money-mining-java/src/main/java/top/zhixinghe1/money/agg/cache/ReverseIndexLoader.java

package top.zhixinghe1.money.agg.cache;

import com.github.benmanes.caffeine.cache.CacheLoader;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.roaringbitmap.RoaringBitmap;
import top.zhixinghe1.money.agg.Constant;
import top.zhixinghe1.money.agg.entity.BufferedRandomAccessFile;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Map;

public class ReverseIndexLoader implements CacheLoader<String, RoaringBitmap> {

    /**
     * 数据目录路径
     */
    private String dataPath;

    /**
     * 行索引
     */
    private Map<String, long[]> lineIndex;

    /**
     * 文件读写器
     */
//    private BufferedRandomAccessFile randomAccessFile;
    private RandomAccessFile randomAccessFile;

    private MappedByteBuffer mappedByteBuffer;

    public ReverseIndexLoader(String dataPath, Map<String, long[]> lineIndex) throws IOException {
        this.dataPath = dataPath;
        this.lineIndex = lineIndex;
        String filePath = String.join(File.separator, dataPath, Constant.WORD_REVERSE_INDEX_FILE);
//        randomAccessFile = new BufferedRandomAccessFile(filePath, "r", 10*1024*1024);
        randomAccessFile = new RandomAccessFile(filePath, "r");
        MappedByteBuffer mappedByteBuffer = randomAccessFile.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, Integer.MAX_VALUE);
    }

    @Override
    public @Nullable RoaringBitmap load(String s) throws Exception {
        long[] basicInfo = lineIndex.get(s);
//        randomAccessFile.seek();
//        String lineContent = new String(randomAccessFile.readLine().getBytes("8859_1"), "UTF-8");
//        String lineContent = randomAccessFile.readUTF();
//        mappedByteBuffer.position((int) basicInfo[0]);
        byte[] buff = new byte[(int) basicInfo[2]];
        mappedByteBuffer.put(buff, (int)basicInfo[0], (int)basicInfo[2]);
        String lineContent = new String(buff);

        String[] split = lineContent.substring(lineContent.indexOf(",") + 1).split(",");
        int[] positionIntegers = new int[split.length];
        for (int i = 0; i < split.length; i++) {
            try {
                positionIntegers[i] = Integer.parseInt(split[i]);
            } catch (Exception e) {
                System.out.println("暂停");
            }
        }

        return RoaringBitmap.bitmapOf(positionIntegers);
    }
}