Neo4jCypherRestClient.java

package com.mycompany.wm.common.repo.neo4j;

import io.vertx.core.json.JsonArray;
import io.vertx.core.json.JsonObject;
import org.apache.commons.io.IOUtils;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.jose4j.base64url.Base64;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Repository;

import javax.annotation.PostConstruct;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

@Repository
public class Neo4jCypherRestClient {

    @Value("${neo4j.host:localhost}")
    private String NEO4J_HOST;

    @Value("${neo4j.protocol:http}")
    private String NEO4J_PROTOCOL;

    @Value("${neo4j.port:7474}")
    private Integer NEO4J_PORT;

    @Value("${neo4j.username:nouser}")
    private String NEO4J_USERNAME;

    @Value("${neo4j.password:nopass}")
    private String NEO4J_PASSWORD;

    private String neo4jUrl;
    private String authorizationHeader;
    HttpClient httpClient;
    @PostConstruct
    public void init() {
        neo4jUrl = String.format("%s://%s:%d", NEO4J_PROTOCOL, NEO4J_HOST, NEO4J_PORT);
        if (!"nouser".equalsIgnoreCase(NEO4J_USERNAME)) {
            /*
            http://neo4j.com/docs/stable/rest-api-security.html
            Authenticate by sending a username and a password to Neo4j using HTTP Basic Auth.
            Requests should include an Authorization header, with a value of Basic <payload>,
            where "payload" is a base64 encoded string of "username:password".
             */
            authorizationHeader = "Basic " + Base64.encode((NEO4J_USERNAME + ":" + NEO4J_PASSWORD).getBytes());
        }

        PoolingHttpClientConnectionManager cnnMgr = new PoolingHttpClientConnectionManager();
        cnnMgr.setMaxTotal(200);
        httpClient = HttpClients.custom().setConnectionManager(cnnMgr).build();

    }

    public Neo4jResultSet query(String cypherQuery, JsonObject params) {
        String resource = "/db/data/transaction/commit";
        JsonObject requestPayload = new JsonObject();
        JsonObject statement = new JsonObject();
        statement.put("statement", cypherQuery);
        if (params != null) {
            statement.put("parameters", params);
        }
        requestPayload.put("statements", new JsonArray().add(statement));

        HttpPost request = new HttpPost(neo4jUrl + resource);
        request.setEntity(new StringEntity(requestPayload.toString(), ContentType.APPLICATION_JSON));
        request.setHeader("Accept", "application/json; charset=UTF-8");
        request.setHeader("Content-Type", "application/json");

        if (authorizationHeader != null) {
            request.setHeader("Authorization", authorizationHeader);
        }

        try {
            HttpResponse response = httpClient.execute(request);
            return createResultSet(new JsonObject(IOUtils.toString(response.getEntity().getContent())));
        } catch (IOException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }

    private Neo4jResultSet createResultSet(JsonObject result) {
        JsonObject resultObject = result.getJsonArray("results").getJsonObject(0);
        JsonArray columns = resultObject.getJsonArray("columns");
        List<JsonArray> rows = (List<JsonArray>) resultObject.getJsonArray("data")
                .getList()
                .stream()
                .map(o -> {
                    Map<String, Object> rowMap = (Map<String, Object>) o;
                    return new JsonArray((List) rowMap.get("row"));
                })
                .collect(Collectors.toList());

        return new Neo4jResultSet(columns, rows);
    }

    public Neo4jResultSet query(String cypherQuery, Object... params) {
        JsonObject paramsJson = null;
        if (params.length > 0) {
            paramsJson = new JsonObject();
            for (int i = 0; i < params.length; i++) {
                paramsJson.put(Integer.toString(i + 1), params[i]);
            }
        }
        return query(cypherQuery, paramsJson);
    }
}