName.db）; DBHelper dbhelper = new DBHelper（getApplicationContext（））;文件exportDir = new File（Environment.getExternalStorageDirectory（），）; if（！exportDir.exists（））{exportDir.mkdirs（）; }文件file =新文件（exportDir，csvname.csv）; try {file.createNewFile（）; CSVWriter csvWrite = new CSVWriter（new FileWriter（file））; SQLiteDatabase db = dbhelper.getReadableDatabase（）; Cursor curCSV = db.rawQuery（SELECT * FROM contacts，null）; csvWrite.writeNext（curCSV.getColumnNames（））; while（curCSV.moveToNext（））{//你要显示哪一列String arrStr [] = {curCSV.getString（0），curCSV.getString（1），curCSV.getString（2）}; csvWrite.writeNext（arrStr）; } csvWrite.close（）; curCSV.close（）; } catch（Exception sqlEx）{Log.e（MainActivity，sqlEx.getMessage（），sqlEx）; }
I am trying to export SQLite data to SD card in android as a CSV file on a directory.
So i have tried this method below and apparently it only shows this text printed out:
FIRST TABLE OF THE DATABASE
DATE,ITEM,AMOUNT,CURRENCY
In my DBHelper.java i have defined the function as follows:
public boolean exportDatabase() {
DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT, Locale.getDefault());
/**First of all we check if the external storage of the device is available for writing.
* Remember that the external storage is not necessarily the sd card. Very often it is
* the device storage.
*/
String state = Environment.getExternalStorageState();
if (!Environment.MEDIA_MOUNTED.equals(state)) {
return false;
}
else {
//We use the Download directory for saving our .csv file.
File exportDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
if (!exportDir.exists())
{
exportDir.mkdirs();
}
File file;
PrintWriter printWriter = null;
try
{
file = new File(exportDir, "MyCSVFile.csv");
file.createNewFile();
printWriter = new PrintWriter(new FileWriter(file));
/**This is our database connector class that reads the data from the database.
* The code of this class is omitted for brevity.
*/
SQLiteDatabase db = this.getReadableDatabase(); //open the database for reading
/**Let's read the first table of the database.
* getFirstTable() is a method in our DBCOurDatabaseConnector class which retrieves a Cursor
* containing all records of the table (all fields).
* The code of this class is omitted for brevity.
*/
Cursor curCSV = db.rawQuery("select * from contacts", null);
//Write the name of the table and the name of the columns (comma separated values) in the .csv file.
printWriter.println("FIRST TABLE OF THE DATABASE");
printWriter.println("DATE,ITEM,AMOUNT,CURRENCY");
while(curCSV.moveToNext())
{
Long date = curCSV.getLong(curCSV.getColumnIndex("date"));
String title = curCSV.getString(curCSV.getColumnIndex("title"));
Float amount = curCSV.getFloat(curCSV.getColumnIndex("amount"));
String description = curCSV.getString(curCSV.getColumnIndex("description"));
/**Create the line to write in the .csv file.
* We need a String where values are comma separated.
* The field date (Long) is formatted in a readable text. The amount field
* is converted into String.
*/
String record = df.format(new Date(date)) + "," + title + "," + amount + "," + description;
printWriter.println(record); //write the record in the .csv file
}
curCSV.close();
db.close();
}
catch(Exception exc) {
//if there are any exceptions, return false
return false;
}
finally {
if(printWriter != null) printWriter.close();
}
//If there are no errors, return true.
return true;
}
}
}
And my columns are:
public static final String DATABASE_NAME = "MyDBName.db";
public static final String CONTACTS_TABLE_NAME = "contacts";
public static final String CONTACTS_COLUMN_ID = "id";
public static final String CONTACTS_COLUMN_TITLE = "title";
public static final String CONTACTS_COLUMN_AMOUNT = "amount";
public static final String CONTACTS_COLUMN_DESC = "description";
Let me know if you need more code.
解决方案 Thanks for your suggestions guys which led me to this answer:
private void exportDB() {
File dbFile=getDatabasePath("MyDBName.db");
DBHelper dbhelper = new DBHelper(getApplicationContext());
File exportDir = new File(Environment.getExternalStorageDirectory(), "");
if (!exportDir.exists())
{
exportDir.mkdirs();
}
File file = new File(exportDir, "csvname.csv");
try
{
file.createNewFile();
CSVWriter csvWrite = new CSVWriter(new FileWriter(file));
SQLiteDatabase db = dbhelper.getReadableDatabase();
Cursor curCSV = db.rawQuery("SELECT * FROM contacts",null);
csvWrite.writeNext(curCSV.getColumnNames());
while(curCSV.moveToNext())
{
//Which column you want to exprort
String arrStr[] ={curCSV.getString(0),curCSV.getString(1), curCSV.getString(2)};
csvWrite.writeNext(arrStr);
}
csvWrite.close();
curCSV.close();
}
catch(Exception sqlEx)
{
Log.e("MainActivity", sqlEx.getMessage(), sqlEx);
}
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