Hadoop入门学习笔记——四、MapReduce的框架配置和YARN的部署

视频课程地址:https://www.bilibili.com/video/BV1WY4y197g7

课程资料链接:https://pan.baidu.com/s/15KpnWeKpvExpKmOC8xjmtQ?pwd=5ay8

Hadoop入门学习笔记(汇总)

目录

  • 四、MapReduce的框架配置和YARN的部署
    • [4.1. 配置MapReduce和YARN](#4.1. 配置MapReduce和YARN)
    • [4.2. YARN集群启停脚本](#4.2. YARN集群启停脚本)
      • [4.2.1. 一键启停脚本](#4.2.1. 一键启停脚本)
      • [4.2.2. 单独进程启停](#4.2.2. 单独进程启停)
    • [4.3. 提交MapReduce示例程序到YARN运行](#4.3. 提交MapReduce示例程序到YARN运行)
      • [4.3.1. 提交wordcount(单词统计)示例程序](#4.3.1. 提交wordcount(单词统计)示例程序)
      • [4.3.2. 提交根据Monte Carlo蒙特卡罗算法求圆周率的示例程序](#4.3.2. 提交根据Monte Carlo蒙特卡罗算法求圆周率的示例程序)

四、MapReduce的框架配置和YARN的部署

本次YARN的部署结构如下图所示:

当前,共有三台服务器(虚拟机)构成集群,集群规划如下所示:

主机 部署的服务
node1 ResourceManager、NodeManager、ProxyServer、JobHistoryServer
node2 NodeManager
node3 NodeManager

MapReduce是运行在YARN上的,所以MapReduce只需要配置,YARN需要部署并启动。

4.1. 配置MapReduce和YARN

1、在node1节点,修改mapred-env.sh文件:

bash 复制代码
# 进入hadoop配置文件目录
cd /export/server/hadoop-3.3.4/etc/hadoop/
# 打开mapred-env.sh文件
vim mapred-env.sh

打开后,在文件中加入以下内容:

bash 复制代码
# 设置JDK路径
export JAVA_HOME=/export/server/jdk
# 设置JobHistoryServer进程的内存为1G
export HADOOP_JOB_HISTORYSERVER_HEAPSIZE=1000
# 设置日志级别为INFO
export HADOOP_MAPRED_ROOT_LOGGER=INFO,RFA

2、再修改同目录下的mapred-site.xml配置文件,在其configuration标签内增加以下内容:

xml 复制代码
  <property>
    <name>mapreduce.framework.name</name>
    <value>yarn</value>
    <description></description>
  </property>
  <property>
    <name>mapreduce.jobhistory.address</name>
    <value>node1:10020</value>
    <description></description>
  </property>
  <property>
    <name>mapreduce.jobhistory.webapp.address</name>
    <value>node1:19888</value>
    <description></description>
  </property>
  <property>
    <name>mapreduce.jobhistory.intermediate-done-dir</name>
    <value>/data/mr-history/tmp</value>
    <description></description>
  </property>
  <property>
    <name>mapreduce.jobhistory.done-dir</name>
    <value>/data/mr-history/done</value>
    <description></description>
  </property>
  <property>
    <name>yarn.app.mapreduce.am.env</name>
    <value>HADOOP_MAPRED_HOME=$HADOOP_HOME</value>
  </property>
  <property>
    <name>mapreduce.map.env</name>
    <value>HADOOP_MAPRED_HOME=$HADOOP_HOME</value>
  </property>
  <property>
    <name>mapreduce.reduce.env</name>
    <value>HADOOP_MAPRED_HOME=$HADOOP_HOME</value>
  </property>

其中,

mapreduce.framework.name 表示MapReduce的运行框架,这里设置为Yarn;

mapreduce.jobhistory.address 表示历史服务器通讯地址和端口号,这里为node1:10020;

mapreduce.jobhistory.webapp.address 表示历史服务器Web端地址和端口号,这里为node1:19888;

mapreduce.jobhistory.intermediate-done-dir 表示历史信息在HDFS的记录临时路径,这里是/data/mr-history/tmp;

mapreduce.jobhistory.done-dir 表示历史信息在HDFS的记录路径,这里是/data/mr-history/done;

yarn.app.mapreduce.am.env 表示MapReduce HOME的路径,这里设置为HADOOP_HOME相同路径;

mapreduce.map.env 表示Map HOME的路径,这里设置为HADOOP_HOME相同路径;

mapreduce.reduce.env 表示Reduce HOME的路径,这里设置为HADOOP_HOME相同路径;

至此,MapReduce的配置完成。

3、接下来,配置YARN。在node1节点,修改yarn-env.sh文件:

bash 复制代码
# 进入hadoop配置文件目录
cd /export/server/hadoop-3.3.4/etc/hadoop/
# 打开yarn-env.sh文件
vim yarn-env.sh

在文件中添加以下内容:

bash 复制代码
# 设置JDK路径的环境变量
export JAVA_HOME=/export/server/jdk
# 设置HADOOP_HOME的环境变量
export HADOOP_HOME=/export/server/hadoop
# 设置配置文件路径的环境变量
export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop
# 设置日志文件路径的环境变量
export HADOOP_LOG_DIR=$HADOOP_HOME/logs

4、修改同目录下的yarn-site.xml配置文件,在其configuration节点中添加以下内容:

xml 复制代码
  <!-- Site specific YARN configuration properties -->
  <property>
    <name>yarn.log.server.url</name>
    <value>http://node1:19888/jobhistory/logs</value>
    <description></description>
  </property>
    <property>
    <name>yarn.web-proxy.address</name>
    <value>node1:8089</value>
    <description>proxy server hostname and port</description>
  </property>
  <property>
    <name>yarn.log-aggregation-enable</name>
    <value>true</value>
    <description>Configuration to enable or disable log aggregation</description>
  </property>
  <property>
    <name>yarn.nodemanager.remote-app-log-dir</name>
    <value>/tmp/logs</value>
    <description>Configuration to enable or disable log aggregation</description>
  </property>

  <!-- Site specific YARN configuration properties -->
  <property>
    <name>yarn.resourcemanager.hostname</name>
    <value>node1</value>
    <description></description>
  </property>
  <property>
    <name>yarn.resourcemanager.scheduler.class</name>
    <value>org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler</value>
    <description></description>
  </property>
  <property>
    <name>yarn.nodemanager.local-dirs</name>
    <value>/data/nm-local</value>
    <description>Comma-separated list of paths on the local filesystem where intermediate data is written.</description>
  </property>
  <property>
    <name>yarn.nodemanager.log-dirs</name>
    <value>/data/nm-log</value>
    <description>Comma-separated list of paths on the local filesystem where logs are written.</description>
  </property>
  <property>
    <name>yarn.nodemanager.log.retain-seconds</name>
    <value>10800</value>
    <description>Default time (in seconds) to retain log files on the NodeManager Only applicable if log-aggregation is disabled.</description>
  </property>
  <property>
    <name>yarn.nodemanager.aux-services</name>
    <value>mapreduce_shuffle</value>
    <description>Shuffle service that needs to be set for Map Reduce applications.</description>
  </property>

其中,核心配置如下:

yarn.resourcemanager.hostname 表示ResourceManager设置在哪个节点,这里是node1节点;

yarn.nodemanager.local-dirs 表示NodeManager中间数据Linux系统本地存储的路径;

yarn.nodemanager.log-dirs 表示NodeManager数据Linux系统日志本地存储的路径;

yarn.nodemanager.aux-services 表示为MapReduce程序开启Shuffle服务;

额外配置如下:

yarn.log.server.url 表示历史服务器的URL;

yarn.web-proxy.address 表示代理服务器的主机和端口号;

yarn.log-aggregation-enable 表示是否开启日志聚合;

yarn.nodemanager.remote-app-log-dir 表示程序日志在HDFS中的存放路径;

yarn.resourcemanager.scheduler.class 表示选择Yarn使用的调度器,这里选的是公平调度器;

5、完成上述配置后,需要将MapReduce和YARN的配置文件分发到node2和node3服务器相同位置中,使用hadoop用户身份执行以下命令

bash 复制代码
# 将mapred-env.sh、mapred-site.xml、yarn-env.sh、yarn-site.xml四个配置文件,复制到node2的相同路径下
scp mapred-env.sh mapred-site.xml yarn-env.sh yarn-site.xml node2:`pwd`/
# 将mapred-env.sh、mapred-site.xml、yarn-env.sh、yarn-site.xml四个配置文件,复制到node3的相同路径下
scp mapred-env.sh mapred-site.xml yarn-env.sh yarn-site.xml node2:`pwd`/

4.2. YARN集群启停脚本

在启动YARN集群前,需要确保HDFS集群已经启动。同样,启停YARN集群也必须使用hadoop用户身份。

4.2.1. 一键启停脚本

  1. $HADOOP_HOME/sbin/start-yarn.shstart-yarn.sh 一键启动YARN集群
  • 会基于yarn-site.xml中配置的yarn.resourcemanager.hostname来决定在哪台机器上启动resourcemanager;
  • 会基于workers文件配置的主机启动NodeManager;
  • 在当前机器启动ProxyServer(代理服务器)。
    命令执行效果如下图所示:

    此时通过jps命令查看进程,可以看到如下效果:

    此时,可以看到ResourceManager、NodeManager和WebAppProxyServer都已经启动,还需要启动HistoryServer,可以通过后续章节介绍的mapred --daemon start historyserver命令启动。
    至此,整个YARN集群启动完成。
    此时,可以通过访问http://node1:8088/ 即可看到YARN集群的监控页面(即ResourceManager的WebUI)
  1. $HADOOP_HOME/sbin/stop-yarn.shstop-yarn.sh 一键关闭YARN集群。
  2. 配置部署好YARN集群后,可以关闭YARN集群、关闭JobHistoryServer、关闭HDFS集群、关闭虚拟机之后,对虚拟机创建快照,保存好当前环境。

4.2.2. 单独进程启停

  1. 在每一台机器,单独启动或停止进程,可以通过如下命令执行:
bash 复制代码
$HADOOP_HOME/bin/yarn --daemon start|stop resourcemanager|nodemanager|proxyserver

start和stop决定启动和停止;

可控制resourcemanager、nodemanager、webappproxyserver三种进程。

例如:

bash 复制代码
# 在node1启动ResourceManager
yarn --daemon start resourcemanager
# 在node1、node2、node3分别启动NodeManager
yarn --daemon start nodemanager
# 在node1启动WebProxyServer
yarn --daemon start proxyserver
  1. 历史服务器(JobHistoryServer)的启动和停止
bash 复制代码
$HADOOP_HOME/bin/mapred --daemon start|stop historyserver

用法:

bash 复制代码
# 启动JobHistoryServer
mapred --daemon start historyserver
# 停止JobHistoryServer
mapred --daemon stop historyserver

4.3. 提交MapReduce示例程序到YARN运行

YARN作为资源调度管控框架,其本身提供资供许多程序运行,常见的有:

  • MapReduce程序
  • Spark程序
  • Flink程序

Hadoop官方提供了一些预置的MapReduce程序代码,存放于$HADOOP_HOME/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.1.jar文件内。

上述程序可使用hadoop har命令提交至YARN运行,其命令语法为:

bash 复制代码
hadoop jar 程序文件 java类名 [程序参数] ... [程序参数]

4.3.1. 提交wordcount(单词统计)示例程序

1、程序内容

  • 给定数据输入的路径(HDFS)、给定结果输出的路径(HDFS)
  • 将输入路径内的数据中的单词进行计数,将结果写到输出路径

2、准备一份待统计的数据文件并上传至HDFS中

使用vim words.txt命令,在Linux本地创建words.txt文件,其内容如下:

itheima itcast itheima itcast

hadoop hdfs hadoop hdfs

hadoop mapreduce hadoop yarn

itheima hadoop itcast hadoop

itheima itcast hadoop yarn mapreduce

使用命令hdfs dfs -mkdir -p /input在HDFS根目录创建input文件夹(用于存储待统计的文件),使用hdfs dfs -mkdir -p /output命令在HDFS根目录创建output文件夹(用于存储统计结果),使用hdfs dfs -put words.txt /input命令将本地的words.txt文件上传至HDFS系统中。

3、提交MapReduce程序

使用如下命令:

bash 复制代码
hadoop jar /export/server/hadoop-3.3.4/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar wordcount hdfs://node1:8020/input/ hdfs://8020/output/wc

其中,

hadoop jar 表示向YARN提交一个Java程序;

/export/server/hadoop-3.3.4/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar 表示所要提交的程序路径;

wordcount 表示要运行的java类名;

hdfs://node1:8020/input/ 表示参数1,在本程序中是待统计的文件夹,这里写了hdfs协议头,指明了是HDFS文件系统的路径(经测试,不写也可以,默认读取HDFS文件系统路径);

hdfs://8020/output/wc 表示参数2,在本程序中是统计结果输出的文件夹,这里写明了hdfs协议头,指明了是HDFS文件系统的路径(经测试,不写也可以,默认读取HDFS文件系统路径),这里需要确保该文件夹不存在,否则会报错。

运行日志如下所示:

bash 复制代码
[hadoop@node1 ~]$ hadoop jar /export/server/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar wordcount hdfs://node1:8020/input hdfs://node1:8020/output/wc
2023-12-14 15:31:53,988 INFO client.DefaultNoHARMFailoverProxyProvider: Connecting to ResourceManager at node1/192.168.88.101:8032
2023-12-14 15:31:55,818 INFO mapreduce.JobResourceUploader: Disabling Erasure Coding for path: /tmp/hadoop-yarn/staging/hadoop/.staging/job_1702538855741_0001
2023-12-14 15:31:56,752 INFO input.FileInputFormat: Total input files to process : 1
2023-12-14 15:31:57,040 INFO mapreduce.JobSubmitter: number of splits:1
2023-12-14 15:31:57,607 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1702538855741_0001
2023-12-14 15:31:57,607 INFO mapreduce.JobSubmitter: Executing with tokens: []
2023-12-14 15:31:58,167 INFO conf.Configuration: resource-types.xml not found
2023-12-14 15:31:58,170 INFO resource.ResourceUtils: Unable to find 'resource-types.xml'.
2023-12-14 15:31:59,119 INFO impl.YarnClientImpl: Submitted application application_1702538855741_0001
2023-12-14 15:31:59,406 INFO mapreduce.Job: The url to track the job: http://node1:8089/proxy/application_1702538855741_0001/
2023-12-14 15:31:59,407 INFO mapreduce.Job: Running job: job_1702538855741_0001
2023-12-14 15:32:23,043 INFO mapreduce.Job: Job job_1702538855741_0001 running in uber mode : false
2023-12-14 15:32:23,045 INFO mapreduce.Job:  map 0% reduce 0%
2023-12-14 15:32:37,767 INFO mapreduce.Job:  map 100% reduce 0%
2023-12-14 15:32:50,191 INFO mapreduce.Job:  map 100% reduce 100%
2023-12-14 15:32:51,220 INFO mapreduce.Job: Job job_1702538855741_0001 completed successfully
2023-12-14 15:32:51,431 INFO mapreduce.Job: Counters: 54
        File System Counters
                FILE: Number of bytes read=84
                FILE: Number of bytes written=553527
                FILE: Number of read operations=0
                FILE: Number of large read operations=0
                FILE: Number of write operations=0
                HDFS: Number of bytes read=248
                HDFS: Number of bytes written=54
                HDFS: Number of read operations=8
                HDFS: Number of large read operations=0
                HDFS: Number of write operations=2
                HDFS: Number of bytes read erasure-coded=0
        Job Counters
                Launched map tasks=1
                Launched reduce tasks=1
                Data-local map tasks=1
                Total time spent by all maps in occupied slots (ms)=11593
                Total time spent by all reduces in occupied slots (ms)=9650
                Total time spent by all map tasks (ms)=11593
                Total time spent by all reduce tasks (ms)=9650
                Total vcore-milliseconds taken by all map tasks=11593
                Total vcore-milliseconds taken by all reduce tasks=9650
                Total megabyte-milliseconds taken by all map tasks=11871232
                Total megabyte-milliseconds taken by all reduce tasks=9881600
        Map-Reduce Framework
                Map input records=6
                Map output records=21
                Map output bytes=233
                Map output materialized bytes=84
                Input split bytes=98
                Combine input records=21
                Combine output records=6
                Reduce input groups=6
                Reduce shuffle bytes=84
                Reduce input records=6
                Reduce output records=6
                Spilled Records=12
                Shuffled Maps =1
                Failed Shuffles=0
                Merged Map outputs=1
                GC time elapsed (ms)=300
                CPU time spent (ms)=2910
                Physical memory (bytes) snapshot=353423360
                Virtual memory (bytes) snapshot=5477199872
                Total committed heap usage (bytes)=196218880
                Peak Map Physical memory (bytes)=228843520
                Peak Map Virtual memory (bytes)=2734153728
                Peak Reduce Physical memory (bytes)=124579840
                Peak Reduce Virtual memory (bytes)=2743046144
        Shuffle Errors
                BAD_ID=0
                CONNECTION=0
                IO_ERROR=0
                WRONG_LENGTH=0
                WRONG_MAP=0
                WRONG_REDUCE=0
        File Input Format Counters
                Bytes Read=150
        File Output Format Counters
                Bytes Written=54

4、查看运行结果

运行完毕后,使用hadoop fs -ls /output/wc可以看到运行结果输出的文件

使用hadoop fs -cat /output/wc/part-r-00000命令,可以看到程序运行的结果

除此之外,在YARN集群的监控页面http://node1:8088/ 点击左侧的Applications菜单,可以看到刚才运行过的任务

再点击任务的ID,可以进入任务详情页面

再点击某一个阶段的Logs链接,可以看到对应阶段的运行的客户端日志(在配置yarn-site.xml文件时,配置了开启日志聚合),这个页面本质上是JobHistoryServer提供的页面(19888端口)

在任务详情页面点击History链接,可以看到任务的历史运行状态,在其中可以看到其Map任务和Reduce任务,也可以继续点进Map和Reduce任务查看相关的日志等信息,对于程序出错时的排查很有帮助。

4.3.2. 提交根据Monte Carlo蒙特卡罗算法求圆周率的示例程序

1、提交程序

bash 复制代码
hadoop jar /export/server/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar pi 3 1000

hadoop jar 表示向YARN提交一个Java程序;

/export/server/hadoop-3.3.4/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar 表示所要提交的程序路径;

pi 表示运行的Java类名;

3 表示使用3个Map任务;

1000 表示样本数为1000,样本数越多,求得的圆周率越准确,但是程序运行时长越长。

运行日志如下所示:

bash 复制代码
[hadoop@node1 ~]$ hadoop jar /export/server/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar pi 3 1000
Number of Maps  = 3
Samples per Map = 1000
Wrote input for Map #0
Wrote input for Map #1
Wrote input for Map #2
Starting Job
2023-12-14 16:06:12,042 INFO client.DefaultNoHARMFailoverProxyProvider: Connecting to ResourceManager at node1/192.168.88.101:8032
2023-12-14 16:06:13,550 INFO mapreduce.JobResourceUploader: Disabling Erasure Coding for path: /tmp/hadoop-yarn/staging/hadoop/.staging/job_1702538855741_0002
2023-12-14 16:06:13,888 INFO input.FileInputFormat: Total input files to process : 3
2023-12-14 16:06:14,149 INFO mapreduce.JobSubmitter: number of splits:3
2023-12-14 16:06:14,658 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1702538855741_0002
2023-12-14 16:06:14,659 INFO mapreduce.JobSubmitter: Executing with tokens: []
2023-12-14 16:06:15,065 INFO conf.Configuration: resource-types.xml not found
2023-12-14 16:06:15,065 INFO resource.ResourceUtils: Unable to find 'resource-types.xml'.
2023-12-14 16:06:15,256 INFO impl.YarnClientImpl: Submitted application application_1702538855741_0002
2023-12-14 16:06:15,403 INFO mapreduce.Job: The url to track the job: http://node1:8089/proxy/application_1702538855741_0002/
2023-12-14 16:06:15,404 INFO mapreduce.Job: Running job: job_1702538855741_0002
2023-12-14 16:06:32,155 INFO mapreduce.Job: Job job_1702538855741_0002 running in uber mode : false
2023-12-14 16:06:32,156 INFO mapreduce.Job:  map 0% reduce 0%
2023-12-14 16:06:47,156 INFO mapreduce.Job:  map 67% reduce 0%
2023-12-14 16:06:50,188 INFO mapreduce.Job:  map 100% reduce 0%
2023-12-14 16:06:57,275 INFO mapreduce.Job:  map 100% reduce 100%
2023-12-14 16:06:58,328 INFO mapreduce.Job: Job job_1702538855741_0002 completed successfully
2023-12-14 16:06:58,589 INFO mapreduce.Job: Counters: 54
        File System Counters
                FILE: Number of bytes read=72
                FILE: Number of bytes written=1108329
                FILE: Number of read operations=0
                FILE: Number of large read operations=0
                FILE: Number of write operations=0
                HDFS: Number of bytes read=786
                HDFS: Number of bytes written=215
                HDFS: Number of read operations=17
                HDFS: Number of large read operations=0
                HDFS: Number of write operations=3
                HDFS: Number of bytes read erasure-coded=0
        Job Counters
                Launched map tasks=3
                Launched reduce tasks=1
                Data-local map tasks=3
                Total time spent by all maps in occupied slots (ms)=39354
                Total time spent by all reduces in occupied slots (ms)=7761
                Total time spent by all map tasks (ms)=39354
                Total time spent by all reduce tasks (ms)=7761
                Total vcore-milliseconds taken by all map tasks=39354
                Total vcore-milliseconds taken by all reduce tasks=7761
                Total megabyte-milliseconds taken by all map tasks=40298496
                Total megabyte-milliseconds taken by all reduce tasks=7947264
        Map-Reduce Framework
                Map input records=3
                Map output records=6
                Map output bytes=54
                Map output materialized bytes=84
                Input split bytes=432
                Combine input records=0
                Combine output records=0
                Reduce input groups=2
                Reduce shuffle bytes=84
                Reduce input records=6
                Reduce output records=0
                Spilled Records=12
                Shuffled Maps =3
                Failed Shuffles=0
                Merged Map outputs=3
                GC time elapsed (ms)=699
                CPU time spent (ms)=11980
                Physical memory (bytes) snapshot=775233536
                Virtual memory (bytes) snapshot=10945183744
                Total committed heap usage (bytes)=466890752
                Peak Map Physical memory (bytes)=227717120
                Peak Map Virtual memory (bytes)=2734153728
                Peak Reduce Physical memory (bytes)=113000448
                Peak Reduce Virtual memory (bytes)=2742722560
        Shuffle Errors
                BAD_ID=0
                CONNECTION=0
                IO_ERROR=0
                WRONG_LENGTH=0
                WRONG_MAP=0
                WRONG_REDUCE=0
        File Input Format Counters
                Bytes Read=354
        File Output Format Counters
                Bytes Written=97
Job Finished in 46.895 seconds
Estimated value of Pi is 3.14133333333333333333

2、查看运行情况

在在YARN集群的监控页面,可以查看对应任务的History信息,可以看到当前任务使用了3个Map任务和1个Reduce任务,同时,也可以查看相应的运行日志信息。

相关推荐
xiaoyaolangwj4 分钟前
高翔【自动驾驶与机器人中的SLAM技术】学习笔记(十三)图优化SLAM的本质
学习·机器人·自动驾驶
静止了所有花开1 小时前
SpringMVC学习笔记(二)
笔记·学习
爱吃生蚝的于勒1 小时前
C语言内存函数
c语言·开发语言·数据结构·c++·学习·算法
L_cl3 小时前
Python学习从0到1 day26 第三阶段 Spark ④ 数据输出
学习
Mephisto.java3 小时前
【大数据学习 | HBASE】hbase的读数据流程与hbase读取数据
大数据·学习·hbase
红中马喽4 小时前
JS学习日记(webAPI—DOM)
开发语言·前端·javascript·笔记·vscode·学习
尘浮生6 小时前
Java项目实战II基于微信小程序的移动学习平台的设计与实现(开发文档+数据库+源码)
java·开发语言·数据库·spring boot·学习·微信小程序·小程序
huangkj-henan6 小时前
DA217应用笔记
笔记
Young_202202026 小时前
学习笔记——KMP
笔记·学习
行然梦实7 小时前
学习日记_20241110_聚类方法(K-Means)
学习·kmeans·聚类