从服务获得错误输出

Question

问题：基于PersonDto中存在的规则值，我正在应用这些规则。在Rule1类中，我有一个修改id字段的逻辑。我正在设置新的id，我得到作为参数。
最后，我将结果存储到ArrayList中。
但是在ArrayList中，所有PersonDto的值都是我在应用规则时传递的最后一个id值。

例如：

 List<String> ids = Arrays.asList("10001", "100002");
    List<PersonDto> result = new ArrayList<PersonDto>();

    persons.stream().forEach(person -> {
        ids.stream().forEach(id -> {
            System.out.println(ruleMapper.getRule(person.getRule()).applyRule(person, id));

            result.add(ruleMapper.getRule(person.getRule()).applyRule(person, id));

        });
    });

正如您在上面的代码片段中所看到的，有两个ID10001和10002，但是当存储并打印结果时，所有元素中的id值都是10002。但是当我在循环中执行System.out.println（）时，我看到了正确的结果。

package com.example.dto;

public class PersonDto {
protected int id;
protected String name;
private String rule;

public int getId() {
    return id;
}

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

public String getName() {
    return name;
}

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



public String getRule() {
    return rule;
}

public void setRule(String rule) {
    this.rule = rule;
}

@Override
public String toString() {
    return "PersonDto [id=" + id + ", name=" + name + ", rule=" + rule + "]";
}

}

规则接口

package com.example.service;

import com.example.dto.PersonDto;

public interface Rules {

public PersonDto applyRule(PersonDto input, String newId);

}

规则1实施

package com.example.service;

import org.springframework.stereotype.Service;

import com.example.dto.PersonDto;

@Service
public class Rule1 implements Rules {

@Override
public PersonDto applyRule(PersonDto input, String newIdt) {
    input.setId(Integer.parseInt(newIdt));
    return input;
}

}

规则规划器

package com.example.service;

import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service

@Autowired
private Map<String, Rules> beans;

public Rules getRule(String ruleName) {
    return beans.get(ruleName);
}

public Map<String, Rules> gelAllBeans() {
    return beans;
  }
}

package com.example.demo;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import com.example.dto.PersonDto;
import com.example.service.RuleMapper;

@RestController
public class StudentContoller {

@Autowired
private RuleMapper ruleMapper;

@GetMapping(value = "/test")
public void saveStudent() throws Exception {
    List<String> orders = Arrays.asList("order 1", "order 2");

    List<PersonDto> persons = new ArrayList<PersonDto>();

    for (int i = 0; i < 10; i++) {
        PersonDto per = new PersonDto();
        per.setId(i);
        per.setName("John Doe_ ".concat(String.valueOf(i)));
        per.setRule("rule" + getRandomRule());
        persons.add(per);
    }


    List<String> ids = Arrays.asList("10001", "100002");
    List<PersonDto> result = new ArrayList<PersonDto>();

    persons.stream().forEach(person -> {
        ids.stream().forEach(id -> {
            System.out.println(ruleMapper.getRule(person.getRule()).applyRule(person, id));

            result.add(ruleMapper.getRule(person.getRule()).applyRule(person, id));

        });
    });


    for (PersonDto person : result) {
        System.out.println(person);
    }

}

private int getRandomRule() {
    Random r = new Random();
    int low = 1;
    int high = 2;
    int result = r.nextInt(high - low) + low;

    return result;
 }

}

PersonDto [id=10001, name=John Doe_ 0, rule=rule1]
PersonDto [id=100002, name=John Doe_ 0, rule=rule1]
PersonDto [id=10001, name=John Doe_ 1, rule=rule1]
PersonDto [id=100002, name=John Doe_ 1, rule=rule1]
PersonDto [id=10001, name=John Doe_ 2, rule=rule1]
PersonDto [id=100002, name=John Doe_ 2, rule=rule1]
PersonDto [id=10001, name=John Doe_ 3, rule=rule1]
PersonDto [id=100002, name=John Doe_ 3, rule=rule1]
PersonDto [id=10001, name=John Doe_ 4, rule=rule1]
PersonDto [id=100002, name=John Doe_ 4, rule=rule1]
PersonDto [id=10001, name=John Doe_ 5, rule=rule1]
PersonDto [id=100002, name=John Doe_ 5, rule=rule1]
PersonDto [id=10001, name=John Doe_ 6, rule=rule1]
PersonDto [id=100002, name=John Doe_ 6, rule=rule1]
PersonDto [id=10001, name=John Doe_ 7, rule=rule1]
PersonDto [id=100002, name=John Doe_ 7, rule=rule1]
PersonDto [id=10001, name=John Doe_ 8, rule=rule1]
PersonDto [id=100002, name=John Doe_ 8, rule=rule1]
PersonDto [id=10001, name=John Doe_ 9, rule=rule1]
PersonDto [id=100002, name=John Doe_ 9, rule=rule1]

PersonDto [id=100002, name=John Doe_ 0, rule=rule1]
PersonDto [id=100002, name=John Doe_ 0, rule=rule1]
PersonDto [id=100002, name=John Doe_ 1, rule=rule1]
PersonDto [id=100002, name=John Doe_ 1, rule=rule1]
PersonDto [id=100002, name=John Doe_ 2, rule=rule1]
PersonDto [id=100002, name=John Doe_ 2, rule=rule1]
PersonDto [id=100002, name=John Doe_ 3, rule=rule1]
PersonDto [id=100002, name=John Doe_ 3, rule=rule1]
PersonDto [id=100002, name=John Doe_ 4, rule=rule1]
PersonDto [id=100002, name=John Doe_ 4, rule=rule1]
PersonDto [id=100002, name=John Doe_ 5, rule=rule1]
PersonDto [id=100002, name=John Doe_ 5, rule=rule1]
PersonDto [id=100002, name=John Doe_ 6, rule=rule1]
PersonDto [id=100002, name=John Doe_ 6, rule=rule1]
PersonDto [id=100002, name=John Doe_ 7, rule=rule1]
PersonDto [id=100002, name=John Doe_ 7, rule=rule1]
PersonDto [id=100002, name=John Doe_ 8, rule=rule1]
PersonDto [id=100002, name=John Doe_ 8, rule=rule1]
PersonDto [id=100002, name=John Doe_ 9, rule=rule1]
PersonDto [id=100002, name=John Doe_ 9, rule=rule1]

Answer 1

persons.stream().forEach(person -> {
    ids.stream().forEach(id -> {
        result.add(ruleMapper.getRule(person.getRule()).applyRule(person, id));
    });
});

这贯穿所有人。对于每个人，它循环通过所有的ID。对于每个ID，您将规则应用于该人员。但是由于规则包含修改人员的ID，所以最后一个ID是存储在人员中的ID。

如果重写是for循环，它等效于

for (Person person: persons) {
    for (String id: ids) {
        person.setId(id);
    }
}

我不确定代码应该做什么。也许第一个ID应该设置在第一个人身上，第二个ID应该设置在第二个人身上，等等。如果是这样的话，然后循环遍历列表中的一个索引，并获得每个索引的人和ID。（并祈祷两个名单有相同的大小）：

for (int i = 0; i < persons.size(); i++) {
    persons.get(i).setIf(ids.get(i));
}