如何用java实现Neo4j中的unique节点
我整晚都在搜索和阅读相关的东西，但我找不到任何可以运行的例子如何用java实现Neo4j中的unique节点,java,neo4j,unique,nodes,Java,Neo4j,Unique,Nodes,我整晚都在搜索和阅读相关的东西，但我找不到任何可以运行的例子 public class TestNeo4j { public enum RelTypes implements RelationshipType { HASFOLLOW } private static final String MATRIX_DB = "target/matrix-db"; private GraphDatabaseService graphDb; private long matrixNodeId;
public class TestNeo4j {
public enum RelTypes implements RelationshipType {
HASFOLLOW
}
private static final String MATRIX_DB = "target/matrix-db";
private GraphDatabaseService graphDb;
private long matrixNodeId;
public static void main(String[] args) throws IOException {
TestNeo4j matrix = new TestNeo4j();
matrix.setUp();
matrix.shutdown();
}
public void setUp() throws IOException {
deleteRecursively(new File(MATRIX_DB));
graphDb = new GraphDatabaseFactory().newEmbeddedDatabase(MATRIX_DB);
registerShutdownHook();
createNodespace();
}
public void shutdown() {
graphDb.shutdown();
}
public void createNodespace() throws IOException {
try (Transaction tx = graphDb.beginTx()) {
FileReader fr = new FileReader("twitter.txt");
BufferedReader br = new BufferedReader(fr);
String line = "";
while ((line = br.readLine()) != null) {
//read data like "1 1"
// "2 3"
String s = line;
String[] sa = s.split(" ");
//build relation twitter and his follow each line
//In my program, for every line, it will create a new
//For example, I will get 1-2, 1-3, 1-4, but I want it to be
// / 4
// 1 - 3
// \ 2
//!!!!i want to use unique node how to change it!!!!
Node node1 = graphDb.createNode();
Node node2 = graphDb.createNode();
node1.setProperty("id", sa[0]);
node2.setProperty("id", sa[1]);
node1.createRelationshipTo(node2, RelTypes.HASFOLLOW);
}
tx.success(); }
}
此外，我运行总是得到一个空的迭代 你确定twitter.txt在你的类路径上并且没有得到
FileNotFoundExceptionFileReaderFileReaderBufferedReaderAutoClosablepublic class TestNeo4j {
public static void main(String[] args) throws Exception {
final GraphDatabaseService graphDb = new GraphDatabaseFactory().newEmbeddedDatabase("db");
final Transaction tx = graphDb.beginTx();
final Node node = graphDb.createNode();
node.setProperty("test", "test");
tx.success();
tx.close();
final ExecutionEngine engine = new ExecutionEngine(graphDb);
System.out.println(engine.execute("START n=node(*) RETURN id(n), n.test").dumpToString());
graphDb.shutdown();
}
}
+----------------+
| id(n) | n.test |
+----------------+
| 0 | "test" |
+----------------+
1 row
MERGE (tweep1:Tweep{user: "twitter_account"})
MERGE (tweep1)-[:FOLLOWS]->(tweep2:Tweep{user: "another_account"})
如果已经存在匹配的节点，则将创建或使用节点“tweep1”。该节点将用于创建与节点“tweep2”的关系。这或多或少回答了您的问题吗？我通过构建hashmap处理了唯一节点问题，认为这是一种原始的方法
public void createNodespace() throws IOException {
try (Transaction tx = graphDb.beginTx()) {
FileReader fr = new FileReader("twitter.txt");
BufferedReader br = new BufferedReader(fr);
String line = "";
Map<String, Node> check = new HashMap<String, Node>();
while ((line = br.readLine()) != null) {
String s = line;
String[] sa = s.split(" ");
if (!check.containsKey(sa[0])) {
Node node1 = graphDb.createNode();
node1.setProperty("id", sa[0]);
check.put(sa[0], node1);
}
if (!check.containsKey(sa[1])) {
Node node2 = graphDb.createNode();
node2.setProperty("id", sa[1]);
check.put(sa[1], node2);
}
check.get(sa[0]).createRelationshipTo(check.get(sa[1]), RelTypes.HASFOLLOW);
}
tx.success();
}
}
public void createNodespace（）引发IOException{
try（事务tx=graphDb.beginTx（））{
FileReader fr=新的FileReader（“twitter.txt”）；
BufferedReader br=新的BufferedReader（fr）；
字符串行=”；
映射检查=新建HashMap（）；
而（（line=br.readLine（））！=null）{
字符串s=行；
字符串[]sa=s.split（“”）；
如果（！check.containsKey（sa[0]））{
Node node1=graphDb.createNode（）；
node1.setProperty（“id”，sa[0]）；
检查。放置（sa[0]，节点1）；
}
如果（！check.containsKey（sa[1]））{
Node node2=graphDb.createNode（）；
node2.setProperty（“id”，sa[1]）；
检查。放置（sa[1]，节点2）；
}
check.get（sa[0]）.createRelationshipTo（check.get（sa[1]），RelTypes.HASFOLLOW）；
}
成功（）；
}
}