JMX和Spring –第3部分

本文是本系列的最后一篇。 看一下第1 部分和第2部分 。

在本系列的最后一篇文章中，我将展示如何在JDK中使用本机JMX支持来实现一种通知机制，该机制可以在HEAP内存超过特定阈值时向侦听器发出警报。

正如我在上一篇文章中讨论的那样，这种方法是理想的，因为它是推式而不是拉式，不是侵入式的，并且对应用程序的计算需求最小。

这些是本文说明的解决方案的关键组件：

  • MemoryWarningService：此组件充当侦听器，并向Memory MBean注册其自身以接收通知。 可以使用介于0到1之间的百分比形式的阈值（其中1为100％）进行配置
  • MemoryThreadDumper：当通知MemoryWarningService HEAP使用量超过阈值并且其职责是将线程转储写入文件时，将调用此组件。
  • MemoryWarningServiceConfigurator：此组件是MBean，它公开一种用于更改MemoryWarningService阈值的方法。

该解决方案还提供用于在测试应用程序时填充HEAP的MemoryHeapFiller类和用于引导Spring环境的MemTest类。

当应用程序运行时（使用MemoryHeapFiller设置），您可以在URL上触发JConsole：service：jmx：rmi：// localhost / jndi / rmi：// localhost：8888 / jemosJmxConnector以jemosAdmin / secure连接并更改阈值各种价值。

该代码不是用于生产的：它不健壮，缺少许多注释，并且写入线程转储的文件名是硬编码的。 但是，它代表了一个很好的起点。

该代码附在下面。 您将需要Maven来构建它。

下载Jemos-jmx-experiments-0.0.1-SNAPSHOT-project

我尝试了一个初始阈值为0.5的场景，将其更改为0.3，然后更改为0.8。 结果如下所示： 

2011-08-15 21:53:21 ClassPathXmlApplicationContext [INFO] Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@a4a63d8: startup date [Mon Aug 15 21:53:21 BST 2011]; root of context hierarchy
2011-08-15 21:53:21 XmlBeanDefinitionReader [INFO] Loading XML bean definitions from class path resource [jemos-jmx-appCtx.xml]
2011-08-15 21:53:21 PropertyPlaceholderConfigurer [INFO] Loading properties file from class path resource [jemos-jmx.properties]
2011-08-15 21:53:21 PropertyPlaceholderConfigurer [INFO] Loading properties file from URL [file:/C:/Users/mtedone/.secure/jmxconnector-credentials.properties]
2011-08-15 21:53:21 ThreadPoolTaskScheduler [INFO] Initializing ExecutorService  'myScheduler'
2011-08-15 21:53:21 ClassPathXmlApplicationContext [INFO] Bean 'myScheduler' of type [class org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2011-08-15 21:53:21 DefaultListableBeanFactory [INFO] Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@30296f76: defining beans [propertyConfigurer,loggerConfigurator,memoryWarningServiceConfigurator,memoryHeapFiller,memoryThreadDumper,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,mbeanExporter,jemosJmxServer,rmiRegistry,clientConnector,memoryMxBean,memoryWarningService,org.springframework.scheduling.annotation.internalAsyncAnnotationProcessor,org.springframework.scheduling.annotation.internalScheduledAnnotationProcessor,myScheduler]; root of factory hierarchy
2011-08-15 21:53:21 AnnotationMBeanExporter [INFO] Registering beans for JMX exposure on startup
2011-08-15 21:53:21 RmiRegistryFactoryBean [INFO] Looking for RMI registry at port '8888'
2011-08-15 21:53:23 RmiRegistryFactoryBean [INFO] Could not detect RMI registry - creating new one
2011-08-15 21:53:23 ConnectorServerFactoryBean [INFO] JMX connector server started: javax.management.remote.rmi.RMIConnectorServer@4355d3a3
2011-08-15 21:53:23 AnnotationMBeanExporter [INFO] Bean with name 'jemosJmxServer' has been autodetected for JMX exposure
2011-08-15 21:53:23 AnnotationMBeanExporter [INFO] Bean with name 'loggerConfigurator' has been autodetected for JMX exposure
2011-08-15 21:53:23 AnnotationMBeanExporter [INFO] Bean with name 'memoryWarningServiceConfigurator' has been autodetected for JMX exposure
2011-08-15 21:53:23 AnnotationMBeanExporter [INFO] Located managed bean 'loggerConfigurator': registering with JMX server as MBean [jemos.mbeans:type=config,name=LoggingConfiguration]
2011-08-15 21:53:23 AnnotationMBeanExporter [INFO] Located MBean 'jemosJmxServer': registering with JMX server as MBean [jemos.mbeans:name=jemosJmxServer,type=RMIConnectorServer]
2011-08-15 21:53:23 AnnotationMBeanExporter [INFO] Located managed bean 'memoryWarningServiceConfigurator': registering with JMX server as MBean [jemos.mbeans:type=config,name=MemoryWarningServiceConfiguration]
2011-08-15 21:53:23 MemoryWarningService [INFO] Percentage is: 0.5
2011-08-15 21:53:23 MemoryWarningService [INFO] Listener added to JMX bean
Adding data...
Adding data...
Adding data...
Adding data...
Adding data...
Adding data...
Adding data...
2011-08-15 21:53:37 MemoryWarningService [INFO] Percentage is: 0.3
2011-08-15 21:53:37 MemoryWarningServiceConfigurator [INFO] Memory threshold set to 0.3
Adding data...
2011-08-15 21:53:38 MemoryWarningService [WARN] Memory usage low!!!
2011-08-15 21:53:38 MemoryWarningService [WARN] percentageUsed = 0.3815679398794023
2011-08-15 21:53:38 MemoryThreadDumper [WARN] Stacks dumped to: C:/tmp/stacks.dump
Adding data...
Adding data...
Adding data...
2011-08-15 21:53:45 MemoryWarningService [INFO] Percentage is: 0.8
2011-08-15 21:53:45 MemoryWarningServiceConfigurator [INFO] Memory threshold set to 0.8
Adding data...
Adding data...
Adding data...
Adding data...
Adding data...
Adding data...
Adding data...
2011-08-15 21:54:01 MemoryWarningService [WARN] Memory usage low!!!
2011-08-15 21:54:01 MemoryWarningService [WARN] percentageUsed = 0.8383333266727508
2011-08-15 21:54:02 MemoryThreadDumper [WARN] Stacks dumped to: C:/tmp/stacks.dump
Adding data...
Adding data...
Adding data...
Exception in thread "JMX server connection timeout 24" java.lang.OutOfMemoryError: Java heap space

内存警告服务 

package uk.co.jemos.experiments.jmx;import java.lang.management.ManagementFactory;
import java.lang.management.MemoryNotificationInfo;
import java.lang.management.MemoryPoolMXBean;
import java.lang.management.MemoryType;import javax.annotation.PostConstruct;
import javax.management.Notification;
import javax.management.NotificationEmitter;
import javax.management.NotificationListener;import org.springframework.beans.factory.annotation.Autowired;/*** A component which sends notifications when the HEAP memory is above a certain* threshold.* * @author mtedone* */
public class MemoryWarningService implements NotificationListener {/** This bean's name */public static final String MBEAN_NAME = "jemos.mbeans:type=monitoring,name=MemoryWarningService";/** The application logger */private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(MemoryWarningService.class);@Autowiredprivate NotificationEmitter memoryMxBean;@Autowiredprivate MemoryThreadDumper threadDumper;/** A pool of Memory MX Beans specialised in HEAP management */private static final MemoryPoolMXBean tenuredGenPool = findTenuredGenPool();/*** {@inheritDoc}*/@Overridepublic void handleNotification(Notification notification, Object handback) {if (notification.getType().equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED)) {long maxMemory = tenuredGenPool.getUsage().getMax();long usedMemory = tenuredGenPool.getUsage().getUsed();LOG.warn("Memory usage low!!!");double percentageUsed = (double) usedMemory / maxMemory;LOG.warn("percentageUsed = " + percentageUsed);threadDumper.dumpStacks();} else {LOG.info("Other notification received..."+ notification.getMessage());}}/*** It sets the threshold percentage.* * @param percentage*/public void setPercentageUsageThreshold(double percentage) {if (percentage <= 0.0 || percentage > 1.0) {throw new IllegalArgumentException("Percentage not in range");} else {LOG.info("Percentage is: " + percentage);}long maxMemory = tenuredGenPool.getUsage().getMax();long warningThreshold = (long) (maxMemory * percentage);tenuredGenPool.setUsageThreshold(warningThreshold);}@PostConstructpublic void completeSetup() {memoryMxBean.addNotificationListener(this, null, null);LOG.info("Listener added to JMX bean");}/*** Tenured Space Pool can be determined by it being of type HEAP and by it* being possible to set the usage threshold.*/private static MemoryPoolMXBean findTenuredGenPool() {for (MemoryPoolMXBean pool : ManagementFactory.getMemoryPoolMXBeans()) {// I don't know whether this approach is better, or whether// we should rather check for the pool name "Tenured Gen"?if (pool.getType() == MemoryType.HEAP&& pool.isUsageThresholdSupported()) {return pool;}}throw new AssertionError("Could not find tenured space");}}

内存线程转储器 

package uk.co.jemos.experiments.jmx;import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;import org.apache.commons.io.IOUtils;
import org.springframework.stereotype.Component;/*** This component dumps the thread stack to the file system.* * @author mtedone* */
@Component
public class MemoryThreadDumper {/** The application logger */private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(MemoryThreadDumper.class);/*** It dumps the Thread stacks* * @throws IOException*/public void dumpStacks() {// hard-coded: This needs to be changed to a property or somethingString stackFileName = "C:/tmp/stacks.dump";ThreadMXBean mxBean = ManagementFactory.getThreadMXBean();ThreadInfo[] threadInfos = mxBean.getThreadInfo(mxBean.getAllThreadIds(), 0);Map<Long, ThreadInfo> threadInfoMap = new HashMap<Long, ThreadInfo>();for (ThreadInfo threadInfo : threadInfos) {threadInfoMap.put(threadInfo.getThreadId(), threadInfo);}File dumpFile = new File(stackFileName);BufferedWriter writer = null;try {writer = new BufferedWriter(new FileWriter(dumpFile));this.dumpTraces(mxBean, threadInfoMap, writer);LOG.warn("Stacks dumped to: " + stackFileName);} catch (IOException e) {throw new IllegalStateException("An exception occurred while writing the thread dump");} finally {IOUtils.closeQuietly(writer);}}private void dumpTraces(ThreadMXBean mxBean,Map<Long, ThreadInfo> threadInfoMap, Writer writer)throws IOException {Map<Thread, StackTraceElement[]> stacks = Thread.getAllStackTraces();writer.write("Dump of "+ stacks.size()+ " thread at "+ new SimpleDateFormat("yyyy/MM/dd HH:mm:ss z").format(new Date(System.currentTimeMillis())) + "\n\n");for (Map.Entry<Thread, StackTraceElement[]> entry : stacks.entrySet()) {Thread thread = entry.getKey();writer.write("\"" + thread.getName() + "\" prio="+ thread.getPriority() + " tid=" + thread.getId() + " "+ thread.getState() + " "+ (thread.isDaemon() ? "deamon" : "worker") + "\n");ThreadInfo threadInfo = threadInfoMap.get(thread.getId());if (threadInfo != null) {writer.write("    native=" + threadInfo.isInNative()+ ", suspended=" + threadInfo.isSuspended()+ ", block=" + threadInfo.getBlockedCount() + ", wait="+ threadInfo.getWaitedCount() + "\n");writer.write("    lock=" + threadInfo.getLockName()+ " owned by " + threadInfo.getLockOwnerName() + " ("+ threadInfo.getLockOwnerId() + "), cpu="+ mxBean.getThreadCpuTime(threadInfo.getThreadId())/ 1000000L + ", user="+ mxBean.getThreadUserTime(threadInfo.getThreadId())/ 1000000L + "\n");}for (StackTraceElement element : entry.getValue()) {writer.write("        ");writer.write(element.toString());writer.write("\n");}writer.write("\n");}}}

内存服务配置MBean 

package uk.co.jemos.experiments.jmx.mbeans;import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.jmx.export.annotation.ManagedOperation;
import org.springframework.jmx.export.annotation.ManagedOperationParameter;
import org.springframework.jmx.export.annotation.ManagedOperationParameters;
import org.springframework.jmx.export.annotation.ManagedResource;
import org.springframework.stereotype.Component;import uk.co.jemos.experiments.jmx.MemoryWarningService;@Component
@ManagedResource(objectName = MemoryWarningServiceConfigurator.MBEAN_NAME, //
description = "Allows clients to set the memory threshold")
public class MemoryWarningServiceConfigurator implementsApplicationContextAware {/** The application logger */private static final org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(MemoryWarningServiceConfigurator.class);public static final String MBEAN_NAME = "jemos.mbeans:type=config,name=MemoryWarningServiceConfiguration";private ApplicationContext ctx;@ManagedOperation(description = "Sets the memory threshold for the memory warning system")@ManagedOperationParameters({ @ManagedOperationParameter(description = "The memory threshold", name = "memoryThreshold"), })public void setMemoryThreshold(double memoryThreshold) {MemoryWarningService memoryWarningService = (MemoryWarningService) ctx.getBean("memoryWarningService");memoryWarningService.setPercentageUsageThreshold(memoryThreshold);LOG.info("Memory threshold set to " + memoryThreshold);}@Overridepublic void setApplicationContext(ApplicationContext applicationContext)throws BeansException {ctx = applicationContext;}}

Spring配置 

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"xmlns:util="http://www.springframework.org/schema/util"xmlns:task="http://www.springframework.org/schema/task"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsdhttp://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.0.xsdhttp://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.0.xsd"><bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"  ><property name="locations"><list><value>classpath:jemos-jmx.properties</value><value>file:///${user.home}/.secure/jmxconnector-credentials.properties</value></list></property></bean><context:component-scan base-package="uk.co.jemos.experiments.jmx" /><context:mbean-export default-domain="jemos.mbeans" /><bean id="jemosJmxServer" class="org.springframework.jmx.support.ConnectorServerFactoryBean"       depends-on="rmiRegistry"><property name="objectName" value="connector:name=rmi" /><property name="serviceUrl"value="service:jmx:rmi://localhost/jndi/rmi://localhost:${jemos.jmx.rmi.port}/jemosJmxConnector" /><property name="environment"><!-- the following is only valid when the sun jmx implementation is used --><map><entry key="jmx.remote.x.password.file" value="${user.home}/.secure/jmxremote.password" /><entry key="jmx.remote.x.access.file" value="${user.home}/.secure/jmxremote.access" /></map></property></bean><bean id="rmiRegistry" class="org.springframework.remoting.rmi.RmiRegistryFactoryBean"><property name="port" value="${jemos.jmx.rmi.port}" /></bean><bean id="clientConnector" class="org.springframework.jmx.support.MBeanServerConnectionFactoryBean"       depends-on="jemosJmxServer"><property name="serviceUrl"value="service:jmx:rmi://localhost/jndi/rmi://localhost:${jemos.jmx.rmi.port}/jemosJmxConnector" /><property name="environment"><map><entry key="jmx.remote.credentials"><beanfactory-method="commaDelimitedListToStringArray"><constructor-arg value="${jmx.username},${jmx.password}" /></bean></entry></map></property></bean><bean id="memoryMxBean" class="java.lang.management.ManagementFactory"factory-method="getMemoryMXBean" /><bean id="memoryWarningService" class="uk.co.jemos.experiments.jmx.MemoryWarningService"><property name="percentageUsageThreshold" value="0.5" /></bean><task:annotation-driven scheduler="myScheduler" />   <task:scheduler id="myScheduler" pool-size="10" />    </beans>

参考： JMX和Spring –我们的JCG合作伙伴 Marco Tedone的第3部分 ，位于Marco Tedone的博客博客中。


翻译自: https://www.javacodegeeks.com/2012/07/jmx-and-spring-part-3.html

本文来自互联网用户投稿，该文观点仅代表作者本人，不代表本站立场。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如若转载，请注明出处：http://www.mzph.cn/news/371728.shtml

如若内容造成侵权/违法违规/事实不符，请联系多彩编程网进行投诉反馈email:809451989@qq.com，一经查实，立即删除！

相关文章

QScrollArea不能显示滚动条

QScrollArea不能显示滚动条

转载请注明出处&#xff1a;http://www.cnblogs.com/dachen408/p/7147141.html 问题&#xff1a;QScrollArea不能显示滚动条 解决方案&#xff1a;设置QScrollArea->setWidgetResizeable&#xff08;false&#xff09;解决问题。 例子&#xff1a; ui.scrollArea->setWi…
阅读更多...
java婚庆网站源码_基于jsp的婚庆网站-JavaEE实现婚庆网站 - java项目源码

java婚庆网站源码_基于jsp的婚庆网站-JavaEE实现婚庆网站 - java项目源码

基于jspservletpojomysql实现一个javaee/javaweb的婚庆网站, 该项目可用各类java课程设计大作业中, 婚庆网站的系统架构分为前后台两部分, 最终实现在线上进行婚庆网站各项功能,实现了诸如用户管理, 登录注册, 权限管理等功能, 并实现对各类婚庆网站相关的实体进行管理。该婚庆…
阅读更多...
JQuery实现的模块交换动画效果

JQuery实现的模块交换动画效果

<!doctype html> <html><head><meta http-equiv"content-type" content"text/html;charsetutf-8" /><title>JQuery实现的模块交换动画效果</title><meta name"Keywords" content"jquery&#xff0c…
阅读更多...
CKD 实现

CKD 实现

主要功能&#xff1a;1、新物料&#xff08;部品号&#xff09;的入库管理 部品号的验证、描述、品名、重量、单价等 2、部品号-供应商的核对 校验部品号/供应商的对应情况、入库、移除等 3、BOM清单的导入 基础清单的导入 4、订单 CKD套件管理 物料齐套管理 箱单管理 汇总 5、…
阅读更多...
JMX和Spring –第2部分

JMX和Spring –第2部分

这篇文章从本教程的第1部分继续。 嗨&#xff0c;在我的前一篇文章中&#xff0c;我解释了如何通过Spring设置JMX服务器以及如何通过身份验证和授权保护对它的访问。 在本文中&#xff0c;我将展示如何实现一个简单的MBean&#xff0c;该MBean允许用户在运行时更改Log4j记录器…
阅读更多...
android p wifi一直在扫描_（一百六十八）Android P wifi 扫描失败结果上报流程梳理-扫描上报梳理②...

android p wifi一直在扫描_（一百六十八）Android P wifi 扫描失败结果上报流程梳理-扫描上报梳理②...

接(一百五十五)Android P wifi 扫描失败结果上报流程梳理-扫描上报梳理 扫描失败上报梳理发现梳理的差了很多&#xff0c;特补充1.WificondScannerImplOverridepublic boolean startSingleScan(WifiNative.ScanSettings settings,WifiNative.ScanEventHandler eventHandler) {i…
阅读更多...
（五）什么是RDD-JavaPython版Spark

（五）什么是RDD-JavaPython版Spark

什么是RDD 视频教程&#xff1a; 1、优酷 2、YouTube RDD是个抽象类&#xff0c;全称为Resilient Distributed Datasets&#xff0c;是一个容错的、并行的数据结构&#xff0c;可以让用户显式地将数据存储到磁盘和内存中&#xff0c;并能控制数据的分区。同时&#xff0c;RDD还…
阅读更多...
LazyInitializationException的四种解决方案–第1部分

LazyInitializationException的四种解决方案–第1部分

在今天的帖子中&#xff0c;我们将讨论常见的LazyInitializationException错误。 我们将看到四种避免该错误的方法&#xff0c;以及每种方法的优缺点。在本文的最后&#xff0c;我们将讨论EclipseLink如何处理该异常。 为了看到LazyInitializationException错误并进行处理&…
阅读更多...
linux驱动

linux驱动

jeffies hz xtime 每秒钟系统时钟节拍数 prco < 内核内存视窗 include/linux/list.h < 内核的数据结构&#xff0c;链表 workques_struct 工作队列转载于:https://www.cnblogs.com/asreg/p/7148606.html
阅读更多...
java 条码识别_条码识别示例代码

java 条码识别_条码识别示例代码

package api.jisuapi.barcode;import api.util.HttpUtil;import net.sf.json.JSONArray;import net.sf.json.JSONObject;public class Read {public static final String APPKEY "your_appkey_here";// 你的appkeypublic static final String URL "https://ap…
阅读更多...
终极JPA查询和技巧列表–第2部分

终极JPA查询和技巧列表–第2部分

这一部分是该系列文章的第一部分 。 JPA&#xff1a;NamedQuery&#xff0c;使用日期查询&#xff0c;有关getSingleResult方法的警告 为了避免重复查询代码&#xff0c;提高性能并简化维护查询&#xff0c;我们可以使用NamedQueries。 NamedQuery使用JPQL作为语法&#xff0c…
阅读更多...
设置UITableView设置contentsize

设置UITableView设置contentsize

由于UITableView是继承自UIScrollView的&#xff0c;所以他是可以设置contentsize的。 但是&#xff0c;我在试验的过程中&#xff0c;初始化UITableView实例后&#xff0c;直接设置它的contentsize是不起作用&#xff0c;在搜寻相关资料得知&#xff0c;UITableView会自动设置…
阅读更多...
java 线程什么时候结束_java线程什么时候让出cpu?

java 线程什么时候结束_java线程什么时候让出cpu?

Thread.sleep();sleep就是正在执行的线程主动让出cpu&#xff0c;cpu去执行其他线程&#xff0c;在sleep指定的时间过后&#xff0c;cpu才会回到这个线程上继续往下执行&#xff0c;如果当前线程进入了同步锁&#xff0c;sleep方法并不会释放锁&#xff0c;即使当前线程使用sle…
阅读更多...
Hibernate配置方式

Hibernate配置方式

Hibernate配置方式 Hibernate给人的感受是灵活的&#xff0c;要达到同一个目的&#xff0c;我们可以使用几种不同的办法。就拿Hibernate配置来说&#xff0c;常用的有如下三种方式&#xff0c;任选其一。 在 hibernate.cfg.xml 中加入元素 <property>、<mapping>&a…
阅读更多...
js中 javascript:void(0) 用法详解

js中 javascript:void(0) 用法详解

javascript:void(0)表示不做任何动作。如&#xff1a; 复制代码代码如下:<a href"javascript:void(0);" οnclick"alert(ok);"></a> 这里表示这个链接不做跳转动作&#xff0c;执行onClick事件。 我想使用过ajax的都常见这样的代码&#xff1…
阅读更多...
带有ActiveMQ的JMS

带有ActiveMQ的JMS

带有ActiveMQ的JMS JMS是Java Message Service的缩写&#xff0c;它提供了一种以松散耦合&#xff0c;灵活的方式集成应用程序的机制。 JMS以存储和转发的方式跨应用程序异步传递数据。 应用程序通过充当中介的MOM&#xff08;面向消息的中间件&#xff09;进行通信&#xff0c…
阅读更多...
矩阵分解 java_使用矩阵分解为推荐系统

矩阵分解 java_使用矩阵分解为推荐系统

矩阵分解假设“潜在因素”&#xff0c;例如对用户的意大利食物的偏好和项目食物的意外性与矩阵中的评级有关 .因此&#xff0c;整个问题类型转变为矩阵重构问题&#xff0c;存在许多不同的解决方案 . 一个简单的&#xff0c;可能很慢的解决方案是(除了ALS和其他一些矩阵重建的可…
阅读更多...
用户故事排球教练助手

用户故事排球教练助手

计划&#xff1a;估计这个任务需要一周时间 需求分析&#xff1a;作为一名排球教练助手&#xff0c;我需要了解每场每位队员的技术动作&#xff0c;每场比赛每位队员的得分情况&#xff0c;以便教练更好的了解到每位队员的发挥情况和特长。 设计文档&#xff1a;用户进入此界面…
阅读更多...
TMS320DM642学习----第一篇（硬件连接）

TMS320DM642学习----第一篇（硬件连接）

DSP设备型号&#xff1a;SEED-DTK-VPM642&#xff08;目前实验室用途&#xff1a;视频处理&#xff0c;图像处理方向&#xff0c;预计搭载目标跟踪以及云台防抖等算法&#xff09; 官网链接&#xff1a;http://www.seeddsp.com/index.php/Home/Product/detail/name/1/id/174.ht…
阅读更多...
字符串内存内部

字符串内存内部

本文基于我对StackOverflow的回答 。 我正在尝试解释String类如何存储文本&#xff0c;内部存储和常量池如何工作。 这里要理解的要点是String Java对象与其内容– private value字段下的char[]之间的区别。 String基本上是char[]数组的包装器&#xff0c;将其封装并使其无法修…
阅读更多...
最新文章

Copyright @ 2022~2023