java csv - 讀寫及其操做.

時間 2019-11-25

標籤 java csv 讀寫及其欄目 Java 简体版

原文原文鏈接

　　今天幫同窗處理數據, 主要是從1w多條記錄中隨機獲取8k條, 而後再從8k條記錄中隨機獲取2k條記錄. 最後將2k條記錄中隨機分紅10組,使得每組的記錄都不重複.java

　　下面將個人代碼都貼上來, 好之後處理csv文件.sql

　　首先使用第三方的jar文件 javcsv.jar : 連接: http://pan.baidu.com/s/1qW5b3u0 密碼: qjmx

　　雖然該類庫能夠相對方便提供操做, 可是爲了方便處理, 我將處理的字段都放在配置文件中, 而後將每一條記錄都封裝爲Map<String, String>對象,我將讀寫的基礎類封裝爲 CSVBasic:

package spt.csv;

import java.io.Serializable;
import java.nio.charset.Charset;

import spt.util.PropertyConfig;

/**
 * CSV文件操做基礎類.
 */
abstract public class CSVBasic implements Serializable {

    private Charset charset;    //編碼.
    private char delimiter;    //分隔符.
    private String fileName;

    /**
     * 默認編碼.
     * 
     * @return
     */
    public static Charset getDefaultCharset() {
        return Charset.forName(PropertyConfig.getProperty("charset"));
    }

    /**
     * 默認分割符.
     * 
     * @return
     */
    public static char getDefaultDelimiter() {
        return PropertyConfig.getProperty("delimiter").charAt(0);
    }
    
    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    public Charset getCharset() {
        return charset;
    }

    public void setCharset(Charset charset) {
        this.charset = charset;
    }

    public void setDelimiter(char delimiter) {
        this.delimiter = delimiter;
    }

    public char getDelimiter() {
        return delimiter;
    }

    public CSVBasic() {}
    
    /**使用默認的分隔符和編碼.
     * @param fileName
     */
    public CSVBasic(String fileName) {
        this(fileName, getDefaultDelimiter(), getDefaultCharset());
    }
    
    public CSVBasic(String fileName, char delimiter, Charset charset) {
        setFileName(fileName);
        setDelimiter(delimiter);
        setCharset(charset);
    }

    /**
     * 
     */
    private static final long serialVersionUID = 7916808982930771124L;
}

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　　3.讀取csv文件,並映射記錄爲List<Map<String, String>> 對象:dom

package spt.csv;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import spt.util.PropertyConfig;

import com.csvreader.CsvReader;

/**
 * 讀取csv文件的類.
 */
public class Reader extends CSVBasic {

    private CsvReader reader;

    public CsvReader getReader() {
        return reader;
    }

    public void setReader(CsvReader reader) {
        this.reader = reader;
    }

    public Reader(String fileName) throws FileNotFoundException {
        this(fileName, getDefaultDelimiter(), getDefaultCharset());
    }

    public Reader(String fileName, char delimiter, Charset charset)
            throws FileNotFoundException {
        // set before getting.
        super(fileName, delimiter, charset);
        setReader(new CsvReader(fileName, delimiter, charset));
    }

    /**根據字段列表,見每條記錄映射爲一個Map對象的列表.
     * @param fieldNames
     *            指定配置文件中字段名的'鍵'的列表.
     * @return
     */
    public List<Map<String, String>> getResult(List<String> fieldNames) {
        // 每行中的每個項是一個Map<String, String>的鍵值對.
        List<Map<String, String>> lines = new ArrayList<Map<String, String>>();

        CsvReader r = null;
        try {
            r = getReader();
            r.readHeaders(); // 讀取表頭.

            Map<String, String> itemMap = null; // 每一條記錄是一個Map<String, String>.
            while (r.readRecord()) {
                itemMap = new HashMap<String, String>();
                String k = null;
                // 每一條記錄添加鍵值對.
                for (String fieldName : fieldNames) {
                    // 字段名.
                    k = PropertyConfig.getProperty(fieldName);
                    itemMap.put(k, r.get(k));
                }
                lines.add(itemMap);
            }
            return lines;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        } finally {
            if(r != null)
                r.close();
        }
    }

    @Override
    public String toString() {
        return getFileName();
    }

    /**
     * 
     */
    private static final long serialVersionUID = -1712774594374451546L;
}

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4.將List<Map<String, String>>輸出爲csv文件的類:ide

package spt.csv;

import java.io.IOException;
import java.nio.charset.Charset;
import java.util.List;
import java.util.Map;

import com.csvreader.CsvWriter;

/**
 * csv文件寫入類.
 */
public class Writer extends CSVBasic {

    private CsvWriter writer = null;

    public boolean write(List<String> fieldNames,
            List<Map<String, String>> mapList) {
        CsvWriter writer = null;
        try {
            writer = getWriter();
            // 寫入表頭.
            writer.writeRecord((String[]) fieldNames
                    .toArray(new String[fieldNames.size()]));
            for (Map<String, String> map : mapList) {
                // 存儲每行記錄.
                String[] records = new String[fieldNames.size()];
                for (int i = 0; i < fieldNames.size(); i++)
                    records[i] = map.get(fieldNames.get(i));
                // 寫入每行記錄.
                writer.writeRecord(records);
            }
            return true;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return false;
        } finally {
            if (writer != null)
                writer.close();
        }
    }

    public Writer() {
        this(null, getDefaultDelimiter(), getDefaultCharset());
    }

    public Writer(String fileName) {
        this(fileName, getDefaultDelimiter(), getDefaultCharset());
    }

    public Writer(String fileName, char delimiter, Charset charset) {
        super(fileName, delimiter, charset);
        writer = new CsvWriter(fileName, delimiter, charset);
    }

    public CsvWriter getWriter() {
        return writer;
    }

    public void setWriter(CsvWriter writer) {
        this.writer = writer;
    }

    /**
     * 
     */
    private static final long serialVersionUID = -9141083858975437622L;
}

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5.表中有一個字段NYR, 表示時間, 因爲須要將結果按照時間的前後順序排序, 因此定義一個比較器:工具

package spt.csv;

import java.text.ParseException;
import java.util.Comparator;
import java.util.Map;

import spt.util.DateService;
import spt.util.PropertyConfig;

/**
 *每條記錄是一個Map對象,按照每條記錄中的'時間'的列進行排序.
 */
public class RecordDateComparator implements Comparator<Map<String, String>> {

    @Override
    public int compare(Map<String, String> m1, Map<String, String> m2) {
        try {
            long l01 = DateService.getDate(m1.get(PropertyConfig.getProperty("NYR"))).getTime();
            long l02 = DateService.getDate(m2.get(PropertyConfig.getProperty("NYR"))).getTime();
            //long的範圍和int的範圍不一樣.
            long diff = l01 - l02;
            if(diff < 0)
                return -1;
            else if(diff > 0)
                return 1;
            return 0;
        } catch (ParseException e) {
            e.printStackTrace();
            return 0;
        }
    }

}

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6,在main類中:this

package spt.csv;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Random;

import spt.util.PropertyConfig;

/**
 * 從1w多條記錄中先選出8k條,而後在8k條記錄中選出2k條,最後將2k條記錄分紅10組.
 */
public class ReadWriteDemo {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // if (args.length < 1)
        // throw new NullPointerException("請指定文件路徑");
        System.out.println("執行中...執行過程請不要關閉此窗口!");
        final int first_size = Integer.parseInt(PropertyConfig
                .getProperty("first_size")); // 初次提取長度(8k).
        final int second_size = Integer.parseInt(PropertyConfig
                .getProperty("second_size")); // 初次提取(2k).
        final int groupCount = Integer.parseInt(PropertyConfig
                .getProperty("groupCount")); // 分組個數(10).
        String file = PropertyConfig.getProperty("input_file"); // 源文件路徑.

        List<String> fieldNames = null;
        try {
            fieldNames = initFields();
            Reader csv = new Reader(file);
            // 總記錄.
            List<Map<String, String>> totalList = csv.getResult(fieldNames);
            // 初次提取的值(8k).
            List<Map<String, String>> firstTaken = random(totalList, first_size);
            // 再次提取的值(2k).
            List<Map<String, String>> secondTaken = random(firstTaken,
                    second_size);
            // 每組記錄數(2百).
            List<Map<String, String>> tmpTaken = secondTaken;
            for (int i = 0; i < groupCount; i++) {
                List<Map<String, String>> AGroupTaken = random(tmpTaken,
                        second_size / groupCount);
                // 除去上次已經使用的元素.
                tmpTaken.removeAll(AGroupTaken);
                // 在當前目錄上輸出(並驗證是否存在).
                String outputFile = null;
                // 若是文件已存在,則自動命名.
                int fileCount = 0;
                do {
                    outputFile = "result" + fileCount++ + ".csv";
                } while (new File(outputFile).exists());
                Writer writer = new Writer(outputFile);
                // (集合)排序.
                Collections.sort(AGroupTaken, new RecordDateComparator());
                writer.write(fieldNames, AGroupTaken);
            }
            System.out.println("done!");
        } catch (FileNotFoundException e) {
            System.out.println("請指定正確的文件路徑!");
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * 隨機產生新的列表(長度比原來小).
     * 
     * @param originalList
     *            輸入列表.
     * @param new_size
     *            新列表的長度.
     */
    public static List<Map<String, String>> random(
            List<Map<String, String>> originalList, int new_size) {
        if (new_size <= 0 || new_size > originalList.size())
            throw new IndexOutOfBoundsException("新列表的長度錯誤!");
        List<Map<String, String>> newList = new ArrayList<Map<String, String>>(
                new_size);
        // 標識是否已被提取.
        boolean[] taken = new boolean[originalList.size()];
        Random r = new Random();
        Map<String, String> map = null; // 即將獲取的元素.
        int rIdx = 0;
        for (int i = 0; i < new_size; i++) {
            do {
                rIdx = r.nextInt(new_size);
                map = originalList.get(rIdx);
            } while (taken[rIdx]); // 若是發現已經提取,則重複操做.
            taken[rIdx] = true; // 標識已被提取.
            newList.add(map);
        }

        return newList;
    }

    private static List<String> initFields() {
        // 全部字段.
        List<String> fieldNames = new ArrayList<String>(14);
        fieldNames.add("id");
        fieldNames.add("AJMC");
        fieldNames.add("JYAQ");
        fieldNames.add("AJLB");
        fieldNames.add("AJFAB");
        fieldNames.add("AJZT");
        fieldNames.add("BASJ");
        fieldNames.add("FXSJ");
        fieldNames.add("FASJSX");
        fieldNames.add("FASJXX");
        fieldNames.add("AJBH");
        fieldNames.add("ZBX");
        fieldNames.add("ZBY");
        fieldNames.add("NYR");
        
        return fieldNames;
    }
}

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7,用到的自定義工具類爲:編碼

package spt.util;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
 * 2015-2-27 提供日期轉換的工具類.
 */
public class DateService {
    // 定義稱線程共享,而不是沒調用一次就建立一個對象.
    private static DateFormat formater = new SimpleDateFormat(PropertyConfig.getProperty("date_format"));

    /**
     * 將字符串類型的日期轉換爲Date.
     * 
     * @param strDate
     * @return
     * @throws ParseException
     */
    public static Date getDate(String strDate) throws ParseException {
        // 若是輸入爲空,則返回null.
        if (Str.isEmpty(strDate))
            return null;
        return formater.parse(strDate);
    }

    /**
     * 將java.util.Date轉換爲java.sql.Date;用於諸如'PreparedStatement.setDate'方法.
     * 
     * @param utilDate
     * @return
     */
    public static java.sql.Date getSQLDate(java.util.Date utilDate) {
        if (utilDate == null)
            return null;
        return new java.sql.Date(utilDate.getTime());
    }

    /**
     * 將指定的日期轉換爲
     * 
     * @param date
     * @return
     */
    public static String getDateStr(java.util.Date date) {
        if (date == null)
            return null;
        return formater.format(date);
    }


    /**
     * 計算指定日期與今天的間隔,判斷是不是須要日期. disDay表示與今天相隔天數,0:等於今天;1:明天;-1:昨天.
     * 
     * @param anotherDate
     * @param disDay
     * @return
     */
    public static boolean isSpecifiedDay(Date anotherDate, int disDay) {
        if (anotherDate == null)
            return false;
        Calendar cNow = Calendar.getInstance();
        cNow.setTime(new Date()); // 每調用一次,都是與當前時間作比較.
        cNow.add(Calendar.DAY_OF_MONTH, disDay);

        Calendar cAnotherDate = Calendar.getInstance();
        cAnotherDate.setTime(anotherDate);

        return cNow.get(Calendar.YEAR) == cAnotherDate.get(Calendar.YEAR)
                && cNow.get(Calendar.MONTH) == cAnotherDate.get(Calendar.MONTH)
                && cNow.get(Calendar.DAY_OF_MONTH) == cAnotherDate.get(Calendar.DAY_OF_MONTH);
    }
}

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package spt.util;

import java.io.IOException;
import java.net.URL;
import java.util.Properties;


/**
 * 2015-2-27
 */
public class PropertyConfig {
    
    /**
     * @param key
     * @return
     */
    public static String getProperty(String key) {
        Properties properties = getProperties();
        return properties.getProperty(key);
    }

    /**
     * @param resources
     * @return
     */
    public static Properties getProperties() {
        final String configFilePath = "raw/properties.properties";
        URL url = PropertyConfig.class.getClassLoader().getResource(configFilePath);
        Properties props = new Properties();
        try {
            props.load(url.openStream());
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        } 
        return props;
    }
}

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package spt.util;

/**
 *字符串工具類.
 */
public class Str {
    /**
     * 判斷一個字符串是否有內容.
     * 
     * @param str
     * @return 若是不不爲空,則返回true,不然返回false.
     */
    public static boolean hasLength(String str) {
        return !isEmpty(str);
    }
    
    /**判斷字符串是否爲空.
     * @param str
     * @return
     */
    public static boolean isEmpty(String str) {
        return str == null || str.isEmpty();
    }
}