cassandra入门（二）：自定义类型使用和ORM

直接贴代码，cql和代码有些地方与分享电子书里的javaDriver21.pdf有些出入，请以博文为准，cql和代码都是实测跑通的。

cql脚本（在cqlsh.bat窗口里跑）：

CREATE KEYSPACE complex
WITH replication = {'class' : 'SimpleStrategy', 'replication_factor' :
3};
CREATE TYPE complex.phone (
alias text,
number text
);
CREATE TYPE complex.address (
street text,
city text,
zip_code int,
phones list<frozen<phone>>
);
CREATE TABLE complex.accounts (
email text PRIMARY KEY,
name text,
addr frozen<address>
);

自定义类型：phone和address。
表：accounts 。

maven依赖：

		<dependency>
			<groupId>com.datastax.cassandra</groupId>
			<artifactId>cassandra-driver-core</artifactId>
			<version>2.1.5</version>
		</dependency>
		<dependency>
			<groupId>com.datastax.cassandra</groupId>
			<artifactId>cassandra-driver-mapping</artifactId>
			<version>2.1.5</version>
		</dependency>

Phone类：

import com.datastax.driver.mapping.annotations.UDT;

@UDT(keyspace = "complex", name = "phone")
public class Phone {

    private String alias;

    private String number;


    public Phone() {

    }


    public Phone(String alias, String number) {
        this.alias = alias;
        this.number = number;
    }


    public String getAlias() {
        return alias;
    }


    public void setAlias(String alias) {
        this.alias = alias;
    }


    public String getNumber() {
        return number;
    }


    public void setNumber(String number) {
        this.number = number;
    }

}

Address类：

import java.util.List;

import com.datastax.driver.mapping.annotations.Field;
import com.datastax.driver.mapping.annotations.Frozen;
import com.datastax.driver.mapping.annotations.UDT;

@UDT(keyspace = "complex", name = "address")
public class Address {
    private String street;
    
    private String city;
    
    @Field(name = "zip_code")
    private int zipCode;
    
    @Frozen("list<frozen<phone>>")
    private List<Phone> phones;


    public Address() {

    }


    public Address(String street, String city, int zipCode, List<Phone> phones) {
        this.street = street;
        this.city = city;
        this.zipCode = zipCode;
        this.phones = phones;
    }


    public String getStreet() {
        return street;
    }


    public void setStreet(String street) {
        this.street = street;
    }


    public String getCity() {
        return city;
    }


    public void setCity(String city) {
        this.city = city;
    }


    public int getZipCode() {
        return zipCode;
    }


    public void setZipCode(int zipCode) {
        this.zipCode = zipCode;
    }


    public List<Phone> getPhones() {
        return phones;
    }


    public void setPhones(List<Phone> phones) {
        this.phones = phones;
    }
}

Account类：

import com.datastax.driver.mapping.annotations.Column;
import com.datastax.driver.mapping.annotations.Frozen;
import com.datastax.driver.mapping.annotations.PartitionKey;
import com.datastax.driver.mapping.annotations.Table;
import com.google.common.base.Objects;


@Table(keyspace = "complex", name = "accounts")
public class Account {
    @PartitionKey
    private String email;
    
    private String name;
    
    @Column(name = "addr")
    @Frozen
    private Address address;


    public Account() {
    }


    public Account(String name, String email, Address address) {
        this.name = name;
        this.email = email;
        this.address = address;
    }


    public String getName() {
        return name;
    }


    public void setName(String name) {
        this.name = name;
    }


    public String getEmail() {
        return email;
    }


    public void setEmail(String email) {
        this.email = email;
    }


    public Address getAddress() {
        return address;
    }


    public void setAddress(Address address) {
        this.address = address;
    }


    @Override
    public boolean equals(Object other) {
        if (other instanceof Account) {
            Account that = (Account) other;
            return Objects.equal(this.name, that.name) && Objects.equal(this.email, that.email);
        }
        return false;
    }


    @Override
    public int hashCode() {
        return Objects.hashCode(name, email);
    }
}

ORMClient类：

import java.util.ArrayList;
import java.util.List;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.Host;
import com.datastax.driver.core.Metadata;
import com.datastax.driver.core.Session;
import com.datastax.driver.mapping.Mapper;
import com.datastax.driver.mapping.MappingManager;
import com.google.common.util.concurrent.ListenableFuture;


public class ORMClient {

    private Cluster cluster;
    private Session session;

    Mapper<Account> mapper;


    public Session getSession() {
        return this.session;
    }


    /**
     * 连接集群，创建执行cql的session对象。
     * 
     * @param node
     */
    public void connect(String node) {
        cluster = Cluster.builder().addContactPoint(node).build();
        Metadata metadata = cluster.getMetadata();
        System.out.printf("Connected to cluster: %s\n", metadata.getClusterName());
        for (Host host : metadata.getAllHosts()) {
            System.out.printf("Datacenter: %s; Host: %s; Rack: %s\n", host.getDatacenter(),
                host.getAddress(), host.getRack());
        }
        session = cluster.connect();
        System.out.println();
        mapper = new MappingManager(getSession()).mapper(Account.class);
    }


    public void insert() {
        Phone phone = new Phone("home", "707-555-3537");
        List<Phone> phones = new ArrayList<Phone>();
        phones.add(phone);
        Address address = new Address("25800 Arnold Drive", "Sonoma", 95476, phones);
        Account account = new Account("John Doe", "jd@example.com", address);
        mapper.save(account);
    }


    public void select() {
        Account whose = mapper.get("jd@example.com");
        if (whose == null) {
            System.out.println("Account is null");
            return;
        }
        System.out.println("Account name: " + whose.getName());
        // 异步查询
        ListenableFuture<Account> future = mapper.getAsync("jd@example.com");
        try {
            whose = future.get();
            System.out.println("getAsync, Account name: " + whose.getName());
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }


    public void delete() {
        Account account = new Account("John Doe", "jd@example.com", null);
        mapper.delete(account);
    }


    public void update() {
        // 没有看到mapper对象关于update的api
    }


    public void close() {
        session.close();
        cluster.close();
    }


    public void dropSchema() {
        session.execute("DROP KEYSPACE complex;");
    }


    public static void main(String[] args) {
        ORMClient client = new ORMClient();
        try {
            client.connect("127.0.0.1");
            client.insert();
            client.select();
            client.delete();
            client.select();
            client.dropSchema();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        finally {
            client.close();
        }
    }
}

运行打印：
Connected to cluster: Test Cluster
Datacenter: datacenter1; Host: /127.0.0.1; Rack: rack1

Account name: John Doe
getAsync, Account name: John Doe
Account is null

看到文档最后，还有一个通过注解@Accessor来做查询的，好像更便利，like this:

@Accessor
public interface UserAccessor {

    @Query("SELECT * FROM complex.users WHERE id = ?")
    User getOnePosition(UUID userId);

    ......
}

下篇文章说这个注解@Accessor的用法。