本文主要介绍 Derby 的基本使用(简介可参考:Derby 数据库介绍(1)--简介)，文中所使用到的软件版本：Java 1.8.0_341、Derby 10.14.2.0。
1、嵌入模式
直接使用 JDBC 连接数据库，可创建和启动数据库。
1.1、内存数据库
@Test public void embeddedMemory() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.EmbeddedDriver", "jdbc:derby:memory:myDb;create=true", user, "");business(con, user);con.close(); }private void business(Connection con, String user) throws SQLException {String tableName = "a_student";Statement st = con.createStatement();String sql = "select 1 from sys.sysTABLES a,sys.sysschemas b where a.schemaid=b.schemaid and upper(b.schemaname)=? and upper(a.tablename)=?";PreparedStatement pst = con.prepareStatement(sql);pst.setString(1, user.toUpperCase());pst.setString(2, tableName.toUpperCase());ResultSet rs = pst.executeQuery();if (!rs.next()) {//表不存在则创建并初始化数据，这里根据业务需要进行操作st.executeUpdate("create table " + tableName + "(id int, name varchar(32))");st.executeUpdate("insert into " + tableName + "(id,name) values (1,'李白')");st.executeUpdate("insert into " + tableName + "(id,name) values (2,'杜甫')");}rs = st.executeQuery("select * from " + tableName);while (rs.next()) {log.info("id={},name={}", rs.getInt("id"), rs.getString("name"));} }
1.2、文件数据库
@Test public void embeddedFile() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.EmbeddedDriver", "jdbc:derby:d:/temp/myDb;create=true", user, "");business(con, user);con.close(); }
1.3、资源数据库
@Test public void embeddedJar() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.EmbeddedDriver", "jdbc:derby:classpath:myDb", user, "");business(con, user);con.close(); }
jar 包不在 classpath 之中：
@Test public void embeddedJar2() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.EmbeddedDriver", "jdbc:derby:jar:(d:/temp/my.jar)myDb", user, "");business(con, user);con.close(); }
2、服务器模式
在服务端启动 Derby 数据库服务：
cd ${DERBY_HOME}/bin
NetworkServerControl.bat start -p 1527 -noSecurityManager
客户端通过 JDBC 访问 Derby 服务。
2.1、内存数据库
@Test public void networkMemory() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.ClientDriver", "jdbc:derby://localhost:1527/memory:myDb;create=true", user, "123456");business(con, user);con.close(); }
2.2、文件数据库
@Test public void networkFile() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.ClientDriver", "jdbc:derby://localhost:1527/d:/temp/myDb;create=true", user, "123456");business(con, user);con.close(); }
2.3、资源数据库
@Test public void networkJar() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.ClientDriver", "jdbc:derby://localhost:1527/classpath:myDb", user, "123");business(con, user);con.close(); }
jar 包不在 classpath 之中：
@Test public void networkJar2() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.ClientDriver", "jdbc:derby://localhost:1527/jar:(d:/temp/my.jar)myDb", user, "123");business(con, user);con.close(); }
3、混合模式
应用通过代码的方式启动数据库服务，应用内访问数据库可以使用进程模式，其他应用通过服务器模式访问。
@Test public void networkServerControl() throws Exception {NetworkServerControl server = new NetworkServerControl(InetAddress.getByName("0.0.0.0"), 1527);server.start (null);CountDownLatch countDownLatch = new CountDownLatch(1);new Thread(() -> {try {//模拟其他应用访问 networkMemory();} catch (Exception e) {e.printStackTrace();}countDownLatch.countDown();}).start();countDownLatch.await();server.shutdown(); }
完整代码：
package com.abc.demo.db;import lombok.extern.slf4j.Slf4j; import org.apache.derby.drda.NetworkServerControl; import org.junit.Test;import java.net.InetAddress; import java.sql.*; import java.util.concurrent.CountDownLatch;@Slf4j public class DerbyCae {@Testpublic void embeddedMemory() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.EmbeddedDriver", "jdbc:derby:memory:myDb;create=true", user, "");business(con, user);con.close();}@Testpublic void embeddedFile() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.EmbeddedDriver", "jdbc:derby:d:/temp/myDb;create=true", user, "");business(con, user);con.close();}@Testpublic void embeddedJar() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.EmbeddedDriver", "jdbc:derby:classpath:myDb", user, "");business(con, user);con.close();}@Testpublic void embeddedJar2() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.EmbeddedDriver", "jdbc:derby:jar:(d:/temp/my.jar)myDb", user, "");business(con, user);con.close();}@Testpublic void networkMemory() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.ClientDriver", "jdbc:derby://localhost:1527/memory:myDb;create=true", user, "123456");business(con, user);con.close();}@Testpublic void networkFile() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.ClientDriver", "jdbc:derby://localhost:1527/d:/temp/myDb;create=true", user, "123456");business(con, user);con.close();}@Testpublic void networkJar() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.ClientDriver", "jdbc:derby://localhost:1527/classpath:myDb", user, "123");business(con, user);con.close();}@Testpublic void networkJar2() throws SQLException {String user = "admin";Connection con = JdbcUtil.getConnection("org.apache.derby.jdbc.ClientDriver", "jdbc:derby://localhost:1527/jar:(d:/temp/my.jar)myDb", user, "123");business(con, user);con.close();}@Testpublic void networkServerControl() throws Exception {NetworkServerControl server = new NetworkServerControl(InetAddress.getByName("0.0.0.0"), 1527);server.start (null);CountDownLatch countDownLatch = new CountDownLatch(1);new Thread(() -> {try {//模拟其他应用访问 networkMemory();} catch (Exception e) {e.printStackTrace();}countDownLatch.countDown();}).start();countDownLatch.await();server.shutdown();}private void business(Connection con, String user) throws SQLException {String tableName = "a_student";Statement st = con.createStatement();String sql = "select 1 from sys.sysTABLES a,sys.sysschemas b where a.schemaid=b.schemaid and upper(b.schemaname)=? and upper(a.tablename)=?";PreparedStatement pst = con.prepareStatement(sql);pst.setString(1, user.toUpperCase());pst.setString(2, tableName.toUpperCase());ResultSet rs = pst.executeQuery();if (!rs.next()) {//表不存在则创建并初始化数据，这里根据业务需要进行操作st.executeUpdate("create table " + tableName + "(id int, name varchar(32))");st.executeUpdate("insert into " + tableName + "(id,name) values (1,'李白')");st.executeUpdate("insert into " + tableName + "(id,name) values (2,'杜甫')");}rs = st.executeQuery("select * from " + tableName);while (rs.next()) {log.info("id={},name={}", rs.getInt("id"), rs.getString("name"));}} }
package com.abc.demo.db;import lombok.extern.slf4j.Slf4j;import java.sql.*;@Slf4j public class JdbcUtil {private JdbcUtil() {}public static Connection getConnection(String driver, String url, String username, String password) {Connection con = null;try {Class.forName(driver);con = DriverManager.getConnection(url, username, password);} catch (ClassNotFoundException | SQLException e) {log.warn("url={},username={},password={}", url, username, password);e.printStackTrace();}return con;} }
