Question

我目前正在学习Java中的一些数据库技巧，我发现这本书正在阅读。在某些时候，ite鼓励我尝试使用以下类的手动DataBase连接：

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

public class DemoSelect {

    public static void main (String[] args){

        //Connection parameters
        String usr = "sa";
        String pwd = "";
        String driver = "org.hsqldb.jdbcDriver";
        String url = "jdbc:hsqldb:hsql://localhost/xdb";

        Connection con = null;
        PreparedStatement pstm = null;
        ResultSet rs = null;

        try{

            //Starting up the driver
            Class.forName(driver);

            //Conecting
            con = DriverManager.getConnection (url,usr,pwd);

            //Writting a query
            String sql = "SELECT empno, ename, hiredate, deptno FROM emp";

            //Setting up the SQL statement
            pstm = con.prepareStatement(sql);

            //Execute the SQL query
            rs = pstm.executeQuery();

            //Iterating the results
            while (rs.next()){

                //Simple method to show the data
                System.out.print(rs.getInt("empno")+", ");
                System.out.print(rs.getString("ename")+ ", ");
                System.out.print(rs.getDate("hiredate")+", ");
                System.out.println(rs.getInt("deptno"));

            }

        }catch (Exception e){

            e.printStackTrace();
            throw new RuntimeException(e);

        }finally{

            try{

                //Closing all the opened resources
                if (rs!=null) rs.close();
                if (pstm!=null) pstm.close();
                if (con!=null) con.close();

            }catch (Exception e){

                e.printStackTrace();
                throw new RuntimeException(e);

            }

        }

    } 

}

但是当我尝试运行它时，它会产生一个错误，其中包含以下描述：

java.lang.ClassNotFoundException: org.hsqldb.jdbcDriver
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:186)
    at cap3.jdbc.DemoSelect.main(DemoSelect.java:25)
Exception in thread "main" java.lang.RuntimeException: java.lang.ClassNotFoundException:      org.hsqldb.jdbcDriver
        at cap3.jdbc.DemoSelect.main(DemoSelect.java:53)
    Caused by: java.lang.ClassNotFoundException: org.hsqldb.jdbcDriver
        at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:186)
    at cap3.jdbc.DemoSelect.main(DemoSelect.java:25)
 Java Result: 1
 BUILD SUCCESSFUL (total time: 0 seconds)`

我能错过什么？

我正在使用NetBeans，我下载了HSQL驱动程序。我设法将.jar文件导入库中，我得到以下错误代码：

java.sql.SQLTransientConnectionException: java.net.ConnectException: Connection refused: connect
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCConnection.<init>(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.getConnection(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:579)
at java.sql.DriverManager.getConnection(DriverManager.java:221)
at cap3.jdbc.DemoSelect.main(DemoSelect.java:28)
Caused by: org.hsqldb.HsqlException: java.net.ConnectException: Connection refused: connect
at org.hsqldb.ClientConnection.openConnection(Unknown Source)
at org.hsqldb.ClientConnection.initConnection(Unknown Source)
at org.hsqldb.ClientConnection.<init>(Unknown Source)
... 6 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:69)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:337)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:198)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:180)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391)
at java.net.Socket.connect(Socket.java:579)
at java.net.Socket.connect(Socket.java:528)
at java.net.Socket.<init>(Socket.java:425)
at java.net.Socket.<init>(Socket.java:208)
at org.hsqldb.server.HsqlSocketFactory.createSocket(Unknown Source)
... 9 more
Exception in thread "main" java.lang.RuntimeException: java.sql.SQLTransientConnectionException: java.net.ConnectException: Connection refused: connect
at cap3.jdbc.DemoSelect.main(DemoSelect.java:53)
Caused by: java.sql.SQLTransientConnectionException: java.net.ConnectException: Connection refused: connect
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCConnection.<init>(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.getConnection(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:579)
at java.sql.DriverManager.getConnection(DriverManager.java:221)
at cap3.jdbc.DemoSelect.main(DemoSelect.java:28)
Caused by: org.hsqldb.HsqlException: java.net.ConnectException: Connection refused: connect
at org.hsqldb.ClientConnection.openConnection(Unknown Source)
at org.hsqldb.ClientConnection.initConnection(Unknown Source)
at org.hsqldb.ClientConnection.<init>(Unknown Source)
... 6 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:69)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:337)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:198)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:180)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391)
at java.net.Socket.connect(Socket.java:579)
at java.net.Socket.connect(Socket.java:528)
at java.net.Socket.<init>(Socket.java:425)
at java.net.Socket.<init>(Socket.java:208)
at org.hsqldb.server.HsqlSocketFactory.createSocket(Unknown Source)
... 9 more
Java Result: 1
BUILD SUCCESSFUL (total time: 1 second)

Answer 1

hsql驱动程序不在您的类路径中。您必须以某种方式在classpath中包含该驱动程序jar文件。例如你以这种方式运行你的程序java -cp .;hsqldb.jar DemoSelect。使用：作为分隔符代替;如果你在* nix。

另请参阅文档here

Answer 2

问：我能错过什么？

答：听起来你错过了HSQL驱动程序，甚至HSQL本身：）

问：您确定在系统上成功安装了HSQL吗？这是一个很好的链接：

http://hsqldb.org/web/howto.html

问：您是否在类路径中包含HSQL JDBC驱动程序？或者，如果您使用的是IDE，那么“库”设置是否包含HSQL JDBC驱动程序？

这是将第三方.jar文件（如HDBC）添加到Eclipse项目的良好链接：

http://www.wikihow.com/Add-JARs-to-Project-Build-Paths-in-Eclipse-%28Java%29

这里有一个关于JDBC连接的不同HSQL选项的链接：

http://hsqldb.org/doc/guide/ch04.html

您使用的是Eclipse，Netbeans还是“其他”？

Answer 3

您的第二次尝试是尝试连接到网络服务器。所以你必须先启动网络服务器。

您可以按照我在这篇文章中的回答来使用hsql server。

Concept of In Memory Database and how to see if my data is being populated in HSQL DB?

Answer 4

应使用PC（托管应用程序）的IP而不是localhost / 127.0.0.1

Answer 5

对我来说，问题出在类路径中。我正在使用eclipse tomcat和hslqdb.jar。

选择“运行配置...” - ＆gt; tomcat服务器 - ＆gt; classpath - ＆gt;用户条目 - ＆gt;添加jar

您可能忘记将hsqldb.jar添加到服务器的类路径中。

Answer 6

如果您不小心从属性文件中注释了hsql.jdbc.driver=org.hsqldb.jdbcDriver，也会发生这种情况。 :-D

Answer 7

只是添加你提到的东西没有帮助。

“选择”运行配置...“ - ＆gt; tomcat服务器 - ＆gt; classpath - ＆gt;用户条目 - ＆gt;添加jar”

这是一个好的开始，但你还必须包含sqltool.jar。

HSQL驱动无法正常工作？

7 个答案: