neo4j入门
neo4j是java编写的图（或叫网络）NoSQL。 这里的图的意思是，通过结点和关系，描绘一张数据图形；有些人可能想当然的理解为以图形结构存储数据。
neo4j有一套完整的解决方案，支持备份/恢复、高级监控、ha等（企业版，收费）
可做为(java)嵌入式开发，支持多种语言。
neo4j的查询语言是cypher--一种类人类语言，虽然neo4j也（有限的）支持sql，但sql在路径搜索上不如cypher直观。
参考资料：
http://docs.neo4j.org.cn/index.html
http://docs.neo4j.org/?_ga=1.12903472.666951846.1402043619
cypher参考： http://docs.neo4j.org/refcard/2.1.1/
neo4j提供一个web管理（需要html5支持），可在web控制台执行cypher语句和监控db状态。
大部分图nosql遵守(注意：非强制)的三个特性：node(结点)、relationship(关系)、property(属性)
以下是一些演示。
创建node
CREATE (u:USER) SET u.name='张良',u.sex='M',u.userid='u1001'; CREATE (u:USER) SET u.name='钱倩',u.sex='F',u.userid='u1002'; CREATE (u:USER) SET u.name='王星宇',u.sex='M',u.userid='u1003'; CREATE (u:USER) SET u.name='张闻',u.sex='M',u.userid='u1004'; CREATE (u:USER) SET u.name='张一飞',u.sex='M',u.userid='u1005'; CREATE (u:USER) SET u.name='周远',u.sex='M',u.userid='u1006'; CREATE (u:USER) SET u.name='谢晁',u.sex='M',u.userid='u1007'; CREATE (u:USER) SET u.name='翁莉',u.sex='F',u.userid='u1008'; CREATE (u:USER) SET u.name='张茜静',u.sex='F',u.userid='u1009'; CREATE (u:USER) SET u.name='孙雯君',u.sex='F',u.userid='u1010'; CREATE (u:USER) SET u.name='隋燕',u.sex='F',u.userid='u1011'; CREATE (g:GROUP) SET g.name='s4a',g.groupid='g101'; CREATE (g:GROUP) SET g.name='3G',g.groupid='g102'; CREATE (g:GROUP) SET g.name='TJ加油卡',g.groupid='g103'; CREATE (d:DEPT) SET d.name='开发部',d.deptid='d101'; CREATE (d:DEPT) SET d.name='测试部',d.deptid='d102'; CREATE (d:DEPT) SET d.name='人事部',d.deptid='d103';
建立关系
MATCH (g {groupid:'g101'}), (d {deptid:'d101'}) MERGE (g)-[:BELONG]->(d );
MATCH (g {groupid:'g102'}), (d {deptid:'d101'}) MERGE (g)-[:BELONG]->(d );
MATCH (g {groupid:'g103'}), (d {deptid:'d101'}) MERGE (g)-[:BELONG]->(d );
MATCH (u {userid:'u1001'}), (g {groupid:'g101'}) MERGE (u)-[:BELONG {role:'member'}]->(g);
MATCH (u {userid:'u1002'}), (g {groupid:'g101'}) MERGE (u)-[:BELONG {role:'member'}]->(g);
MATCH (u {userid:'u1003'}), (g {groupid:'g101'}) MERGE (u)-[:BELONG {role:'member'}]->(g);
MATCH (u {userid:'u1004'}), (g {groupid:'g101'}) MERGE (u)-[:BELONG {role:'member'}]->(g);
MATCH (u {userid:'u1005'}), (g {groupid:'g102'}) MERGE (u)-[:BELONG {role:'member'}]->(g);
MATCH (u {userid:'u1006'}), (g {groupid:'g103'}) MERGE (u)-[:BELONG {role:'member'}]->(g);
MATCH (u {userid:'u1007'}), (d {deptid:'d101'}) MERGE (u)-[:BELONG {role:'admin'}]->(d);
MATCH (u {userid:'u1008'}), (d {deptid:'d101'}) MERGE (u)-[:BELONG {role:'member'}]->(d);
MATCH (u {userid:'u1009'}), (d {deptid:'d102'}) MERGE (u)-[:BELONG {role:'member'}]->(d);
MATCH (u {userid:'u1010'}), (d {deptid:'d102'}) MERGE (u)-[:BELONG {role:'member'}]->(d);
MATCH (u {userid:'u1011'}), (d {deptid:'d103'}) MERGE (u)-[:BELONG {role:'member'}]->(d);
也可以通过这种方式建立结果和关系。
START会创建结点和关系；而MERGE是在已存在结点间建立关系。
START (u:USER)-[r:BELONG]->(g:GROUP) SET u.userid='u1001',r.role='member',g.name='TJ加油卡',g.groupid='g103';
一些查询操作
//查看所有用户
MATCH (u:USER) RETURN u;
//查询组与部门的对应关系
MATCH (g:GROUP)-->(d:DEPT) return g.name as 组,d.name as 部门;
//查询所有部门成员
MATCH (u:USER)-[*]->(d:DEPT ) return u,d;
//查询s4a组所有成员
MATCH (u:USER)-[r:BELONG]->(g {groupid:'g101'}) return u,r,g;
//查询开发部所有成员
MATCH (u:USER)-[*]->(d:DEPT {deptid:'d101'}) return u,d;
//查询开发部主管
MATCH (u:USER)-[* {role:'admin'}]->(d:DEPT {deptid:'d101'}) return u,d;
//增加周远为TJ加油卡的组长
MATCH (u {userid:'u1006'}), (g {groupid:'g103'}) MERGE (u)-[:BELONG {role:'admin'}]->(g);
//增加周远为TJ加油卡的成员
MATCH (u {userid:'u1006'}), (g {groupid:'g103'}) MERGE (u)-[:BELONG {role:'member'}]->(g);
//移除周远在TJ加油卡的角色
MATCH (u {userid:'u1006'})-[r]->(g {groupid:'g103'}) REMOVE r.role;
//移除周远在TJ加油卡的关系
MATCH (u {userid:'u1006'})-[r]->(g {groupid:'g103'}) DELETE r;
//设置周渊为TJ加油卡的组长
MATCH (u {userid:'u1006'})-[r]->(g {groupid:'g103'}) SET r.role='admin';
//查看上面操作结果
MATCH (u {userid:'u1006'})-[r]->(g {groupid:'g103'}) return u,r,g;
在java下应用neo4j(嵌入式)
package org.sl.neo4j;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.factory.GraphDatabaseFactory;
public class Neo4jPool {
public static String DB_PATH = "D:/jars/neo4j-community-2.1.1/neo4jdb/neo4jtest1";
// public static String DB_PATH = "http://127.0.0.1:7474";
private static ThreadLocal<GraphDatabaseService> tl = new ThreadLocal<GraphDatabaseService>();
public static GraphDatabaseService getConnect(){
GraphDatabaseService graphDb;
synchronized(tl){
if(tl.get() == null){
graphDb = new GraphDatabaseFactory().newEmbeddedDatabase( DB_PATH );
registerShutdownHook(graphDb);
tl.set(graphDb);
}else{
graphDb = tl.get();
}
}
return graphDb;
}
static void registerShutdownHook(final GraphDatabaseService graphDb){
Runtime.getRuntime().addShutdownHook(new Thread(){
public void run(){
graphDb.shutdown();
}
});
}
}
static void t1(){
GraphDatabaseService db = Neo4jPool.getConnect();
Transaction tx = db.beginTx();
try{
Node n1 = db.createNode();
n1.setProperty("name", "n1");
n1.setProperty("value", "v1");
Node n2 = db.createNode();
n2.setProperty("name", "n2");
n2.setProperty("value", "v2");
n2.setProperty("desc", "desc2");
RelationshipType rt = DynamicRelationshipType.withName("relat1");
Relationship rela = n1.createRelationshipTo(n2, rt); //RelTypes.KNOWS
rela.setProperty("name", "rela1");
tx.success();
}catch(Exception ex){
ex.printStackTrace();
tx.failure();
}finally{
tx.close();
}
}
static void t2(){
GraphDatabaseService db = Neo4jPool.getConnect();
Transaction tx = db.beginTx();
try{
// NodesFunction nn = new NodesFunction(nn);
Iterable<Node> nodes = db.getAllNodes();
for(Node n: nodes){
System.out.println(n.getProperty("name"));
}
tx.success();
}catch(Exception ex){
ex.printStackTrace();
tx.failure();
}finally{
tx.close();
}
}
static void t5(){
GraphDatabaseService db = Neo4jPool.getConnect();
Transaction tx = db.beginTx();
try{
ExecutionEngine engine = new ExecutionEngine( db );
String query = "START n=node(*) RETURN n,n.name";
ExecutionResult rs = engine.execute(query);
ResourceIterator<Node> riter = rs.columnAs("n");
while(riter.hasNext()){
Node n = riter.next();
// n.setProperty("desc", "desc222222");
// Iterable<String>ps = n.getPropertyKeys();
Iterator<String> piter = n.getPropertyKeys().iterator();
while(piter.hasNext()){
String key = piter.next();
System.out.println(key+":"+n.getProperty(key));
}
// n.setProperty("desc", "desc21");
}
tx.success();
}catch(Exception ex){
ex.printStackTrace();
tx.failure();
}
tx.close();
db.shutdown();
}
static void t6(){
GraphDatabaseService db = Neo4jPool.getConnect();
Transaction tx = db.beginTx();
try{
String sql = "START n=node(1) SET n.desc='desc0000' ";
ExecutionEngine engine = new ExecutionEngine( db );
engine.execute(sql);
tx.success();
}catch(Exception ex){
ex.printStackTrace();
tx.failure();
}
}