Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.nifi.dbcp; import org.apache.commons.dbcp.BasicDataSource; import org.apache.nifi.annotation.behavior.DynamicProperty; import org.apache.nifi.annotation.documentation.CapabilityDescription; import org.apache.nifi.annotation.documentation.Tags; import org.apache.nifi.annotation.lifecycle.OnDisabled; import org.apache.nifi.annotation.lifecycle.OnEnabled; import org.apache.nifi.components.PropertyDescriptor; import org.apache.nifi.controller.AbstractControllerService; import org.apache.nifi.controller.ConfigurationContext; import org.apache.nifi.expression.AttributeExpression; import org.apache.nifi.processor.exception.ProcessException; import org.apache.nifi.processor.util.StandardValidators; import org.apache.nifi.reporting.InitializationException; import org.apache.nifi.util.file.classloader.ClassLoaderUtils; import java.net.MalformedURLException; import java.sql.Connection; import java.sql.Driver; import java.sql.DriverManager; import java.sql.SQLException; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.concurrent.TimeUnit; /** * Implementation of for Database Connection Pooling Service. Apache DBCP is used for connection pooling functionality. * */ @Tags({ "dbcp", "jdbc", "database", "connection", "pooling", "store" }) @CapabilityDescription("Provides Database Connection Pooling Service. Connections can be asked from pool and returned after usage.") @DynamicProperty(name = "JDBC property name", value = "JDBC property value", supportsExpressionLanguage = true, description = "Specifies a property name and value to be set on the JDBC connection(s). " + "If Expression Language is used, evaluation will be performed upon the controller service being enabled. " + "Note that no flow file input (attributes, e.g.) is available for use in Expression Language constructs for these properties.") public class DBCPConnectionPool extends AbstractControllerService implements DBCPService { public static final PropertyDescriptor DATABASE_URL = new PropertyDescriptor.Builder() .name("Database Connection URL") .description( "A database connection URL used to connect to a database. May contain database system name, host, port, database name and some parameters." + " The exact syntax of a database connection URL is specified by your DBMS.") .defaultValue(null).addValidator(StandardValidators.NON_EMPTY_VALIDATOR).required(true) .expressionLanguageSupported(true).build(); public static final PropertyDescriptor DB_DRIVERNAME = new PropertyDescriptor.Builder() .name("Database Driver Class Name").description("Database driver class name").defaultValue(null) .required(true).addValidator(StandardValidators.NON_EMPTY_VALIDATOR).expressionLanguageSupported(true) .build(); public static final PropertyDescriptor DB_DRIVER_LOCATION = new PropertyDescriptor.Builder() .name("database-driver-locations").displayName("Database Driver Location(s)") .description( "Comma-separated list of files/folders and/or URLs containing the driver JAR and its dependencies (if any). For example '/var/tmp/mariadb-java-client-1.1.7.jar'") .defaultValue(null).required(false).addValidator(StandardValidators.createListValidator(true, true, StandardValidators.createURLorFileValidator())) .expressionLanguageSupported(true).build(); public static final PropertyDescriptor DB_USER = new PropertyDescriptor.Builder().name("Database User") .description("Database user name").defaultValue(null) .addValidator(StandardValidators.NON_EMPTY_VALIDATOR).expressionLanguageSupported(true).build(); public static final PropertyDescriptor DB_PASSWORD = new PropertyDescriptor.Builder().name("Password") .description("The password for the database user").defaultValue(null).required(false).sensitive(true) .addValidator(StandardValidators.NON_EMPTY_VALIDATOR).expressionLanguageSupported(true).build(); public static final PropertyDescriptor MAX_WAIT_TIME = new PropertyDescriptor.Builder().name("Max Wait Time") .description( "The maximum amount of time that the pool will wait (when there are no available connections) " + " for a connection to be returned before failing, or -1 to wait indefinitely. ") .defaultValue("500 millis").required(true).addValidator(StandardValidators.TIME_PERIOD_VALIDATOR) .sensitive(false).build(); public static final PropertyDescriptor MAX_TOTAL_CONNECTIONS = new PropertyDescriptor.Builder() .name("Max Total Connections") .description( "The maximum number of active connections that can be allocated from this pool at the same time, " + " or negative for no limit.") .defaultValue("8").required(true).addValidator(StandardValidators.INTEGER_VALIDATOR).sensitive(false) .build(); public static final PropertyDescriptor VALIDATION_QUERY = new PropertyDescriptor.Builder() .name("Validation-query").displayName("Validation query") .description("Validation query used to validate connections before returning them. " + "When connection is invalid, it get's dropped and new valid connection will be returned. " + "Note!! Using validation might have some performance penalty.") .required(false).addValidator(StandardValidators.NON_EMPTY_VALIDATOR).expressionLanguageSupported(true) .build(); private static final List<PropertyDescriptor> properties; static { final List<PropertyDescriptor> props = new ArrayList<>(); props.add(DATABASE_URL); props.add(DB_DRIVERNAME); props.add(DB_DRIVER_LOCATION); props.add(DB_USER); props.add(DB_PASSWORD); props.add(MAX_WAIT_TIME); props.add(MAX_TOTAL_CONNECTIONS); props.add(VALIDATION_QUERY); properties = Collections.unmodifiableList(props); } private volatile BasicDataSource dataSource; @Override protected List<PropertyDescriptor> getSupportedPropertyDescriptors() { return properties; } @Override protected PropertyDescriptor getSupportedDynamicPropertyDescriptor(final String propertyDescriptorName) { return new PropertyDescriptor.Builder().name(propertyDescriptorName).required(false) .addValidator(StandardValidators .createAttributeExpressionLanguageValidator(AttributeExpression.ResultType.STRING, true)) .addValidator(StandardValidators.ATTRIBUTE_KEY_PROPERTY_NAME_VALIDATOR) .expressionLanguageSupported(true).dynamic(true).build(); } /** * Configures connection pool by creating an instance of the * {@link BasicDataSource} based on configuration provided with * {@link ConfigurationContext}. * * This operation makes no guarantees that the actual connection could be * made since the underlying system may still go off-line during normal * operation of the connection pool. * * @param context * the configuration context * @throws InitializationException * if unable to create a database connection */ @OnEnabled public void onConfigured(final ConfigurationContext context) throws InitializationException { final String drv = context.getProperty(DB_DRIVERNAME).evaluateAttributeExpressions().getValue(); final String user = context.getProperty(DB_USER).evaluateAttributeExpressions().getValue(); final String passw = context.getProperty(DB_PASSWORD).evaluateAttributeExpressions().getValue(); final Long maxWaitMillis = context.getProperty(MAX_WAIT_TIME).asTimePeriod(TimeUnit.MILLISECONDS); final Integer maxTotal = context.getProperty(MAX_TOTAL_CONNECTIONS).asInteger(); final String validationQuery = context.getProperty(VALIDATION_QUERY).evaluateAttributeExpressions() .getValue(); dataSource = new BasicDataSource(); dataSource.setDriverClassName(drv); // Optional driver URL, when exist, this URL will be used to locate driver jar file location final String urlString = context.getProperty(DB_DRIVER_LOCATION).evaluateAttributeExpressions().getValue(); dataSource.setDriverClassLoader(getDriverClassLoader(urlString, drv)); final String dburl = context.getProperty(DATABASE_URL).evaluateAttributeExpressions().getValue(); dataSource.setMaxWait(maxWaitMillis); dataSource.setMaxActive(maxTotal); if (validationQuery != null && !validationQuery.isEmpty()) { dataSource.setValidationQuery(validationQuery); dataSource.setTestOnBorrow(true); } dataSource.setUrl(dburl); dataSource.setUsername(user); dataSource.setPassword(passw); context.getProperties().keySet().stream().filter(PropertyDescriptor::isDynamic) .forEach((dynamicPropDescriptor) -> dataSource.addConnectionProperty( dynamicPropDescriptor.getName(), context.getProperty(dynamicPropDescriptor).evaluateAttributeExpressions().getValue())); } /** * using Thread.currentThread().getContextClassLoader(); will ensure that you are using the ClassLoader for you NAR. * * @throws InitializationException * if there is a problem obtaining the ClassLoader */ protected ClassLoader getDriverClassLoader(String locationString, String drvName) throws InitializationException { if (locationString != null && locationString.length() > 0) { try { // Split and trim the entries final ClassLoader classLoader = ClassLoaderUtils.getCustomClassLoader(locationString, this.getClass().getClassLoader(), (dir, name) -> name != null && name.endsWith(".jar")); // Workaround which allows to use URLClassLoader for JDBC driver loading. // (Because the DriverManager will refuse to use a driver not loaded by the system ClassLoader.) final Class<?> clazz = Class.forName(drvName, true, classLoader); if (clazz == null) { throw new InitializationException("Can't load Database Driver " + drvName); } final Driver driver = (Driver) clazz.newInstance(); DriverManager.registerDriver(new DriverShim(driver)); return classLoader; } catch (final MalformedURLException e) { throw new InitializationException("Invalid Database Driver Jar Url", e); } catch (final Exception e) { throw new InitializationException("Can't load Database Driver", e); } } else { // That will ensure that you are using the ClassLoader for you NAR. return Thread.currentThread().getContextClassLoader(); } } /** * Shutdown pool, close all open connections. */ @OnDisabled public void shutdown() { try { dataSource.close(); } catch (final SQLException e) { throw new ProcessException(e); } } @Override public Connection getConnection() throws ProcessException { try { final Connection con = dataSource.getConnection(); return con; } catch (final SQLException e) { throw new ProcessException(e); } } @Override public String toString() { return "DBCPConnectionPool[id=" + getIdentifier() + "]"; } }