2022-05-25

Java

java-spring-boot-1

试着跟着教程写了个超级简单的 CRUD api

自上而下是 API Layer, Service Layer, Data Access Layer,

DB 用了 PostgreSQL

API Layer: Controller

@RestController

@RequestMapping(path = "api/v1/student")

@Autowired
public StudentController(StudentService studentService) {
    this.studentService = studentService
}

CRUD 四天王：

@GetMapping

@PostMapping

@DeleleMapping

@PutMapping

注解的类里面调用 service类对象的方法，把参数传过去执行

为啥需要特地分一层出来？

可能是因为这一层描述需要做什么，而 Service 层用来定义具体怎么做

Service Layer: Service

需要用到 @Service 注解整个类

同样的，@Autowired 注解构造方法，然后喂给它一个 Repository 对象当参数

repository 对象有好多省力的方法，existsById，findById，findAll 啥的

这里用到了 @Transactional 注解，然后原来 java 也有箭头函数的糖吃？

@Transactional
    public void updateStudent(Long studentId, String name, String email) {
        Student student = studentRepository.findById(studentId).orElseThrow(
                () -> new IllegalStateException(
                        "student with id " + studentId + " does not exists"
                )
        );
        if (name != null && name.length() > 0 && !Objects.equals(student.getName(), name)) {
            student.setName(name);
        }
        if (email != null && email.length() > 0 && !Objects.equals(student.getEmail(), email)) {
            Optional<Student> studentOptional = studentRepository.findStudentByEmail(email);
            if (studentOptional.isPresent()) {
                throw new IllegalStateException("email taken");
            }
            student.setEmail(email);
        }
    }

Data Access Layer: Repository, Config, Student

@Repository 注解也是需要的

StudentRepository 是个接口而不是具体的类，扩展 JpaRepository<对象类, 主键类>

可能是为了方便写 sql 吧… 第一次见到的语法

@Repository
public interface StudentRepository
        extends JpaRepository<Student, Long> {

    // SELECT * FROM STUDENT WHERE EMAIL=email;
    @Query("SELECT s FROM Student s WHERE s.email = ?1")
    Optional<Student> findStudentByEmail(String email);

}

Config 需要注解 @Configuration

这个示例里面，是用了 CommandLineRunner 去返回一个箭头函数，里面写死了两个 Student 类的对象，再用了 repository.saveAll 去保存 Student 类的数组

Student 类本身需要 @Entity 和 @Table

@Id
@SequenceGenerator(
        name = "student_sequence",
        sequenceName = "student_sequence",
        allocationSize = 1
)
@GeneratedValue(
        strategy = GenerationType.SEQUENCE,
        generator = "student_sequence"
)

这段没看懂… 有点序列化那意思？后面再去看看 JPA 的教程

另外，age 是在 Getter 里算出来的，注解了 @Transient

杂项

application.properties 里面可以指定端口 server.port

可以指定 datasource url，username，pswd，

还有涉及到 hibernate 的 ddl-auto, show-sql, dialect 之类

idea 可以在 controller 里面当场测 api，但如果跑在本地还设置了代理会 500

postgres 建库完需要给用户授予权限

grant all privileges on database "student" to postgres;

pom 可以认为是后端用到的 mvn package.json

好在 mvn repository 不会像 node_modules 每个 repo 到处都是

db 没配置好之前 spring-boot-starter-data-jpa 会在运行的时候报错

后面也许可以做个大的玩具看看了

多几个对象的 CRUD 啥的（

JPA - Java Persistence API

ORM - Object Relational Mapping

好处是不用手写 sql

……这件事情大一就该开始干了

没事想不开去陪跑什么蓝桥杯啊真的是……

2022-04-25

csapp

csapp-01-datalab

Environment

hp2570p running Ubuntu 22.04 LTS

with i7-3630QM and 16GB DDR3

➜  datalab-handout git:(master) ✗ make btest
gcc -O -Wall -m32 -lm -o btest bits.c btest.c decl.c tests.c
In file included from btest.c:16:
/usr/include/stdio.h:27:10: fatal error: bits/libc-header-start.h: No such file or directory
   27 | #include <bits/libc-header-start.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from decl.c:1:
/usr/include/stdio.h:27:10: fatal error: bits/libc-header-start.h: No such file or directory
   27 | #include <bits/libc-header-start.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from /usr/lib/gcc/x86_64-linux-gnu/11/include/limits.h:203,
                 from /usr/lib/gcc/x86_64-linux-gnu/11/include/syslimits.h:7,
                 from /usr/lib/gcc/x86_64-linux-gnu/11/include/limits.h:34,
                 from tests.c:3:
/usr/include/limits.h:26:10: fatal error: bits/libc-header-start.h: No such file or directory
   26 | #include <bits/libc-header-start.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make: *** [Makefile:11: btest] Error 1
➜  datalab-handout git:(master) ✗ make clean
rm -f *.o btest fshow ishow *~
➜  datalab-handout git:(master) ✗ make btest
gcc -O -Wall -m32 -lm -o btest bits.c btest.c decl.c tests.c
In file included from btest.c:16:
/usr/include/stdio.h:27:10: fatal error: bits/libc-header-start.h: No such file or directory
   27 | #include <bits/libc-header-start.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from decl.c:1:
/usr/include/stdio.h:27:10: fatal error: bits/libc-header-start.h: No such file or directory
   27 | #include <bits/libc-header-start.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
In file included from /usr/lib/gcc/x86_64-linux-gnu/11/include/limits.h:203,
                 from /usr/lib/gcc/x86_64-linux-gnu/11/include/syslimits.h:7,
                 from /usr/lib/gcc/x86_64-linux-gnu/11/include/limits.h:34,
                 from tests.c:3:
/usr/include/limits.h:26:10: fatal error: bits/libc-header-start.h: No such file or directory
   26 | #include <bits/libc-header-start.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make: *** [Makefile:11: btest] Error

solved by running

1	sudo apt install gcc-multilib

2022-03-31

test

test-day-150

Today’s Task

Catalog Clear DB Pipelines AWS support
Upgrade Nucleus

Additional Task

Sanity Check

Thought

1

WFH 实属效率黑洞

我也讨厌那些看起来很圣洁的自我成长术语，啥正念啊延迟满足啊

玩的时候放开玩，干活的时候专注干

但我想把手上事情做完，还想做点能提升自己的事情

2022-03-17

test

test-day-140

Today’s Task

Fix Solr Release Script
Hadar Script Modify
Investigate on Unknown component when deploying STG

Additional Task

Resolve Merge Conflict when merging retro into release
Manually deploy latest logstash indexer to STG
Delete old image release jenkins pipeline
Failure Tracking

Thought

2022-03-16

test

test-day-139

Today’s Task

Fix Solr Release Script
Hadar Script Modify
Investigate on Unknown component when deploying STG

Additional Task

Redeploy player-control manually on IAD2
Delete pipelines and create numerous MRs about deleting groovy scripts from original repo

Thought

1

WFH 的效率低下，需要用什么办法来解决呢？

2022-03-15

test

test-day-138

Today’s Task

Fix Solr Release Script
Hadar Script Modify
Investigate on Unknown component when deploying STG

Additional Task

Thought

1

Release Script deleting progress

access
catalog
crypto
customerportal
dynamic-config-ui
hyas
kakapo
keymaster
liquibase-deploy
nam
nexus
nucleus
nucleussolr
playercard ( no need to build )
playerownership-cassandra
playerownership
porpoise
saola
sloth
tos
vaquita

2

WFH 第二天

感觉每天时间多了好多！

省下了路上的通勤开销，每天可以多两个小时

反正平时周末一样也是闷在家里不出门

但相应的，手机的使用时长也高出太多

进程切换需要极大开销

2022-03-15

test

test-day-137

Today’s Task

Investigate on Catalog Clear DB Issue
Investigate on Nucleus Solr Building Script

Additional Task

Manually build image for solr series

Thought

2022-03-13

test

clear-catalog-stg-tips

啥时候需要做

每次 CM 铺 Cataglog STG 前

做什么

会用魔法登上 MySQL 删库

再重新创建一份新的

重启一下 pod

然后往里面塞很多数据

为什么需要

容易卡，导致别的 component regression 败一大堆

比如说 rating, commerce, subscription v2 三巨头

怎么做

坑

如果执行失败了，或者执行中止，需要手动从断掉的地方登上去执行

如果卡在删库那一步，不要中止，直接去重铺一次 catalog stg

2022-03-10

test

test-day-136

Today’s Task

Investigate on Sox Audit

Additional Task

Thought

1

昨晚试着往 sox audit 里面加了几行 log.debug()

发现它并没有删掉任何一行 cassandra log

但是找到了 24497 条记录……

等下回 CM 再执行看看

2

发现 Jenkins Credentials 是有问题的…

如果通过 withCredentials 定义在 groovy 脚本的 top level

在 step 里面 echo 可以直接拿到明文？？？

3

Groovy 里面的 def 额可以用来声明变量和函数，而类型会在运行时根据值来推断出来

2022-03-09

test

test-day-135

Today’s Task

Investigate on Sox Audit Code and Cassandra

Additional Task

Saola Kafka Release Support
Nucleus Liquibase Cassandra on AWS Image Support
Learned how to update ChromeDriver Version on Web Hub from Peter Xin

Thought

1

Web Hub 上 ChromeDriver 的版本需要人工手动更新，万恶的 Google Auto Update

它会自动更新 Chrome 版本，而 ChromeDriver 版本必须和 Chrome 匹配

selenium/lib 下的 chromedriver，下下来的新版本先拖进去一份备份，后缀是版本号

然后再替换掉原来的那份 chromedriver

Chrome 没法固定住版本，在 Win 下用 Chrome 跑也是为了测试的时候更贴近用户使用场景

毕竟没有神仙会从 Linux 用 Chromium 访问……