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Martin Hope
SerikStartAndroid
Asked: 2022-09-24 19:29:10 +0800 CST
  • 0

大家好。我实现了两阶段提交（2PC）

有 2 个阶段 - 准备、提交和有一个阶段以防回滚

通信 - REST API（/prepare、/commit、/rollback 端点）

根据 /prepare 阶段 2pc 的规范，我需要在数据库中阻塞一行。

在当前的实现中，我将布尔字段锁定在参与表中的每个微服务中，并在第一阶段将值设置为 true，在第二阶段设置为 false。

我知道我的实现非常简单而且不太正确。

我的问题是：如何在第一阶段阻止表格中的一行？

已经尝试过：

  1. select ... for update - 但它不起作用，因为它只在一个事务级别阻塞，我需要阻塞到第二阶段

  2. 我在考虑 dbms_lock （基本级别锁），但我不完全确定这是否是正确的解决方案。

我的堆栈：Java、Spring Data、MySql

如何在第一阶段锁定行以使其保持到分布式事务中的整个提交（第二阶段）完成为止是正确的。

P/S SAGA 实现我知道（非常有趣的 2PC 实现）

非常感谢。

mysql
Martin Hope
SerikStartAndroid
Asked: 2020-08-18 23:06:02 +0800 CST
  • 0

船运：

@Service
public class ProducerImp implements Producer {
    @Autowired
    private AmqpTemplate amqpTemplate;

    @Value("${jsa.rabbitmq.exchange}")
    private String exchange;

    @Value("${jsa.rabbitmq.routingkey}")
    private String routingKey;


    @Override
    public void produceMsg(MessageDTO msg) {
        amqpTemplate.convertAndSend(exchange, routingKey, msg);
        System.out.println("Send msg = " + msg);
    }
}

监听器（其余相同）：

@Component
public class SubscribeServiceImpl {
    @RabbitListener(queues="jsa.queue")
    public void recievedMessage(MessageDTO msg) {
        System.out.println("Recieved Message: " + msg.getMessage());
    }

}

问题是该消息仅到达其中一个听众。如何做到让每个人都来？

spring
Martin Hope
SerikStartAndroid
Asked: 2020-10-23 12:48:39 +0800 CST
  • 1

有2个对象

   @Entity
@Table(name = "real_estate", schema="data1c")
@Proxy(lazy = false)
public class RealEstate {
    @Id
    @Column(name = "id")
    UUID id;
    @Column(name = "name")
    String name;
    @ManyToOne(cascade={CascadeType.PERSIST, CascadeType.MERGE}, fetch = FetchType.EAGER)
    @JoinColumn(name="city", nullable = false)
    private City city;
    @Column(name = "website")
    String website;
    @Column(name = "logo")
    String logo;
    @Column(name = "logo_web")
    String logoWeb;
    @Column(name = "foto")
    String foto;
    @Column(name = "foto_web")
    String fotoWeb;
    @Column(name = "longitude")
    Double longitude;
    @Column(name = "latitude")
    Double latitude;


    public UUID getId() {
        return id;
    }

    public void setId(UUID id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public City getCity() {
        return city;
    }

    public void setCity(City city) {
        this.city = city;
    }

    public String getWebsite() {
        return website;
    }

    public void setWebsite(String website) {
        this.website = website;
    }

    public String getLogo() {
        return logo;
    }

    public void setLogo(String logo) {
        this.logo = logo;
    }

    public String getLogoWeb() {
        return logoWeb;
    }

    public void setLogoWeb(String logoWeb) {
        this.logoWeb = logoWeb;
    }

    public String getFoto() {
        return foto;
    }

    public void setFoto(String foto) {
        this.foto = foto;
    }

    public String getFotoWeb() {
        return fotoWeb;
    }

    public void setFotoWeb(String fotoWeb) {
        this.fotoWeb = fotoWeb;
    }

    public Double getLongitude() {
        return longitude;
    }

    public void setLongitude(Double longitude) {
        this.longitude = longitude;
    }

    public Double getLatitude() {
        return latitude;
    }

    public void setLatitude(Double latitude) {
        this.latitude = latitude;
    }


    @Override
    public String toString() {
        return "RealEstate{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", city=" + city +
                ", website='" + website + '\'' +
                ", logo='" + logo + '\'' +
                ", logoWeb='" + logoWeb + '\'' +
                ", foto='" + foto + '\'' +
                ", fotoWeb='" + fotoWeb + '\'' +
                ", longitude=" + longitude +
                ", latitude=" + latitude +
                '}';
    }
}

城市对象：

@Entity
@Table(name = "city", schema="data1c")
@Proxy(lazy = false)
public class City  {
    @Id
    @Column(name = "id")
    private UUID id;
    @Column(name = "name")
    private String name;

    public UUID getId() {
        return id;
    }

    public void setId(UUID id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }


    @Override
    public String toString() {
        return "City{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

我需要从 api 中获取数据并将其上传到数据库。

一个示例 json 是这样的：

 {
            "id": "c67ec057-ea71-11e5-b9a5-b4b52f5405e7",
            "name": "Проект очереди 1",
            "city": "a4874e7c-2906-11e9-80d9-00155d101f25",
            "website": "",
            "logo": "",
            "logoWeb": "",
            "foto": "",
            "fotoWeb": "",
            "longitude": 0,
            "latitude": 0
        }

问题是 city 不是作为一个对象出现的，而是作为一个 id（标识符）出现的。我如何序列化？帮助

我正在尝试这样的事情：

public RealEstate serializerealrest() throws IOException {
        String body = "{\n" +
                "            \"id\": \"c67ec057-ea71-11e5-b9a5-b4b52f5405e7\",\n" +
                "            \"name\": \"Проект очереди 1\",\n" +
                "            \"city\": \"a4874e7c-2906-11e9-80d9-00155d101f25\",\n" +
                "            \"logo\": \"\",\n" +
                "            \"logoWeb\": \"\",\n" +
                "            \"foto\": \"\",\n" +
                "            \"fotoWeb\": \"\",\n" +
                "            \"longitude\": 0,\n" +
                "            \"latitude\": 0\n" +
                "        }";
        RealEstate realEstate = mapper.readValue(body, new TypeReference<RealEstate>(){});
        return realEstate;
    }
java
Martin Hope
SerikStartAndroid
Asked: 2020-04-25 15:46:49 +0800 CST
  • 0

有一个控制器，其中有一个第三方库（是的，在 javastrip 上））））“dhtmlXTreeObject”，它绘制一棵树。他有自己的 ClickHandler。我正在为 click 函数中的全局变量赋值。但问题是变量没有更新。请帮助变量type1 type2。tonclick_checks 和 tonclick 函数。

我了解连接js库不好，tonclick_checks和tonclick在控制器范围内不起作用。但是如何更新变量。非常感谢您提前。

Import {
  AfterViewInit, Component, DoCheck, EventEmitter, NgModule, NgZone, OnDestroy, OnInit,
  Output
} from '@angular/core';

declare var dhtmlXTreeObject: any;


@Component({
  selector: 'ngx-treemo',
  styleUrls: ['./treemo.component.scss'],
  templateUrl: './treemo.component.html',
})
export class TreemoComponent implements AfterViewInit, OnDestroy, OnInit, DoCheck {
  type: ChartType;
  graphic: boolean;
  table: boolean;
  chartTypes: ChartType[];
  data: any;
  modael1: any;
  model: any;
  modaltree: any;
  type1: string;
  type2: string;
  newtype1: string;
  newtype2: string;
  options: any = {};
  themeSubscription: any;

  constructor(private http: HttpClient,
              private theme: NbThemeService,
              private zone: NgZone ) {
    this.graphic = true;
    this.table = false;
    this.chartTypes = ['Bar', 'Line', 'Radar'];
    this.type = 'Bar';
    this.type1 = '523';
    this.type2 = '1t1';
    this.newtype1 = '523';
    this.newtype2 = '0t';

  }


  onChange(deviceValue) {
  }

  ngOnInit(): void {

    const myTree_checks = new dhtmlXTreeObject('treeboxbox_tree_checks', '100%', '100%', 0);
    myTree_checks.setImagePath('../../../../assets/skinstree/web/imgs/dhxtree_web/');
    myTree_checks.enableDragAndDrop(true);
    myTree_checks.setOnClickHandler(this.tonclick_checks);
    myTree_checks.enableMultiLineItems('100%');


    const myTree1 = new dhtmlXTreeObject('treeboxbox_tree_types', '100%', '100%', 0);
    myTree1.setImagePath('../../../../assets/skinstree/web/imgs/dhxtree_web/');
    myTree1.enableDragAndDrop(true);
    myTree1.setOnClickHandler(this.tonclick);
    myTree1.enableMultiLineItems('100%');

    }


  tonclick_checks(id)   {
    this.type1 = id;
   // console.log(this.type1);
  }
  tonclick(id) {
    this.type2 = id;
   // console.log(this.type2);
  }
}
angular2
Martin Hope
SerikStartAndroid
Asked: 2020-08-04 13:21:48 +0800 CST
  • 0

有代码

static void Main(string[] args)
    {
        String line=string.Empty;
        for (int i = 1; i < 8; i++)
        {
            using (StreamReader sr = new StreamReader(@"C:\Users\Serik\Desktop\pdf_test\"+i+".txt"))
            {
                line =line+ sr.ReadToEnd();
            }
        }
            byte[] bytes = Convert.FromBase64String(line);
            FileStream stream =
            new FileStream(@"C:\Users\Serik\Desktop\pdf_test\file.pdf", FileMode.CreateNew);
            System.IO.BinaryWriter writer =
                new BinaryWriter(stream);
            writer.Write(bytes, 0, bytes.Length);
            writer.Close();

从 base64 字符串生成一个 pdf 文件。但是有一个假设，如果存储 base64 的字符串对我来说太长（大 pdf 文件），那么程序将无法运行（因为字符串有允许的长度）如何处理这个？除了字符串还能用什么？

c#
Martin Hope
SerikStartAndroid
Asked: 2020-08-01 17:17:59 +0800 CST
  • 0

有json

{"Data": [{"Uzel": "asd","Number": "1","Parent": "0","Update": "3"},{"Uzel": "asd","Number": "1.1","Parent": "1","Update": "2"},{"Uzel": "asd","Number": "2.2.1.2.1.2","Parent": "2.2.1.2.1","Update": "0"},{"Uzel": "asd","Number": "1.1.1","Parent": "1.1","Update": "2"},{"Uzel": "asd","Number": "1.1.2","Parent": "1.1","Update": "0"},{"Uzel": "zxc","Number": "1.1.3","Parent": "1.1","Update": "0"},{"Uzel": "ert","Number": "1.1.4","Parent": "1.1","Update": "0"},{"Uzel": "fgh","Number": "1.2","Parent": "1","Update": "0"},{"Uzel": "cvb","Number": "1.2.1","Parent": "1.2","Update": "0"},{"Uzel": "2012 год ","Number": "1.2.2","Parent": "1.2","Update": "0"},{"Uzel": "uio","Number": "1.2.3","Parent": "1.2","Update": "0"},{"Uzel": "2014 год ","Number": "1.2.4","Parent": "1.2","Update": "0"},{"Uzel": "xxx","Number": "1.2.5","Parent": "1.2","Update": "0"},{"Uzel": "xxx","Number": "1.3","Parent": "1","Update": "0"},{"Uzel": "zzz","Number": "1.3.1","Parent": "1.3","Update": "0"},{"Uzel": "aaa","Number": "1.3.2","Parent": "1.3","Update": "0"},{"Uzel": "qqq","Number": "1.3.3","Parent": "1.3","Update": "0"},{"Uzel": "vvv","Number": "1.3.4","Parent": "1.3","Update": "0"},{"Uzel": "vvv","Number": "1.4","Parent": "1","Update": "0"},{"Uzel": "www","Number": "1.4.1","Parent": "1.4","Update": "0"},{"Uzel": "eee","Number": "1.4.2","Parent": "1.4","Update": "0"},{"Uzel": "uuu","Number": "1.4.3","Parent": "1.4","Update": "0"},{"Uzel": "iii","Number": "1.4.4","Parent": "1.4","Update": "0"},{"Uzel": "ttt","Number": "1.4.5","Parent": "1.4","Update": "0"},{"Uzel": "uuu","Number": "1.4.6","Parent": "1.4","Update": "0"},{"Uzel": "nnn","Number": "1.5","Parent": "1","Update": "0"},{"Uzel": "ooo","Number": "1.5.1","Parent": "1.5","Update": "0"},{"Uzel": "nnn","Number": "1.5.2","Parent": "1.5","Update": "0"},{"Uzel": "ppp","Number": "1.5.3","Parent": "1.5","Update": "0"},{"Uzel": "bbb","Number": "1.5.4","Parent": "1.5","Update": "0"},{"Uzel": "fff","Number": "1.5.5","Parent": "1.5","Update": "0"},{"Uzel": "jjj","Number": "1.5.6","Parent": "1.5","Update": "0"},{"Uzel": "lll","Number": "2","Parent": "0","Update": "0"},{"Uzel": "mmm","Number": "2.1","Parent": "2","Update": "0"},{"Uzel": "eee","Number": "2.1.1","Parent": "2.1","Update": "0"},{"Uzel": "rrr","Number": "2.1.1.1","Parent": "2.1.1","Update": "0"},{"Uzel": "opop","Number": "2.1.1.1.1","Parent": "2.1.1.1","Update": "0"},{"Uzel": "asd","Number": "2.1.1.1.2","Parent": "2.1.1.1","Update": "0"},{"Uzel": "asd","Number": "2.1.1.1.3","Parent": "2.1.1.1","Update": "0"},{"Uzel": "asd","Number": "2.1.1.2","Parent": "2.1.1","Update": "0"},{"Uzel": "asd","Number": "2.1.1.2.1","Parent": "2.1.1.2","Update": "0"},{"Uzel": "fgh","Number": "2.1.1.2.2","Parent": "2.1.1.2","Update": "0"},{"Uzel": "tyu","Number": "2.1.1.3","Parent": "2.1.1","Update": "0"},{"Uzel": "uio","Number": "2.1.1.4","Parent": "2.1.1","Update": "0"},{"Uzel": "zxc","Number": "2.1.1.5","Parent": "2.1.1","Update": "0"},{"Uzel": "dsa","Number": "2.1.1.5.1","Parent": "2.1.1.5","Update": "0"},{"Uzel": "poi","Number": "2.1.2","Parent": "2.1","Update": "0"},{"Uzel": "qaxz","Number": "2.1.2.1","Parent": "2.1.2","Update": "0"},{"Uzel": "ert","Number": "2.1.2.1.1","Parent": "2.1.2.1","Update": "0"}]}

它需要转换成这个

 {"Data": [{"Uzel": "asd","Number": "1","Parent": "0","Update": "3", children:[{"Uzel": "asd","Number": "1.1","Parent": "1","Update": "2","children":[{"Uzel": "asd","Number": "1.1.1","Parent": "1.1","Update": "2"},{"Uzel": "asd","Number": "1.1.2","Parent": "1.1","Update": "0"},{"Uzel": "zxc","Number": "1.1.3","Parent": "1.1","Update": "0"},{"Uzel": "ert","Number": "1.1.4","Parent": "1.1","Update": "0"}],{"Uzel": "fgh","Number": "1.2","Parent": "1","Update": "0"}}]}]}

也就是再增加一个参数children，把parent与另一个元素的编号相关联的数组的所有元素都放到这个元素里面。

嵌套是多层次的——孩子可以有自己的孩子，他有自己的孩子，等等。

我明白递归，但我做不到，请帮忙。我不发送代码，因为根不正确。JavaScript

javascript