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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！
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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RoaringBitmap private RoaringBitmap buildBitmap(ListidList) { RoaringBitmap roaringBitmap = new RoaringBitmap(); idList.forEach(id -> roaringBitmap.add(Integer.valueOf(id.trim()))); roaringBitmap.runOptimize(); return roaringBitmap; }
// a + b - c private RoaringBitmap mergeBitmap(Lista, 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()); }
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)); } }
@Test
public 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);
}
@Test
public 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);
}
@Test
public void select(){
HobbyDO hobbyDO = hobbyDOMapper.selectByPrimaryKey(1);
hobbyDO.getBitmap().forEach((IntConsumer) System.out::println);
}到此，关于“RoaringBitmap的使用方法”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注创新互联网站，小编会继续努力为大家带来更多实用的文章！
