獲取子級層次結構路徑，直到java中的父項爲止

Question

我有一個場景來獲取子字段的子層次結構，直到父級進行字段級驗證。 有人可以提供一些解決方案。

POJO類

Student.java

package com.poc.next.validations; 

import java.util.ArrayList; 
import java.util.List; 

public class Student { 
    private String studentName; 
    private List<Subject> subjects; 

    public String getStudentName() { 
     return studentName; 
    } 

    public void setStudentName(String studentName) { 
     this.studentName = studentName; 
    } 

    public List<Subject> getSubjects() { 
     if (subjects == null) { 
      return new ArrayList<>(); 
     } 
     return subjects; 
    } 

    public void setSubjects(List<Subject> subjects) { 
     this.subjects = subjects; 
    } 
} 

Subject.java

package com.poc.next.validations; 

import java.util.ArrayList; 
import java.util.List; 

public class Subject { 

    private String subjectName; 
    private List<RevisionMarks> revisionMarks; 

    public String getSubjectName() { 
     return subjectName; 
    } 

    public void setSubjectName(String subjectName) { 
     this.subjectName = subjectName; 
    } 

    public List<RevisionMarks> getRevisionMarks() { 
     if (revisionMarks == null) { 
      return new ArrayList<>(); 
     } 
     return revisionMarks; 
    } 

    public void setRevisionMarks(List<RevisionMarks> revisionMarks) { 
     this.revisionMarks = revisionMarks; 
    } 
} 

RevisionMarks.java

package com.poc.next.validations; 

public class RevisionMarks { 

    private Integer mark; 
    private String revision; 

    public Integer getMark() { 
     return mark; 
    } 

    public void setMark(Integer mark) { 
     this.mark = mark; 
    } 

    public String getRevision() { 
     return revision; 
    } 

    public void setRevision(String revision) { 
     this.revision = revision; 
    } 
} 

現在我們添加一個驗證來檢查在RevisionMarks類中的給定標記是否有效。如果它等於零，我必須將其添加到錯誤dto並將其發送回UI。這裏面臨的挑戰是我必須提供像「主體[0] .revisionMarks [0] .mark」一樣的動態層次結構。

主類 RevisionValidation.java

package com.poc.next.validations; 

import java.util.ArrayList; 
import java.util.Iterator; 
import java.util.List; 

public class RevisionValidation { 

    public static void main(String[] args) { 
     Student student = populateStudentData(); 
     Iterator<Subject> iterator = student.getSubjects().iterator(); 
     while (iterator.hasNext()) { 
      Subject subject = (Subject) iterator.next(); 
      RevisionMarks revisionMarks = subject.getRevisionMarks().get(0); 
      System.out.println(revisionMarks.getMark()); 
      if (revisionMarks.getMark() == 0) { 
       ErrorDTO errorDTO = new ErrorDTO(true, "Invalid Marks", "Error", "subjects[0].revisionMarks[0].mark", 
         "invalid_mark"); 
       System.out.println(errorDTO); 
      } 
     } 
    } 

    private static Student populateStudentData() { 
     List<RevisionMarks> revisionMarks = new ArrayList<>(); 
     RevisionMarks revisionMark = new RevisionMarks(); 
     revisionMark.setMark(0); 
     revisionMark.setRevision("Test 1"); 
     revisionMarks.add(revisionMark); 

     List<Subject> subjects = new ArrayList<>(); 
     Subject subject = new Subject(); 
     subject.setSubjectName("CS"); 
     subject.setRevisionMarks(revisionMarks); 
     subjects.add(subject); 

     Student student = new Student(); 
     student.setStudentName("Sample"); 
     student.setSubjects(subjects); 
     return student; 
    } 

} 

如何動態創建一個像 「科目[0] .revisionMarks [0] .mark」 fieldPath會。 歡迎任何建議。提前致謝。

Answer 1

使用計數器：

int counter = 0; 
    Iterator<Subject> iterator = student.getSubjects().iterator(); 
    while (iterator.hasNext()) { 
     Subject subject = (Subject) iterator.next(); 
     RevisionMarks revisionMarks = subject.getRevisionMarks().get(0); 
     System.out.println(revisionMarks.getMark()); 
     if (revisionMarks.getMark() == 0) { 
      ErrorDTO errorDTO = new ErrorDTO(true, "Invalid Marks", "Error", "subjects[" + counter + "].revisionMarks[0].mark", 
        "invalid_mark"); 
      System.out.println(errorDTO); 
     } 
     ++counter; 
    } 

Answer 2

我會建議使用，而不是重新發明輪子JSR3驗證。 https://www.mkyong.com/java/how-to-convert-java-object-to-from-json-jackson/

您可以爲POJO中的每個字段添加必要的註釋，並添加@Valid註釋以使驗證器檢查嵌套的POJO對象。

鏈接 https://www.beyondjava.net/blog/how-to-invoke-jsr-303-bean-validation-programmatically/顯示如何以編程方式調用驗證程序。

通過驗證，您可以提供任何消息並進行本地化，並且xpaths會自動構建指向POJO或嵌套POJO中的問題。