Java实现对象转CSV格式

目录介绍代码样例测试样例

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

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;

/**

* 对象转csv格式

*

* @describe

* 1百万数据测试 2~3秒

* 调用顺序如下(根据情况自行选择)

* String s = ObjToCSV.create(userDatas)

* .fieldsAll() //转换全部列

* .addIncludeFields() //只包含某些列

* .addExcludeFields("roleData") //排除某些列

* .addHead() //添加头部字段

* .addContent() //一个对象(一行)

* .addContents() //多个对象(多行)

* .addEnding((data)->{ //结尾说明

* jsONObject jsonObject = new JSONObject();

* jsonObject.put("count",data.getNumber());

* jsonObject.put("time",data.getCreateDate());

* return jsonObject.toJSONString();

* })

* .ToString(); //结果

*/

@Data

public class ObjToCSV {

private String separator = "\u0001|\u0001"; //默认分隔符

private StringBuilder str = new StringBuilder();

private T object;

private List objects;

private List excludeFields = new ArrayList(100) {{

add("serialVersionUID");

}};

private List includeFields = new ArrayList(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;

//行数

this.number=1;

}

private ObjToCSV(T object) {

this.object = object;

//行数

this.number=1;

}

private ObjToCSV(List objects) {

if (objects.isEmpty()) {

throw new NullPointerException("不能是空");

}

this.object = objects.get(0);

this.objects = objects;

//行数

this.number=objects.size();

}

private ObjToCSV(List objects, String separator) {

if (objects.isEmpty()) {

throw new NullPointerException("不能是空");

}

this.object = objects.get(0);

this.objects = objects;

this.separator = separator;

//行数

this.number=objects.size();

}

// 排除和包含都有,那么以包含的为主

private boolean decideFields(String fieldName) {

//包含

if (includeFields.contains(fieldName)) {

return false;

}

//排除

if (excludeFields.contains(fieldName)) {

return true;

}

// 开启全部放行

if (fieldsAll) {

return false;

}

//默认拦截全部

return true;

}

public static ObjToCSV create(T object, String separator) {

return new ObjToCSV(object, separator);

}

public static ObjToCSV create(T object) {

return new ObjToCSV(object);

}

public static ObjToCSV create(List object, String separator) {

return new ObjToCSV(object, separator);

}

public static ObjToCSV create(List object) {

return new ObjToCSV(object);

}

//全部放行

public ObjToCSV fieldsAll() {

fieldsAll = true;

return this;

}

//包含

public ObjToCSV addIncludeFields(String... fieldName) {

includeFields.addAll(Arrays.asList(fieldName));

return this;

}

//排除

public ObjToCSV addExcludeFields(String... fieldName) {

excludeFields.addAll(Arrays.asList(fieldName));

return this;

}

//添加头部

public ObjToCSV addHead() {

StringBuilder str1 = new StringBuilder();

Class> aClass = this.object.getClass();

Field[] fields = aClass.getDeclaredFields();

int length = fields.length;

for (int i = 0; ihttp:// < 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;

}

//在结尾补充自定义的描述

public ObjToCSV addEnding(Function functor){

String apply = functor.apply( this);

this.str.append(apply);

return this;

}

//将对象转换为CSV格式字符串

@SneakyThrows

public ObjToCSV 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;

}

//将多个对象转换为csv格式

public ObjToCSV addContents() {

for (T t : this.objects) {

this.object=t;

addContent();

}

return this;

}

//将结果输出为字符串

public String ToString() {

return str.toString();

}

}

测试样例

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 {

//单个对象

@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);

}

//多个对象,可以使用自定义分隔符

@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());

jsohttp://nObject.put("time",data.getCreateDate());

jsonObject.put("separator",data.getSeparator());

return jsonObject.toJSONString();

})

.ToString();

System.out.println(s);

}

//排除不显示的,其他都显示

@Test

public void show3(){

List userDatas = RandomUserData.getUserDatas(10);

String s = ObjToCSV.create(userDatas,"|")

.fieldsAll()//显示全部字段

.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 ,其他都不显示

@Test

public void show4(){

List userDatas = RandomUserData.getUserDatas(10);

String s = ObjToCSV.create(userDatas,"|")

.addIncludeFields("id","name")

.addHead() //添加头部

.addContents() //添加内容

.addEnding((data)->{ //添加结尾信息

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);

}

//内容

@Test

public void show5(){

List userDatas = RandomUserData.getUserDatas(10);

String s = ObjToCSV.create(userDatas,"|")

.fieldsAll()

.addExcludeFields("roleData")//排除指定字段

.addContents() //添加内容

.ToString();

System.out.println(s);

}

@SneakyThrows

public static void main(String[] args) {

List 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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