一、数据库搭建

-- 创建Keyspace
CREATE KEYSPACE school WITH replication = {'class':'SimpleStrategy', 'replication_factor' : 1};

-- 创建表
CREATE TABLE student(
   id int PRIMARY KEY,  
   name text,  
   age int,  
   genders int,  
   address text ,
   interest set<text>,
   phone list<text>,
   education map<text, text>
);

二、引入依赖

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-cassandra</artifactId>
</dependency>

<!-- hutool是下面多线程导入数据引入 -->
<dependency>
	<groupId>cn.hutool</groupId>
	<artifactId>hutool-all</artifactId>
	<version>5.8.26</version>
</dependency>

三、配置文件

spring:
  application:
    name: Spring-Cassandra
  cassandra:
    keyspace-name: school
    contact-points:
      - 192.168.204.131:9042
    port: 9042
    username: ***
    password: ******
    local-datacenter: datacenter1
    request:
      timeout: 60s

检查Cassandra的local-datacenter，可执行下面命令：

[root@localhost apache-cassandra]# bin/nodetool status

 四、创建一个实体类：

import lombok.Data;
import org.springframework.data.cassandra.core.mapping.Column;
import org.springframework.data.cassandra.core.mapping.PrimaryKey;
import org.springframework.data.cassandra.core.mapping.Table;

import java.io.Serializable;
import java.util.List;
import java.util.Map;
import java.util.Set;

@Data
@Table(value="student")
public class Student implements Serializable {
    @PrimaryKey
    private Integer id;
    @Column("name")
    private String name;
    @Column("age")
    private Integer age;
    @Column("genders")
    private Integer genders;
    @Column("address")
    private String address;
    @Column("interest")
    private Set<String> interest;
    @Column("phone")
    private List<String> phone;
    @Column("education")
    private Map<String, String> education;
}

五、创建一个Controller

private final StudentService studentService;

@GetMapping("student")
public List<Student> getStudentByName(String name) {
	return studentService.getStudentByName(name);
}

@GetMapping("count")
public Long count() {
	return studentService.count();
}

@GetMapping("list")
public List<Student> list(String name) {
	Student student = new Student();
	student.setName(name);
	return studentService.list(student);
}

@GetMapping("save")
public String sava() {
	for(int i = 0; i<100; i++) {
		try {
			Thread.sleep(200);
		} catch (InterruptedException e) {
			throw new RuntimeException(e);
		}
		int finalI = i;
		ThreadUtil.execute(() -> {
			System.out.println("线程"+ finalI +"运行");
			List<Student> list = Lists.newArrayList();
			for(int j=0; j<100; j++) {
				UUID uuid = UUID.randomUUID();
				int hash = uuid.toString().hashCode();
				int maxTenDigit = (int) Math.pow(10, 10) - 1; // 10位整数的最大值
				int modHash = Math.abs(hash % maxTenDigit);

				Student student = new Student();
				student.setId(modHash);
				int random = (int) (Math.random() * 100);
				student.setName("GG"+ random);
				student.setAge(random);
				student.setGenders(1);
				student.setAddress("China");
				list.add(student);
//                    studentService.save(student);
			}
			System.out.println("线程"+ finalI +"开始批量插入");
			studentService.batchSave(list);
			System.out.println("线程"+ finalI +"结束批量插入");
		});
	}
	System.out.println("线程结束");
//        ThreadUtil.waitForDie();
	return "success";
}

注意：Cassandra 本身不适合用来做数据分析统计，比如 count，是需要去遍历数据库的，分布式数据库，那么就要通通遍历一次。小数据还可以，数据量大会报查询超时错误。

六、编写service查询数据

service接口省略

1、JPA方式查询

service实现

private final StudentMapper studentMapper;

@Override
public List<Student> getStudentByName(String name) {
	return studentMapper.getStudentByName(name);
}

mapper接口

@Query(value = "select id, address, age, genders, name, interest, phone, education from student where name = ?0 ALLOW filtering")
List<Student> getStudentByName(String name);

Allow filtering:

       如果你的查询条件里，有一个是根据索引查询，那其它非索引非主键字段，可以通过加一个ALLOW FILTERING来过滤实现；

　　虽然查询非索引非主键字段，但是只要加了ALLOW FILTERING条件，它会先根据索引查出来的值，再对结果进行过滤；

    （如果不加ALLOW FILTERING，而又有非索引列，这样是不允许的； 加上ALLOW FILTERING，相当于在结果后再进行过滤。）

2、CassandraTemplate方式查询

private final CassandraTemplate cassandraTemplate;

@Override
public List<Student> list(Student queryInfo) {
	Query query = Query
			.query(where("name").is(queryInfo.getName()));
	query = query.withAllowFiltering();
	query = query.columns(Columns.from("id", "name", "age", "address", "genders", "interest", "phone", "education"));
	System.out.println(query);
	return this.cassandraTemplate.select(query, Student.class);
}

@Override
public void save(Student student) {
	this.cassandraTemplate.insert(student);
}

/**
* 批量插入
*/
@Override
public void batchSave(List<Student> list) {
	CassandraBatchOperations batchOps = cassandraTemplate.batchOps();
	batchOps.insert(list);
	batchOps.execute();
}

@Override
public Long count() {
	return cassandraTemplate.count(Student.class);
}