准备开发一个任务调度系统，其中使用Neo4j来保存和查询任务之间的依赖关系，
整理了一个服务类，记录一下。
使用的Neo4j版本为：2.1.3
服务类：
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import org.apache.log4j.Logger;
import org.neo4j.graphdb.Direction;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Path;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.graphdb.Transaction;
import org.neo4j.graphdb.factory.GraphDatabaseFactory;
import org.neo4j.graphdb.index.Index;
import org.neo4j.graphdb.traversal.Evaluators;
import org.neo4j.graphdb.traversal.PathEvaluator;
import org.neo4j.graphdb.traversal.TraversalDescription;
import org.neo4j.graphdb.traversal.Traverser;
import org.neo4j.kernel.impl.util.FileUtils;
/**
* Neo4j服务类
* @author lxw
*
*/
public class Neo4jService implements Runnable {
private static Logger log = Logger.getLogger(Neo4jService.class);
private final String DB_PATH = "neo4jdb/skynet-neo4j.db";
private GraphDatabaseService db;
private Index<Node> index = null;
public static final String INDEX_ID_KEY = "idx_id";
public static final String JOB_ID_KEY = "job_id";
private boolean running = true;
private enum RelTypes implements RelationshipType{
KNOWS,
}
public Neo4jService() {
init();
}
public void init() {
clearDB();
db = new GraphDatabaseFactory().newEmbeddedDatabase(DB_PATH);
registerShutdownHook();
Transaction tx = db.beginTx();
try {
this.index = db.index().forNodes("jobNodes");
tx.success();
} catch (Exception e) {
log.error(e);
log.error("init() error..");
} finally {
tx.close();
}
}
//添加节点
public boolean addNode(int job_id) {
Transaction tx = db.beginTx();
try {
Node jobNode = db.createNode();
jobNode.setProperty(JOB_ID_KEY, job_id);
this.index.add(jobNode, INDEX_ID_KEY, job_id);
tx.success();
log.info("addNode: [" + job_id + "].");
} catch (Exception e) {
log.error(e);
log.error("addNode() error ..");
return false;
} finally {
tx.close();
}
return true;
}
/**
* 删除节点依赖
* @param parent_job_id
* @param son_job_id
* @return
*/
public boolean deleteNodeRelationShip(int parent_job_id,int son_job_id) {
Transaction tx = db.beginTx();
try {
Node parentJobNode = getNodeByJob(parent_job_id);
Node sonJobNode = getNodeByJob(son_job_id);
Iterable<Relationship> relationships = parentJobNode.getRelationships(RelTypes.KNOWS, Direction.OUTGOING);
for(Relationship r : relationships) {
if(r.getEndNode().equals(sonJobNode)) {
r.delete();
}
}
tx.success();
log.info("deleteNodeRelationShip: [" + parent_job_id + "," + son_job_id + "].");
} catch (Exception e) {
log.error(e);
log.error("deleteNodeRelationShip() error .. paren_job_id is [" + parent_job_id
+ "], son_job_id is [" + son_job_id + "].");
} finally {
tx.close();
}
return false;
}
//删除节点
public boolean deleteNode(int job_id) {
Transaction tx = db.beginTx();
try {
Node jobNode = getNodeByJob(job_id);
jobNode.delete();
tx.success();
log.info("deleteNode: [" + job_id + "].");
} catch (Exception e) {
log.error(e);
log.error("deleteNode() error ..");
return false;
} finally {
tx.close();
}
return true;
}
//添加节点依赖
public boolean addNodeRelationShip(int parent_job_id,int son_job_id) {
Transaction tx = db.beginTx();
try {
Node parentJobNode = getNodeByJob(parent_job_id);
Node sonJobNode = getNodeByJob(son_job_id);
parentJobNode.createRelationshipTo(sonJobNode, RelTypes.KNOWS);
tx.success();
log.info("addNodeRelationShip: [" + parent_job_id + "," + son_job_id + "].");
} catch (Exception e) {
log.error(e);
log.error("addNodeRelationShip() error .. paren_job_id is [" + parent_job_id
+ "], son_job_id is [" + son_job_id + "].");
} finally {
tx.close();
}
return false;
}
//获取节点的子任务，包括自身
public List<Integer> getJobSons (int job_id,int depth) {
List<Integer> jobSons = new ArrayList<Integer>();
PathEvaluator<?> path = null;
if(depth == 0 || depth == -1) {
path = Evaluators.excludeStartPosition();
} else {
path = Evaluators.toDepth(depth);
}
Node jobNode = getNodeByJob(job_id);
if(null != jobNode) {
Transaction tx = db.beginTx();
try {
TraversalDescription td = db.traversalDescription()
.breadthFirst()
.relationships( RelTypes.KNOWS, Direction.OUTGOING )
.evaluator(path);
Traverser t = td.traverse(jobNode);
for(Path p : t) {
log.info("level:" + p.length());
log.info("id:" + p.endNode().getProperty(JOB_ID_KEY));
jobSons.add((Integer) p.endNode().getProperty(JOB_ID_KEY));
}
tx.success();
} catch (Exception e) {
log.error(e);
log.error("getJobSons error .. job_id is [" + job_id + "]");
} finally {
tx.close();
}
}
return jobSons;
}
//获取节点的父任务，包括自身
public List<Integer> getJobParents (int job_id,int depth) {
List<Integer> jobParents = new ArrayList<Integer>();
PathEvaluator<?> path = null;
if(depth == 0 || depth == -1) {
path = Evaluators.excludeStartPosition();
} else {
path = Evaluators.toDepth(depth);
}
Node jobNode = getNodeByJob(job_id);
if(null != jobNode) {
Transaction tx = db.beginTx();
try {
TraversalDescription td = db.traversalDescription()
.breadthFirst()
.relationships( RelTypes.KNOWS, Direction.INCOMING )
.evaluator(path);
Traverser t = td.traverse(jobNode);
for(Path p : t) {
log.info("level:" + p.length());
log.info("id:" + p.endNode().getProperty(JOB_ID_KEY));
jobParents.add((Integer) p.endNode().getProperty(JOB_ID_KEY));
}
tx.success();
} catch (Exception e) {
log.error(e);
log.error("getJobParents error .. job_id is [" + job_id + "]");
} finally {
tx.close();
}
}
return jobParents;
}
//获取节点的一级父任务,不包括自身
public List<Integer> getJobFirstParents (int job_id) {
List<Integer> jobParents = new ArrayList<Integer>();
PathEvaluator<?> path = Evaluators.atDepth(1);
Node jobNode = getNodeByJob(job_id);
if(null != jobNode) {
Transaction tx = db.beginTx();
try {
TraversalDescription td = db.traversalDescription()
.breadthFirst()
.relationships( RelTypes.KNOWS, Direction.INCOMING )
.evaluator(path);
Traverser t = td.traverse(jobNode);
for(Path p : t) {
log.info("level:" + p.length());
log.info("id:" + p.endNode().getProperty(JOB_ID_KEY));
jobParents.add((Integer) p.endNode().getProperty(JOB_ID_KEY));
}
tx.success();
} catch (Exception e) {
log.error(e);
log.error("getJobFirstParents error .. job_id is [" + job_id + "]");
} finally {
tx.close();
}
}
return jobParents;
}
//获取节点的一级子任务，不包括自身
public List<Integer> getJobFirstSons (int job_id) {
List<Integer> jobSons = new ArrayList<Integer>();
PathEvaluator<?> path = Evaluators.atDepth(1);
Node jobNode = getNodeByJob(job_id);
if(null != jobNode) {
Transaction tx = db.beginTx();
try {
TraversalDescription td = db.traversalDescription()
.breadthFirst()
.relationships( RelTypes.KNOWS, Direction.OUTGOING )
.evaluator(path);
Traverser t = td.traverse(jobNode);
for(Path p : t) {
log.info("level:" + p.length());
log.info("id:" + p.endNode().getProperty(JOB_ID_KEY));
jobSons.add((Integer) p.endNode().getProperty(JOB_ID_KEY));
}
tx.success();
} catch (Exception e) {
log.error(e);
log.error("getJobFirstParents error .. job_id is [" + job_id + "]");
} finally {
tx.close();
}
}
return jobSons;
}
//根据job_id获取Node
public Node getNodeByJob(int job_id) {
Node node = null;
Transaction tx = db.beginTx();
try {
node = this.index.get(INDEX_ID_KEY,job_id).getSingle();
tx.success();
} catch (Exception e) {
log.error(e);
log.error("getNodeByJob() error, job_id is [" + job_id + "].");
} finally {
tx.close();
}
return node;
}
private void registerShutdownHook() {
// Registers a shutdown hook for the Neo4j instance so that it
// shuts down nicely when the VM exits (even if you "Ctrl-C" the
// running example before it's completed)
Runtime.getRuntime()
.addShutdownHook( new Thread()
{
@Override
public void run()
{
log.info("neo4j shutdown hook ... ");
db.shutdown();
}
} );
}
private void clearDB() {
try {
FileUtils.deleteRecursively(new File(DB_PATH));
}
catch(IOException e) {
throw new RuntimeException(e);
}
}
@Override
public void run() {
while (running) {
log.info(new Date() + " ### Neo4jService 运行正常！");
try {
Thread.sleep(20000);
} catch (InterruptedException e) {
log.error(e);
}
}
}
public void setRunning(boolean running) {
this.running = running;
}
}
测试类：
import java.util.List;
public class TestNeo4j {
public static void main(String[] args) {
Neo4jService nj = new Neo4jService();
Thread t = new Thread(nj,"Neo4jThread");
t.start();
nj.addNode(0);
nj.addNode(1);
nj.addNode(2);
nj.addNode(3);
nj.addNode(4);
nj.addNode(5);
nj.addNode(6);
nj.addNode(7);
nj.addNode(8);
nj.addNode(9);
nj.addNode(10);
nj.addNodeRelationShip(0,1);
nj.addNodeRelationShip(0,2);
nj.addNodeRelationShip(0,3);
nj.addNodeRelationShip(1,4);
nj.addNodeRelationShip(1,5);
nj.addNodeRelationShip(1,6);
nj.addNodeRelationShip(2,7);
nj.addNodeRelationShip(2,9);
nj.addNodeRelationShip(3,8);
nj.addNodeRelationShip(3,10);
nj.addNodeRelationShip(8,9);
nj.addNodeRelationShip(10,9);
List<Integer> sons = nj.getJobFirstParents(9);
for(Integer i : sons) {
System.out.println(i);
}
nj.deleteNodeRelationShip(2, 9);
sons = nj.getJobFirstParents(9);
System.out.println("after delete 2--9");
for(Integer i : sons) {
System.out.println(i);
}
nj.setRunning(false);
}
}
任务的依赖关系如图：
测试输出：
14/09/11 15:39:03 INFO neo4j.Neo4jService: Thu Sep 11 15:39:03 CST 2014 ### Neo4jService 运行正常！ 14/09/11 15:39:03 INFO neo4j.Neo4jService: addNode: [0]. 14/09/11 15:39:03 INFO neo4j.Neo4jService: addNode: [1]. 14/09/11 15:39:03 INFO neo4j.Neo4jService: addNode: [2]. 14/09/11 15:39:03 INFO neo4j.Neo4jService: addNode: [3]. 14/09/11 15:39:03 INFO neo4j.Neo4jService: addNode: [4]. 14/09/11 15:39:03 INFO neo4j.Neo4jService: addNode: [5]. 14/09/11 15:39:03 INFO neo4j.Neo4jService: addNode: [6]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNode: [7]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNode: [8]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNode: [9]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNode: [10]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [0,1]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [0,2]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [0,3]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [1,4]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [1,5]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [1,6]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [2,7]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [2,9]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [3,8]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [3,10]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [8,9]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: addNodeRelationShip: [10,9]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: level:1 14/09/11 15:39:04 INFO neo4j.Neo4jService: id:2 14/09/11 15:39:04 INFO neo4j.Neo4jService: level:1 14/09/11 15:39:04 INFO neo4j.Neo4jService: id:8 14/09/11 15:39:04 INFO neo4j.Neo4jService: level:1 14/09/11 15:39:04 INFO neo4j.Neo4jService: id:10 2 8 10 14/09/11 15:39:04 INFO neo4j.Neo4jService: deleteNodeRelationShip: [2,9]. 14/09/11 15:39:04 INFO neo4j.Neo4jService: level:1 14/09/11 15:39:04 INFO neo4j.Neo4jService: id:10 14/09/11 15:39:04 INFO neo4j.Neo4jService: level:1 14/09/11 15:39:04 INFO neo4j.Neo4jService: id:8 after delete 2--9 10 8 14/09/11 15:39:23 INFO neo4j.Neo4jService: neo4j shutdown hook ...
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