com.azaptree.services.domain.entity.dao.JDBCEntityDAOSupport.java Source code

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Here is the source code for com.azaptree.services.domain.entity.dao.JDBCEntityDAOSupport.java

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package com.azaptree.services.domain.entity.dao;

/*
 * #%L
 * AZAPTREE-DOMAIN-ENTITY
 * %%
 * Copyright (C) 2012 - 2013 AZAPTREE.COM
 * %%
 * 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.
 * #L%
 */

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.UUID;

import org.apache.commons.lang3.ArrayUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.dao.IncorrectResultSizeDataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.util.Assert;

import com.azaptree.services.domain.entity.Entity;
import com.google.common.collect.ImmutableMap;

public abstract class JDBCEntityDAOSupport<T extends Entity> implements EntityDAO<T> {

    protected final Logger log = LoggerFactory.getLogger(getClass());
    protected final JdbcTemplate jdbc;
    protected final String table;

    /**
     * Maps entity field to table column
     */
    protected Map<String, String> fieldColumnMappings = new HashMap<>();

    public JDBCEntityDAOSupport(final JdbcTemplate jdbc, final String table) {
        Assert.notNull(jdbc, "jdbc is required");
        Assert.hasText("table");
        this.jdbc = jdbc;
        this.table = table;
        initFieldColumnMappings();
        buildImmutableFieldColumnMappings();
    }

    /**
     * Appends LIMIT and OFFSET for POSTGRESQL SQL queries
     * 
     * <code>
    SELECT select_list
     FROM table_expression
     [ ORDER BY ... ]
     [ LIMIT { number | ALL } ] [ OFFSET number ]
       </code>
     * 
     * @param sql
     * @param page
     */
    protected void appendLimitAndOffSet(final StringBuilder sql, final Page page) {
        sql.append(" LIMIT ").append(page.getPageSize()).append(" OFFSET ").append(page.getOffset());
    }

    protected void appendOrderBy(final StringBuilder sql, final SortField... fields) {
        if (ArrayUtils.isNotEmpty(fields)) {
            sql.append(" ORDER BY ");
            SortField f;
            for (int i = 0; i < fields.length;) {
                f = fields[i];
                final String column = fieldColumnMappings.get(f.getFieldName());
                Assert.notNull(column, "Invalid field : " + f.getFieldName());
                sql.append(column).append(' ');
                if (!f.isAscending()) {
                    sql.append("DESC");
                }
                if (++i < fields.length) {
                    sql.append(",");
                }
            }
        }
    }

    protected void buildImmutableFieldColumnMappings() {
        fieldColumnMappings = ImmutableMap.<String, String>builder().putAll(fieldColumnMappings).build();
    }

    protected void check(final Page page, final SortField... fields) {
        Assert.notNull(page, "page is required");
        checkEntityField(fields);
    }

    protected void checkEntityField(final SortField... field) {
        if (ArrayUtils.isEmpty(field)) {
            return;
        }
        for (final SortField f : field) {
            Assert.isTrue(fieldColumnMappings.containsKey(f.getFieldName()), "Invalid field: " + field);
        }
    }

    @Override
    public boolean delete(final UUID id) {
        Assert.notNull(id, "id is required");
        final String sql = new StringBuilder("delete from ").append(table).append(" where entity_id = ?")
                .toString();
        return jdbc.update(sql, id) > 0;
    }

    @Override
    public boolean exists(final UUID id) {
        Assert.notNull(id, "id is required");
        final String sql = new StringBuilder("select 1 from ").append(table).append(" where entity_id = ?")
                .toString();
        final Object[] args = { id };
        try {
            jdbc.queryForInt(sql, args);
            return true;
        } catch (final IncorrectResultSizeDataAccessException e) {
            return false;
        }
    }

    @Override
    public SearchResults<T> findAll(final Page page, final SortField... sort) {
        check(page, sort);
        final StringBuilder sql = new StringBuilder("select * from t_subject");
        appendOrderBy(sql, sort);
        appendLimitAndOffSet(sql, page);

        final long totalCount = getTotalCount();
        final List<T> data = jdbc.query(sql.toString(), getRowMapper());

        return new SearchResults<>(page, totalCount, data);
    }

    @Override
    public T findById(final UUID id) {
        Assert.notNull(id, "id is required");
        final String sql = new StringBuilder("select * from ").append(table).append(" where entity_id = ?")
                .toString();
        final Object[] args = { id };
        try {
            return jdbc.queryForObject(sql, args, getRowMapper());
        } catch (final IncorrectResultSizeDataAccessException e) {
            return null;
        }
    }

    @Override
    public Set<String> getEntityFields() {
        return fieldColumnMappings.keySet();
    }

    protected abstract RowMapper<T> getRowMapper();

    @Override
    public long getTotalCount() {
        return jdbc.queryForLong(new StringBuilder("select count(*) from ").append(table).toString());
    }

    /**
     * <code>
     * EntityId -> entity_id
     * </code>
     */
    protected void initFieldColumnMappings() {
        fieldColumnMappings.put("EntityId", "entity_id");
    }
}