Dynamodb 简明教程

DynamoDB - Load Table

加载表通常包含创建源文件、确保源文件符合与 DynamoDB 兼容的语法、将源文件发送到目的地，然后确认成功填充。

Loading a table generally consists of creating a source file, ensuring the source file conforms to a syntax compatible with DynamoDB, sending the source file to the destination, and then confirming a successful population.

利用 GUI 控制台、Java 或其他选项执行任务。

Utilize the GUI console, Java, or another option to perform the task.

Load Table using GUI Console

结合使用命令行和控制台加载数据。您可以通过多种方式加载数据，其中一些方式如下 -

Load data using a combination of the command line and console. You can load data in multiple ways, some of which are as follows −

The Console
The Command Line
Code and also
Data Pipeline (a feature discussed later in the tutorial)

然而，为了速度，此示例同时使用 shell 和控制台。首先，使用以下语法将源数据加载到目标中 −

However, for speed, this example uses both the shell and console. First, load the source data into the destination with the following syntax −

aws dynamodb batch-write-item -–request-items file://[filename]

例如 -

For example −

aws dynamodb batch-write-item -–request-items file://MyProductData.json

通过访问 − 中的控制台验证操作的成功

Verify the success of the operation by accessing the console at −

https://console.aws.amazon.com/dynamodb

从导航窗格选择 Tables ，并从表格列表中选择目标表格。

Choose Tables from the navigation pane, and select the destination table from the table list.

选择 Items 选项卡以检查用于填充表格的数据。选择 Cancel 以返回到表格列表。

Select the Items tab to examine the data you used to populate the table. Select Cancel to return to the table list.

Load Table using Java

首先创建一个源文件以使用 Java。我们的源文件使用 JSON 格式。每个产品有两个主键属性（Id 和命名法）和一个 JSON 映射（Stat）。

Employ Java by first creating a source file. Our source file uses JSON format. Each product has two primary key attributes (ID and Nomenclature) and a JSON map (Stat) −

[
   {
      "ID" : ... ,
      "Nomenclature" : ... ,
      "Stat" : { ... }
   },
   {
      "ID" : ... ,
      "Nomenclature" : ... ,
      "Stat" : { ... }
   },
    ...
]

您可以查看以下示例 -

You can review the following example −

{
   "ID" : 122,
   "Nomenclature" : "Particle Blaster 5000",
   "Stat" : {
      "Manufacturer" : "XYZ Inc.",
      "sales" : "1M+",
      "quantity" : 500,
      "img_src" : "http://www.xyz.com/manuals/particleblaster5000.jpg",
      "description" : "A laser cutter used in plastic manufacturing."
   }
}

下一步是将文件放在您的应用程序使用的目录中。

The next step is to place the file in the directory used by your application.

Java 主要使用 putItem 和 path methods 来执行加载。

Java primarily uses the putItem and path methods to perform the load.

您可以查看以下代码示例来处理文件并加载它−

You can review the following code example for processing a file and loading it −

import java.io.File;
import java.util.Iterator;

import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient;
import com.amazonaws.services.dynamodbv2.document.DynamoDB;
import com.amazonaws.services.dynamodbv2.document.Item;
import com.amazonaws.services.dynamodbv2.document.Table;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.node.ObjectNode;

public class ProductsLoadData {
   public static void main(String[] args) throws Exception {
      AmazonDynamoDBClient client = new AmazonDynamoDBClient()
         .withEndpoint("http://localhost:8000");

      DynamoDB dynamoDB = new DynamoDB(client);
      Table table = dynamoDB.getTable("Products");
      JsonParser parser = new JsonFactory()
         .createParser(new File("productinfo.json"));

      JsonNode rootNode = new ObjectMapper().readTree(parser);
      Iterator<JsonNode> iter = rootNode.iterator();
      ObjectNode currentNode;

      while (iter.hasNext()) {
         currentNode = (ObjectNode) iter.next();
         int ID = currentNode.path("ID").asInt();
         String Nomenclature = currentNode.path("Nomenclature").asText();

         try {
            table.putItem(new Item()
               .withPrimaryKey("ID", ID, "Nomenclature", Nomenclature)
               .withJSON("Stat", currentNode.path("Stat").toString()));
            System.out.println("Successful load: " + ID + " " + Nomenclature);
         } catch (Exception e) {
            System.err.println("Cannot add product: " + ID + " " + Nomenclature);
            System.err.println(e.getMessage());
            break;
         }
      }
      parser.close();
   }
}