Java tutorial
/**************************************************************** * 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 org.apache.james.mailbox.model; import java.util.Objects; import com.google.common.base.MoreObjects; import com.google.common.base.Preconditions; import com.google.common.base.Strings; import com.google.common.hash.Hashing; public class BlobId { public static BlobId fromBytes(byte[] bytes) { Preconditions.checkNotNull(bytes); return new BlobId(Hashing.sha256().hashBytes(bytes).toString()); } public static BlobId fromString(String raw) { Preconditions.checkArgument(!Strings.isNullOrEmpty(raw)); return new BlobId(raw); } private final String id; private BlobId(String id) { this.id = id; } public String asString() { return id; } @Override public final boolean equals(Object o) { if (o instanceof BlobId) { BlobId blobId = (BlobId) o; return Objects.equals(this.id, blobId.id); } return false; } @Override public final int hashCode() { return Objects.hash(id); } @Override public String toString() { return MoreObjects.toStringHelper(this).add("id", id).toString(); } }