为什么缺少一条消息？如何修复它？

Question

我对 RIAK KV 完全陌生。我实际上是在大学里学习的，并且必须编写一些 Java 代码来将 5000 个数据集存储在 RIAK 集群中。于是我开始写代码：

package main;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Random;
import java.util.Scanner;

import org.w3c.dom.NameList;

public class Product {
    String artikelnummer;
    String name;
    String color;
    Integer price;
    String picture;
    Integer max = 999;
    String filepath = "./assets/products.txt";
    ArrayList<String> productNames;

    public Product() throws FileNotFoundException{
        productNames = readFile(filepath);
        name = randomName();
        color = randomColor();
        price = randomPrice(max);
        picture = randomPic();
    }

    private String randomPic() {
        String[] picNames = {"ikea0.jpg","ikea1.jpg","ikea2.jpg","ikea3.jpg","ikea4.jpg","ikea5.jpg","ikea6.jpg","ikea7.jpg","ikea8.jpg","ikea9.jpg"};
        Random randPicIndex = new Random();
        int randomPicIndex = randPicIndex.nextInt(9);
        return picNames[randomPicIndex];
    }

    public Integer randomPrice(int max){
        Random rand = new Random();

        int randomNum = rand.nextInt(max);
        price = randomNum;
        return price;
    }

    public String randomColor(){
        String[] colorArray =  {"blue","red","yellow","magenta","green","black","white","cyan","purple","brown"};
        Random randIndex = new Random();
        int randomIndex = randIndex.nextInt(10);
        int i = randomIndex;
        color = colorArray[i];
        return color;
    }

    public String randomName(){
        Random randomName = new Random();
        name = productNames.get(randomName.nextInt(productNames.size()));
        return name;
    }

    public ArrayList<String> readFile(String filepath) throws FileNotFoundException {
        Scanner scanner = new Scanner(new File(filepath));
        ArrayList<String> nameList = new ArrayList<String>();
        while (scanner.hasNextLine()){
            nameList.add(scanner.nextLine());
        }
        scanner.close();
        return nameList;
    }

    //Class for testing purposes
    public void printProduct(){
        System.out.println("Produktdatenblatt: Artikelnummer --> "+ artikelnummer + " " + name + " mit Farbe: " + color + " mit dem Preis: " + price + " ein Bild --> " + picture);
        System.out.println("Hat funktioniert!!!");
    }
}

您可以在上面看到包含产品 Class 的代码。为了随机生成 500 个产品并将这些产品存储在 Rick 的 KV 数据库中，我写了以下内容：

package main;
import io.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueue.WaitStrategy;
import java.io.FileNotFoundException;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.concurrent.ExecutionException;
import com.basho.riak.client.api.RiakClient;
import com.basho.riak.client.api.annotations.RiakKey;
import com.basho.riak.client.api.annotations.RiakLinks;
import com.basho.riak.client.api.commands.kv.StoreValue;
import com.basho.riak.client.core.RiakCluster;
import com.basho.riak.client.core.RiakNode;
import com.basho.riak.client.core.query.Location;
import com.basho.riak.client.core.query.Namespace;
import com.basho.riak.client.core.query.RiakObject;
import com.basho.riak.client.core.query.links.RiakLink;
import com.basho.riak.client.core.util.BinaryValue;

public class ProductRiakCluster {
    static String artikelnummer;

    public static void main(String args[]) throws FileNotFoundException, UnknownHostException, ExecutionException, InterruptedException {
        System.out.println("main-method started...");
        System.out.println("Starting create RiakCluster...");

        for (int i = 5000; i > 0; i--) {
            dataGenerator(i);

            RiakClient client = RiakClient.newClient(8087, "127.0.0.1");
            System.out.println("RiakClient " + client);

            RiakObject riakObj = new RiakObject();
            System.out.println("RiakObjekt " + riakObj);

            Namespace productsBucket = new Namespace("products");
            System.out.println("Bucket " + productsBucket);

            Location productObjectLocation = new Location(productsBucket, artikelnummer);
            System.out.println("Location " + productObjectLocation);

            StoreValue storeP = new StoreValue.Builder(riakObj).withLocation(productObjectLocation).build();
            StoreValue.Response response = client.execute(storeP);

            client.shutdown();
        }
        System.out.println("RiakCluster setup finished...");
    }

    public static class ProductPojo {
        @RiakKey
        public String artikelnummer;
        public String name;
        public String color;
        public Integer price;

        @RiakLinks
        public Collection < RiakLink > picture = new ArrayList < RiakLink > ();
    }

    private static void dataGenerator(int i) {
        System.out.println("Started DataGenerator...");

        try {
            artikelnummer = String.valueOf(i);
            generateRandomProduct(artikelnummer);

        } catch (FileNotFoundException e) {
            System.out.println("File not found...");
            e.printStackTrace();
        }
    }

    private static void generateRandomProduct(String artikelnummer) throws FileNotFoundException {
        System.out.println("Method <generateRandomProduct> is running..." + artikelnummer);

        Product product = new Product();
        ProductPojo propo = new ProductPojo();

        propo.artikelnummer = artikelnummer;
        propo.name = product.name;
        propo.color = product.color;
        propo.price = product.price;
        propo.picture.add(new RiakLink("pictures", product.picture, "Produktbild"));

        product.printProduct();
    }
}

我启动这个程序后出现以下错误：

RiakClient com.basho.riak.client.api.RiakClient@2096442d
RiakObjekt RiakObject{contentType: application/octet-stream, value: null, riakIndexes: null, links: null, userMeta: null, vtag: null, isDeleted: false, isModified: false, vclock: null, lastModified: 0}
Bucket {type: default, bucket: products}
Location {namespace: {type: default, bucket: products}, key: 1}

Exception in thread "main" shaded.com.google.protobuf.UninitializedMessageException: Message missing required fields: value
at shaded.com.google.protobuf.AbstractMessage$Builder.newUninitializedMessageException(AbstractMessage.java:372)
at shaded.com.basho.riak.protobuf.RiakKvPB$RpbContent$Builder.build(RiakKvPB.java:18352)
at com.basho.riak.client.core.converters.RiakObjectConverter.convert(RiakObjectConverter.java:198)
at com.basho.riak.client.core.operations.StoreOperation$Builder.withContent(StoreOperation.java:158)
at com.basho.riak.client.api.commands.kv.StoreValue.buildCoreOperation(StoreValue.java:151)
at com.basho.riak.client.api.commands.kv.StoreValue.buildCoreOperation(StoreValue.java:72)
at com.basho.riak.client.api.GenericRiakCommand.executeAsync(GenericRiakCommand.java:41)
at com.basho.riak.client.api.commands.kv.StoreValue.executeAsync(StoreValue.java:112)
at com.basho.riak.client.api.RiakCommand.execute(RiakCommand.java:91)
at com.basho.riak.client.api.RiakClient.execute(RiakClient.java:355)
at main.ProductRiakCluster.main(ProductRiakCluster.java:49)

我对此的想法：我生成了一个 "artikelnummer" 但它没有出现在 Pojo class 中，因此 Pojo 具有空值。但是我不知道如何解决这个问题。

Answer 1

问题是您没有将任何东西传递给 RiakObject。

Return 生成的 ProductPojo 实例并将其保存在变量中，比如 productToSave。

然后，调用 new StoreValue.Builder(productToSave)，或使用 RiakObject，如下所示：

RiakObject riakObj = new RiakObject();
riakObj.setValue(BinaryValue.create(productToSave));

附带说明一下，不幸的是，您的代码存在一些编程问题。例如，通过静态成员在方法之间交换数据是不好的。您也不必在每次需要时都创建和关闭客户端 - 为所有查询重复使用一个实例。

为什么缺少一条消息？如何修复它？

Why is there a message missing? How can is fix it?

java

riak

key-value-store

java-client