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Intial Cloud SQL Connectivity App.
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‎cloud-sql/servlet/pom.xml

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<!--
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Copyright 2018 Google LLC
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<project>
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<modelVersion>4.0.0</modelVersion>
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<packaging>war</packaging>
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<version>1.0-SNAPSHOT</version>
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<groupId>com.example.cloudsql</groupId>
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<artifactId>tabs-vs-spaces</artifactId>
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<!--
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The parent pom defines common style checks and testing strategies for our samples.
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Removing or replacing it should not affect the execution of the samples in anyway.
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-->
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<parent>
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<groupId>com.google.cloud.samples</groupId>
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<artifactId>shared-configuration</artifactId>
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<version>1.0.10</version>
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</parent>
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<properties>
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<maven.compiler.target>1.8</maven.compiler.target>
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<maven.compiler.source>1.8</maven.compiler.source>
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<failOnMissingWebXml>false</failOnMissingWebXml>
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</properties>
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<dependencies>
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<dependency>
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<groupId>javax.servlet</groupId>
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<artifactId>javax.servlet-api</artifactId>
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<version>3.1.0</version>
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<type>jar</type>
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<scope>provided</scope>
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</dependency>
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<dependency>
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<groupId>mysql</groupId>
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<artifactId>mysql-connector-java</artifactId>
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<version>8.0.11</version>
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</dependency>
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<dependency>
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<groupId>com.google.cloud.sql</groupId>
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<artifactId>mysql-socket-factory-connector-j-8</artifactId>
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<version>1.0.11</version>
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</dependency>
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<dependency>
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<groupId>com.zaxxer</groupId>
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<artifactId>HikariCP</artifactId>
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<version>3.1.0</version>
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</dependency>
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</dependencies>
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<build>
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<plugins>
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<plugin>
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<groupId>org.eclipse.jetty</groupId>
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<artifactId>jetty-maven-plugin</artifactId>
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<version>9.4.10.v20180503</version>
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<configuration>
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<scanIntervalSeconds>1</scanIntervalSeconds>
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</configuration>
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</plugin>
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<plugin>
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<groupId>com.google.cloud.tools</groupId>
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<artifactId>appengine-maven-plugin</artifactId>
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<version>1.3.2</version>
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</plugin>
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</plugins>
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</build>
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</project>

‎cloud-sql/servlet/src/main/java/com/example/cloudsql/ConnectionPoolContextListener.java

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/*
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* Copyright 2018 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.cloudsql;
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import com.zaxxer.hikari.HikariConfig;
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import com.zaxxer.hikari.HikariDataSource;
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import java.sql.Connection;
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import java.sql.PreparedStatement;
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import java.sql.SQLException;
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import javax.servlet.ServletContextEvent;
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import javax.servlet.ServletContextListener;
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import javax.servlet.annotation.WebListener;
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import javax.sql.DataSource;
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@WebListener
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public class ConnectionPoolContextListener implements ServletContextListener {
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private static final String DB_USER = System.getenv("DB_USER");
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private static final String DB_PASS = System.getenv("DB_PASS");
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private static final String DB_NAME = System.getenv("DB_NAME");
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private DataSource createConnectionPool(){
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// [START cloud_sql_create_connection_pool]
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// Create a configuration object, and use it to specify how to connect to our database.
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HikariConfig config = new HikariConfig();
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// Add information about how to connect to the database
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config.setJdbcUrl(String.format("jdbc:mysql:///%s", DB_NAME));
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config.setUsername(DB_USER); // e.g. "root", "postgres"
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config.setPassword(DB_PASS); // e.g. "my-password"
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// Configure the Cloud SQL JDBC Socket Factory to provide authentication
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config.addDataSourceProperty("socketFactory", "com.google.cloud.sql.mysql.SocketFactory");
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config.addDataSourceProperty("cloudSqlInstance", "kvg-testing:us-central1:test1");
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config.addDataSourceProperty("useSSL", "false");
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config.setMaximumPoolSize(5); // Limit the maximum number of connections
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config.setIdleTimeout(60000); // Terminate unused connections after 10m
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// Using the config, create a connection pool to manage connections to your database.
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DataSource pool = new HikariDataSource(config);
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// [START cloud_sql_create_connection_pool]
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return pool;
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}
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private void createTableSchema(DataSource pool){
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// Safely attempt to create the table schema
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try (Connection conn = pool.getConnection()){
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PreparedStatement createTableStatement = conn.prepareStatement(
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"CREATE TABLE IF NOT EXISTS votes ( "
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+ "vote_id SERIAL NOT NULL, ts timestamp NOT NULL, team CHAR(6) NOT NULL, "
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+ "PRIMARY KEY (vote_id) );"
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);
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createTableStatement.execute();
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} catch (SQLException e) {
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throw new Error("Unable to create table 'votes'! \n" + e.toString());
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}
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}
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@Override
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public void contextDestroyed(ServletContextEvent event) {
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// This function is called when the Servlet is destroyed
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DataSource pool = (DataSource) event.getServletContext().getAttribute("pool");
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if (pool != null) {
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try {
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pool.unwrap(HikariDataSource.class).close();
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} catch (SQLException e) {
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// Handle exception
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System.out.println("Any error occurred while the application was shutting down: " + e);
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}
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}
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}
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@Override
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public void contextInitialized(ServletContextEvent event) {
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// This function is called when the application starts and will safely create a connection pool
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// that can be used to connect to
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DataSource pool = (DataSource) event.getServletContext().getAttribute("pool");
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if (pool == null) {
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pool = createConnectionPool();
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event.getServletContext().setAttribute("pool", pool);
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}
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createTableSchema(pool);
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}
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}

‎cloud-sql/servlet/src/main/java/com/example/cloudsql/IndexServlet.java

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/*
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* Copyright 2018 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.cloudsql;
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import java.io.IOException;
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import java.io.PrintWriter;
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import java.sql.Connection;
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import java.sql.PreparedStatement;
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import java.sql.ResultSet;
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import java.sql.SQLException;
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import java.sql.Timestamp;
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import java.util.ArrayList;
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import java.util.Date;
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import java.util.List;
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import javax.servlet.ServletException;
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import javax.servlet.annotation.WebServlet;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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import javax.sql.DataSource;
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@WebServlet(name = "Index", value = "")
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public class IndexServlet extends HttpServlet {
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@Override
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public void doGet(HttpServletRequest req, HttpServletResponse resp)
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throws IOException, ServletException {
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// Extract the pool from the Servlet Context, reusing the one that was created
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// in the ContextListener when the application was started
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DataSource pool = (DataSource) req.getServletContext().getAttribute("pool");
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// [START cloud_sql_example_query]
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int tabCt, voteCt;
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List<String> recentVotesTeams = new ArrayList<>();
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List<Timestamp> recentVotesTimes = new ArrayList<>();
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// It's important to always close a connection when you are finished with it, so that it is
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// returned to the pool and can be reused by other applications.
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// A try-with-resources statement automatically closes the connection when it exits the scope,
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// even if an error occurs. It's important to always close a connection when you are finished
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// with it, so that it is returned to the pool and can be reused later.
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try (Connection conn = pool.getConnection()){
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// PreparedStatements are compiled by the database immediately and executed at a later date.
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// Databases can reused already compiled queries, improving efficiency.
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PreparedStatement voteStmt = conn.prepareStatement(
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"SELECT team, ts FROM votes ORDER BY ts DESC LIMIT 5");
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// Execute the statement
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ResultSet voteResults = voteStmt.executeQuery();
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// Process the results
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while(voteResults.next()){
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recentVotesTeams.add(voteResults.getString(1));
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recentVotesTimes.add(voteResults.getTimestamp(2));
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}
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// PreparedStatements can also be executed multiple times with different arguments. This can
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// improve efficiency, and project a query from being vulnerable to an SQL injection.
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PreparedStatement voteCtStmt = conn.prepareStatement(
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"SELECT COUNT(vote_id) FROM votes WHERE team=?");
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voteCtStmt.setString(1, "tabs");
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ResultSet tabResult = voteCtStmt.executeQuery();
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tabResult.next(); // Move to the first result
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tabCt = tabResult.getInt(1);
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voteCtStmt.setString(1, "spaces");
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ResultSet spacesResult = voteCtStmt.executeQuery();
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spacesResult.next(); // Move to the first result
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voteCt = spacesResult.getInt(1);
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} catch (SQLException e) {
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// If something goes wrong, the application needs to react appropriately. This might mean
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// getting a new connection and executing the query again, or it might mean redirecting the
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// user to a different page to let them know something went wrong.
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e.printStackTrace();
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throw new Error("Unable to successfully complete SQL transaction! \n" + e.toString());
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}
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// [END cloud_sql_example_query]
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// Add variables and render the page
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req.setAttribute("tabVoteCt", tabCt);
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req.setAttribute("spaceVoteCt", voteCt);
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req.setAttribute("winningTeam", tabCt > voteCt ? "TABS" : "SPACES");
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req.setAttribute("voteDiff", tabCt > voteCt ? tabCt-voteCt: voteCt-tabCt);
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req.setAttribute("votesTeam", recentVotesTeams);
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req.setAttribute("votesTs", recentVotesTimes);
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req.getRequestDispatcher("/index.jsp").forward(req, resp);
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}
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@Override
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public void doPost(HttpServletRequest req, HttpServletResponse resp)
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throws IOException {
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// Get the team from the request and record the time of the vote.
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String team = req.getParameter("team");
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if (team != null) team = team.toLowerCase();
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Timestamp now = new Timestamp(new Date().getTime());
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if (team == null || !team.equals("tabs") && !team.equals("spaces")){
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resp.setStatus(400);
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resp.getWriter().append("Invalid team specified.");
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return;
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}
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// Reuse the pool that was created in the ContextListener when the Servlet started.
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DataSource pool = (DataSource) req.getServletContext().getAttribute("pool");
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// Open the connection safely, making sure it will be closed when finished.
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try (Connection conn = pool.getConnection()) {
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// A PreparedStatement can be cached by the database, improving it's efficiency.
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PreparedStatement voteStmt = conn.prepareStatement(
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"INSERT INTO votes (ts, team) VALUES (?, ?);");
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voteStmt.setTimestamp(1, now);
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voteStmt.setString(2, team);
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// Finally, execute the statement. If it fails, an error will be thrown.
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voteStmt.execute();
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} catch (SQLException e) {
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// Let the user know the vote wasn't cast correctly.
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throw new Error("Unable to cast vote! \n" + e.toString());
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}
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PrintWriter out = resp.getWriter();
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out.printf("Vote successfully cast for '%s' at time %s!\n", team, now);
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}
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}

‎cloud-sql/servlet/src/main/webapp/css/index.css

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/*
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Copyright 2018 Google LLC
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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* {
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box-sizing: border-box;
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}
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#main {
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display: flex;
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background: whitesmoke;
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text-align: center;
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}
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#main > article {
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margin: auto;
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width: 60%;
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}
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#main > aside {
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margin: auto;
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width: 20%;
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}

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