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Java實(shí)現(xiàn)對(duì)象轉(zhuǎn)CSV格式

更新時(shí)間：2022年06月20日 09:33:00 作者：胡安民

CSV是一種逗號(hào)分隔值格式的文件，一般用來(lái)存儲(chǔ)數(shù)據(jù)的純文本格式文件。Java對(duì)象轉(zhuǎn)CSV,有現(xiàn)成的工具包,commons-lang3 的ReflectionToStringBuilder 就可以簡(jiǎn)單的解決的對(duì)象轉(zhuǎn)CSV，快跟隨小編一起學(xué)習(xí)一下吧

介紹

csv全稱(chēng)“Comma-Separated Values”，是一種逗號(hào)分隔值格式的文件，是一種用來(lái)存儲(chǔ)數(shù)據(jù)的純文本格式文件。CSV文件由任意數(shù)目的記錄組成，記錄間以某種換行符分隔；每條記錄由字段組成，字段間的分隔符是其它字符或字符串。

Java對(duì)象轉(zhuǎn)CSV,有現(xiàn)成的工具包,commons-lang3 的ReflectionToStringBuilder 就可以簡(jiǎn)單的解決的對(duì)象轉(zhuǎn)CSV 但是復(fù)雜點(diǎn)的處理還是不行,而且在運(yùn)行速度上,我測(cè)試了下我自己寫(xiě)的,比這個(gè)快多了,1百萬(wàn)條數(shù)據(jù)大約也就2秒左右, 如果對(duì)速度有要求的話(huà),我們可以使用多線(xiàn)程進(jìn)行分割,比如1千萬(wàn)條數(shù)據(jù),那么我開(kāi)10個(gè)線(xiàn)程,1個(gè)線(xiàn)程執(zhí)行100萬(wàn)條數(shù)據(jù),所有線(xiàn)程執(zhí)行完畢后在按照順序拼接到一起,這樣1千萬(wàn)條數(shù)據(jù)也就最多3~5秒執(zhí)行完畢

代碼樣例

package com.file.csv;

import com.date.LocalDateUtils;
import lombok.Data;
import lombok.SneakyThrows;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.function.Function;

/**
 * 對(duì)象轉(zhuǎn)csv格式
 *
 * @describe
 * 1百萬(wàn)數(shù)據(jù)測(cè)試 2~3秒
 * 調(diào)用順序如下(根據(jù)情況自行選擇)
 *         String s = ObjToCSV.create(userDatas)
 *                 .fieldsAll()   //轉(zhuǎn)換全部列
 *                 .addIncludeFields() //只包含某些列
 *                 .addExcludeFields("roleData") //排除某些列
 *                 .addHead() //添加頭部字段
 *                 .addContent() //一個(gè)對(duì)象(一行)
 *                 .addContents() //多個(gè)對(duì)象(多行)
 *                 .addEnding((data)->{ //結(jié)尾說(shuō)明
 *                     JSONObject jsonObject = new JSONObject();
 *                     jsonObject.put("count",data.getNumber());
 *                     jsonObject.put("time",data.getCreateDate());
 *                     return  jsonObject.toJSONString();
 *                 })
 *                 .ToString(); //結(jié)果
 */
@Data
public class ObjToCSV<T> {

    private String separator = "\u0001|\u0001";  //默認(rèn)分隔符
    private StringBuilder str = new StringBuilder();
    private T object;
    private List<T> objects;
    private List<String> excludeFields = new ArrayList<String>(100) {{
        add("serialVersionUID");
    }};
    private List<String> includeFields = new ArrayList<String>(100);
    private boolean fieldsAll = false;
    private  int number;//多少行一共
    //日期串 20220617204504
    private  String createDate=LocalDateUtils.getLocalDateTimeStr1() ;

    private ObjToCSV(T object, String separator) {
        this.object = object;
        this.separator = separator;
        //行數(shù)
        this.number=1;
    }
    private ObjToCSV(T object) {
        this.object = object;
        //行數(shù)
        this.number=1;

    }
    private ObjToCSV(List<T> objects) {
        if (objects.isEmpty()) {
            throw new NullPointerException("不能是空");
        }
        this.object = objects.get(0);
        this.objects = objects;
        //行數(shù)
        this.number=objects.size();
    }
    private ObjToCSV(List<T> objects, String separator) {
        if (objects.isEmpty()) {
            throw new NullPointerException("不能是空");
        }
        this.object = objects.get(0);
        this.objects = objects;
        this.separator = separator;
        //行數(shù)
        this.number=objects.size();

    }


    // 排除和包含都有,那么以包含的為主
    private boolean decideFields(String fieldName) {

        //包含
        if (includeFields.contains(fieldName)) {
            return false;
        }
        //排除
        if (excludeFields.contains(fieldName)) {
            return true;
        }

        // 開(kāi)啟全部放行
        if (fieldsAll) {
            return false;
        }

        //默認(rèn)攔截全部
        return true;
    }

    public static <T> ObjToCSV<T> create(T object, String separator) {
        return new ObjToCSV<T>(object, separator);
    }
    public static <T> ObjToCSV<T> create(T object) {
        return new ObjToCSV<T>(object);
    }
    public static <T> ObjToCSV<T> create(List<T> object, String separator) {
        return new ObjToCSV<T>(object, separator);
    }
    public static <T> ObjToCSV<T> create(List<T> object) {
        return new ObjToCSV<T>(object);
    }
    //全部放行
    public ObjToCSV<T> fieldsAll() {
        fieldsAll = true;
        return this;
    }

    //包含
    public ObjToCSV<T> addIncludeFields(String... fieldName) {
        includeFields.addAll(Arrays.asList(fieldName));
        return this;
    }

    //排除
    public ObjToCSV<T> addExcludeFields(String... fieldName) {
        excludeFields.addAll(Arrays.asList(fieldName));
        return this;
    }

    //添加頭部
    public ObjToCSV<T> addHead() {
        StringBuilder str1 = new StringBuilder();
        Class<?> aClass = this.object.getClass();
        Field[] fields = aClass.getDeclaredFields();
        int length = fields.length;
        for (int i = 0; i < length; i++) {
            Field field = fields[i];
            field.setAccessible(true);
            if (decideFields(field.getName())) {
                continue;
            }
            str1.append(field.getName()).append(separator);
        }
        int length1 = separator.length();
        String substring = str1.substring(0, str1.length() - length1);
        this.str.append(substring + "\n");
        return this;
    }
    //在結(jié)尾補(bǔ)充自定義的描述
    public ObjToCSV<T> addEnding(Function<ObjToCSV,String> functor){
        String apply = functor.apply( this);
        this.str.append(apply);
        return this;
    }


    //將對(duì)象轉(zhuǎn)換為CSV格式字符串
    @SneakyThrows
    public ObjToCSV<T> addContent() {
        StringBuilder str1 = new StringBuilder();
        Class<?> aClass = this.object.getClass();
        Field[] fields = aClass.getDeclaredFields();
        int length = fields.length;
        for (int i = 0; i < length; i++) {
            Field field = fields[i];
            field.setAccessible(true);
            if (decideFields(field.getName())) {
                continue;
            }
            Object o = field.get(object);
            String value = "";
            if (o != null) {
                value = String.valueOf(o);
            }
            str1.append(value).append(separator);
        }
        int length1 = separator.length();
        String substring = str1.substring(0, str1.length() - length1);
        this.str.append(substring + "\n");

        return this;
    }
    //將多個(gè)對(duì)象轉(zhuǎn)換為csv格式
    public ObjToCSV<T> addContents() {
        for (T t : this.objects) {
            this.object=t;
            addContent();
        }
        return this;
    }
    //將結(jié)果輸出為字符串
    public String ToString() {
        return str.toString();
    }



}

測(cè)試樣例

package com.file;

import com.alibaba.fastjson.JSONObject;
import com.data.RandomUserData;
import com.entity.UserData;
import com.file.csv.ObjToCSV;
import com.file.csv.ObjToCSV;
import com.function.impl.CodeStartAndStopTimeUtil;
import lombok.SneakyThrows;
import org.junit.Test;

import java.util.List;

public class ObjToCSVTest {


    //單個(gè)對(duì)象
    @Test
    public  void show1(){
        UserData userOne = RandomUserData.getUserOne();
        String s = ObjToCSV.create(userOne)
                .fieldsAll()
//                .addIncludeFields()
                .addExcludeFields("roleData")
//                .addHead()
                .addContent()
//                .addContents()
                .addEnding((data)->{
                    JSONObject jsonObject = new JSONObject();
                    jsonObject.put("count",data.getNumber());
                    jsonObject.put("time",data.getCreateDate());
                    jsonObject.put("separator",data.getSeparator());
                    return  jsonObject.toJSONString();
                })
                .ToString();
        System.out.println(s);

    }


    //多個(gè)對(duì)象,可以使用自定義分隔符
    @Test
    public  void show2(){
        UserData userOne = RandomUserData.getUserOne();
        String s = ObjToCSV.create(userOne,"|")
                .fieldsAll()
                .addExcludeFields("roleData")
                .addContent()
                .addEnding((data)->{
                    JSONObject jsonObject = new JSONObject();
                    jsonObject.put("count",data.getNumber());
                    jsonObject.put("time",data.getCreateDate());
                    jsonObject.put("separator",data.getSeparator());
                    return  jsonObject.toJSONString();
                })
                .ToString();
        System.out.println(s);
    }



    //排除不顯示的,其他都顯示
    @Test
    public  void show3(){
        List<UserData> userDatas = RandomUserData.getUserDatas(10);

        String s = ObjToCSV.create(userDatas,"|")
                .fieldsAll()//顯示全部字段
                .addExcludeFields("roleData")//排除指定字段
                .addHead()
                .addContents()
                .addEnding((data)->{
                    JSONObject jsonObject = new JSONObject();
                    jsonObject.put("count",data.getNumber());
                    jsonObject.put("time",data.getCreateDate());
                    jsonObject.put("separator",data.getSeparator());

                    return  jsonObject.toJSONString();
                })
                .ToString();
        System.out.println(s);
    }

    //只包含指定字段 ,其他都不顯示
    @Test
    public  void show4(){
        List<UserData> userDatas = RandomUserData.getUserDatas(10);

        String s = ObjToCSV.create(userDatas,"|")
                .addIncludeFields("id","name")
                .addHead()  //添加頭部
                .addContents() //添加內(nèi)容
                .addEnding((data)->{  //添加結(jié)尾信息
                    JSONObject jsonObject = new JSONObject();
                    jsonObject.put("count",data.getNumber());
                    jsonObject.put("time",data.getCreateDate());
                    jsonObject.put("separator",data.getSeparator());
                    return  jsonObject.toJSONString();
                })
                .ToString();
        System.out.println(s);
    }


    //內(nèi)容
    @Test
    public  void show5(){
        List<UserData> userDatas = RandomUserData.getUserDatas(10);
        String s = ObjToCSV.create(userDatas,"|")
                .fieldsAll()
                .addExcludeFields("roleData")//排除指定字段
                .addContents() //添加內(nèi)容
                .ToString();
        System.out.println(s);
    }

    @SneakyThrows
    public static void main(String[] args) {
        List<UserData> userDatas = RandomUserData.getUserDatas(100);
        String s = ObjToCSV.create(userDatas)
                .fieldsAll()
//                .addIncludeFields()
                .addExcludeFields("roleData")
//                .addHead()
//                .addContent()
                .addContents()
                .addEnding((data)->{
                    JSONObject jsonObject = new JSONObject();
                    jsonObject.put("count",data.getNumber());
                    jsonObject.put("time",data.getCreateDate());
                    return  jsonObject.toJSONString();
                })
                .ToString();
        System.out.println(s);


    }
}

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