java - 在 Android 中使用 openCSV 导出 CSV

Question

我正在尝试将整个表从我的本地 sqlite 数据库导出到一个 .csv 文件中，并使用 opencsv 库将其存储在我的 sdcard 上。

导出代码

private ArrayList<ChartTable> mChartList;
private String[] mExport;

private void exportCsv() {
        mDatabaseHelper = new DatabaseHelper(this);
        try {
            mWriter = new CSVWriter(new FileWriter(Environment.getExternalStorageDirectory().getAbsolutePath() + "/charts.csv"));
            mChartList = mDatabaseHelper.getChartsList();
            mExport = mChartList.toArray(new String[mChartList.size()]);
            mWriter.writeNext(mExport);
            mWriter.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

getChartsList()

public ArrayList<ChartTable> getChartsList() {
        SQLiteDatabase db = this.getReadableDatabase();
        ArrayList<ChartTable> chartsList = new ArrayList<ChartTable>();
        String[] sumColumns = {
                ID_COL  + ", " 
                + USER_ID_COL + ", "
                + PATIENT_ID_COL + ", "
                + FIRST_NAME_COL + ", "
                + LAST_NAME_COL + ", "
                + DOB_COL + ", "
                + PHONE_COL + ", "
                + PHOTO_PATH_COL + ", "
                + TIME_STAMP_COL
        };
        Cursor c = db.query(true, CHART_TABLE, sumColumns, null, null, null, null, null, null);

        if (c.moveToFirst()) {
            do {
                ChartTable ct = new ChartTable();
                ct.setId(c.getInt(c.getColumnIndex(ID_COL)));
                ct.setUserId((c.getString(c.getColumnIndex(USER_ID_COL))));
                ct.setPatientId((c.getString(c.getColumnIndex(PATIENT_ID_COL))));
                ct.setFirstName((c.getString(c.getColumnIndex(FIRST_NAME_COL))));
                ct.setLastName(c.getString(c.getColumnIndex(LAST_NAME_COL)));
                ct.setDob(c.getString(c.getColumnIndex(DOB_COL)));
                ct.setPhone(c.getString(c.getColumnIndex(PHONE_COL)));
                ct.setPhoto(c.getString(c.getColumnIndex(PHOTO_PATH_COL)));
                ct.setTimeStamp(c.getString(c.getColumnIndex(TIME_STAMP_COL)));
                chartsList.add(ct);
            } while (c.moveToNext());
        }
        c.close();
        db.close();

        return chartsList;
    }

LogCat

03-21 03:14:41.558: E/AndroidRuntime(1494): FATAL EXCEPTION: main
03-21 03:14:41.558: E/AndroidRuntime(1494): java.lang.ArrayStoreException: source[0] of type com.xxxxxx.models.ChartTable cannot be stored in destination array of type java.lang.String[]
03-21 03:14:41.558: E/AndroidRuntime(1494):     at java.lang.System.arraycopy(Native Method)
03-21 03:14:41.558: E/AndroidRuntime(1494):     at java.util.ArrayList.toArray(ArrayList.java:519)
03-21 03:14:41.558: E/AndroidRuntime(1494):     at com.xxxxxx.activities.ImportExportActivity.exportCsv(ImportExportActivity.java:66)
03-21 03:14:41.558: E/AndroidRuntime(1494):     at com.xxxxxx.activities.ImportExportActivity.access$1(ImportExportActivity.java:61)
03-21 03:14:41.558: E/AndroidRuntime(1494):     at com.xxxxxx.activities.ImportExportActivity$2.onClick(ImportExportActivity.java:51)
03-21 03:14:41.558: E/AndroidRuntime(1494):     at android.view.View.performClick(View.java:4204)

我很清楚这个错误，我无法转换 ArrayList<ChartTable>到 String[] .此外，我的逻辑是有缺陷的。如您所见，ArrayList<ChartTable>包含许多 ChartTable 对象，这些对象分别包含我希望在每个 CSV 行中输出的字符串。所以我实际上需要从我的 ArrayList<ChartTable> 中获取每个 ChartTable 对象如果我想使用此方法，请将其转换为 String[]。现在我在想，也许我正在尝试将方形钉子装入圆孔中。

根据这些信息，执行我正在尝试的操作的正确方法是什么？有没有更简单的方法来转储整个表？或者我应该简单地拉出每个 ChartTable 对象并遍历它们。

感谢您的宝贵时间。如果需要任何进一步的信息，请询问。

Answer 1

虽然我仍在寻找“更好”的解决方案，但我用它来解决了我的问题。

private void exportChartCsv() {
        mDatabaseHelper = new DatabaseHelper(this);
        try {
            mWriter = new CSVWriter(new FileWriter(Environment.getExternalStorageDirectory().getAbsolutePath() + "/charts.csv"));
            mChartList = mDatabaseHelper.getChartsList();
            String[] mExportChartHeaders = {
                    "Chart ID", 
                    "User ID", 
                    "Patient ID", 
                    "First Name", 
                    "Last Name", 
                    "Date of Birth", 
                    "Telephone Number", 
                    "Photo Path", 
                    "TimeStamp", 
                    "Questions Completed"
            };

            mWriter.writeNext(mExportChartHeaders);

            for (ChartTable chartTable : mChartList) {
                mId = String.valueOf(chartTable.getId());
                mUserId = chartTable.getUserId();
                mPatientId = chartTable.getPatientId();
                mFirstName = chartTable.getFirstName();
                mLastName = chartTable.getLastName();
                mDateOfBirth = chartTable.getDob();
                mTelephoneNumber = chartTable.getPhone();
                mPhotoPath = chartTable.getPhoto();
                mTimeStamp = chartTable.getTimeStamp();
                mQuestionsCompleted = String.valueOf(chartTable.getQuestionsCompleted());

                String[] mExportChart = {mId, mUserId, mPatientId, mFirstName, mLastName, mDateOfBirth, mTelephoneNumber, mPhotoPath, mTimeStamp, mQuestionsCompleted};
                mWriter.writeNext(mExportChart);
            }
            mWriter.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        mDatabaseHelper.close();
    }

虽然我认为这不是最好的解决方案，但它非常简单易懂。如果有人提出更好的解决方案，我会很乐意接受他们的回答