Java-对象转CSV

爱被打了一巴掌 2023-10-02 19:57 12阅读 0赞

### 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<T> {
        
    
        private String separator = "\u0001|\u0001";  //默认分隔符
        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;
            //行数
            this.number=1;
        }
        private ObjToCSV(T object) {
        
            this.object = object;
            //行数
            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;
            //行数
            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 <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;
        }
    
        //添加头部
        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;
        }
        //在结尾补充自定义的描述
        public ObjToCSV<T> addEnding(Function<ObjToCSV,String> 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<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;
        }
        //将多个对象转换为csv格式
        public ObjToCSV<T> 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());
                        jsonObject.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<UserData> 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<UserData> 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<UserData> 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<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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