Package org.skife.jdbi.v2

Source Code of org.skife.jdbi.v2.ClasspathStatementLocator

/*
* Copyright 2004-2007 Brian McCallister
*
* 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 org.skife.jdbi.v2;

import org.skife.jdbi.v2.exceptions.UnableToCreateStatementException;
import org.skife.jdbi.v2.tweak.StatementLocator;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

/**
* looks for [name], then [name].sql on the classpath
*/
public class ClasspathStatementLocator implements StatementLocator
{
    /**
     * Very basic sanity test to see if a string looks like it might be sql
     */
    public static boolean looksLikeSql(String sql)
    {
        final String local = sql.substring(0, 7).toLowerCase();
        return local.startsWith("insert ")
               || local.startsWith("update ")
               || local.startsWith("select ")
               || local.startsWith("call ")
               || local.startsWith("delete ")
               || local.startsWith("create ")
               || local.startsWith("alter ")
               || local.startsWith("drop ");
    }

    /**
     * If the passed in name doesn't look like SQL it will search the classpath for a file
     * which looks like the provided name.
     * <p>
     * The "looks like" algorithm is not very sophisticated, it basically looks for the string
     * to begin with insert, update, select, call, delete, create, alter, or drop followed
     * by a space.
     * <p>
     * If no resource is found using the passed in string, the string s returned as-is
     *
     * @param name Name or statement literal
     * @return SQL to execute (which will go to a StatementRRewrter first)
     * @throws UnableToCreateStatementException if an IOException occurs reading a found resource
     */
    public String locate(String name, StatementContext ctx) throws Exception
    {
        if (looksLikeSql(name))
        {
            return name;
        }
        final ClassLoader loader = selectClassLoader();
        InputStream in_stream = loader.getResourceAsStream(name);
        if (in_stream == null)
        {
            in_stream = loader.getResourceAsStream(name + ".sql");
        }
        if (in_stream == null)
        {
            return name;
        }
        final BufferedReader reader = new BufferedReader(new InputStreamReader(in_stream));
        final StringBuffer buffer = new StringBuffer();
        String line;
        try
        {
            while ((line = reader.readLine()) != null)
            {
                if (isComment(line))
                {
                    // comment
                    continue;
                }
                buffer.append(line).append(" ");
            }
            reader.close();
        }
        catch (IOException e)
        {
            throw new UnableToCreateStatementException(e.getMessage(), e);
        }
        return buffer.toString();
    }

    /**
     * There *must* be a better place to put this without creating a util class just for it
     */
    private static ClassLoader selectClassLoader()
    {
        ClassLoader loader;
        if (Thread.currentThread().getContextClassLoader() != null)
        {
            loader = Thread.currentThread().getContextClassLoader();
        }
        else
        {
            loader = ClasspathStatementLocator.class.getClassLoader();
        }
        return loader;
    }

    private static boolean isComment(final String line)
    {
        return line.startsWith("#") || line.startsWith("--") || line.startsWith("//");
    }
}
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