org.apache.crunch.contrib.io.jdbc.DataBaseSource.java Source code

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Here is the source code for org.apache.crunch.contrib.io.jdbc.DataBaseSource.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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
 *
 *     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.apache.crunch.contrib.io.jdbc;

import java.sql.Driver;

import org.apache.crunch.io.FormatBundle;
import org.apache.crunch.io.impl.FileSourceImpl;
import org.apache.crunch.types.writable.Writables;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.lib.db.DBConfiguration;
import org.apache.hadoop.mapreduce.lib.db.DBInputFormat;
import org.apache.hadoop.mapreduce.lib.db.DBWritable;

/**
 * Source from reading from a database via a JDBC connection. Underlying
 * database reading is provided by {@link DBInputFormat}.
 * <p>
 * A type that is input via this class must be a Writable that also implements
 * DBWritable. On the {@link DBWritable#readFields(java.sql.ResultSet)} method
 * needs to be fully implemented form {@link DBWritable}.
 * 
 * @param <T> The input type of this source
 */
public class DataBaseSource<T extends DBWritable & Writable> extends FileSourceImpl<T> {

    private DataBaseSource(Class<T> inputClass, String driverClassName, String url, String username,
            String password, String selectClause, String countClause) {
        super(new Path("dbsource"), Writables.writables(inputClass), FormatBundle.forInput(DBInputFormat.class)
                .set(DBConfiguration.DRIVER_CLASS_PROPERTY, driverClassName).set(DBConfiguration.URL_PROPERTY, url)
                .set(DBConfiguration.USERNAME_PROPERTY, username).set(DBConfiguration.PASSWORD_PROPERTY, password)
                .set(DBConfiguration.INPUT_CLASS_PROPERTY, inputClass.getCanonicalName())
                .set(DBConfiguration.INPUT_QUERY, selectClause)
                .set(DBConfiguration.INPUT_COUNT_QUERY, countClause));
    }

    static class Builder<T extends DBWritable & Writable> {

        private Class<T> inputClass;
        private String driverClass;
        private String url;
        private String username;
        private String password;
        private String selectClause;
        public String countClause;

        private DataBaseSource<T> dataBaseSource;

        public Builder(Class<T> inputClass) {
            this.inputClass = inputClass;
        }

        Builder<T> setDriverClass(Class<? extends Driver> driverClass) {
            this.driverClass = driverClass.getName();
            return this;
        }

        Builder<T> setUrl(String url) {
            this.url = url;
            return this;
        }

        Builder<T> setUsername(String username) {
            this.username = username;
            return this;
        }

        Builder<T> setPassword(String password) {
            this.password = password;
            return this;
        }

        Builder<T> selectSQLQuery(String selectClause) {
            this.selectClause = selectClause;
            return this;
        }

        Builder<T> countSQLQuery(String countClause) {
            this.countClause = countClause;
            return this;
        }

        DataBaseSource<T> build() {
            return new DataBaseSource<T>(inputClass, driverClass, url, username, password, selectClause,
                    countClause);
        }
    }

    @Override
    public long getSize(Configuration configuration) {
        // TODO Do something smarter here
        return 1000 * 1000;
    }

    @Override
    public long getLastModifiedAt(Configuration configuration) {
        return -1;
    }
}