脑补一下JDBC基础知识，原文链接：http://docs.oracle.com/javase/tutorial/jdbc/basics/gettingstarted.html
If you are using Java DB, it already comes with a JDBC driver. If you are using MySQL, install the latest version of Connector/J. Contact the vendor of your database to obtain a JDBC driver for your DBMS. There are many possible implementations of JDBC drivers. These implementations are categorized as follows: Type 1: Drivers that implement the JDBC API as a mapping to another data access API, such as ODBC (Open Database Connectivity). Drivers of this type are generally dependent on a native library, which limits their portability. The JDBC-ODBC Bridge is an example of a Type 1 driver. Note: The JDBC-ODBC Bridge should be considered a transitional solution. It is not supported by Oracle. Consider using this only if your DBMS does not offer a Java-only JDBC driver. Type 2: Drivers that are written partly in the Java programming language and partly in native code. These drivers use a native client library specific to the data source to which they connect. Again, because of the native code, their portability is limited. Oracle's OCI (Oracle Call Interface) client-side driver is an example of a Type 2 driver. Type 3: Drivers that use a pure Java client and communicate with a middleware server using a database-independent protocol. The middleware server then communicates the client's requests to the data source. Type 4: Drivers that are pure Java and implement the network protocol for a specific data source. The client connects directly to the data source. Check which driver types comes with your DBMS. Java DB comes with two Type 4 drivers, an Embedded driver and a Network Client Driver. MySQL Connector/J is a Type 4 driver. Installing a JDBC driver generally consists of copying the driver to your computer, then adding the location of it to your class path. In addition, many JDBC drivers other than Type 4 drivers require you to install a client-side API. No other special configuration is usually needed.
PS：天天群里吵吵什么JDBC多少种类型，这里给脑补一下，谁看到就好好看看那。另外原文中有标红的部分请注意一下。