I will show Java code that save results of select query into a text file.
Contents
- ▼1. Prerequisites
- ▼2. Java code for saving results of select query on Cosmos DB into a text file
- 2-1. Making a directory
- 2-2. Deploying Apache Maven project
- 2-3. Removing the existing App.java and AppTest.java
- 2-4. Starting Visual Studio Code
- 2-5. Adding Cosmos DB library into pom.xml and save it (Ctrl+S)
- 2-6. Coding for saving results of select query on Cosmos DB into a text file
- 2-7. Checking output of text file
- ▼3. Reference
▼1. Prerequisites
1-1. Free Azure Cosmos DB Account
You can use trial free Cosmos DB Account
https://azure.microsoft.com/ja-jp/try/cosmosdb/
1-2. Installing Visual Studio Code
sudo snap install --classic code
https://code.visualstudio.com/docs/setup/linux
1-3. Installing Maven
Ref: Apache Kafka Word Count 実装 – Java No.44
line of 2-3
1-4. Creating sample data
Ref: Java Azure Cosmos DB (SQL API) Database の作成方法 No.14

▼2. Java code for saving results of select query on Cosmos DB into a text file
2-1. Making a directory
Making a directory to create an application.
mkidr cosmosdbtest
cd cosmosdbtest
2-2. Deploying Apache Maven project
cd cosmosdbtest
mvn archetype:generate -DinteractiveMode=false -DgroupId=org.example.cosmosdb.sql -DartifactId=sqldemo -DarchetypeArtifactId=maven-archetype-quickstart
(a part of stdout) xxxx [INFO] Scanning for projects... [INFO] [INFO] ------------------< org.apache.maven:standalone-pom >-------------- [INFO] Building Maven Stub Project (No POM) 1 [INFO] --------------------------------[ pom ]---------------------------- [INFO] [INFO] >>> maven-archetype-plugin:3.2.0:generate (default-cli) > generate-sources @ standalone-pom >>> [INFO] [INFO] <<< maven-archetype-plugin:3.2.0:generate (default-cli) < generate-sources @ standalone-pom <<< [INFO] [INFO] [INFO] --- maven-archetype-plugin:3.2.0:generate (default-cli) @ standalone-pom --- [INFO] Generating project in Batch mode [INFO] ------------------------------------------------------------------- [INFO] Using following parameters for creating project from Old (1.x) Archetype: maven-archetype-quickstart:1.0 [INFO] ------------------------------------------------------------------- [INFO] Parameter: basedir, Value: /home/xxx/cosmosdbtest/sqldemo [INFO] Parameter: package, Value: org.example.cosmosdb.sql [INFO] Parameter: groupId, Value: org.example.cosmosdb.sql [INFO] Parameter: artifactId, Value: sqldemo [INFO] Parameter: packageName, Value: org.example.cosmosdb.sql [INFO] Parameter: version, Value: 1.0-SNAPSHOT [INFO] project created from Old (1.x) Archetype in dir: /home/xxx/cosmosdbtest/sqldemo [INFO] ------------------------------------------------------------------- [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------- [INFO] Total time: 3.524 s [INFO] Finished at: 2022-11-10T18:50:33+09:00 [INFO] -------------------------------------------------------------------
2-3. Removing the existing App.java and AppTest.java
rm ./sqldemo/src/main/java/org/example/comsosdb/sql/App.java
rm ./sqldemo/src/test/java/org/example/cosmosdb/sql/AppTest.java
2-4. Starting Visual Studio Code
cd ./sqldemo
code .
2-5. Adding Cosmos DB library into pom.xml and save it (Ctrl+S)
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.azure</groupId>
<artifactId>azure-cosmos</artifactId>
<version>4.30.1</version>
</dependency>
</dependencies>
2-6. Coding for saving results of select query on Cosmos DB into a text file
cosmosdblocalout.java is created.
package org.example.cosmosdb.sql;
import com.azure.cosmos.*;
import com.azure.cosmos.models.CosmosQueryRequestOptions;
import com.azure.cosmos.util.CosmosPagedIterable;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintStream;
import java.util.*;
public class cosmosdblocalout {
// select data from Csomos DB and save to local file
public static class Family {
public String id;
public String lastName;
public boolean isRegistered;
public String getId() {
return id;
}
public String getLastName() {
return lastName;
}
public Family(String idv, String lastNamev, boolean isv) {
id = idv;
lastName = lastNamev;
isRegistered = isv;
}
public String toJson(String idv, String lastNamev, boolean isv) {
return "{id:" + idv + ",lastName:" + lastNamev + ",isRegistered:" + isv + "}";
}
public Family() {
}
}
public static void main(String[] args) {
String databaseName = "testdb";
String endpoint = "https://xxx.documents.azure.com:443";
String masterkey = "xxx";
String containerName = "coll";
try (CosmosClient cosmosClient = new CosmosClientBuilder().endpoint(endpoint).key(masterkey)
.gatewayMode(GatewayConnectionConfig.getDefaultConfig()).consistencyLevel(ConsistencyLevel.SESSION)
.connectionSharingAcrossClientsEnabled(true).contentResponseOnWriteEnabled(true)
.userAgentSuffix("Applicationtest").preferredRegions(Collections.singletonList("East US")).buildClient()) {
CosmosDatabase database = cosmosClient.getDatabase(databaseName);
CosmosContainer container = database.getContainer(containerName);
// run select query
String query = "SELECT * FROM c";
CosmosQueryRequestOptions options = new CosmosQueryRequestOptions();
options.setMaxDegreeOfParallelism(2);
CosmosPagedIterable<Family> results = container.queryItems(query, options, Family.class);
File file = new File("/home/xxx/cosmosdbtest/sqldemo/output.txt");
try {
PrintStream ps = new PrintStream(file);
System.setOut(ps);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
for (Family result : results) {
System.out.println(result.toJson(result.getId(), result.getLastName(), result.isRegistered));
}
} catch (CosmosException e) {
e.printStackTrace();
System.err.println(e.getMessage());
}
}
2-7. Checking output of text file
cat output.txt
{id:1,lastName:Travase,isRegistered:false}
{id:2,lastName:Ken,isRegistered:true}
{id:3,lastName:Sai,isRegistered:false}
▼3. Reference
- Azure Cosmos DB Free Account https://docs.microsoft.com/ja-jp/azure/cosmos-db/optimize-dev-test#try-azure-cosmos-db-for-free
- https://code.visualstudio.com/docs/setup/linux
- Apache Kafka Word Count 実装 – Java No.44
- Java Azure Cosmos DB (SQL API) Database の作成方法 No.14
Have a nice day, ahead !!!