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// Copyright 2008 Google Inc.
//
// Licensed 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 com.google.gwtorm.jdbc;
import com.google.gwtorm.client.KeyUtil;
import com.google.gwtorm.client.OrmException;
import com.google.gwtorm.client.Schema;
import com.google.gwtorm.client.SchemaFactory;
import com.google.gwtorm.jdbc.gen.SchemaFactoryGen;
import com.google.gwtorm.jdbc.gen.SchemaGen;
import com.google.gwtorm.schema.SchemaModel;
import com.google.gwtorm.schema.java.JavaSchemaModel;
import com.google.gwtorm.schema.sql.DialectH2;
import com.google.gwtorm.schema.sql.DialectMySQL;
import com.google.gwtorm.schema.sql.DialectPostgreSQL;
import com.google.gwtorm.schema.sql.SqlDialect;
import com.google.gwtorm.server.GeneratedClassLoader;
import com.google.gwtorm.server.StandardKeyEncoder;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Collections;
import java.util.Map;
import java.util.WeakHashMap;
import javax.sql.DataSource;
/**
* Constructor for application {@link Schema} extensions.
* <p>
* Applications should use the Database class to create instances of their
* Schema extension interface, and thus open and connect to the JDBC data store.
* <p>
* Creating a new Database instance is expensive, due to the type analysis and
* code generation performed to implement the Schema and Access interfaces.
* Applications should create and cache their Database instance for the live of
* the application.
* <p>
* Database instances are thread-safe, but returned Schema instances are not.
*
* @param <T>
*/
public class Database<T extends Schema> implements SchemaFactory<T> {
private static final Map<SchemaKey, String> schemaFactoryNames =
Collections.synchronizedMap(new WeakHashMap<SchemaKey, String>());
private static class SchemaKey {
final Class<?> schema;
final SqlDialect dialect;
SchemaKey(Class<?> s, SqlDialect d) {
schema = s;
dialect = d;
}
@Override
public int hashCode() {
return schema.hashCode() * 31 + dialect.getClass().hashCode();
}
@Override
public boolean equals(Object o) {
if (o instanceof SchemaKey) {
SchemaKey a = this;
SchemaKey b = (SchemaKey) o;
return a.schema == b.schema
&& a.dialect.getClass() == b.dialect.getClass();
}
return false;
}
}
static {
KeyUtil.setEncoderImpl(new StandardKeyEncoder());
}
private final DataSource dataSource;
private final JavaSchemaModel schemaModel;
private final AbstractSchemaFactory<T> implFactory;
private final SqlDialect implDialect;
/**
* Create a new database interface, generating the interface implementations.
*
* @param ds JDBC connection information
* @param schema application extension of the Schema interface to implement.
* @throws OrmException the schema interface is incorrectly defined, or the
* driver class is not available through the current class loader.
*/
public Database(final DataSource ds, final Class<T> schema)
throws OrmException {
dataSource = ds;
SqlDialect dialect;
try {
final Connection c = ds.getConnection();
try {
final String url = c.getMetaData().getURL();
if (url.startsWith("jdbc:postgresql:")) {
dialect = new DialectPostgreSQL();
} else if (url.startsWith("jdbc:h2:")) {
dialect = new DialectH2();
} else if (url.startsWith("jdbc:mysql:")) {
dialect = new DialectMySQL();
} else {
throw new OrmException("No dialect known for " + url);
}
dialect = dialect.refine(c);
} finally {
c.close();
}
} catch (SQLException e) {
throw new OrmException("Unable to determine driver URL", e);
}
schemaModel = new JavaSchemaModel(schema);
final GeneratedClassLoader loader = newLoader(schema);
final SchemaKey key = new SchemaKey(schema, dialect);
final String cachedName = schemaFactoryNames.get(key);
AbstractSchemaFactory<T> factory = null;
if (cachedName != null) {
factory = newFactory(loader, cachedName);
}
if (factory == null) {
final SchemaGen gen = new SchemaGen(loader, schemaModel, dialect);
gen.defineClass();
factory = new SchemaFactoryGen<T>(loader, gen).create();
schemaFactoryNames.put(key, factory.getClass().getName());
}
implFactory = factory;
implDialect = dialect;
}
@SuppressWarnings("unchecked")
private AbstractSchemaFactory<T> newFactory(final ClassLoader cl,
final String name) {
try {
final Class<?> ft = Class.forName(name, true, cl);
return (AbstractSchemaFactory<T>) ft.newInstance();
} catch (InstantiationException e) {
return null;
} catch (IllegalAccessException e) {
return null;
} catch (ClassNotFoundException e) {
return null;
}
}
SqlDialect getDialect() {
return implDialect;
}
SchemaModel getSchemaModel() {
return schemaModel;
}
/**
* Open a new connection to the database and get a Schema wrapper.
*
* @return a new JDBC connection, wrapped up in the application's Schema.
* @throws OrmException the connection could not be opened to the database.
* The JDBC exception detail should be examined to determine the root
* cause of the connection failure.
*/
public T open() throws OrmException {
final Connection conn;
try {
conn = dataSource.getConnection();
} catch (SQLException e) {
throw new OrmException("Cannot open database connection", e);
}
try {
if (!conn.getAutoCommit()) {
conn.setAutoCommit(true);
}
} catch (SQLException e) {
try {
conn.close();
} catch (SQLException e2) {
}
throw new OrmException("Cannot force auto-commit on connection", e);
}
return implFactory.create(this, conn);
}
private static <T> GeneratedClassLoader newLoader(final Class<T> schema) {
return new GeneratedClassLoader(schema.getClassLoader());
}
}
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