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 * <p> * http://www.apache.org/licenses/LICENSE-2.0 * <p> * 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 com.buaa.cfs.security.token; import com.buaa.cfs.io.DataOutputBuffer; import com.buaa.cfs.io.Text; import com.buaa.cfs.io.Writable; import com.buaa.cfs.security.UserGroupInformation; import org.apache.commons.codec.digest.DigestUtils; import java.io.IOException; import java.util.Arrays; /** * An identifier that identifies a token, may contain public information about a token, including its kind (or type). */ public abstract class TokenIdentifier implements Writable { private String trackingId = null; /** * Get the token kind * * @return the kind of the token */ public abstract Text getKind(); /** * Get the Ugi with the username encoded in the token identifier * * @return the username. null is returned if username in the identifier is empty or null. */ public abstract UserGroupInformation getUser(); /** * Get the bytes for the token identifier * * @return the bytes of the identifier */ public byte[] getBytes() { DataOutputBuffer buf = new DataOutputBuffer(4096); try { this.write(buf); } catch (IOException ie) { throw new RuntimeException("i/o error in getBytes", ie); } return Arrays.copyOf(buf.getData(), buf.getLength()); } /** * Returns a tracking identifier that can be used to associate usages of a token across multiple client sessions. * <p> * Currently, this function just returns an MD5 of {{@link #getBytes()}. * * @return tracking identifier */ public String getTrackingId() { if (trackingId == null) { trackingId = DigestUtils.md5Hex(getBytes()); } return trackingId; } }