Java 部署时servlet上下文侦听器中的(批处理)数据库架构
因此,我有一个文件Java 部署时servlet上下文侦听器中的(批处理)数据库架构,java,mysql,sql,database,jdbc,Java,Mysql,Sql,Database,Jdbc,因此,我有一个文件schema.sql,其中包含数据库的模式,我希望在部署应用程序时相应地创建表 ServletContextListener如下所示 /** * This class doesn't really belong to the Ui package, but it does depend on * servlet technology like all the other classes here, so I've just put it here for the momen
schema.sql
,其中包含数据库的模式,我希望在部署应用程序时相应地创建表
ServletContextListener
如下所示
/**
* This class doesn't really belong to the Ui package, but it does depend on
* servlet technology like all the other classes here, so I've just put it here for the moment.
*
* The class may be moved in the future
*
* When the application is deployed and started, this class connects to the database,
* checks if the environment is compatible, checks various other things like whether
* Core.User.HASH_ALGO or Core.User.STRING_ENCODING are supported (see Core.User for
* details).
*/
package Ui;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletContext;
import com.mysql.jdbc.Driver;
import java.sql.*;
import java.io.*;
import java.net.URL;
/**
* Web application lifecycle listener.
*/
public class AppContextListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
ServletContext s = sce.getServletContext();
String db_uri = s.getInitParameter("DB_HOST");
String db_user = s.getInitParameter("DB_USERNAME");
String db_pass = s.getInitParameter("DB_PASSWORD");
try {
Connection connection = DriverManager.getConnection(db_uri, db_user, db_pass);
//TODO check if version is compatible ;-), set app as unusable if necessary
s.setAttribute("db", connection);
Statement st = null;
if(null != connection) {
st = connection.createStatement();
String schema = null;
try {
InputStream str = s.getResourceAsStream("/WEB-INF/sql/schema.sql");
schema = readStream(str);
}
catch(Exception e) {
//TODO set global application state as unusable, with a message
}
finally {
int i = st.executeUpdate(schema);
}
}
} catch(SQLException e) {
//TODO set global application state as unusable, with a message
}
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
//TODO disconnect from the DB
}
protected String readStream(InputStream stream) {
BufferedInputStream bis = new BufferedInputStream(stream);
ByteArrayOutputStream buf = new ByteArrayOutputStream();
try {
int result = bis.read();
while(result != -1) {
byte b = (byte)result;
buf.write(b);
result = bis.read();
}
}
catch(IOException e) {
return null;
}
finally {
return buf.toString();
}
}
}
模式如下:
SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
SET AUTOCOMMIT=0;
START TRANSACTION;
SET time_zone = "+00:00";
CREATE TABLE IF NOT EXISTS `users` (
`id` int(11) NOT NULL,
`username` varchar(20) COLLATE utf8_bin DEFAULT NULL,
`password` varchar(40) COLLATE utf8_bin NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `username` (`username`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
COMMIT;
错误是:
您的SQL语法有错误;检查与您的MySQL服务器版本对应的手册,了解可在“SET AUTOCOMMIT=0”附近使用的正确语法;
启动交易
因此,在我看来,它似乎不接受一个镜头中的多个命令。让它工作的正确方法是什么?使用一个单独的
模式。sql
是必须的。我没有足够的环境来测试这一点,但是您是否尝试过使用addBatch(模式)
和executeBatch()
作为一个批来进行测试
否则,您可能无法使用schema.split(;”)
将命令拆分,并一次执行一个命令。如果您这样做,如果您掉入环路,请确保不要让tran保持打开状态
祝你好运。对不起。至于tran,我的意思是,一旦你做了
启动交易
,就要尽一切可能确保交易结束。过去我们遇到过一些问题,特别是在连接池环境中,留下一个打开的事务会导致非常不愉快的事情。