如何在 eclipse(part2) 中配置 javadb？

Question

这是我之前的问题How to configure javadb in eclipse? 的继续。我能够对我的代码进行一些更改，但现在它给了我这个错误 -> 错误：java.net.ConnectException：连接到端口 1527 上的服务器 localhost 时出错，消息连接被拒绝：连接。希望你们能帮我解决这个问题。

这是我的代码：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class Test {

public static void main(String[] args) {
    try {
        Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();
    } catch (InstantiationException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }

    final String DB_URL = "jdbc:derby://localhost:1527/CoffeeDB;create=true";

    try{
        Connection conn = DriverManager.getConnection(DB_URL);
        Statement stmt = conn.createStatement();

        String sql = ("CREATE TABLE Coffee(Description CHAR(25),ProdNum CHAR(10) NOT NULL PRIMARY KEY,Price DOUBLE)");
        stmt.execute(sql);

        sql = "INSERT INTO Coffee VALUES('Bolivian Dark','14-001',8.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Bolivian Medium','14-002',8.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Brazilian Dark','15-001',7.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Brazilian Medium','15-002',7.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Brazilian Decaf','15-003',8.55)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Central American Dark','16-001',9.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Central American Medium','16-002',9.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Sumatra Dark','17-001',7.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Sumatra Decaf','17-002',8.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Sumatra Medium','17-003',7.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Sumatra Organic Dark','17-004',11.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Kona Medium','18-001',18.45)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Kona Dark','18-002',18.45)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('French Roast Dark','19-001',9.65)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Galapagos Medium','20-001',6.85)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Guatemalan Dark','21-001',9.95)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Guatemalan Decaf','21-002',10.45)";
        stmt.executeUpdate(sql);

        sql = "INSERT INTO Coffee VALUES('Guatemalan Medium','21-003',9.95)";
        stmt.executeUpdate(sql);

        String sqlStatement = "SELECT Description FROM Coffee";
        ResultSet result = stmt.executeQuery(sqlStatement);

        System.out.println("Coffees found in the Database");
        System.out.println("-----------------------------");

        while(result.next()){
            System.out.println(result.getString("Description"));
        }

        conn.close();
    }catch(Exception ex){
        System.out.println("ERROR: " + ex.getMessage());
    }

}

}

Answer 1

我一直在尝试使用您当前的代码，发现当服务器未启动时会发生异常。解决这个问题的方法是用一种简单的方式启动服务器：

通过命令提示符转到 derby 服务器下载的解压缩文件夹中的 lib 文件夹。对我来说是这样的：

C:\>cd opt\db-derby-10.11.1.1-lib\lib

C:\opt\db-derby-10.11.1.1-lib\lib>java -jar derbyrun.jar server start
Sat Oct 03 16:26:29 IST 2015 : Security manager installed using the Basic server security policy.
Sat Oct 03 16:26:29 IST 2015 : Apache Derby Network Server - 10.11.1.1 - (1616546) started and ready to accept connections on port 1527

您可以通过不同的方式在 Eclipse 中启动服务器。您需要安装插件，然后启动服务器。以下参考资料应该对您有所帮助：

Derby Plugin How To
Getting Started with Derby Plugin for Eclipse