java - 使用流通过 Builder 从 csv 文件创建对象

Question

我想使用 PlanetBuilder 和流从 .csv 文件创建一个“Planet”对象。到目前为止，我只能读取 csv 文件并为每一行创建一个 Planet 对象，但不幸的是我不知道如何将构造函数值分配给该对象，所以它基本上只是创建一个空的 Planet 对象每行。有人可以告诉我如何为每行分配值吗？

创建对象后，我会将它们添加到行星列表

这是创建新行星对象的方法。

public List<Planet> csvDataToPlanets(String filePath) {
    List<Planet> planets = new ArrayList<>();
    try (Stream<String> lines = Files.lines(Paths.get(filePath))) {
        List<List<String>> places = lines.skip(1).map(line -> Arrays.asList(line.split(","))).collect(Collectors.toList());
        places.forEach(place -> new PlanetBuilder().createPlanet());
    } catch (IOException e) {
        e.printStackTrace();
    }
    return planets;
}

这是 CSV 文件。

planet_name,inhabitants,has_stargate,has_dhd,teams_visited
Abydos,0,True,False,[sg-1]
Adara II,117778380,True,True,[sg-1]
Adora,0,False,False,[sg-1]
Alaris,13663,True,True,[sg-1]
Alebran's planet,186402846,False,False,[sg-1; sg-6]
Alpha Site,460849025,True,True,[sg-1; sg-4]
Altair,8087,False,False,[sg-1; sg-2]
Amon Shek,0,True,True,[sg-1; sg-9]
Amra,467925616,True,False,[sg-1]
Apophis's training camp,10188,True,True,[sg-1]
Ardena,13693,True,True,[sg-1; sg-5]
Argos,0,True,True,[sg-1]
Arkad's planet,257318689,True,False,[sg-1; sg-14]
Arkhan's planet,464136466,False,False,[sg-1]

以及我的 Planet 类和 Planetbuilder 类

public class Planet {
private String name;
private long inhabitants;
private boolean stargateAvailable;
private boolean dhdAvailable;
private List<String> teamsVisited;


public Planet(String name, long inhabitants, boolean stargateAvailable, boolean dhdAvailable, List<String> teamsVisited) {
}

public String getName() {
    return name;
}

public long getInhabitants() {
    return inhabitants;
}

public boolean isStargateAvailable() {
    return stargateAvailable;
}

public boolean isDhdAvailable() {
    return dhdAvailable;
}

public List<String> getTeamsVisited() {
    return teamsVisited;
}

@Override
public String toString() {
    return name;
}


public class PlanetBuilder {
private String name;
private long inhabitants;
private boolean stargateAvailable;
private boolean dhdAvailable;
private List<String> teamsVisited;

public PlanetBuilder Name(String name) {
    this.name = name;
    return this;
}

public PlanetBuilder Inhabitants(long inhabitants) {
    this.inhabitants = inhabitants;
    return this;
}

public PlanetBuilder StargateAvailable(boolean stargateAvailable) {
    this.stargateAvailable = stargateAvailable;
    return this;
}

public PlanetBuilder DhdAvailable(boolean dhdAvailable) {
    this.dhdAvailable = dhdAvailable;
    return this;
}

public PlanetBuilder TeamsVisited(List<String> teamsVisited) {
    this.teamsVisited = teamsVisited;
    return this;
}

public Planet createPlanet() {
    return new Planet(name, inhabitants, stargateAvailable, dhdAvailable, teamsVisited);
}

Answer 1

最简单的答案是扩展 places.forEach(place ->...) 内部的逻辑调用，以便您从 place 中获取每个值(这是值的 List<String>)并为每个属性添加对构建器的调用(根据需要解析它们)。例如。 places.forEach(place -> new PlanetBuilder().Name(place.get(0)).createPlanet()); (在这种情况下不需要解析)

但这绝对不是最好的解决方案。

理想情况下，您会转向使用像 http://beanio.org/ 这样的库或http://flatworm.sourceforge.net/为您处理解码工作。