This document summarizes how to connect to Cloud SQL from App Engine using Java. It discusses creating a Cloud SQL instance and bucket, uploading files to the bucket, and connecting to the database using JDBC. The key steps are to use the Google Cloud SQL JDBC connector and connection string, handling both local testing and production environments. Sample code shows querying the database using prepared statements once a connection is established.

1. GAE Developer - Day4
Simon @ MiCloud
2014Q1

2. Last Class
● Memcache basic
● Task Queue concept
● Push Queue
● Pull Queue

3. ● Create a Bucket
● Create a CloudSQL
Before Today

4. Create a Bucket
$ gcloud auth login
$ gcloud config set project [my-project-id]
$ gsutil mb gs://[my-bucket]
$ gsutil ls gs://[my-bucket]

5. Sample Database
http://www.mysqltutorial.org/mysql-sample-database.aspx

6. Create a CloudSQL
$ gcloud sql -h
$ gcloud sql instances create [inst-name]
$ gcloud sql instances list
$ gcloud sql instances import instance-name --uri
gs://your-bucket/sql-dump-file.gz
$ gcloud sql instances patch --assign-ip [inst-name]
$ gcloud sql instances get [inst-name]

7. Create a CloudSQL
$ gcloud sql instances set-root-password test-sql
-p [password]
$ gcloud sql instances patch test-sql
--authorized-networks=[your-ip-address]

8. Connect Cloud SQL - MySQL Workbench
http://www.mysql.com/products/workbench/

9. Today
● Use CloudStorage - BlobStore
● Connect CloudSQL

10. Using Cloud Storage

11. Use CloudStorage - BlobStore

12. Create Upload Url
BlobstoreService blobstoreService =
BlobstoreServiceFactory.getBlobstoreService();
UploadOptions uploadOptions =
UploadOptions.Builder.withGoogleStorageBucketName(
"BUCKET-NAME"); //Name without “gs://”
String uploadUrl = blobstoreService.createUploadUrl(
"/callback-url", uploadOptions);
resp.getWriter().println("<form action=" + uploadUrl
+ " method="post" enctype="multipart/form-data">");
resp.getWriter().println("<input type="file" name="field-name"");

13. public void doPost(HttpServletRequest req,
HttpServletResponse resp) throws IOException {
BlobstoreService blobstoreService =
BlobstoreServiceFactory.getBlobstoreService();
Map<String, List<FileInfo>> blobs = blobstoreService.getFileInfos(req);
List<FileInfo> keys = blobs.get("field-name"); //input file name on
form
if (keys != null && keys.size() > 0) {
FileInfo fileKey = keys.get(0);
String objectUploaded = fileKey.getGsObjectName();
…. (Save the objectUploaded mapping to datastore or database)
Create Callback Handler

14. Serving Data
public void doGet(HttpServletRequest req, HttpServletResponse resp){
BlobstoreService blobstoreService =
BlobstoreServiceFactory.getBlobstoreService();
BlobKey blobKey =
blobstoreService.createGsBlobKey("/gs/<bucket>/<object>");
try {
blobstoreService.serve(blobKey, resp);
} catch (IOException e){
e.printStackTrace();
}
….

15. Other Storage API
● Image API
● Cloud Storage Client Library

16. Connect Cloud SQL

17. Before Connect
● CloudSQL instance ready
● Authorized
○ root password
○ instance ip address
○ access ip address

18. Configure Connectors
● Hostname is Cloud SQL instance IP address
● Connection URL includes instance IP and
database name
● Java connection is:
jdbc:mysql://<instance-ip>:3306/

19. Local Test Configure
appengine-web.xml
<?xml version="1.0" encoding="utf-8"?>
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
<application>mitac-cp300</application>
<version>eord</version>
….
<use-google-connector-j>true</use-google-connector-j>
….
</appengine-web-app>

20. Connect from App Engine
● JDBC
● Java Persistence API (JPA)
● Java Data Objects (JDO)
● Other JPAs custom additions: Hibernate, EclipseLink
jdbc:google:mysql://...
(instead of jdbc:mysql://...)

21. Detect running environment
Connection conn = null;
if (SystemProperty.environment.value() ==
SystemProperty.Environment.Value.Production) {
// app is running in production
Class.forName("com.mysql.jdbc.GoogleDriver");
String url= "jdbc:google:mysql://instance-name/";
conn = DriverManager.getConnection(url);
...
} else {
// app is running on localhost
Class.forName("com.mysql.jdbc.Driver");
String url= "jdbc:mysql://db-ip-address/";
conn = DriverManager.getConnection(url);
...
}
conn.~

22. DriverManager.registerDriver(new AppEngineDriver());
conn = DriverManager.getConnection(connUrl);
String sql = "SELECT count(*) as total FROM " + tableName + "";
PreparedStatement stmt = conn.prepareStatement(sql);
ResultSet results = stmt.executeQuery();
while (results.next()) {
int total = results.getInt("total");
…
}
Query Example - Standard JDBC

23. Other Frameworks
Popular frameworks for programming MySQL
● Hibernate (Java)
● JOOQ (Java)
● JPA ( Java )
● Django (Python)