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<? super Integer>) 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<Integer> 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(List<String> idList) {
RoaringBitmap roaringBitmap = new RoaringBitmap();
idList.forEach(id -> roaringBitmap.add(Integer.valueOf(id.trim())));
roaringBitmap.runOptimize();
return roaringBitmap;
}// a + b - c
private RoaringBitmap mergeBitmap(List<RoaringBitmap> a, List<RoaringBitmap> b,
List<RoaringBitmap> c) {
// a + b
List<RoaringBitmap> 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<RoaringBitmap> 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<RoaringBitmap> {
@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，请继续关注天达云网站，小编会继续努力为大家带来更多实用的文章！