RoaringBitmap的使用方法

这篇文章主要介绍"RoaringBitmap的使用方法"，在日常操作中，相信很多人在RoaringBitmap的使用方法问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答"RoaringBitmap的使用方法"的疑惑有所帮助！接下来，请跟着小编一起来学习吧！

1、简单Demo

参考: RoaringBitmap

public class Demo {    @Test    public void test1(){        // 向r1中添加1、2、3、1000四个数字        RoaringBitmap r1 = RoaringBitmap.bitmapOf(1, 2, 3, 1000);        // 返回第3个数字是1000        System.out.println(r1.select(3));        r1.add(5);        // 返回10000的索引,是4        System.out.println(r1.rank(1000));        System.out.println(r1.rank(3));        System.out.println(r1.rank(2));        System.out.println(r1.rank(1));        // 是否包含1000和7,true和false        System.out.println(r1.contains(1000));        System.out.println(r1.contains(7));        RoaringBitmap r2 = new RoaringBitmap();        // 向r2添加10000-12000共2000个数字        r2.add(10000L, 12000L);        // 将两个r1,r2进行合并,数值进行合并,合并产生新的RoaringBitmap        RoaringBitmap r3 = RoaringBitmap.or(r1, r2);        // r1和r2进行位运算,并将结果赋值给r1        r1.or(r2);        // 判断r1与r3是否相等,true        System.out.println(r1.equals(r3));        // 查看r1中存储了多少个值,2004        System.out.println(r1.getLongCardinality());        // 两种遍历方式        for(int i : r1){            System.out.println(i);        }        r1.forEach((Consumer) i -> System.out.println(i.intValue()));    }    @Test    public void test2(){        RoaringBitmap roaringBitmap = new RoaringBitmap();        roaringBitmap.add(1L, 10L);        // 遍历输出        roaringBitmap.forEach((IntConsumer)i -> System.out.println(i));        // 遍历放入List中        List numbers = new ArrayList<>();        roaringBitmap.forEach((IntConsumer) numbers::add);        System.out.println(numbers);        roaringBitmap.runOptimize();        int size = roaringBitmap.serializedSizeInBytes();        ByteBuffer buffer = ByteBuffer.allocate(size);        roaringBitmap.serialize(buffer);        // 将RoaringBitmap的数据转成字节数组,这样就可以直接存入数据库了,数据库字段类型BLOB        byte[] bitmapData = buffer.array();    }}

// List变成RoaringBitmapprivate RoaringBitmap buildBitmap(List idList) {    RoaringBitmap roaringBitmap = new RoaringBitmap();    idList.forEach(id -> roaringBitmap.add(Integer.valueOf(id.trim())));    roaringBitmap.runOptimize();    return roaringBitmap;}

// a + b - cprivate RoaringBitmap mergeBitmap(List a, List b,                                                         List c) {      // a + b    List blacklistBitMaps = Lists.newLinkedList();    blacklistBitMaps.addAll(a);    blacklistBitMaps.addAll(b);    RoaringBitmap blacklistBitMap = aggregationToBitMap(blacklistBitMaps);            // c     RoaringBitmap whitelistBitMap = aggregationToBitMap(c);            // a + b - c    blacklistBitMap.andNot(whitelistBitMap);            return blacklistBitMap;}private RoaringBitmap aggregationToBitMap(List list) {    if (CollectionUtils.isEmpty(list)) {        return new RoaringBitmap();    }    if (list.size() == 1) {        return list.get(0);    }    return FastAggregation.or(list.listIterator());}

2、和数据库Blob字段结合使用

create table hobby(    id int auto_increment primary key,    name varchar(255) not null,    hobbies blob null);

// 忽略get、set方法public class HobbyDO {    private Integer id;    private String name;    private RoaringBitmap bitmap;}

public interface HobbyDOMapper {    int insert(HobbyDO record);    HobbyDO selectByPrimaryKey(Integer id);            Integer updateBitmap(@Param("id") Integer id, @Param("bitmap") byte[] bitmap);}

public class HobbyBitmapBlobHandler extends BaseTypeHandler {    @Override    public void setNonNullParameter(PreparedStatement ps, int i, RoaringBitmap parameter, JdbcType jdbcType)            throws SQLException {        byte[] content = serializeRoaringBitmap(parameter);        if (content == null) {            return;        }        ByteArrayInputStream bis = new ByteArrayInputStream(content);        ps.setBinaryStream(i, bis, content.length);    }    @Override    public RoaringBitmap getNullableResult(ResultSet rs, String columnName) throws SQLException {        return deSerializeRoaringBitmap(rs.getBlob(columnName));    }    @Override    public RoaringBitmap getNullableResult(ResultSet rs, int columnIndex) throws SQLException {        return deSerializeRoaringBitmap(rs.getBlob(columnIndex));    }    @Override    public RoaringBitmap getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {        return deSerializeRoaringBitmap(cs.getBlob(columnIndex));    }    private byte[] serializeRoaringBitmap(RoaringBitmap roaringBitmap) {        if (roaringBitmap == null) {            return null;        }        int size = roaringBitmap.serializedSizeInBytes();        ByteBuffer buffer = ByteBuffer.allocate(size);        roaringBitmap.serialize(buffer);        return buffer.array();    }    private RoaringBitmap deSerializeRoaringBitmap(Blob blob) {        if (blob == null) {            return null;        }        byte[] content;        try {            content = blob.getBytes(1, (int) blob.length());        } catch (SQLException e) {            e.printStackTrace();            return null;        }        ByteBuffer buffer = ByteBuffer.wrap(content);        return new RoaringBitmap(new ImmutableRoaringBitmap(buffer));    }}

@Testpublic void insert() {    HobbyDO hobby = new HobbyDO();    hobby.setName("lwh");    RoaringBitmap bitmap = new RoaringBitmap();    bitmap.add(111);    bitmap.add(222);    bitmap.add(333);    hobby.setBitmap(bitmap);    hobbyDOMapper.insert(hobby);}@Testpublic void update(){    RoaringBitmap bitmap = new RoaringBitmap();    bitmap.add(133);    bitmap.add(222);    bitmap.add(333);    int size = bitmap.serializedSizeInBytes();    ByteBuffer buffer = ByteBuffer.allocate(size);    bitmap.serialize(buffer);    byte[] bitmapData = buffer.array();    hobbyDOMapper.updateBitmap(1, bitmapData);}@Testpublic void select(){    HobbyDO hobbyDO = hobbyDOMapper.selectByPrimaryKey(1);    hobbyDO.getBitmap().forEach((IntConsumer) System.out::println);}

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