net.duckling.falcon.api.boostrap.SQLReader.java Source code

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Here is the source code for net.duckling.falcon.api.boostrap.SQLReader.java

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/*
 * Copyright (c) 2008-2016 Computer Network Information Center (CNIC), Chinese Academy of Sciences.
 * 
 * This file is part of Duckling project.
 *
 * 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 net.duckling.falcon.api.boostrap;

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

import org.apache.commons.lang.StringUtils;
import org.apache.log4j.Logger;

/**
 * SQL?
 * @author xiejj@cnic.cn
 *
 */
public class SQLReader {
    private static final String ENCODE_UTF8 = "UTF-8";

    private String delimeter = ";";

    private static final Logger LOG = Logger.getLogger(SQLReader.class);

    private BufferedReader reader;

    /**
     * 
     * @param reader SQLreader
     */
    public SQLReader(BufferedReader reader) {
        this.reader = reader;
    }

    /**
     * 
     * @param in      SQL?
     * @param encode   ??
     * @throws UnsupportedEncodingException   ????
     */
    public SQLReader(InputStream in, String encode) throws UnsupportedEncodingException {
        String charEncode = encode;
        if (charEncode == null) {
            charEncode = ENCODE_UTF8;
        }
        reader = new BufferedReader(new InputStreamReader(in, charEncode));
    }

    /**
     * 
     * @param reader   SQLreader
     */
    public SQLReader(Reader reader) {
        this.reader = new BufferedReader(reader);
    }

    private void changeDelimiter(String line) {
        delimeter = parseDelimiter(line);
        if (StringUtils.isEmpty(delimeter)) {
            LOG.error("Wrong format SQL");
            throw new WrongSQLException("delimiter is empty:" + line);
        }
    }

    private boolean isClosed() {
        return reader == null;
    }

    private boolean isComment(String line) {
        return line.startsWith("/*");
    }

    private boolean isDelimiter(String line) {
        if (line != null) {
            String ignored = line.toLowerCase();
            return ignored.startsWith("delimiter");
        }
        return false;
    }

    private String parseDelimiter(String line) {
        return line.substring("delimiter".length()).trim();
    }

    /**
     *  ?
     */
    public void close() {
        if (reader != null) {
            try {
                reader.close();
            } catch (IOException e) {
                LOG.error("Exception has happended while reading initialize SQL.");
                LOG.error(e.getMessage());
                LOG.debug("", e);
            }
            reader = null;
        }
    }

    /**
     * ??SQL
     * @return   ?SQLSQLnull
     */
    public String next() {
        if (!isClosed()) {
            StringBuilder buffer = new StringBuilder();

            String line = null;
            try {
                while ((line = reader.readLine()) != null) {
                    line = line.trim();
                    if (isDelimiter(line)) {
                        changeDelimiter(line);
                    } else if (!isComment(line)) {
                        if (line.endsWith(delimeter)) {
                            line = line.substring(0, line.length() - delimeter.length());
                            buffer.append(line);
                            buffer.append("\n");
                            return StringUtils.trimToNull(buffer.toString());
                        } else {
                            buffer.append(line);
                            buffer.append("\n");
                        }
                    }
                }
            } catch (IOException e) {
                LOG.error(e.getMessage());
                LOG.debug("", e);
                close();
            }
            if (line == null) {
                close();
            }
            return StringUtils.trimToNull(buffer.toString());
        }
        return null;
    }
}