Java-对象转CSV

转x33g5p2x  于2022-06-30 转载在 Java  
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介绍

csv全称“Comma-Separated Values”，是一种逗号分隔值格式的文件，是一种用来存储数据的纯文本格式文件。CSV文件由任意数目的记录组成，记录间以某种换行符分隔；每条记录由字段组成，字段间的分隔符是其它字符或字符串。

Java对象转CSV,有现成的工具包,commons-lang3 的ReflectionToStringBuilder 就可以简单的解决的对象转CSV 但是复杂点的处理还是不行,而且在运行速度上,我测试了下我自己写的,比这个快多了,1百万条数据大约也就2秒左右, 如果对速度有要求的话,我们可以使用多线程进行分割,比如1千万条数据,那么我开10个线程,1个线程执行100万条数据,所有线程执行完毕后在按照顺序拼接到一起,这样1千万条数据也就最多3~5秒执行完毕

代码样例

  1. package com.file.csv;
  3. import com.date.LocalDateUtils;
  4. import lombok.Data;
  5. import lombok.SneakyThrows;
  7. import java.lang.reflect.Field;
  8. import java.util.ArrayList;
  9. import java.util.Arrays;
  10. import java.util.List;
  11. import java.util.function.Function;
  13. /**
  14.  * 对象转csv格式
  15.  *
  16.  * @describe
  17.  * 1百万数据测试 2~3秒
  18.  * 调用顺序如下(根据情况自行选择)
  19.  *         String s = ObjToCSV.create(userDatas)
  20.  *                 .fieldsAll()   //转换全部列
  21.  *                 .addIncludeFields() //只包含某些列
  22.  *                 .addExcludeFields("roleData") //排除某些列
  23.  *                 .addHead() //添加头部字段
  24.  *                 .addContent() //一个对象(一行)
  25.  *                 .addContents() //多个对象(多行)
  26.  *                 .addEnding((data)->{ //结尾说明
  27.  *                     JSONObject jsonObject = new JSONObject();
  28.  *                     jsonObject.put("count",data.getNumber());
  29.  *                     jsonObject.put("time",data.getCreateDate());
  30.  *                     return  jsonObject.toJSONString();
  31.  *                 })
  32.  *                 .ToString(); //结果
  33.  */
  34. @Data
  35. public class ObjToCSV<T> {
  37.     private String separator = "\u0001|\u0001";  //默认分隔符
  38.     private StringBuilder str = new StringBuilder();
  39.     private T object;
  40.     private List<T> objects;
  41.     private List<String> excludeFields = new ArrayList<String>(100) {{
  42.         add("serialVersionUID");
  43.     }};
  44.     private List<String> includeFields = new ArrayList<String>(100);
  45.     private boolean fieldsAll = false;
  46.     private  int number;//多少行一共
  47.     //日期串 20220617204504
  48.     private  String createDate=LocalDateUtils.getLocalDateTimeStr1() ;
  50.     private ObjToCSV(T object, String separator) {
  51.         this.object = object;
  52.         this.separator = separator;
  53.         //行数
  54.         this.number=1;
  55.     }
  56.     private ObjToCSV(T object) {
  57.         this.object = object;
  58.         //行数
  59.         this.number=1;
  61.     }
  62.     private ObjToCSV(List<T> objects) {
  63.         if (objects.isEmpty()) {
  64.             throw new NullPointerException("不能是空");
  65.         }
  66.         this.object = objects.get(0);
  67.         this.objects = objects;
  68.         //行数
  69.         this.number=objects.size();
  70.     }
  71.     private ObjToCSV(List<T> objects, String separator) {
  72.         if (objects.isEmpty()) {
  73.             throw new NullPointerException("不能是空");
  74.         }
  75.         this.object = objects.get(0);
  76.         this.objects = objects;
  77.         this.separator = separator;
  78.         //行数
  79.         this.number=objects.size();
  81.     }
  83.     // 排除和包含都有,那么以包含的为主
  84.     private boolean decideFields(String fieldName) {
  86.         //包含
  87.         if (includeFields.contains(fieldName)) {
  88.             return false;
  89.         }
  90.         //排除
  91.         if (excludeFields.contains(fieldName)) {
  92.             return true;
  93.         }
  95.         // 开启全部放行
  96.         if (fieldsAll) {
  97.             return false;
  98.         }
  100.         //默认拦截全部
  101.         return true;
  102.     }
  104.     public static <T> ObjToCSV<T> create(T object, String separator) {
  105.         return new ObjToCSV<T>(object, separator);
  106.     }
  107.     public static <T> ObjToCSV<T> create(T object) {
  108.         return new ObjToCSV<T>(object);
  109.     }
  110.     public static <T> ObjToCSV<T> create(List<T> object, String separator) {
  111.         return new ObjToCSV<T>(object, separator);
  112.     }
  113.     public static <T> ObjToCSV<T> create(List<T> object) {
  114.         return new ObjToCSV<T>(object);
  115.     }
  116.     //全部放行
  117.     public ObjToCSV<T> fieldsAll() {
  118.         fieldsAll = true;
  119.         return this;
  120.     }
  122.     //包含
  123.     public ObjToCSV<T> addIncludeFields(String... fieldName) {
  124.         includeFields.addAll(Arrays.asList(fieldName));
  125.         return this;
  126.     }
  128.     //排除
  129.     public ObjToCSV<T> addExcludeFields(String... fieldName) {
  130.         excludeFields.addAll(Arrays.asList(fieldName));
  131.         return this;
  132.     }
  134.     //添加头部
  135.     public ObjToCSV<T> addHead() {
  136.         StringBuilder str1 = new StringBuilder();
  137.         Class<?> aClass = this.object.getClass();
  138.         Field[] fields = aClass.getDeclaredFields();
  139.         int length = fields.length;
  140.         for (int i = 0; i < length; i++) {
  141.             Field field = fields[i];
  142.             field.setAccessible(true);
  143.             if (decideFields(field.getName())) {
  144.                 continue;
  145.             }
  146.             str1.append(field.getName()).append(separator);
  147.         }
  148.         int length1 = separator.length();
  149.         String substring = str1.substring(0, str1.length() - length1);
  150.         this.str.append(substring + "\n");
  151.         return this;
  152.     }
  153.     //在结尾补充自定义的描述
  154.     public ObjToCSV<T> addEnding(Function<ObjToCSV,String> functor){
  155.         String apply = functor.apply( this);
  156.         this.str.append(apply);
  157.         return this;
  158.     }
  160.     //将对象转换为CSV格式字符串
  161.     @SneakyThrows
  162.     public ObjToCSV<T> addContent() {
  163.         StringBuilder str1 = new StringBuilder();
  164.         Class<?> aClass = this.object.getClass();
  165.         Field[] fields = aClass.getDeclaredFields();
  166.         int length = fields.length;
  167.         for (int i = 0; i < length; i++) {
  168.             Field field = fields[i];
  169.             field.setAccessible(true);
  170.             if (decideFields(field.getName())) {
  171.                 continue;
  172.             }
  173.             Object o = field.get(object);
  174.             String value = "";
  175.             if (o != null) {
  176.                 value = String.valueOf(o);
  177.             }
  178.             str1.append(value).append(separator);
  179.         }
  180.         int length1 = separator.length();
  181.         String substring = str1.substring(0, str1.length() - length1);
  182.         this.str.append(substring + "\n");
  184.         return this;
  185.     }
  186.     //将多个对象转换为csv格式
  187.     public ObjToCSV<T> addContents() {
  188.         for (T t : this.objects) {
  189.             this.object=t;
  190.             addContent();
  191.         }
  192.         return this;
  193.     }
  194.     //将结果输出为字符串
  195.     public String ToString() {
  196.         return str.toString();
  197.     }
  200. }

测试样例

  1. package com.file;
  3. import com.alibaba.fastjson.JSONObject;
  4. import com.data.RandomUserData;
  5. import com.entity.UserData;
  6. import com.file.csv.ObjToCSV;
  7. import com.file.csv.ObjToCSV;
  8. import com.function.impl.CodeStartAndStopTimeUtil;
  9. import lombok.SneakyThrows;
  10. import org.junit.Test;
  12. import java.util.List;
  14. public class ObjToCSVTest {
  16.     //单个对象
  17.     @Test
  18.     public  void show1(){
  19.         UserData userOne = RandomUserData.getUserOne();
  20.         String s = ObjToCSV.create(userOne)
  21.                 .fieldsAll()
  22. //                .addIncludeFields()
  23.                 .addExcludeFields("roleData")
  24. //                .addHead()
  25.                 .addContent()
  26. //                .addContents()
  27.                 .addEnding((data)->{
  28.                     JSONObject jsonObject = new JSONObject();
  29.                     jsonObject.put("count",data.getNumber());
  30.                     jsonObject.put("time",data.getCreateDate());
  31.                     jsonObject.put("separator",data.getSeparator());
  32.                     return  jsonObject.toJSONString();
  33.                 })
  34.                 .ToString();
  35.         System.out.println(s);
  37.     }
  39.     //多个对象,可以使用自定义分隔符
  40.     @Test
  41.     public  void show2(){
  42.         UserData userOne = RandomUserData.getUserOne();
  43.         String s = ObjToCSV.create(userOne,"|")
  44.                 .fieldsAll()
  45.                 .addExcludeFields("roleData")
  46.                 .addContent()
  47.                 .addEnding((data)->{
  48.                     JSONObject jsonObject = new JSONObject();
  49.                     jsonObject.put("count",data.getNumber());
  50.                     jsonObject.put("time",data.getCreateDate());
  51.                     jsonObject.put("separator",data.getSeparator());
  52.                     return  jsonObject.toJSONString();
  53.                 })
  54.                 .ToString();
  55.         System.out.println(s);
  56.     }
  59.     //排除不显示的,其他都显示
  60.     @Test
  61.     public  void show3(){
  62.         List<UserData> userDatas = RandomUserData.getUserDatas(10);
  64.         String s = ObjToCSV.create(userDatas,"|")
  65.                 .fieldsAll()//显示全部字段
  66.                 .addExcludeFields("roleData")//排除指定字段
  67.                 .addHead()
  68.                 .addContents()
  69.                 .addEnding((data)->{
  70.                     JSONObject jsonObject = new JSONObject();
  71.                     jsonObject.put("count",data.getNumber());
  72.                     jsonObject.put("time",data.getCreateDate());
  73.                     jsonObject.put("separator",data.getSeparator());
  75.                     return  jsonObject.toJSONString();
  76.                 })
  77.                 .ToString();
  78.         System.out.println(s);
  79.     }
  81.     //只包含指定字段 ,其他都不显示
  82.     @Test
  83.     public  void show4(){
  84.         List<UserData> userDatas = RandomUserData.getUserDatas(10);
  86.         String s = ObjToCSV.create(userDatas,"|")
  87.                 .addIncludeFields("id","name")
  88.                 .addHead()  //添加头部
  89.                 .addContents() //添加内容
  90.                 .addEnding((data)->{  //添加结尾信息
  91.                     JSONObject jsonObject = new JSONObject();
  92.                     jsonObject.put("count",data.getNumber());
  93.                     jsonObject.put("time",data.getCreateDate());
  94.                     jsonObject.put("separator",data.getSeparator());
  95.                     return  jsonObject.toJSONString();
  96.                 })
  97.                 .ToString();
  98.         System.out.println(s);
  99.     }
  101.     //内容
  102.     @Test
  103.     public  void show5(){
  104.         List<UserData> userDatas = RandomUserData.getUserDatas(10);
  105.         String s = ObjToCSV.create(userDatas,"|")
  106.                 .fieldsAll()
  107.                 .addExcludeFields("roleData")//排除指定字段
  108.                 .addContents() //添加内容
  109.                 .ToString();
  110.         System.out.println(s);
  111.     }
  113.     @SneakyThrows
  114.     public static void main(String[] args) {
  115.         List<UserData> userDatas = RandomUserData.getUserDatas(100);
  116.         String s = ObjToCSV.create(userDatas)
  117.                 .fieldsAll()
  118. //                .addIncludeFields()
  119.                 .addExcludeFields("roleData")
  120. //                .addHead()
  121. //                .addContent()
  122.                 .addContents()
  123.                 .addEnding((data)->{
  124.                     JSONObject jsonObject = new JSONObject();
  125.                     jsonObject.put("count",data.getNumber());
  126.                     jsonObject.put("time",data.getCreateDate());
  127.                     return  jsonObject.toJSONString();
  128.                 })
  129.                 .ToString();
  130.         System.out.println(s);
  132.     }
  133. }

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原文链接 : https://huanmin.blog.csdn.net/article/details/125354037

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