DynamicWeb 项目中的嵌入式数据库答案

【问题标题】：Embedded database in DynamicWeb projectDynamicWeb 项目中的嵌入式数据库
【发布时间】：2016-08-25 14:44:57
【问题描述】：

如何在我的 WebApp 项目中实现嵌入式数据库？因此，为了测试我使用 Tomcat 的项目。有没有办法让我在 web 应用程序中拥有一个“本地”/独立数据库？

我的本地数据库（db.script）：

SET DATABASE UNIQUE NAME HSQLDB56C1DBAB62
SET DATABASE GC 0
SET DATABASE DEFAULT RESULT MEMORY ROWS 0
SET DATABASE EVENT LOG LEVEL 0
SET DATABASE TRANSACTION CONTROL LOCKS
SET DATABASE DEFAULT ISOLATION LEVEL READ COMMITTED
SET DATABASE TRANSACTION ROLLBACK ON CONFLICT TRUE
SET DATABASE TEXT TABLE DEFAULTS ''
SET DATABASE SQL NAMES FALSE
SET DATABASE SQL REFERENCES FALSE
SET DATABASE SQL SIZE TRUE
SET DATABASE SQL TYPES FALSE
SET DATABASE SQL TDC DELETE TRUE
SET DATABASE SQL TDC UPDATE TRUE
SET DATABASE SQL TRANSLATE TTI TYPES TRUE
SET DATABASE SQL TRANSLATE TTI TYPES TRUE
SET DATABASE SQL CONCAT NULLS TRUE
SET DATABASE SQL UNIQUE NULLS TRUE
SET DATABASE SQL CONVERT TRUNCATE TRUE
SET DATABASE SQL AVG SCALE 0
SET DATABASE SQL DOUBLE NAN TRUE
SET FILES WRITE DELAY 500 MILLIS
SET FILES BACKUP INCREMENT TRUE
SET FILES CACHE SIZE 10000
SET FILES CACHE ROWS 50000
SET FILES SCALE 32
SET FILES LOB SCALE 32
SET FILES DEFRAG 0
SET FILES NIO TRUE
SET FILES NIO SIZE 256
SET FILES LOG TRUE
SET FILES LOG SIZE 50
CREATE USER "Chris" PASSWORD DIGEST '4a7d1ed414474e4033ac29ccb8653d9b'
ALTER USER "Chris" SET LOCAL TRUE
CREATE SCHEMA PUBLIC AUTHORIZATION DBA
SET SCHEMA PUBLIC
CREATE MEMORY TABLE PUBLIC.CUSTOMER(ID VARCHAR(20))
ALTER SEQUENCE SYSTEM_LOBS.LOB_ID RESTART WITH 1
SET DATABASE DEFAULT INITIAL SCHEMA PUBLIC
GRANT USAGE ON DOMAIN INFORMATION_SCHEMA.SQL_IDENTIFIER TO PUBLIC
GRANT USAGE ON DOMAIN INFORMATION_SCHEMA.YES_OR_NO TO PUBLIC
GRANT USAGE ON DOMAIN INFORMATION_SCHEMA.TIME_STAMP TO PUBLIC
GRANT USAGE ON DOMAIN INFORMATION_SCHEMA.CARDINAL_NUMBER TO PUBLIC
GRANT USAGE ON DOMAIN INFORMATION_SCHEMA.CHARACTER_DATA TO PUBLIC
GRANT DBA TO "Chris"
SET SCHEMA SYSTEM_LOBS
INSERT INTO BLOCKS VALUES(0,2147483647,0)
SET SCHEMA PUBLIC
INSERT INTO CUSTOMER VALUES('CHRIS')

这是我连接到数据库的 Java 类（只是一个测试类）：

package jdbc;

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

/**
 * Dies Klasse liefert eine  JDBC Connection zurück
 * @author Christian
 *
 */
public class JDBCConnector {

    private Connection connection;

    public JDBCConnector(String url, String user, String password){
        try{
          Class.forName("org.hsqldb.jdbcDriver");
          connection = DriverManager.getConnection(url, user, password);
          if(connection != null){
              System.out.println("Verbindung hergestellt");
          }
        }catch ( ClassNotFoundException e ){
            System.err.println("Der Datenbanktreiber konnte nicht geladen werden");
            e.printStackTrace();
        } catch (SQLException e) {
            System.err.println("Beim Erstellen der Verbindung ist ein Feheler aufgetreten.\n"
                    + "Bitte überprüfen Sie die URL, sowie Usernamen und Passwort");
        }
    }

    public Connection getConnection() throws Exception{
        if(connection != null){
            return connection;
        }else{
            throw new Exception("Connection == null");
        }
    } 

    public String getFirstEntry(){
        try {
            Statement stmt = connection.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM CUSTOMER");
            String s = "";
            while(rs.next()){
                s = rs.getString(1);
                System.out.println("s: " + s);
            }
            return s;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return "";
    }


}

这里是JSP文件，被调用来连接数据库：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ page import="jdbc.JDBCConnector"  %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<% JDBCConnector connector = new JDBCConnector("jdbc:hsqldb:file:/Gefaehrdungsbeurteilung_Full/gefaehrdungsbeurteilung_full/server/db/db", "Chris", "0000"); 
    out.append(connector.getFirstEntry());
    %>
</body>
</html>

如果我执行，我会收到以下错误：

Verbindung hergestellt
java.sql.SQLSyntaxErrorException: user lacks privilege or object not found: CUSTOMER
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCStatement.fetchResult(Unknown Source)
    at org.hsqldb.jdbc.JDBCStatement.executeQuery(Unknown Source)
    at jdbc.JDBCConnector.getFirstEntry(JDBCConnector.java:45)
    at org.apache.jsp.gefaehrdungsbeurteilung_005ffull.server.jsp.Access_jsp._jspService(Access_jsp.java:121)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)
Caused by: org.hsqldb.HsqlException: user lacks privilege or object not found: CUSTOMER
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.ParserDQL.readTableName(Unknown Source)
    at org.hsqldb.ParserDQL.readTableOrSubquery(Unknown Source)
    at org.hsqldb.ParserDQL.XreadTableReference(Unknown Source)
    at org.hsqldb.ParserDQL.XreadFromClause(Unknown Source)
    at org.hsqldb.ParserDQL.XreadTableExpression(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQuerySpecification(Unknown Source)
    at org.hsqldb.ParserDQL.XreadSimpleTable(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryPrimary(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryTerm(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryExpressionBody(Unknown Source)
    at org.hsqldb.ParserDQL.XreadQueryExpression(Unknown Source)
    at org.hsqldb.ParserDQL.compileCursorSpecification(Unknown Source)
    at org.hsqldb.ParserCommand.compilePart(Unknown Source)
    at org.hsqldb.ParserCommand.compileStatements(Unknown Source)
    at org.hsqldb.Session.executeDirectStatement(Unknown Source)
    at org.hsqldb.Session.execute(Unknown Source)
    ... 31 more

路径一定是对的，因为当我添加http://localhost:8080/Gefaehrdungsbeurteilung_Full/gefaehrdungsbeurteilung_full/server/db/db.script时，我看到了脚本文件。在脚本文件中，您会看到声明了客户...

【问题讨论】：

Gefaehrdungsbeurteilung_Full/gefaehrdungsbeurteilung_full/server/db/db.script 在哪里？
在 webcontent 下，然后是路径 gefaehrdungsbeurteilung_full/se‌rver/db/。

标签： java database web-applications

【解决方案1】：

您可以选择Derby- 它在同一个堆栈上。或SQLLite。

【讨论】：

【解决方案2】：

jdbc:hsqldb:file:/Gefaehrdun... 是绝对路径，因为它以 / 开头。如果使用绝对路径，则需要将数据库放在 Tomcat 之外的那个确切位置。

如果您使用 jdbc:hsqldb:file:Gefaehrdun...（不以 / 开头），它将是相对的，但我不确定它是否与 WEB-INF/classes、tomcat/bin 或其他相关。您需要进行实验。

【讨论】：

谢谢，我做了一点实验：)

【解决方案3】：

你应该看看H2。它很小，可嵌入。

http://www.h2database.com/html/main.html

【讨论】：

好的，但是当我使用h2或hsqldb的嵌入式模式时，访问数据库时总是遇到curios错误。这个错误，当我运行相同的类和数据库作为简单的java项目时，我没有得到......
@Chris 谢谢。现在我猜想 db.script 没有针对数据库执行。
好的，但是我能做什么？所以我的路径错了？或者这里发生了什么？因为在互联网上，我读到通常嵌入数据库也应该在 WebApplication 中工作
对不起，我不能帮你。阅读 hsqldb 的文档/教程。找出 db.script 应该在哪里。我猜它应该位于您的应用程序的资源中。请记住，Web 应用程序的类路径不同于简单的应用程序。