Spring boot + neo4j ☞ create a multi-point network

Reference address: https://spring.io/guides/gs/accessing-data-neo4j/

1, Spring boot directory structure chart

2, Nodes (vertices) before relationships (edges)

(1) Create Employee node entity - include two relationships

package com.appleyk.data.nodeentity; import java.util.Collections; import java.util.HashSet; import java.util.Optional; import java.util.Set; import java.util.stream.Collectors; import org.neo4j.ogm.annotation.GraphId; import org.neo4j.ogm.annotation.NodeEntity; import org.neo4j.ogm.annotation.Relationship; @NodeEntity public class Employee { @GraphId private Long id; private String name; public Employee(String name) { this.name = name; } /** * Neo4j There is no real two-way relationship, we only ignore the direction of the relationship when querying * You can refer to the following link to make a correct understanding of the relationship between neo4j: * https://dzone.com/articles/modelling-data-neo4j */ @Relationship(type = "Colleague", direction = Relationship.UNDIRECTED) //@Relationship(type = "colleague") public Set<Employee> colleagues; @Relationship(type = "Administration") public Set<Employee> manages; /* * Specify colleague relationship -- > */ public void worksWith(Employee person) { if (colleagues == null) { colleagues = new HashSet<>(); } colleagues.add(person); } /* * Specify management relationship -- > */ public void management(Employee person) { if (manages == null) { manages = new HashSet<>(); } manages.add(person); } /** * List the network of this node (Employee) */ public String toString() { /* java8 New, special and new * Optional.ofNullable(arg) Parameter can be null * If the value is not null, the orElse method returns the value of the Optional instance (relationship) * Collections.emptySet():Prevent null pointer * | * | * V * When the code needs a collection and the collection may not exist, try to use an empty collection instead of null */ return this.name + " Colleague => " + Optional.ofNullable(this.colleagues).orElse( Collections.emptySet()).stream().map( person -> person.getName()).collect(Collectors.toList()) + " Administration => " + Optional.ofNullable(this.manages).orElse( Collections.emptySet()).stream().map( person -> person.getName()).collect(Collectors.toList()); } public String getName() { return name; } public void setName(String name) { this.name = name; } }

(2) Create Employee add, delete, modify and query interface

package com.appleyk.data.Repository; import org.springframework.data.neo4j.repository.GraphRepository; import org.springframework.stereotype.Repository; import com.appleyk.data.nodeentity.Employee; @Repository public interface EmployeeRepository extends GraphRepository<Employee>{ Employee findByName(String name); }

3, When spring boot is started, the relationship between nodes is created

(1)

package com.appleyk; import java.util.Arrays; import java.util.List; import org.springframework.boot.CommandLineRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.boot.builder.SpringApplicationBuilder; import org.springframework.boot.web.support.SpringBootServletInitializer; import org.springframework.context.annotation.Bean; import com.appleyk.data.Repository.EmployeeRepository; import com.appleyk.data.nodeentity.Employee; /** * * Here is a typical structure: * * com +- example +- myproject +- Application.java -- * Note that this position is habitually placed at the beginning of the project, that is, the first layer of the root package - domain + - customer. Java |+- * CustomerRepository.java | + - service | +- CustomerService.java | + - web +- * CustomerController.java * * * The file will declare the main method and the basic @ Configuration * * @author [email protected] * @date 2017 December 1, 2008 08:46:41 */ @SpringBootApplication // same as @Configuration @EnableAutoConfiguration @ComponentScan public class Application extends SpringBootServletInitializer{ /** * SpringApplication Class provides a convenient way to start Spring applications from the main() method. In many cases, you just delegate * SpringApplication.run This static method: * * @param args */ public static void main(String[] args) { SpringApplication.run(Application.class, args); } @Override protected SpringApplicationBuilder configure(SpringApplicationBuilder application) { return application.sources(Application.class); } /** * Spring-Boot Loading, creating and initializing data during startup * @param personRepository * @return */ @Bean CommandLineRunner demo(EmployeeRepository employeeRepository) { return args -> { //Delete the Employees node before creating employeeRepository.deleteAll(); Employee boss = new Employee("CEO"); Employee manager= new Employee("project manager"); Employee p1 = new Employee("Employee 1"); Employee p2 = new Employee("Employee 2"); List<Employee> team = Arrays.asList(boss,manager,p1,p2); System.err.println("Connect neo4j Before the graph base creates the relation node..."); team.stream().forEach(person -> System.err.println("\t" + person.toString())); employeeRepository.save(boss); employeeRepository.save(manager); employeeRepository.save(p1); employeeRepository.save(p2); boss = employeeRepository.findByName(boss.getName()); /* * Boss Management Manager (Level 1 direct relationship) */ boss.management(manager); /* * At the same time, Boss and others are colleagues, and vice versa */ boss.worksWith(manager); boss.worksWith(p1); boss.worksWith(p2); //Building relationships employeeRepository.save(boss); /* * Managers manage employees 1 and 2 (direct relationship) * First check the node, then add the relationship (edge) */ manager = employeeRepository.findByName(manager.getName()); manager.management(p1); manager.management(p2); /* * As we know above that Boss and manager are colleagues, and vice versa, only the colleague relationship between manager and other people is added below */ manager.worksWith(p1); manager.worksWith(p2); employeeRepository.save(manager); /* * Employee 1 and employee 2 are colleague relationships, which do not consider direction, so create an Ok relationship */ p1 = employeeRepository.findByName(p1.getName()); p1.worksWith(p2); employeeRepository.save(p1); System.out.println("After creating a relationship node, query the node information by looking up the node name..."); team.stream().forEach(person -> System.out.println( "\t" + employeeRepository.findByName(person.getName()).toString())); }; } }

(3) Neo4j chart Library - Employee employee relationship map query (ALL)

4, Query relationship (findByName)

(1)

package com.appleyk.controller; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; import com.appleyk.data.Repository.EmployeeRepository; import com.appleyk.data.nodeentity.Employee; import com.appleyk.result.ResponseMessage; import com.appleyk.result.ResponseResult; @RestController @RequestMapping("/rest/v1.0.1/database/employee") public class EmployeeController { @Autowired EmployeeRepository employeeRepository; @RequestMapping("/get") public ResponseResult GetEmployees(@RequestParam(value = "name") String name) { Employee employee = employeeRepository.findByName(name); if (employee != null) { /* * Print the relationship of name, the following relationship! =null is a set set. The set has not been processed! */ System.out.println(employee.getManages()); System.out.println("========Upper management[" + employee.getName() + "]Next colleague============"); System.out.println(employee.getColleagues()); return new ResponseResult(ResponseMessage.OK); } return new ResponseResult(ResponseMessage.INTERNAL_SERVER_ERROR); } }

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5 May 2020, 02:52 | Views: 7463