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在上一篇博客，博主为大家讲述了centos6.9上编译hadoop2.9.1全过程，这一章节博主将带着大家一起来安装hadoop。 本篇博客中可能用到的额外的命令： #关闭selinux sudo vi /etc/sysconfig/selinux 修改enforcing为disabled #查看防火墙状态 sudo service iptables status #关闭防火墙 sudo service iptables stop #永久关闭防火墙 sudo chkconfig iptables off #copy主机配置文件到其它服务器 sudo scp /etc/hosts centos-aaron-h2:/etc/hosts 一、首先上传编译好的hadoop2.9.1.tar.gz（建议使用ALT+P上传） 二、新建apps文件夹，并且解压hadoop文件 #进入hadoop用户目录 cd ~ #新建apps目录 mkdir apps #解压hadoop文件 tar -zxvf centos6.9-hadoop-2.9.1.tar.gz -C apps/ 三、进入hadoop目录，认识下 bin 操作命令 sbin 系统启动管理命令 etc 配置文件 include c语言本地库的头文件 lib 本地库 share doc文档、 jar包 四、进入hadoop2.9

I'm trying to get some values from a H2 db table. The query which does what I need is this: SELECT cast(creationDate as date) as DATE, SUM(paymentValue) as TOTAL,fxRate FROM payment group by DATE where "creationDate", "paymentValue", "fxRate" are columns of the table "payment". CreationDate is a timestamp so I have to get only the date from it. When I try to write it in Java @Query("SELECT cast(creationDate as date) as daydate , SUM(paymentValue) as value1, fxRate as value2 FROM payment " + "group by cast(creationDate as date)") List<Payment> findPaymentValuePerDay (); I get the error [Ljava

I use an H2 embedded database in Java, and after creating the database and adding some tables and data, it gets saved as a file in a directorey of my computer. But whenever I open this file with the H2 Console, it shows no tables at all? Why are the tables not there? I am using this URL in my java code: jdbc:h2:file://C:/Temp/H2/ourDB And I log into the console with the following information: After logging in, I can't see the tables that were created in Java? You have used a different database URL in the H2 Console (not jdbc:h2:file://C:/Temp/H2/ourDB ). You need to use the same one, otherwise

使用Spring Data Repository 不区分大小写查询 原文链接： https://www.baeldung.com/spring-data-case-insensitive-queries 作者： Shubhra Srivastava 译者：liululee 1. 概览 Spring Data JPA 查询默认是大小写敏感的，换句话说，字段值的比较是区分大小写的。 本教程中，我们将探讨如何在 Spring Data JPA repository 快速新建不区分大小写的查询. 2. 依赖 首先，确保 pom.xml 包含 Spring Data 和 H2 依赖。 <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> <version>2.1.3.RELEASE</version> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> <version>1.4.199</version> </dependency> 最新版本请移步

最近工作需要在登录时使用滑动验证码做登录校验，在生成验证码图片的时候碰到了不小的麻烦 : (。 网上能查到的做法基本上都是使用一张已存在的实际图片作为滑块的图形模板，然后按照此模板做二重循环逐像素地从源图像抠出滑块以及新图。 这种方式优点就是可以控制每个像素，如改变局部的 Alpha 值、做局部的高斯模糊等。缺点也显而易见——太麻烦，且二重循环对内存也是不小的负担。 笔者的想法是：首先生成滑块 1）根据规定好的路径生成闭合区间；2） 设置 Graphics2D 的渲染区间，限制仅渲染此闭合区间的内部 （ setClip 方法）；3）使用原图来渲染当前 Image（ drawImage 方法）。最后在源图扣掉滑块的地方加上阴影。 研究了一下 Java 的 awt 图像处理，这里对这几天的成果做一个记录，本文仅涉及图像处理方面，去掉了其它业务逻辑。 生成闭合区间 Java awt中提供了 Shape 接口，来代表任意一种几何图形。考虑我们要实现如下滑块图形： 上图左边的滑块可以先简化为右侧，原理是一样的。右边的图像一共有 A、B、C、D、E、F 六个顶点。其中 CD 之间是一段圆弧。Graphics2D的坐标系从左上角开始，X轴往下、Y轴往右是正方向。这里先算出各顶点坐标：A(0,0)、B(0,50)、C(15,50)、D(35,50)、E(50,50)、F(50,0)。 注意到H1

When starting H2 tcp server and the host pc has multiple IP address's how can I define the IP that the server is going to bind to listen for connections ? We can define the tcp port but there does not seems to be a way to define the ip address. Thank you, Oscar D.Shawley http://www.h2database.com/html/advanced.html#server_bind_address Usually server sockets accept connections on any/all local addresses. This may be a problem on multi-homed hosts. To bind only to one address, use the system property h2.bindAddress . This setting is used for both regular server sockets and for SSL server sockets

Im currently accessing an embedded H2 database in java using jOOQ to generate table classes etc. I can currently execute queries such as create.select().from(TEST).fetch() in my code, return results etc. However I cant query the information schema. I can access it ok using the H2 console, and creating a view for a given information_schema table works fine. My question is how should I be accessing the information_schema eg to perform a query such as SELECT * FROM INFORMATION_SCHEMA.TABLES from within my java code? Do I have to create a view, can the schema be accessed through jooq-meta or some

i am using H2 in memory database for testing and my configuration is as follows: 1- SpringTestingConfig: @Configuration @ComponentScan(basePackages = "com.myapp.data", excludeFilters = { @Filter(Configuration.class) }) @PropertySource("classpath:/test.properties") @Profile("test") public class SpringTestingConfig { @Bean public DataSource dataSource() { DriverManagerDataSource dataSource = new DriverManagerDataSource(); dataSource.setDriverClassName("org.h2.Driver"); dataSource.setUrl("jdbc:h2:mem:test;MODE=Mysql;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE;INIT=CREATE SCHEMA IF NOT EXISTS MYAPP")

I am working on a java plugin interfacing with an H2 database. What I really want is an "Insert Ignore" statement; however, I'm aware that H2 doesn't support this. I am also aware of Merge, but this is really not what I want, if the record exists I don't want to change it. What I am considering is to just run the insert and let the duplicate key exception happen. However, I don't want this to fill my log file. The DB call happens in an imported class that I can't change. So my questions are: Is this a reasonable thing to do? I'm not one for letting errors happen, but this seems like the best