java neo4j

在第1部分中 ，我們討論了使用Java REST綁定建立與Neo4j Server的連接。 現(xiàn)在讓我們?cè)敿?xì)了解事務(wù)，批處理以及REST請(qǐng)求的實(shí)際情況。確保org.neo4j.rest.logging_filter to true) as described in Part 1打開(kāi)日志記錄（將系統(tǒng)屬性org.neo4j.rest.logging_filter to true) as described in Part 1設(shè)置org.neo4j.rest.logging_filter to true) as described in Part 1 。

我們將更改代碼以執(zhí)行這些Neo4j API調(diào)用。

范例1：

Transaction tx = graphDb.beginTx();Map props=new HashMap();props.put("id", 100);props.put("name","firstNode");Node node=graphDb.createNode(props);props.put("id",200);props.put("name","secondNode");Node node2=graphDb.createNode(props);node.createRelationshipTo(node2, DynamicRelationshipType.withName("KNOWS"));tx.success();tx.finish();result=engine.query("start n=node(*) return count(n) as total", Collections.EMPTY_MAP);Iterator iterator=result.iterator();if(iterator.hasNext()) {Map row= iterator.next();out.print("Total nodes: " + row.get("total"));}

檢查日志（對(duì)我來(lái)說(shuō)，它們默認(rèn)顯示在Tomcat控制臺(tái)上），然后查找REST調(diào)用。 上面的代碼產(chǎn)生了：

INFO: 1 * Client out-bound request 1 > POST http://localhost:7474/db/data/node 1 > Accept: application/json; stream=true 1 > X-Stream: true 1 > Content-Type: application/json 1 > {"id":100,"name":"firstNode"}INFO: 1 * Client in-bound response 1 < 201 1 < Access-Control-Allow-Origin: * 1 < Transfer-Encoding: chunked 1 < Content-Encoding: UTF-8 1 < Location: http://localhost:7474/db/data/node/1 1 < Content-Type: application/json; stream=true 1 < Server: Jetty(6.1.25) 1 < {"extensions":{},"paged_traverse":"http://localhost:7474/db/data/node/1/paged/traverse/{returnType}{?pageSize,leaseTime}","outgoing_relationships":"http://localhost:7474/db/data/node/1/relationships/out","traverse":"http://localhost:7474/db/data/node/1/traverse/{returnType}","all_typed_relationships":"http://localhost:7474/db/data/node/1/relationships/all/{-list|&|types}","property":"http://localhost:7474/db/data/node/1/properties/{key}","all_relationships":"http://localhost:7474/db/data/node/1/relationships/all","self":"http://localhost:7474/db/data/node/1","properties":"http://localhost:7474/db/data/node/1/properties","outgoing_typed_relationships":"http://localhost:7474/db/data/node/1/relationships/out/{-list|&|types}","incoming_relationships":"http://localhost:7474/db/data/node/1/relationships/in","incoming_typed_relationships":"http://localhost:7474/db/data/node/1/relationships/in/{-list|&|types}","create_relationship":"http://localhost:7474/db/data/node/1/relationships","data":{"name":"firstNode","id":100}}INFO: 2 * Client out-bound request 2 > POST http://localhost:7474/db/data/node 2 > Accept: application/json; stream=true 2 > X-Stream: true 2 > Content-Type: application/json 2 > {"id":200,"name":"secondNode"}INFO: 2 * Client in-bound response 2 < 201 2 < Access-Control-Allow-Origin: * 2 < Transfer-Encoding: chunked 2 < Content-Encoding: UTF-8 2 < Location: http://localhost:7474/db/data/node/2 2 < Content-Type: application/json; stream=true 2 < Server: Jetty(6.1.25) 2 < {"extensions":{},"paged_traverse":"http://localhost:7474/db/data/node/2/paged/traverse/{returnType}{?pageSize,leaseTime}","outgoing_relationships":"http://localhost:7474/db/data/node/2/relationships/out","traverse":"http://localhost:7474/db/data/node/2/traverse/{returnType}","all_typed_relationships":"http://localhost:7474/db/data/node/2/relationships/all/{-list|&|types}","property":"http://localhost:7474/db/data/node/2/properties/{key}","all_relationships":"http://localhost:7474/db/data/node/2/relationships/all","self":"http://localhost:7474/db/data/node/2","properties":"http://localhost:7474/db/data/node/2/properties","outgoing_typed_relationships":"http://localhost:7474/db/data/node/2/relationships/out/{-list|&|types}","incoming_relationships":"http://localhost:7474/db/data/node/2/relationships/in","incoming_typed_relationships":"http://localhost:7474/db/data/node/2/relationships/in/{-list|&|types}","create_relationship":"http://localhost:7474/db/data/node/2/relationships","data":{"name":"secondNode","id":200}}INFO: 3 * Client out-bound request 3 > POST http://localhost:7474/db/data/node/1/relationships 3 > Accept: application/json; stream=true 3 > X-Stream: true 3 > Content-Type: application/json 3 > {"to":"http://localhost:7474/db/data/node/2","type":"KNOWS"}INFO: 3 * Client in-bound response 3 < 201 3 < Access-Control-Allow-Origin: * 3 < Transfer-Encoding: chunked 3 < Content-Encoding: UTF-8 3 < Location: http://localhost:7474/db/data/relationship/0 3 < Content-Type: application/json; stream=true 3 < Server: Jetty(6.1.25) 3 < {"extensions":{},"start":"http://localhost:7474/db/data/node/1","property":"http://localhost:7474/db/data/relationship/0/properties/{key}","self":"http://localhost:7474/db/data/relationship/0","properties":"http://localhost:7474/db/data/relationship/0/properties","type":"KNOWS","end":"http://localhost:7474/db/data/node/2","data":{}}INFO: 4 * Client out-bound request 4 > POST http://localhost:7474/db/data/cypher 4 > Accept: application/json; stream=true 4 > X-Stream: true 4 > Content-Type: application/json 4 > {"query":"start n=node(*) return count(n) as total","params":{}}INFO: 4 * Client in-bound response 4 < 200 4 < Access-Control-Allow-Origin: * 4 < Transfer-Encoding: chunked 4 < Content-Encoding: UTF-8 4 < Content-Type: application/json; stream=true 4 < Server: Jetty(6.1.25) 4 < {"columns":["total"],"data":[[3]]}

網(wǎng)上總共有4個(gè)REST調(diào)用，用于那段很小的代碼。 您絕對(duì)希望盡可能避免這種情況。 選項(xiàng)1是盡可能使用Cypher。 通過(guò)不使用嵌入式樣式API并切換到Cypher，我們可以將前三個(gè)REST調(diào)用轉(zhuǎn)換為一個(gè)。

范例2：

Map<String,Object> props=new HashMap<String, Object>();props.put("id", 100);props.put("name","firstNode");Map<String,Object> props2=new HashMap<String, Object>();props2.put("id",200);props2.put("name","secondNode");Map<String,Object> params=new HashMap<String, Object>();params.put("props1",props);params.put("props2",props2);engine.query("create (n1 {props1})-[:KNOWS]->(n2 {props2})", params);

這將產(chǎn)生：

1 > POST http://localhost:7474/db/data/cypher {"query":"create (n1 {props1})-[:KNOWS]->(n2 {props2})","params":{"props1":{"id":100,"name":"firstNode"},"props2":{"id":100,"name":"firstNode"}}}Jul 24, 2013 10:38:47 PM com.sun.jersey.api.client.filter.LoggingFilter log INFO: 1 * Client in-bound response 1 < 200 1 < Access-Control-Allow-Origin: * 1 < Transfer-Encoding: chunked 1 < Content-Encoding: UTF-8 1 < Content-Type: application/json; stream=true 1 < Server: Jetty(6.1.25) 1 < {"columns":[],"data":[]}

批處理事務(wù)中的所有操作

https://github.com/neo4j/java-rest-binding上的文檔指出：

“在1.8中，它嘗試將tx中的所有操作收集為批處理操作，然后將在服務(wù)器上執(zhí)行該批處理操作。 這暗示著在“ tx”中檢索到的結(jié)果不是立即可用的，而是僅在調(diào)用tx.success和tx.finish之后才可用。

但是，請(qǐng)注意，這不是從示例1中看到的默認(rèn)行為。要啟用此功能，需要設(shè)置以下系統(tǒng)屬性： org.neo4j.rest.batch_transaction=true

設(shè)置系統(tǒng)屬性并重新運(yùn)行示例1后，REST調(diào)用將如下所示（僅請(qǐng)求）：

INFO: 1 * Client out-bound request 1 > POST http://localhost:7474/db/data/batch 1 > Accept: application/json; stream=true 1 > X-Stream: true 1 > Content-Type: application/json 1 > [{"id":1,"to":"node","body":{"id":200,"name":"secondNode"},"method":"POST"},{"id":2,"to":"node","body":{"id":200,"name":"secondNode"},"method":"POST"},{"id":3,"to":"{1}/relationships","body":{"to":"{2}","type":"KNOWS"},"method":"POST"}]INFO: 2 * Client out-bound request 2 > POST http://localhost:7474/db/data/cypher 2 > Accept: application/json; stream=true 2 > X-Stream: true 2 > Content-Type: application/json 2 > {"query":"start n=node(*) return count(n) as total","params":{}}

您還可以顯式創(chuàng)建批處理操作，如下所示：

List<Node> response =graphDb.executeBatch(new BatchCallback<List<Node>>() {@Overridepublic List<Node> recordBatch(RestAPI batchRestApi) {List<Node> nodes=new ArrayList<Node>();Map props=new HashMap<String, Object>();props.put("id",600);nodes.add(batchRestApi.createNode(props));Map props2=new HashMap<String, Object>();props2.put("id",500);nodes.add(batchRestApi.createNode(props2));return nodes;}});

轉(zhuǎn)換為：

INFO: 1 * Client out-bound request 1 > POST http://localhost:7474/db/data/batch 1 > Accept: application/json; stream=true 1 > X-Stream: true 1 > Content-Type: application/json 1 > [{"id":1,"to":"node","body":{"id":600},"method":"POST"},{"id":2,"to":"node","body":{"id":500},"method":"POST"}]

強(qiáng)烈建議在較細(xì)粒度的Neo4j Java API上使用任何Cypher / Batching方法。 在最后一篇文章中，我們將了解事務(wù)在REST綁定的上下文中的行為。

參考： Neo4j Java REST綁定–我們JCG合作伙伴 Luanne Misquitta的第2部分（批處理），來(lái)自Thought Bytes博客。

翻譯自: https://www.javacodegeeks.com/2013/08/neo4j-java-rest-binding-part-2-batching.html

java neo4j

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