com.google.visualization.datasource.render.CsvRenderer.java Source code

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Here is the source code for com.google.visualization.datasource.render.CsvRenderer.java

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// Copyright 2009 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.visualization.datasource.render;

import com.google.visualization.datasource.base.ResponseStatus;
import com.google.visualization.datasource.datatable.ColumnDescription;
import com.google.visualization.datasource.datatable.DataTable;
import com.google.visualization.datasource.datatable.TableCell;
import com.google.visualization.datasource.datatable.TableRow;
import com.google.visualization.datasource.datatable.ValueFormatter;
import com.google.visualization.datasource.datatable.value.ValueType;

import com.ibm.icu.util.ULocale;

import org.apache.commons.lang.StringUtils;

import java.util.List;
import java.util.Map;

/**
 * Takes a data table and returns a csv string.
 *
 * @author Nimrod T.
 */
public class CsvRenderer {

    /**
     * Private constructor.
     */
    private CsvRenderer() {
    }

    /**
     * Generates a csv string representation of a data table.
     *
     * @param dataTable The data table.
     * @param locale The locale. If null, uses the default from
     *     {@code LocaleUtil#getDefaultLocale}.
     * @param separator The separator string used to delimit row values. 
     *     If the separator is {@code null}, comma is used as a separator.
     *
     * @return The char sequence with the csv string.
     */
    public static CharSequence renderDataTable(DataTable dataTable, ULocale locale, String separator) {
        if (separator == null) {
            separator = ",";
        }

        // Deal with empty data table.
        if (dataTable.getColumnDescriptions().isEmpty()) {
            return "";
        }

        // Deal with non-empty data table.
        StringBuilder sb = new StringBuilder();
        List<ColumnDescription> columns = dataTable.getColumnDescriptions();
        // Append column labels
        for (ColumnDescription column : columns) {
            sb.append(escapeString(column.getLabel())).append(separator);
        }

        Map<ValueType, ValueFormatter> formatters = ValueFormatter.createDefaultFormatters(locale);

        // Remove last comma.
        int length = sb.length();
        sb.replace(length - 1, length, "\n");

        // Append the data cells.
        List<TableRow> rows = dataTable.getRows();
        for (TableRow row : rows) {
            List<TableCell> cells = row.getCells();
            for (TableCell cell : cells) {
                String formattedValue = cell.getFormattedValue();
                if (formattedValue == null) {
                    formattedValue = formatters.get(cell.getType()).format(cell.getValue());
                }
                if (cell.isNull()) {
                    sb.append("null");
                } else {
                    ValueType type = cell.getType();
                    // Escape the string with quotes if its a text value or if it contains a comma.
                    if (formattedValue.indexOf(',') > -1 || type.equals(ValueType.TEXT)) {
                        sb.append(escapeString(formattedValue));
                    } else {
                        sb.append(formattedValue);
                    }
                }
                sb.append(separator);
            }

            // Remove last comma.
            length = sb.length();
            sb.replace(length - 1, length, "\n");
        }
        return sb.toString();
    }

    /**
     * Escapes a string that is written to a csv file. The escaping is as follows:
     * 1) surround with ".
     * 2) double each internal ".
     *
     * @param input The input string.
     *
     * @return An escaped string.
     */
    private static String escapeString(String input) {
        StringBuilder sb = new StringBuilder();
        sb.append("\"");
        sb.append(StringUtils.replace(input, "\"", "\"\""));
        sb.append("\"");
        return sb.toString();
    }

    /**
     * Renders an error message.
     *
     * @param responseStatus The response status.
     * 
     * @return An error message.
     */
    public static String renderCsvError(ResponseStatus responseStatus) {
        StringBuilder sb = new StringBuilder();
        sb.append("Error: ").append(responseStatus.getReasonType().getMessageForReasonType(null));
        sb.append(". ").append(responseStatus.getDescription());
        return escapeString(sb.toString());
    }
}