今天下载了jdk1.6.0,以后要慢慢来学习1.6中的新特性和其中的一些经典实例。先看看关于Java DB的这个最简例子：
Simple JDBC Application （源码SimpleApp.java、文档及derby.jar,derbynet.jar,derbyclient.ar文件请从jdk1.6.0中找）
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这个例子是一个最小限度的JDBC 应用程序。 关于这个程序：
- 以内嵌式模式（缺省的）或作为一个服务器环境中的客户端运行，这依靠于传递给程序的参数
- 假如运行在内嵌式模式，则启动Derby 引擎
- 假如运行在客户端模式，则连接到 Derby 网络服务器
- 创建并连接到数据库
- 创建一个表
- 插入数据
- 更新数据
- 查询数据
- 删除表
- 关闭连接
- 假如运行在内嵌式模式，则关闭 Derby。
以下是源码：
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
/*
* @author janet
*/
public class SimpleApp
{
/* 缺省的模式是内嵌式的*/
public String framework = "embedded";
public String driver = "org.apache.derby.jdbc.EmbeddedDriver";
public String protocol = "jdbc:derby:";
public static void main(String[] args)
{
new SimpleApp().go(args);
}
void go(String[] args)
{
/* 处理参数，确定这个程序作为内嵌式使用还是作为客户端使用*/
parseArguments(args);
System.out.println("SimpleApp starting in " + framework + " mode.");
try
{
/*
装载驱动程序，假如是内嵌式模式，这将启动Derby, 因为它还没有运行.
*/
Class.forName(driver).newInstance();
System.out.println("Loaded the appropriate driver.");
Connection conn = null;
Properties props = new Properties();
props.put("user", "user1");
props.put("passWord", "user1");
//create=true将创建数据库derbyDB
conn = DriverManager.getConnection(protocol +"derbyDB;create=true", props);
System.out.println("Connected to and created database derbyDB");
conn.setAutoCommit(false);//设置自动提交模式
Statement s = conn.createStatement();
/*
创建一个表，加入几条记录并更新一条.
*/
s.execute("create table derbyDB(num int, addr varchar(40))");
System.out.println("Created table derbyDB");
s.execute("insert into derbyDB values (1956,'Webster St.')");
System.out.println("Inserted 1956 Webster");
s.execute("insert into derbyDB values (1910,'Union St.')");
System.out.println("Inserted 1910 Union");
s.execute(
"update derbyDB set num=180, addr='Grand Ave.' where num=1956");
System.out.println("Updated 1956 Webster to 180 Grand");
s.execute(
"update derbyDB set num=300, addr='Lakeshore Ave.' where num=180");
System.out.println("Updated 180 Grand to 300 Lakeshore");
/*
查询并校验结果.
*/
ResultSet rs = s.executeQuery(
"SELECT num, addr FROM derbyDB ORDER BY num");
if (!rs.next())
{
throw new Exception("Wrong number of rows");
}
if (rs.getInt(1) != 300)
{
throw new Exception("Wrong row returned");
}
if (!rs.next())
{
throw new Exception("Wrong number of rows");
}
if (rs.getInt(1) != 1910)
{
throw new Exception("Wrong row returned");
}
if (rs.next())
{
throw new Exception("Wrong number of rows");
}
System.out.println("Verified the rows");
s.execute("drop table derbyDB");//删除表
System.out.println("Dropped table derbyDB");
rs.close();
s.close();
System.out.println("Closed result set and statement");
conn.commit();
conn.close();
System.out.println("Committed transaction and closed connection");
boolean gotSQLExc = false;
if (framework.equals("embedded"))
{
try
{
DriverManager.getConnection("jdbc:derby:;shutdown=true");//关闭数据库服务
}
catch (SQLException se)
{
gotSQLExc = true;
}
if (!gotSQLExc)
{
System.out.println("Database did not shut down normally");
}
else
{
System.out.println("Database shut down normally");
}
}
}
catch (Throwable e)
{
System.out.println("exception thrown:");
if (e instanceof SQLException)
{
printSQLError((SQLException) e);
}
else
{
e.printStackTrace();
}
}
System.out.println("SimpleApp finished");
}
static void printSQLError(SQLException e)
{
while (e != null)
{
System.out.println(e.toString());
e = e.getNextException();
}
}
private void parseArguments(String[] args)
{
// System.setProperty("derby.system.home", "c:\\DBdata");//这样可以设置数据库数据的存放目录
int length = args.length;
for (int index = 0; index < length; index++)
{
if (args[index].equalsIgnoreCase("jccjdbcclient"))
{
framework = "jccjdbc";
driver = "com.ibm.db2.jcc.DB2Driver";
protocol = "jdbc:derby:net://localhost:1527/";
}
if (args[index].equalsIgnoreCase("derbyclient"))
{
framework = "derbyclient";
driver = "org.apache.derby.jdbc.ClientDriver";
protocol = "jdbc:derby://localhost:1527/";
}
}
}
}
进入讨论组讨论。
