本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# TryDaxTests.java
<a name="DAX.client.run-application-java.TryDaxTests"></a>

`TryDaxTests.java` 檔案包含對 Amazon DynamoDB 中測試資料表執行讀取操作的方法。這些方法皆未考慮其存取資料的方法 (使用 DynamoDB 用戶端或 DAX 用戶端)，因此不需修改應用程式邏輯。

您可以使用幾種方法修改程式：
+ 修改 `queryTest` 方法，使其使用不同的 `KeyConditionExpression`。
+ 將 `ScanFilter` 新增至 `scanTest` 方法，使其只傳回一部分的項目。

**注意**  
 若要執行此程式，您可以設定 Maven 將適用於 Java 的 DAX 軟體開發套件的用戶端與 適用於 Java 的 AWS SDK 用作依存項目。如需詳細資訊，請參閱 [使用用戶端做為 Apache Maven 依存項目](DAX.client.java-sdk-v1.md#DAXClient.Maven)。  
或者，您必須在 classpath 中同時下載和包含 DAX Java 用戶端及 適用於 Java 的 AWS SDK。請參閱 [Java 與 DAX](DAX.client.run-application-java.md) 以取得設定您 `CLASSPATH` 變數的範例。

```
import java.util.Iterator;

import com.amazonaws.services.dynamodbv2.document.DynamoDB;
import com.amazonaws.services.dynamodbv2.document.Item;
import com.amazonaws.services.dynamodbv2.document.ItemCollection;
import com.amazonaws.services.dynamodbv2.document.QueryOutcome;
import com.amazonaws.services.dynamodbv2.document.ScanOutcome;
import com.amazonaws.services.dynamodbv2.document.Table;
import com.amazonaws.services.dynamodbv2.document.spec.QuerySpec;

public class TryDaxTests {

    void getItemTest(String tableName, DynamoDB client, int pk, int sk, int iterations) {
        long startTime, endTime;
        System.out.println("GetItem test - partition key " + pk + " and sort keys 1-" + sk);
        Table table = client.getTable(tableName);

        for (int i = 0; i < iterations; i++) {
            startTime = System.nanoTime();
            try {
                for (Integer ipk = 1; ipk <= pk; ipk++) {
                    for (Integer isk = 1; isk <= sk; isk++) {
                        table.getItem("pk", ipk, "sk", isk);
                    }
                }
            } catch (Exception e) {
                System.err.println("Unable to get item:");
                e.printStackTrace();
            }
            endTime = System.nanoTime();
            printTime(startTime, endTime, pk * sk);
        }
    }

    void queryTest(String tableName, DynamoDB client, int pk, int sk1, int sk2, int iterations) {
        long startTime, endTime;
        System.out.println("Query test - partition key " + pk + " and sort keys between " + sk1 + " and " + sk2);
        Table table = client.getTable(tableName);

        HashMap<String, Object> valueMap = new HashMap<String, Object>();
        valueMap.put(":pkval", pk);
        valueMap.put(":skval1", sk1);
        valueMap.put(":skval2", sk2);

        QuerySpec spec = new QuerySpec()
                .withKeyConditionExpression("pk = :pkval and sk between :skval1 and :skval2")
                .withValueMap(valueMap);

        for (int i = 0; i < iterations; i++) {
            startTime = System.nanoTime();
            ItemCollection<QueryOutcome> items = table.query(spec);

            try {
                Iterator<Item> iter = items.iterator();
                while (iter.hasNext()) {
                    iter.next();
                }
            } catch (Exception e) {
                System.err.println("Unable to query table:");
                e.printStackTrace();
            }
            endTime = System.nanoTime();
            printTime(startTime, endTime, iterations);
        }
    }

    void scanTest(String tableName, DynamoDB client, int iterations) {
        long startTime, endTime;
        System.out.println("Scan test - all items in the table");
        Table table = client.getTable(tableName);

        for (int i = 0; i < iterations; i++) {
            startTime = System.nanoTime();
            ItemCollection<ScanOutcome> items = table.scan();
            try {

                Iterator<Item> iter = items.iterator();
                while (iter.hasNext()) {
                    iter.next();
                }
            } catch (Exception e) {
                System.err.println("Unable to scan table:");
                e.printStackTrace();
            }
            endTime = System.nanoTime();
            printTime(startTime, endTime, iterations);
        }
    }

    public void printTime(long startTime, long endTime, int iterations) {
        System.out.format("\tTotal time: %.3f ms - ", (endTime - startTime) / (1000000.0));
        System.out.format("Avg time: %.3f ms\n", (endTime - startTime) / (iterations * 1000000.0));
    }
}
```