我正在开发 android 应用程序，其中 SQlite 作为数据库。我想以编程方式将某些结果从 DB 导出为 excel 文件格式，想将该 excel 存储到本地设备路径 我遇到了以下链接
那么，为 android 应用程序实现 Export to Excel 的具体程序是什么？
【问题讨论】：
这里的人是我已经成功实施的答案
//new async task for file export to csv
private class ExportDatabaseCSVTask extends AsyncTask<String, String, Boolean> {
private final ProgressDialog dialog = new ProgressDialog(SearchResultActivity.this);
boolean memoryErr = false;
// to show Loading dialog box
@Override
protected void onPreExecute() {
this.dialog.setMessage("Exporting database...");
this.dialog.show();
}
// to write process
protected Boolean doInBackground(final String... args) {
boolean success = false;
String currentDateString = new SimpleDateFormat(Constants.SimpleDtFrmt_ddMMyyyy).format(new Date());
File dbFile = getDatabasePath("HLPL_FRETE.db");
Log.v(TAG, "Db path is: " + dbFile); // get the path of db
File exportDir = new File(Environment.getExternalStorageDirectory() + File.separator + Constants.FileNm.FILE_DIR_NM, "");
long freeBytesInternal = new File(getApplicationContext().getFilesDir().getAbsoluteFile().toString()).getFreeSpace();
long megAvailable = freeBytesInternal / 1048576;
if (megAvailable < 0.1) {
System.out.println("Please check"+megAvailable);
memoryErr = true;
}else {
exportDirStr = exportDir.toString();// to show in dialogbox
Log.v(TAG, "exportDir path::" + exportDir);
if (!exportDir.exists()) {
exportDir.mkdirs();
}
try {
List<SalesActivity> listdata = salesLst;
SalesActivity sa = null;
String lob = null;
for (int index = 0; index < listdata.size();) {
sa = listdata.get(index);
lob = sa.getLob();
break;
}
if (Constants.Common.OCEAN_LOB.equals(lob)) {
file = new File(exportDir, Constants.FileNm.FILE_OFS + currentDateString + ".csv");
} else {
file = new File(exportDir, Constants.FileNm.FILE_AFS + currentDateString + ".csv");
}
file.createNewFile();
CSVWriter csvWrite = new CSVWriter(new FileWriter(file));
// this is the Column of the table and same for Header of CSV
// file
if (Constants.Common.OCEAN_LOB.equals(lob)) {
csvWrite.writeNext(Constants.FileNm.CSV_O_HEADER);
}else{
csvWrite.writeNext(Constants.FileNm.CSV_A_HEADER);
}
String arrStr1[] = { "SR.No", "CUTSOMER NAME", "PROSPECT", "PORT OF LOAD", "PORT OF DISCHARGE" };
csvWrite.writeNext(arrStr1);
if (listdata.size() > 0) {
for (int index = 0; index < listdata.size(); index++) {
sa = listdata.get(index);
String pol;
String pod;
if (Constants.Common.OCEAN_LOB.equals(sa.getLob())) {
pol = sa.getPortOfLoadingOENm();
pod = sa.getPortOfDischargeOENm();
} else {
pol = sa.getAirportOfLoadNm();
pod = sa.getAirportOfDischargeNm();
}
int srNo = index;
String arrStr[] = { String.valueOf(srNo + 1), sa.getCustomerNm(), sa.getProspectNm(), pol, pod };
csvWrite.writeNext(arrStr);
}
success = true;
}
csvWrite.close();
} catch (IOException e) {
Log.e("SearchResultActivity", e.getMessage(), e);
return success;
}
}
return success;
}
// close dialog and give msg
protected void onPostExecute(Boolean success) {
if (this.dialog.isShowing()) {
this.dialog.dismiss();
}
if (success) {
dialogBox(Constants.Flag.FLAG_EXPRT_S);
} else {
if (memoryErr==true) {
dialogBox(Constants.Flag.FLAG_MEMORY_ERR);
} else {
dialogBox(Constants.Flag.FLAG_EXPRT_F);
}
}
}
}
【讨论】：
这是我的回答：这行得通！ Excel 文件与 .csv 文件相同。 第一步：下载这个jar文件https://code.google.com/p/opencsv/downloads/detail?name=opencsv-2.4.jar&can=2&q=
第二步：
private class ExportDatabaseCSVTask extends AsyncTask<String ,String, String>{
private final ProgressDialog dialog = new ProgressDialog(MainActivity.this);
@Override
protected void onPreExecute() {
this.dialog.setMessage("Exporting database...");
this.dialog.show();
}
protected String doInBackground(final String... args){
File exportDir = new File(Environment.getExternalStorageDirectory(), "");
if (!exportDir.exists()) {
exportDir.mkdirs();
}
File file = new File(exportDir, "ExcelFile.csv");
try {
file.createNewFile();
CSVWriter csvWrite = new CSVWriter(new FileWriter(file));
//data
ArrayList<String> listdata= new ArrayList<String>();
listdata.add("Aniket");
listdata.add("Shinde");
listdata.add("pune");
listdata.add("anything@anything");
//Headers
String arrStr1[] ={"First Name", "Last Name", "Address", "Email"};
csvWrite.writeNext(arrStr1);
String arrStr[] ={listdata.get(0), listdata.get(1), listdata.get(2), listdata.get(3)};
csvWrite.writeNext(arrStr);
csvWrite.close();
return "";
}
catch (IOException e){
Log.e("MainActivity", e.getMessage(), e);
return "";
}
}
@SuppressLint("NewApi")
@Override
protected void onPostExecute(final String success) {
if (this.dialog.isShowing()){
this.dialog.dismiss();
}
if (success.isEmpty()){
Toast.makeText(MainActivity.this, "Export successful!", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(MainActivity.this, "Export failed!", Toast.LENGTH_SHORT).show();
}
}
}
在您的 .java 文件中写入 Async 任务
Step3：添加调用这个任务
ExportDatabaseCSVTask task=new ExportDatabaseCSVTask();
task.execute();
ExcelFile.csv 文件将在您的 sdcard 中创建。
【讨论】：
ExportDatabaseCSVTask：
public class ExportDatabaseCSVTask extends AsyncTask<String, Void, Boolean> {
private final ProgressDialog dialog = new ProgressDialog(MainActivity.this);
@Override
protected void onPreExecute() {
this.dialog.setMessage("Exporting database...");
this.dialog.show();
}
protected Boolean doInBackground(final String... args) {
String currentDBPath = "/data/"+ "your Package name" +"/databases/abc.db";
File dbFile = getDatabasePath(""+currentDBPath);
System.out.println(dbFile); // displays the data base path in your logcat
File exportDir = new File(Environment.getExternalStorageDirectory(), "/your Folder Name/");
if (!exportDir.exists()) { exportDir.mkdirs(); }
File file = new File(exportDir, "myfile.csv");
try {
file.createNewFile();
CSVWriter csvWrite = new CSVWriter(new FileWriter(file));
Cursor curCSV = simpledb.rawQuery("select * from " + tablename,null);
csvWrite.writeNext(curCSV.getColumnNames());
while(curCSV.moveToNext()) {
String arrStr[]=null;
String[] mySecondStringArray = new String[curCSV.getColumnNames().length];
for(int i=0;i<curCSV.getColumnNames().length;i++)
{
mySecondStringArray[i] =curCSV.getString(i);
}
csvWrite.writeNext(mySecondStringArray);
}
csvWrite.close();
curCSV.close();
return true;
} catch (IOException e) {
Log.e("MainActivity", e.getMessage(), e);
return false;
}
}
protected void onPostExecute(final Boolean success) {
if (this.dialog.isShowing()) { this.dialog.dismiss(); }
if (success) {
Toast.makeText(MainActivity.this, "Export successful!", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(MainActivity.this, "Export failed", Toast.LENGTH_SHORT).show();
}
}
}
CSVWriter：
public class CSVWriter {
private PrintWriter pw;
private char separator;
private char quotechar;
private char escapechar;
private String lineEnd;
/** The character used for escaping quotes. */
public static final char DEFAULT_ESCAPE_CHARACTER = '"';
/** The default separator to use if none is supplied to the constructor. */
public static final char DEFAULT_SEPARATOR = ',';
/**
* The default quote character to use if none is supplied to the
* constructor.
*/
public static final char DEFAULT_QUOTE_CHARACTER = '"';
/** The quote constant to use when you wish to suppress all quoting. */
public static final char NO_QUOTE_CHARACTER = '\u0000';
/** The escape constant to use when you wish to suppress all escaping. */
public static final char NO_ESCAPE_CHARACTER = '\u0000';
/** Default line terminator uses platform encoding. */
public static final String DEFAULT_LINE_END = "\n";
/**
* Constructs CSVWriter using a comma for the separator.
*
* @param writer
* the writer to an underlying CSV source.
*/
public CSVWriter(Writer writer) {
this(writer, DEFAULT_SEPARATOR, DEFAULT_QUOTE_CHARACTER,
DEFAULT_ESCAPE_CHARACTER, DEFAULT_LINE_END);
}
/**
* Constructs CSVWriter with supplied separator, quote char, escape char and line ending.
*
* @param writer
* the writer to an underlying CSV source.
* @param separator
* the delimiter to use for separating entries
* @param quotechar
* the character to use for quoted elements
* @param escapechar
* the character to use for escaping quotechars or escapechars
* @param lineEnd
* the line feed terminator to use
*/
public CSVWriter(Writer writer, char separator, char quotechar, char escapechar, String lineEnd) {
this.pw = new PrintWriter(writer);
this.separator = separator;
this.quotechar = quotechar;
this.escapechar = escapechar;
this.lineEnd = lineEnd;
}
/**
* Writes the next line to the file.
*
* @param nextLine
* a string array with each comma-separated element as a separate
* entry.
*/
public void writeNext(String[] nextLine) {
if (nextLine == null)
return;
StringBuffer sb = new StringBuffer();
for (int i = 0; i < nextLine.length; i++) {
if (i != 0) {
sb.append(separator);
}
String nextElement = nextLine[i];
if (nextElement == null)
continue;
if (quotechar != NO_QUOTE_CHARACTER)
sb.append(quotechar);
for (int j = 0; j < nextElement.length(); j++) {
char nextChar = nextElement.charAt(j);
if (escapechar != NO_ESCAPE_CHARACTER && nextChar == quotechar) {
sb.append(escapechar).append(nextChar);
} else if (escapechar != NO_ESCAPE_CHARACTER && nextChar == escapechar) {
sb.append(escapechar).append(nextChar);
} else {
sb.append(nextChar);
}
}
if (quotechar != NO_QUOTE_CHARACTER)
sb.append(quotechar);
}
sb.append(lineEnd);
pw.write(sb.toString());
}
/**
* Flush underlying stream to writer.
*
* @throws IOException if bad things happen
*/
public void flush() throws IOException {
pw.flush();
}
/**
* Close the underlying stream writer flushing any buffered content.
*
* @throws IOException if bad things happen
*
*/
public void close() throws IOException {
pw.flush();
pw.close();
}
}
【讨论】：
我最近在我的应用中实现了 excel 导出功能。我还包含了有关如何将过滤后的数据导出到 Excel 而不是整个表格的完整代码。
您需要为此创建第二个表。第二个将保存此操作所需的数据（在我的第二个表中，我删除了我的自动增量 ID 列，因为我不想在我的 excel 文件中使用它）。
您需要先清除第二个表，然后再添加条目。
然后使用 SqliteToExcel 对象将 db 导出为 excel 并将文件保存在某处。
然后我有一个电子邮件意图，其中附有用于共享的 excel 文件（允许与电子邮件以外的其他应用程序共享）。这是我的方法：
private void ExportData() {
//CHECK IF YOU HAVE WRITE PERMISSIONS OR RETURN
int permission = ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE);
if (permission != PackageManager.PERMISSION_GRANTED) {
Toast.makeText(getContext(), "Storage permissions not granted", Toast.LENGTH_SHORT).show();
return;
}
//get database object
myDbhelper = new MyDbHelper(getContext());
SQLiteDatabase database = myDbhelper.getWritableDatabase();
//delete all entries in the second table
database.delete("Table2",null,null);
//Create a cursor of the main database with your filters and sort order applied
Cursor cursor = getActivity().getContentResolver().query(
uri,
projections,
selection,
args,
sortOrder);
//loop through cursor and add entries from first table to second table
try {
while (cursor.moveToNext()) {
final String ColumnOneIndex = cursor.getString(cursor.getColumnIndexOrThrow("COLUMN_ONE"));
final String ColumnTwoIndex = cursor.getString(cursor.getColumnIndexOrThrow("COLUMN_TWO"));
final String ColumnThreeIndex = cursor.getString(cursor.getColumnIndexOrThrow("COLUMN_THREE"));
//add entries from table one into the table two
ContentValues values = new ContentValues();
values.put("TABLE2_COLUMN_1", ColumnOneIndex);
values.put("TABLE2_COLUMN_2", ColumnTwoIndex );
values.put("TABLE2_COLUMN_3", ColumnThreeIndex);
database.insert("table2", null, values);
}
} finally {
//close cursor after looping is complete
cursor.close();
}
//create a string for where you want to save the excel file
final String savePath = Environment.getExternalStorageDirectory() + "/excelfileTemp";
File file = new File(savePath);
if (!file.exists()) {
file.mkdirs();
}
//create the sqLiteToExcel object
SQLiteToExcel sqLiteToExcel = new SQLiteToExcel(getContext(), "databasefile.db",savePath);
//use sqLiteToExcel object to create the excel file
sqLiteToExcel.exportSingleTable("table2","excelfilename.xls", new SQLiteToExcel.ExportListener() {
@Override
public void onStart() {
}
@Override
public void onCompleted(String filePath) {
//now attach the excel file created and be directed to email activity
Uri newPath = Uri.parse("file://" + savePath + "/" +"excelfilename.xls");
StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
StrictMode.setVmPolicy(builder.build());
Intent emailintent = new Intent(Intent.ACTION_SEND);
emailintent.setType("application/vnd.ms-excel");
emailintent.putExtra(Intent.EXTRA_SUBJECT, "Subject");
emailintent.putExtra(Intent.EXTRA_TEXT, "I'm email body.");
emailintent.putExtra(Intent.EXTRA_STREAM,newPath);
startActivity(Intent.createChooser(emailintent, "Send Email"));
}
@Override
public void onError(Exception e) {
System.out.println("Error msg: " + e);
Toast.makeText(getContext(), "Failed to Export data", Toast.LENGTH_SHORT).show();
}
});
}
我在我的应用中实现了这个方法并且它有效
【讨论】：
每行的CSV格式为“string,string,string/n”， "," 是列分隔符，"/n" 是行。 从数据库中获取数据并像这样导出它们：
public static Boolean exportToCSV(List<Data> data, File file) {
try {
final String head = "ValueX, ValueY \n";
if (!file.exists()) {
file.createNewFile();
}
FileWriter fileWriter = new FileWriter(file.getAbsoluteFile());
BufferedWriter writer = new BufferedWriter(fileWriter);
writer.write(head);
for (Item item : items) {
final String line = String.format("%s,%s\n",
item.getValueX(),
item.getValueY());
writer.write(line);
}
writer.close();
} catch (IOException e) {
return false;
}
return true;
}
【讨论】：