JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

JDBC^TM Guide: Getting Started

3 Overview of the major interfaces

There are two major sets of interfaces. First there is a JDBC API for application writers. Second there is a lower level JDBC Driver API.

3.1 The JDBC API

The JDBC API is expressed as a series of abstract Java interfaces that allow an application programmer to open connections to particular databases, execute SQL statements, and process the results.

The most important interfaces are:

java.sql.DriverManager which handles loading of drivers and provides support for creating new database connections
java.sql.Connection which represents a connection to a particular database
java.sql.Statement which acts as a container for executing a SQL statement on a given connection
java.sql.ResultSet which controls access to the row results of a given Statement

The java.sql.Statement interface has two important sub-types: java.sql.PreparedStatement for executing a pre-compiled SQL statement, and java.sql.CallableStatement for executing a call to a database stored procedure.

The following chapters provide more information on how these interfaces work. See the separate JDBC API documents for complete documentation of JDBC interfaces and classes.

3.2 The JDBC Driver Interface

The java.sql.Driver interface is fully defined in Chapter 9. For the most part the database drivers simply need to provide implementations of the abstract classes provided by the JDBC API. Specifically, each driver must provide implementations of java.sql.Connection, java.sql.Statement, java.sql.PreparedStatement, java.sql.CallableStatement, and java.sql.ResultSet.

In addition, each database driver needs to provide a class which implements the java.sql.Driver interface used by the generic java.sql.DriverManager class when it needs to locate a driver for a particular database URL.

JavaSoft is providing an implementation of JDBC on top of ODBC, shown as the JDBC-ODBC bridge in the picture. Since JDBC is patterned after ODBC, this implementation is small and efficient.

Another useful driver is one that goes directly to a DBMS-independent network protocol. It would be desirable to publish the protocol to allow multiple server implementations, e.g. on top of ODBC or on specific DBMSs (although there are already products that use a fixed protocol such as this, we are not yet trying to standardize it). Only a few optimizations are needed on the client side, e.g. for schema caching and tuple look-ahead, and the JDBC Manager itself is very small and efficient as well. The net result is a very small and fast all-Java client side implementation that speaks to any server speaking the published protocol.

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