回顾
我们上一节看了 calcite 的 DriverManager，本节重点看一下 calcite org.apache.calcite.jdbc.Driver
源码
基础属性
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8public class Driver extends UnregisteredDriver {
// 驱动前缀
public static final String CONNECT_STRING_PREFIX = "jdbc:calcite:";
// 构造器
final Function0<CalcitePrepare> prepareFactory = this.createPrepareFactory();
public Driver() {
}
基本方法
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26// 创建属性工厂
protected Function0<CalcitePrepare> createPrepareFactory() {
return CalcitePrepare.DEFAULT_FACTORY;
}
// 链接前缀
protected String getConnectStringPrefix() {
return "jdbc:calcite:";
}
// 获取工厂类
protected String getFactoryClassName(UnregisteredDriver.JdbcVersion jdbcVersion) {
switch (jdbcVersion) {
case JDBC_30:
case JDBC_40:
throw new IllegalArgumentException("JDBC version not supported: " + jdbcVersion);
case JDBC_41:
default:
return "org.apache.calcite.jdbc.CalciteJdbc41Factory";
}
}
protected DriverVersion createDriverVersion() {
return DriverVersion.load(Driver.class, "org-apache-calcite-jdbc.properties", "Calcite JDBC Driver", "unknown version", "Calcite", "unknown version");
}
核心方法
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74 protected Handler createHandler() {
return new HandlerImpl() {
public void onConnectionInit(AvaticaConnection connection_) throws SQLException {
// 链接初始化
CalciteConnectionImpl connection = (CalciteConnectionImpl)connection_;
super.onConnectionInit(connection);
String model = this.model(connection);
if (model != null) {
try {
new ModelHandler(connection, model);
} catch (IOException var5) {
throw new SQLException(var5);
}
}
connection.init();
}
// 模型的初始化
String model(CalciteConnectionImpl connection) {
String model = connection.config().model();
if (model != null) {
return model;
} else {
// 工厂
SchemaFactory schemaFactory = (SchemaFactory)connection.config().schemaFactory(SchemaFactory.class, (Object)null);
Properties info = connection.getProperties();
String schemaName = (String)Util.first(connection.config().schema(), "adhoc");
if (schemaFactory == null) {
JsonSchema.Type schemaType = connection.config().schemaType();
if (schemaType != null) {
switch (schemaType) {
case JDBC:
schemaFactory = Factory.INSTANCE;
break;
case MAP:
schemaFactory = org.apache.calcite.schema.impl.AbstractSchema.Factory.INSTANCE;
}
}
}
if (schemaFactory != null) {
JsonBuilder json = new JsonBuilder();
Map<String, Object> root = json.map();
root.put("version", "1.0");
root.put("defaultSchema", schemaName);
List<Object> schemaList = json.list();
root.put("schemas", schemaList);
Map<String, Object> schema = json.map();
schemaList.add(schema);
schema.put("type", "custom");
schema.put("name", schemaName);
schema.put("factory", schemaFactory.getClass().getName());
Map<String, Object> operandMap = json.map();
schema.put("operand", operandMap);
Iterator var11 = Util.toMap(info).entrySet().iterator();
while(var11.hasNext()) {
Map.Entry<String, String> entry = (Map.Entry)var11.next();
if (((String)entry.getKey()).startsWith("schema.")) {
operandMap.put(((String)entry.getKey()).substring("schema.".length()), entry.getValue());
}
}
return "inline:" + json.toJsonString(root);
} else {
return null;
}
}
}
};
}
基本方法
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10protected Collection<ConnectionProperty> getConnectionProperties() {
List<ConnectionProperty> list = new ArrayList();
Collections.addAll(list, BuiltInConnectionProperty.values());
Collections.addAll(list, CalciteConnectionProperty.values());
return list;
}
public Meta createMeta(AvaticaConnection connection) {
return new CalciteMetaImpl((CalciteConnectionImpl)connection);
}
获取链接
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7 CalciteConnection connect(CalciteSchema rootSchema, JavaTypeFactory typeFactory) {
return (CalciteConnection)((CalciteFactory)this.factory).newConnection(this, this.factory, "jdbc:calcite:", new Properties(), rootSchema, typeFactory);
}
CalciteConnection connect(CalciteSchema rootSchema, JavaTypeFactory typeFactory, Properties properties) {
return (CalciteConnection)((CalciteFactory)this.factory).newConnection(this, this.factory, "jdbc:calcite:", properties, rootSchema, typeFactory);
}
UnregisteredDriver
属性
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7public abstract class UnregisteredDriver implements Driver {
final DriverVersion version = this.createDriverVersion();
protected final AvaticaFactory factory = this.createFactory();
public final Handler handler = this.createHandler();
protected UnregisteredDriver() {
}
获取链接
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20 public Connection connect(String url, Properties info) throws SQLException {
// 是否支持的 url 类型
if (!this.acceptsURL(url)) {
return null;
} else {
// 获取链接前缀
String prefix = this.getConnectStringPrefix();
assert url.startsWith(prefix);
String urlSuffix = url.substring(prefix.length());
// 构建属性
Properties info2 = ConnectStringParser.parse(urlSuffix, info);
// 构建链接
AvaticaConnection connection = this.factory.newConnection(this, this.factory, url, info2);
this.handler.onConnectionInit(connection);
return connection;
}
}
AvaticaJdbc41Factory.newConnection
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8public AvaticaConnection newConnection(
UnregisteredDriver driver,
AvaticaFactory factory,
String url,
Properties info) {
// 创建了:AvaticaJdbc41Connection(是java.sql.Connection的实现)包裹:Driver/AvaticaFactory/url/{ model = "/model.json" }
return new AvaticaJdbc41Connection(driver, factory, url, info);
}
小结
-
DriverManager.getConnection 首先会委托给对应的 driver 实现类
-
实际底层对应的是 AvaticaJdbc41Factory 类,去创建一个: java.sql.Connection 的实现类(AvaticaJdbc41Connection)
参考资料
https://www.lixin.help/2021/04/11/Calcite-Driver-Register.html
