ch.systemsx.cisd.openbis.generic.client.web.server.util.TSVRenderer.java Source code

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Here is the source code for ch.systemsx.cisd.openbis.generic.client.web.server.util.TSVRenderer.java

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/*
 * Copyright 2008 ETH Zuerich, CISD
 *
 * 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 ch.systemsx.cisd.openbis.generic.client.web.server.util;

import java.util.List;

import org.apache.commons.lang.StringUtils;

import ch.systemsx.cisd.openbis.generic.shared.basic.IColumnDefinition;

/**
 * Creates list of lines with tab separated columns;
 * 
 * @author Tomasz Pylak
 */
public class TSVRenderer {
    private static final String TAB = "\t";

    private final String lineSeparator;

    /**
     * @param entities list of entities which will be exported
     * @param columnDefs column definitions. Each definition know column's header and is able to
     *            extract an appropriate value from the entity.
     * @param lineSeparator character used as a lineSeparator separator
     */
    public static <T> String createTable(List<T> entities, List<IColumnDefinition<T>> columnDefs,
            String lineSeparator) {
        return new TSVRenderer(lineSeparator).createTable(entities, columnDefs);
    }

    private <T> String createTable(List<T> entities, List<IColumnDefinition<T>> columnDefs) {
        StringBuffer sb = new StringBuffer();
        appendHeader(columnDefs, sb);
        for (T entity : entities) {
            appendEntity(entity, columnDefs, sb);
        }
        return sb.toString();
    }

    private TSVRenderer(String lineSeparator) {
        this.lineSeparator = lineSeparator;
    }

    private <T> void appendEntity(T entity, List<IColumnDefinition<T>> columnDefs, StringBuffer sb) {
        boolean isFirst = true;
        for (IColumnDefinition<T> column : columnDefs) {
            if (isFirst == false) {
                sb.append(TAB);
            } else {
                isFirst = false;
            }
            sb.append(cleanWhitespaces(column.getValue(entity)));
        }
        sb.append(lineSeparator);
    }

    /**
     * @return <var>value</var> with white-spaces cleaned in the same way that HTML works (all
     *         contiguous white-spaces are replaced with single space)
     */
    private String cleanWhitespaces(String value) {
        String[] tokens = StringUtils.split(value);
        String result = StringUtils.join(tokens, " ");
        return result;
    }

    private <T> void appendHeader(List<IColumnDefinition<T>> columnDefs, StringBuffer sb) {
        boolean isFirst = true;
        for (IColumnDefinition<T> column : columnDefs) {
            if (isFirst == false) {
                sb.append(TAB);
            } else {
                isFirst = false;
            }
            sb.append(column.getHeader());
        }
        sb.append(lineSeparator);
    }
}