com.migu.flume.interceptor.plugin.SearchAndAppendInterceptor.java Source code

Introduction

Here is the source code for com.migu.flume.interceptor.plugin.SearchAndAppendInterceptor.java

Source

/**
 * 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 com.migu.flume.interceptor.plugin;

import com.google.common.base.Charsets;
import com.google.common.base.Preconditions;
import org.apache.commons.lang.StringUtils;
import org.apache.flume.Context;
import org.apache.flume.Event;
import org.apache.flume.interceptor.Interceptor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.nio.charset.Charset;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * <p>
 * Interceptor that allows search-and-replace of event body strings using
 * regular expressions. This only works with event bodies that are valid
 * strings. The charset is configurable.
 * <p>
 * Usage:
 * <pre>
 *   agent.source-1.interceptors.search-replace.searchPattern = ^INFO:
 *   agent.source-1.interceptors.search-replace.replaceString = Log msg:
 * </pre>
 * <p>
 * Any regular expression search pattern and replacement pattern that can be
 * used with {@link Matcher#replaceAll(String)} may be used,
 * including backtracking and grouping.
 */
public class SearchAndAppendInterceptor implements Interceptor {

    private static final Logger logger = LoggerFactory.getLogger(SearchAndAppendInterceptor.class);

    //String???
    private final String searchPattern;
    //??
    private final String appendDelimiterString;
    private final Charset charset;

    private SearchAndAppendInterceptor(String searchPattern, String appendDelimiterString, Charset charset) {
        this.searchPattern = searchPattern;
        this.appendDelimiterString = appendDelimiterString;
        this.charset = charset;
    }

    @Override
    public void initialize() {
    }

    @Override
    public void close() {
    }

    @Override
    public Event intercept(Event event) {
        String origBody = new String(event.getBody(), charset);
        // = Pattern.compile(searchPattern);
        //??
        String[] searchRegexs = searchPattern.split(",");
        int l = searchRegexs.length;
        StringBuilder appendString = new StringBuilder();
        for (int i = 0; i < l; i++) {
            Pattern pattern = Pattern.compile(searchRegexs[i]);
            Matcher matcher = pattern.matcher(origBody);
            if (matcher.find() && matcher.groupCount() > 0) {
                //?????
                appendString.append(appendDelimiterString + matcher.group(1));
            } else {
                appendString.append(appendDelimiterString + "NULL");
            }
        }

        //Matcher matcher = searchPattern.matcher(origBody);
        // String newBody = matcher.replaceAll(replaceString);
        //
        String newBody = origBody + appendString;
        event.setBody(newBody.getBytes(charset));
        return event;
    }

    @Override
    public List<Event> intercept(List<Event> events) {
        for (Event event : events) {
            intercept(event);
        }
        return events;
    }

    public static class Builder implements Interceptor.Builder {
        private static final String SEARCH_PAT_KEY = "searchPattern";
        //"|"
        private static final String APPEND_DELIMITER_KEY = "appendDelimiter";
        private static final String CHARSET_KEY = "charset";

        //String???
        private String searchRegex;
        private String appendDelimiterString;
        private Charset charset = Charsets.UTF_8;

        @Override
        public void configure(Context context) {
            String searchPattern = context.getString(SEARCH_PAT_KEY);
            Preconditions.checkArgument(!StringUtils.isEmpty(searchPattern),
                    "Must supply a valid search pattern " + SEARCH_PAT_KEY + " (may not be empty)");

            appendDelimiterString = context.getString(APPEND_DELIMITER_KEY);
            //"|"
            if (appendDelimiterString == null) {
                appendDelimiterString = "|";
            }

            //?intercept??
            // searchRegex = Pattern.compile(searchPattern);
            searchRegex = searchPattern;

            if (context.containsKey(CHARSET_KEY)) {
                // May throw IllegalArgumentException for unsupported charsets.
                charset = Charset.forName(context.getString(CHARSET_KEY));
            }
        }

        @Override
        public Interceptor build() {
            Preconditions.checkNotNull(searchRegex, "Regular expression search pattern required");
            Preconditions.checkNotNull(appendDelimiterString, "Replacement string required");
            return new SearchAndAppendInterceptor(searchRegex, appendDelimiterString, charset);
        }
    }
}