org.jasig.ssp.util.liquibase.MessageTemplateCheckSumPrecondition.java Source code

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Here is the source code for org.jasig.ssp.util.liquibase.MessageTemplateCheckSumPrecondition.java

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/**
 * Licensed to Apereo under one or more contributor license
 * agreements. See the NOTICE file distributed with this work
 * for additional information regarding copyright ownership.
 * Apereo licenses this file to you 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 the following location:
 *
 *   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 org.jasig.ssp.util.liquibase;

/***
 *   Use this in liquibase scripts to verify checksum has not changed from the default value
 *   so users custom template changes are not overwritten
 *   
 *  <customPrecondition className="org.jasig.ssp.util.liquibase.MessageTemplateCheckSumPrecondition">
 *   <param name="messageTemplateId" value="0b7e484d-44e4-4f0d-8db5-3518d015b495"/>
 *   <param name="columnName" value="body"/>
 *   </customPrecondition>
 *  where the columnName is the name of the column that is used to generate the checksum
 */
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import liquibase.database.Database;
import liquibase.database.jvm.JdbcConnection;
import liquibase.exception.CustomPreconditionErrorException;
import liquibase.exception.CustomPreconditionFailedException;
import liquibase.precondition.CustomPrecondition;

import org.apache.commons.lang.StringUtils;

public class MessageTemplateCheckSumPrecondition implements CustomPrecondition {

    private String messageTemplateId;

    private String columnName;

    public MessageTemplateCheckSumPrecondition() {
    }

    public String getMessageTemplateId() {
        return messageTemplateId;
    }

    public void setMessageTemplateId(String messageTemplateId) {
        this.messageTemplateId = messageTemplateId;
    }

    public String getColumnName() {
        return columnName;
    }

    public void setColumnName(String columnName) {
        this.columnName = columnName;
    }

    @Override
    public void check(Database database)
            throws CustomPreconditionFailedException, CustomPreconditionErrorException {

        if (StringUtils.isBlank(columnName))
            throw new CustomPreconditionErrorException("columnName is empty");
        if (StringUtils.isBlank(messageTemplateId))
            throw new CustomPreconditionErrorException("messageTemplateId is empty");

        final String query = "select " + columnName + " from message_template where id = '" + messageTemplateId
                + "'";
        String columnValue = processQuery(database, query);

        String currentChecksum = "";
        try {
            currentChecksum = getCheckSum(StringUtils.deleteWhitespace(columnValue));
        } catch (NoSuchAlgorithmException e) {
            throw new CustomPreconditionErrorException("Unable to calculate checksum");
        }

        final String defaultCheckSumQuery = "select " + columnName + "_checksum"
                + " from message_template where id = '" + messageTemplateId + "'";
        final String defaultCheckSum = processQuery(database, defaultCheckSumQuery);

        if (!defaultCheckSum.equals(currentChecksum))
            throw new CustomPreconditionFailedException("checkSums did not match for message template id: "
                    + messageTemplateId + " and column" + columnName);
    }

    private String processQuery(Database database, String query) throws CustomPreconditionErrorException {
        PreparedStatement preparedQuery = null;
        ResultSet rs = null;
        CustomPreconditionErrorException error = null;
        try {
            JdbcConnection conn = (JdbcConnection) database.getConnection();
            preparedQuery = conn.prepareStatement(query);
            rs = preparedQuery.executeQuery();
            rs.next();
            return rs.getString(1);
        } catch (Exception e) {
            throw new CustomPreconditionErrorException("Query [" + query + "] failed", e);
        } finally {
            if (rs != null) {
                try {
                    rs.close();
                } catch (Exception ee) {
                    if (error == null) {
                        throw new CustomPreconditionErrorException(
                                "Failed to cleanup result set after query [" + query + "]", ee);
                    }
                }
            }
            if (preparedQuery != null) {
                try {
                    preparedQuery.close();
                } catch (Exception ee) {
                    if (error == null) {
                        throw new CustomPreconditionErrorException(
                                "Failed to cleanup statement after query [" + query + "]", ee);
                    }
                }
            }
        }
    }

    private String getCheckSum(String value) throws NoSuchAlgorithmException {
        MessageDigest md = MessageDigest.getInstance("SHA1");

        byte[] mdbytes = md.digest(value.getBytes());
        StringBuffer sb = new StringBuffer("");
        for (int i = 0; i < mdbytes.length; i++) {
            sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
        }
        return sb.toString();
    }
}