# super-csv

**Repository Path**: outllok/super-csv

## Basic Information

- **Project Name**: super-csv
- **Description**: 使用super-csv官方提供的例子-简化版
- **Primary Language**: Java
- **License**: Apache-2.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2019-05-08
- **Last Updated**: 2020-12-19

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# super-csv

#### 介绍
使用super-csv官方提供的例子-简化版


1. github下载地址

      https://github.com/super-csv/super-csv

      需要的jar     super-csv-2.4.0.jar

2. 写入

 方式一  使用CsvBeanWriter

```
import org.supercsv.cellprocessor.FmtBool;
import org.supercsv.cellprocessor.FmtDate;
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.LMinMax;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.prefs.CsvPreference;
import java.io.FileWriter;
import java.util.Arrays;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.List;

public class Write {


    //第一步 定义单元格约束 若出错，会生成一张只有表头而没有内容的csv文件
    private static CellProcessor[] getProcessors() {

        final CellProcessor[] processors = new CellProcessor[] {
                new UniqueHashCode(), // customerNo (must be unique) 唯一值
                new NotNull(), // firstName //不允许为空null 但可以是 ""
                new NotNull(), // lastName
                new FmtDate("dd/MM/yyyy"), // birthDate 日期的格式
                new NotNull(), // mailingAddress
                new Optional(new FmtBool("Y", "N")), //married 可为空 true->Y false->N
                new Optional(), // numberOfKids
                new NotNull(), // favouriteQuote
                new NotNull(), // email
                new LMinMax(0L, LMinMax.MAX_LONG) // loyaltyPoints
        };

        return processors;
    }

    //第二步 写入内容到csv文件中  特殊字符使用\转义  \n换行
    private static void writeWithCsvBeanWriter() throws Exception {

        // 创建自定义的实体类
        final CustomerBean john = new CustomerBean(
                "1", "John", "Dunbar",
                 new GregorianCalendar(1945, Calendar.JUNE, 13).getTime(),
                "1600 Amphitheatre Parkway\nMountain View, CA 94043\nUnited States",
                null, null,
                "\"May the Force be with you.\" - Star Wars",
                "jdunbar@gmail.com", 0L);

        final CustomerBean bob = new CustomerBean(
                "2", "Bob", "Down",
                 new GregorianCalendar(1919, Calendar.FEBRUARY, 25).getTime(),
                "1601 Willow Rd.\nMenlo Park, CA 94025\nUnited States",
                true, 0,
                "\"Frankly, my dear, I don't give a damn.\" - Gone With The Wind",
                "bobdown@hotmail.com", 123456L);

        final List<CustomerBean> customers = Arrays.asList(john, bob);


        ICsvBeanWriter beanWriter = null;
        try {
            beanWriter = new CsvBeanWriter(new FileWriter("/writeWithCsvBeanWriter.csv"),
                    CsvPreference.STANDARD_PREFERENCE);

            // 定义表头元素的值
            final String[] header = new String[] { "customerNo", "firstName", "lastName", "birthDate",
                    "mailingAddress", "married", "numberOfKids", "favouriteQuote", "email", "loyaltyPoints" };
            final CellProcessor[] processors = getProcessors();
            //写入表头
            beanWriter.writeHeader(header);
            // 写入数据
            for(final CustomerBean customer : customers ) {
                beanWriter.write(customer, header, processors);
            }
        }
        finally {
            if( beanWriter != null ) {
                beanWriter.close();
            }
        }
    }

    public static void main(String[] args)  throws Exception{

        writeWithCsvBeanWriter();
    }

}



public class CustomerBean {
    
       private String customerNo;
       private String firstName;
       private String lastName;
       private Date birthDate;
       private String   mailingAddress;
       private Boolean   married;
       private Integer numberOfKids;
       private String   favouriteQuote;
       private String    email;
       private Long    loyaltyPoints;

       //….省略get/set 构造方法


}

```


方式二   使用 CsvListWriter  不推荐 除非没有其它的实现方式

```
import org.supercsv.cellprocessor.FmtBool;
import org.supercsv.cellprocessor.FmtDate;
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.LMinMax;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.CsvListWriter;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.io.ICsvListWriter;
import org.supercsv.prefs.CsvPreference;

import java.io.FileWriter;
import java.util.Arrays;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.List;

public class CsvListWriterTest {


    //第一步 定义单元格约束 若出错，会生成一张只有表头而没有内容的csv文件
    private static CellProcessor[] getProcessors() {

        final CellProcessor[] processors = new CellProcessor[] {
                new UniqueHashCode(), // customerNo (must be unique) 唯一值
                new NotNull(), // firstName //不允许为空null 但可以是 ""
                new NotNull(), // lastName
                new FmtDate("dd/MM/yyyy"), // birthDate 日期的格式
                new NotNull(), // mailingAddress
                new Optional(new FmtBool("Y", "N")), //married 可为空 true->Y false->N
                new Optional(), // numberOfKids
                new NotNull(), // favouriteQuote
                new NotNull(), // email
                new LMinMax(0L, LMinMax.MAX_LONG) // loyaltyPoints
        };

        return processors;
    }

    //第二步 写入内容到csv文件中  特殊字符使用\转义  \n换行
    private static void writeWithCsvListWriter() throws Exception {

        // create the customer Lists (CsvListWriter also accepts arrays!)
        final List<Object> john = Arrays.asList(new Object[]
                { "1", "John", "Dunbar",
                new GregorianCalendar(1945, Calendar.JUNE, 13).getTime(),
                "1600 Amphitheatre Parkway\nMountain View, CA 94043\nUnited States", null, null,
                "\"May the Force be with you.\" - Star Wars",
                        "jdunbar@gmail.com", 0L });

        final List<Object> bob = Arrays.asList(new Object[] { "2", "Bob", "Down",
                new GregorianCalendar(1919, Calendar.FEBRUARY, 25).getTime(),
                "1601 Willow Rd.\nMenlo Park, CA 94025\nUnited States", true, 0,
                "\"Frankly, my dear, I don't give a damn.\" - Gone With The Wind", "bobdown@hotmail.com", 123456L });

        ICsvListWriter listWriter = null;
        try {
            listWriter = new CsvListWriter(new FileWriter("/writeWithCsvListWriter.csv"),
                    CsvPreference.STANDARD_PREFERENCE);

            final CellProcessor[] processors = getProcessors();
            final String[] header = new String[] { "customerNo", "firstName", "lastName", "birthDate",
                    "mailingAddress", "married", "numberOfKids", "favouriteQuote", "email", "loyaltyPoints" };

            // write the header
            listWriter.writeHeader(header);

            // write the customer lists
            listWriter.write(john, processors);
            listWriter.write(bob, processors);

        }
        finally {
            if( listWriter != null ) {
                listWriter.close();
            }
        }
    }

    public static void main(String[] args)  throws Exception{

        writeWithCsvListWriter();
    }

}

```



方式3 使用CsvMapWriter
如果不能使用csvbeanwriter，csvmapwriter是一个很好的折衷方案

```
import org.supercsv.cellprocessor.FmtBool;
import org.supercsv.cellprocessor.FmtDate;
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.LMinMax;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.CsvMapWriter;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.io.ICsvMapWriter;
import org.supercsv.prefs.CsvPreference;
import java.io.FileWriter;
import java.util.*;

public class CsvMapWriterTest {


    //第一步 定义单元格约束 若出错，会生成一张只有表头而没有内容的csv文件
    private static CellProcessor[] getProcessors() {

        final CellProcessor[] processors = new CellProcessor[] {
                new UniqueHashCode(), // customerNo (must be unique) 唯一值
                new NotNull(), // firstName //不允许为空null 但可以是 ""
                new NotNull(), // lastName
                new FmtDate("dd/MM/yyyy"), // birthDate 日期的格式
                new NotNull(), // mailingAddress
                new Optional(new FmtBool("Y", "N")), //married 可为空 true->Y false->N
                new Optional(), // numberOfKids
                new NotNull(), // favouriteQuote
                new NotNull(), // email
                new LMinMax(0L, LMinMax.MAX_LONG) // loyaltyPoints
        };

        return processors;
    }
    //第二步 写入内容到csv文件中  特殊字符使用\转义  \n换行
    private static void writeWithCsvMapWriter() throws Exception {

        final String[] header = new String[] { "customerNo", "firstName", "lastName", "birthDate", "mailingAddress",
                "married", "numberOfKids", "favouriteQuote", "email", "loyaltyPoints" };

        // create the customer Maps (using the header elements for the column keys)
        final Map<String, Object> john = new HashMap<String, Object>();
        john.put(header[0], "1");
        john.put(header[1], "John");
        john.put(header[2], "Dunbar");
        john.put(header[3], new GregorianCalendar(1945, Calendar.JUNE, 13).getTime());
        john.put(header[4], "1600 Amphitheatre Parkway\nMountain View, CA 94043\nUnited States");
        john.put(header[5], null);
        john.put(header[6], null);
        john.put(header[7], "\"May the Force be with you.\" - Star Wars");
        john.put(header[8], "jdunbar@gmail.com");
        john.put(header[9], 0L);

        final Map<String, Object> bob = new HashMap<String, Object>();
        bob.put(header[0], "2");
        bob.put(header[1], "Bob");
        bob.put(header[2], "Down");
        bob.put(header[3], new GregorianCalendar(1919, Calendar.FEBRUARY, 25).getTime());
        bob.put(header[4], "1601 Willow Rd.\nMenlo Park, CA 94025\nUnited States");
        bob.put(header[5], true);
        bob.put(header[6], 0);
        bob.put(header[7], "\"Frankly, my dear, I don't give a damn.\" - Gone With The Wind");
        bob.put(header[8], "bobdown@hotmail.com");
        bob.put(header[9], 123456L);

        ICsvMapWriter mapWriter = null;
        try {
            mapWriter = new CsvMapWriter(new FileWriter("/writeWithCsvMapWriter.csv"),
                    CsvPreference.STANDARD_PREFERENCE);

            final CellProcessor[] processors = getProcessors();

            // write the header
            mapWriter.writeHeader(header);

            // write the customer maps
            mapWriter.write(john, header, processors);
            mapWriter.write(bob, header, processors);

        }
        finally {
            if( mapWriter != null ) {
                mapWriter.close();
            }
        }
    }

    public static void main(String[] args)  throws Exception{

        writeWithCsvMapWriter();
    }

}

```


3.读取
   
方式一   CsvBeanReader

```
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.ParseBool;
import org.supercsv.cellprocessor.ParseDate;
import org.supercsv.cellprocessor.ParseInt;
import org.supercsv.cellprocessor.constraint.LMinMax;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.StrRegEx;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanReader;
import org.supercsv.io.ICsvBeanReader;
import org.supercsv.prefs.CsvPreference;
import java.io.FileReader;


public class TestCsvBeanReader {


    private static CellProcessor[] getProcessors() {

        final String emailRegex = "[a-z0-9\\._]+@[a-z0-9\\.]+"; // just an example, not very robust!
        StrRegEx.registerMessage(emailRegex, "must be a valid email address");

        final CellProcessor[] processors = new CellProcessor[] {
                new UniqueHashCode(), // customerNo (must be unique)
                new NotNull(), // firstName
                new NotNull(), // lastName
                new ParseDate("dd/MM/yyyy"), // birthDate
                new NotNull(), // mailingAddress
                new Optional(new ParseBool()), // married
                new Optional(new ParseInt()), // numberOfKids
                new NotNull(), // favouriteQuote
                new StrRegEx(emailRegex), // email
                new LMinMax(0L, LMinMax.MAX_LONG) // loyaltyPoints
        };

        return processors;
    }

    private static void readWithCsvBeanReader() throws Exception {

        ICsvBeanReader beanReader = null;
        try {
            beanReader = new CsvBeanReader(new FileReader("/readWithCsvBeanReader.csv"), CsvPreference.STANDARD_PREFERENCE);

            // the header elements are used to map the values to the bean (names must match)
            final String[] header = beanReader.getHeader(true);
            final CellProcessor[] processors = getProcessors();

            CustomerBean customer;
            while( (customer = beanReader.read(CustomerBean.class, header, processors)) != null ) {

                System.out.println(String.format(
                        "lineNo=%s, rowNo=%s, customer=%s",
                        beanReader.getLineNumber(),
                        beanReader.getRowNumber(),
                        customer));
            }

        }
        finally {
            if( beanReader != null ) {
                beanReader.close();
            }
        }
    }

    public static void main(String[] args) throws Exception{

        readWithCsvBeanReader();

    }
}

```
lineNo=4, rowNo=2, customer=CustomerBean{customerNo='1', firstName='John', lastName='Dunbar', birthDate=Wed Jun 13 00:00:00 CST 1945, mailingAddress='1600 Amphitheatre Parkway
Mountain View, CA 94043
United States', married=null, numberOfKids=null, favouriteQuote='"May the Force be with you." - Star Wars', email='jdunbar@gmail.com', loyaltyPoints=0}

lineNo=7, rowNo=3, customer=CustomerBean{customerNo='2', firstName='Bob', lastName='Down', birthDate=Tue Feb 25 00:00:00 CST 1919, mailingAddress='1601 Willow Rd.
Menlo Park, CA 94025
United States', married=true, numberOfKids=0, favouriteQuote='"Frankly, my dear, I don't give a damn." - Gone With The Wind', email='bobdown@hotmail.com', loyaltyPoints=123456}



方式二   CsvListReader

 ```
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.ParseBool;
import org.supercsv.cellprocessor.ParseDate;
import org.supercsv.cellprocessor.ParseInt;
import org.supercsv.cellprocessor.constraint.LMinMax;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.StrRegEx;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvListReader;
import org.supercsv.io.ICsvListReader;
import org.supercsv.prefs.CsvPreference;
import java.io.FileReader;
import java.util.List;

public class TestCsvListReader {
    private static CellProcessor[] getProcessors() {

        final String emailRegex = "[a-z0-9\\._]+@[a-z0-9\\.]+"; // just an example, not very robust!
        StrRegEx.registerMessage(emailRegex, "must be a valid email address");

        final CellProcessor[] processors = new CellProcessor[] {
                new UniqueHashCode(), // customerNo (must be unique)
                new NotNull(), // firstName
                new NotNull(), // lastName
                new ParseDate("dd/MM/yyyy"), // birthDate
                new NotNull(), // mailingAddress
                new Optional(new ParseBool()), // married
                new Optional(new ParseInt()), // numberOfKids
                new NotNull(), // favouriteQuote
                new StrRegEx(emailRegex), // email
                new LMinMax(0L, LMinMax.MAX_LONG) // loyaltyPoints
        };

        return processors;
    }

    private static void readWithCsvListReader() throws Exception {

        ICsvListReader listReader = null;
        try {
            listReader = new CsvListReader(new FileReader("/writeWithCsvBeanWriter.csv"), CsvPreference.STANDARD_PREFERENCE);

            listReader.getHeader(true); // skip the header (can't be used with CsvListReader)
            final CellProcessor[] processors = getProcessors();

            List<Object> customerList;
            while( (customerList = listReader.read(processors)) != null ) {
                System.out.println(String.format("lineNo=%s, rowNo=%s, customerList=%s", listReader.getLineNumber(),
                        listReader.getRowNumber(), customerList));
            }

        }
        finally {
            if( listReader != null ) {
                listReader.close();
            }
        }
    }

    public static void main(String[] args) throws Exception{

        readWithCsvListReader();

    }

}



lineNo=4, rowNo=2, customerList=[1, John, Dunbar, Wed Jun 13 00:00:00 CST 1945, 1600 Amphitheatre Parkway
Mountain View, CA 94043
United States, null, null, "May the Force be with you." - Star Wars, jdunbar@gmail.com, 0]


lineNo=7, rowNo=3, customerList=[2, Bob, Down, Tue Feb 25 00:00:00 CST 1919, 1601 Willow Rd.
Menlo Park, CA 94025
United States, true, 0, "Frankly, my dear, I don't give a damn." - Gone With The Wind, bobdown@hotmail.com, 123456]

方式三  CsvMapReader


import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.ParseBool;
import org.supercsv.cellprocessor.ParseDate;
import org.supercsv.cellprocessor.ParseInt;
import org.supercsv.cellprocessor.constraint.LMinMax;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.StrRegEx;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanReader;
import org.supercsv.io.CsvMapReader;
import org.supercsv.io.ICsvBeanReader;
import org.supercsv.io.ICsvMapReader;
import org.supercsv.prefs.CsvPreference;
import java.io.FileReader;
import java.util.Map;


public class TestCsvMapReader {


    private static CellProcessor[] getProcessors() {

        final String emailRegex = "[a-z0-9\\._]+@[a-z0-9\\.]+"; // just an example, not very robust!
        StrRegEx.registerMessage(emailRegex, "must be a valid email address");

        final CellProcessor[] processors = new CellProcessor[] {
                new UniqueHashCode(), // customerNo (must be unique)
                new NotNull(), // firstName
                new NotNull(), // lastName
                new ParseDate("dd/MM/yyyy"), // birthDate
                new NotNull(), // mailingAddress
                new Optional(new ParseBool()), // married
                new Optional(new ParseInt()), // numberOfKids
                new NotNull(), // favouriteQuote
                new StrRegEx(emailRegex), // email
                new LMinMax(0L, LMinMax.MAX_LONG) // loyaltyPoints
        };

        return processors;
    }

    private static void readWithCsvMapReader() throws Exception {

        ICsvMapReader mapReader = null;
        try {
            mapReader = new CsvMapReader(new FileReader("/writeWithCsvBeanWriter.csv"), CsvPreference.STANDARD_PREFERENCE);

            // the header columns are used as the keys to the Map
            final String[] header = mapReader.getHeader(true);
            final CellProcessor[] processors = getProcessors();

            Map<String, Object> customerMap;
            while( (customerMap = mapReader.read(header, processors)) != null ) {
                System.out.println(String.format("lineNo=%s, rowNo=%s, customerMap=%s", mapReader.getLineNumber(),
                        mapReader.getRowNumber(), customerMap));
            }

        }
        finally {
            if( mapReader != null ) {
                mapReader.close();
            }
        }
    }


    public static void main(String[] args) throws Exception{

        readWithCsvMapReader();

    }

}


lineNo=4, rowNo=2, customerMap={firstName=John, lastName=Dunbar, numberOfKids=null, mailingAddress=1600 Amphitheatre Parkway
Mountain View, CA 94043
United States, birthDate=Wed Jun 13 00:00:00 CST 1945, married=null, loyaltyPoints=0, customerNo=1, favouriteQuote="May the Force be with you." - Star Wars, email=jdunbar@gmail.com}


lineNo=7, rowNo=3, customerMap={firstName=Bob, lastName=Down, numberOfKids=0, mailingAddress=1601 Willow Rd.
Menlo Park, CA 94025
United States, birthDate=Tue Feb 25 00:00:00 CST 1919, married=true, loyaltyPoints=123456, customerNo=2, favouriteQuote="Frankly, my dear, I don't give a damn." - Gone With The Wind, email=bobdown@hotmail.com}





4.部分属性值的写入
   方式一  using CsvBeanWriter
   
  
import org.supercsv.cellprocessor.ConvertNullTo;
import org.supercsv.cellprocessor.FmtBool;
import org.supercsv.cellprocessor.FmtDate;
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.LMinMax;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.prefs.CsvPreference;

import java.io.FileWriter;
import java.util.Arrays;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.List;

public class partialWriteWithCsvBeanWriterTest {



    private static void partialWriteWithCsvBeanWriter() throws Exception {

        // create the customer beans
        final CustomerBean john = new CustomerBean(
                "1", "John", "Dunbar",
                 new GregorianCalendar(1945, Calendar.JUNE, 13).getTime(),
                "1600 Amphitheatre Parkway\nMountain View, CA 94043\nUnited States",
                null, null,
                "\"May the Force be with you.\" - Star Wars",
                "jdunbar@gmail.com", 0L);

        final CustomerBean bob = new CustomerBean(
                "2", "Bob", "Down",
                new GregorianCalendar(1919, Calendar.FEBRUARY, 25).getTime(),
                "1601 Willow Rd.\nMenlo Park, CA 94025\nUnited States",
                true, 0,
                "\"Frankly, my dear, I don't give a damn.\" - Gone With The Wind",
                "bobdown@hotmail.com", 123456L);

        final List<CustomerBean> customers = Arrays.asList(john, bob);

        ICsvBeanWriter beanWriter = null;
        try {
            beanWriter = new CsvBeanWriter(new FileWriter("/partialWriteWithCsvBeanWriter.csv"),
                    CsvPreference.STANDARD_PREFERENCE);

            // only map 5 of the 10 fields
            final String[] header = new String[] { "customerNo", "firstName", "lastName", "married", "numberOfKids" };

            // assign a default value for married (if null), and write numberOfKids as an empty column if null
            final CellProcessor[] processors = new CellProcessor[] {
                    //customerNo
                    new UniqueHashCode(),
                    //firstName
                    new NotNull(),
                    //lastName
                    new NotNull(),
                    //married 若为空显示no response;若为true显示yes,false显示no
                    new ConvertNullTo("no response", new FmtBool("yes", "no")),
                    //numberOfKids
                    new Optional()
            };

            // write the header
            beanWriter.writeHeader(header);

            // write the customer beans
            for( final CustomerBean customer : customers ) {
                beanWriter.write(customer, header, processors);
            }

        }
        finally {
            if( beanWriter != null ) {
                beanWriter.close();
            }
        }
    }

    public static void main(String[] args) throws Exception{

        partialWriteWithCsvBeanWriter();

    }

}


方式二    Partial writing with CsvListWriter

import org.supercsv.cellprocessor.ConvertNullTo;
import org.supercsv.cellprocessor.FmtBool;
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.CsvListWriter;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.io.ICsvListWriter;
import org.supercsv.prefs.CsvPreference;
import java.io.FileWriter;
import java.util.Arrays;
import java.util.List;

public class partialWriteWithCsvListWriterTest {
    

    private static void partialWriteWithCsvListWriter() throws Exception {

        final String[] header = new String[] { "customerNo", "firstName", "lastName", "married", "numberOfKids" };

        // create the customer Lists (CsvListWriter also accepts arrays!)
        final List<Object> john = Arrays.asList(new Object[] { "1", "John", "Dunbar",null, null});
        final List<Object> bob = Arrays.asList(new Object[] { "2", "Bob", "Down", true, 0 });

        ICsvListWriter listWriter = null;
        try {
            listWriter = new CsvListWriter(new FileWriter("/partialWriteWithCsvListWriter.csv"),
                    CsvPreference.STANDARD_PREFERENCE);

            // assign a default value for married (if null), and write numberOfKids as an empty column if null
            final CellProcessor[] processors = new CellProcessor[] {
                    new UniqueHashCode(),
                    new NotNull(),
                    new NotNull(),
                    new ConvertNullTo("no response", new FmtBool("yes", "no")),
                    new Optional()
            };

            // write the header
            listWriter.writeHeader(header);

            // write the customer Lists
            listWriter.write(john, processors);
            listWriter.write(bob, processors);

        }
        finally {
            if( listWriter != null ) {
                listWriter.close();
            }
        }
    }


    public static void main(String[] args) throws Exception{

        partialWriteWithCsvListWriter();

    }

}




方式三  Partial writing with CsvMapWriter

import org.supercsv.cellprocessor.ConvertNullTo;
import org.supercsv.cellprocessor.FmtBool;
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.CsvMapWriter;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.io.ICsvMapWriter;
import org.supercsv.prefs.CsvPreference;
import java.io.FileWriter;
import java.util.*;

public class partialWriteWithCsvMapWriterTest {


    private static void partialWriteWithCsvMapWriter() throws Exception {

        final String[] header = new String[] { "customerNo", "firstName", "lastName", "married", "numberOfKids" };

        // create the customer Maps (using the header elements for the column keys)
        final Map<String, Object> john = new HashMap<String, Object>();
        john.put(header[0], "1");
        john.put(header[1], "John");
        john.put(header[2], "Dunbar");
        john.put(header[3], null);
        john.put(header[4], null);

        final Map<String, Object> bob = new HashMap<String, Object>();
        bob.put(header[0], "2");
        bob.put(header[1], "Bob");
        bob.put(header[2], "Down");
        bob.put(header[3], true);
        bob.put(header[4], 0);

        ICsvMapWriter mapWriter = null;
        try {
            mapWriter = new CsvMapWriter(new FileWriter("/partialWriteWithCsvMapWriter.csv"),
                    CsvPreference.STANDARD_PREFERENCE);

            // assign a default value for married (if null), and write numberOfKids as an empty column if null
            final CellProcessor[] processors = new CellProcessor[] {
                    new UniqueHashCode(), new NotNull(),
                    new NotNull(),
                    new ConvertNullTo("no response", new FmtBool("yes", "no")),
                    null };

            // write the header
            mapWriter.writeHeader(header);

            // write the customer Maps
            mapWriter.write(john, header, processors);
            mapWriter.write(bob, header, processors);

        }
        finally {
            if( mapWriter != null ) {
                mapWriter.close();
            }
        }
    }

    public static void main(String[] args) throws Exception{

        partialWriteWithCsvMapWriter();

    }

}



5.读取csv文件，部分列的值
    方式一  Partial reading with CsvBeanReader
    
import org.supercsv.cellprocessor.ConvertNullTo;
import org.supercsv.cellprocessor.FmtBool;
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanReader;
import org.supercsv.io.CsvListWriter;
import org.supercsv.io.ICsvBeanReader;
import org.supercsv.io.ICsvListWriter;
import org.supercsv.prefs.CsvPreference;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.Arrays;
import java.util.List;

public class partialReadWithCsvBeanReaderTest {


    private static void partialReadWithCsvBeanReader() throws Exception {

        ICsvBeanReader beanReader = null;
        try {
            beanReader = new CsvBeanReader(new FileReader("/partialWriteWithCsvBeanWriter.csv"), CsvPreference.STANDARD_PREFERENCE);

            beanReader.getHeader(true); // skip past the header (we're defining our own)

            // only map the first 3 columns - setting header elements to null means those columns are ignored
            final String[] header = new String[] { "customerNo", "firstName", "lastName", null, null};

            // no processing required for ignored columns
            final CellProcessor[] processors = new CellProcessor[] {
                    new UniqueHashCode(),
                    new NotNull(),
                    new NotNull(),
                    null,
                    null};

            CustomerBean customer;
            while( (customer = beanReader.read(CustomerBean.class, header, processors)) != null ) {
                System.out.println(String.format("lineNo=%s, rowNo=%s, customer=%s", beanReader.getLineNumber(),
                        beanReader.getRowNumber(), customer));
            }

        }
        finally {
            if( beanReader != null ) {
                beanReader.close();
            }
        }
    }

    public static void main(String[] args) throws Exception{

        partialReadWithCsvBeanReader();

    }

}

```


lineNo=2, rowNo=2, customer=CustomerBean{customerNo='1', firstName='John', lastName='Dunbar', birthDate=null, mailingAddress='null', married=null, numberOfKids=null, favouriteQuote='null', email='null', loyaltyPoints=null}

lineNo=3, rowNo=3, customer=CustomerBean{customerNo='2', firstName='Bob', lastName='Down', birthDate=null, mailingAddress='null', married=null, numberOfKids=null, favouriteQuote='null', email='null', loyaltyPoints=null}


   
方式二  Partial reading with  CsvMapReader 
             读取的特点，若为空的字段值不显示

```
import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.LMinMax;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.io.CsvBeanReader;
import org.supercsv.io.CsvMapReader;
import org.supercsv.io.ICsvBeanReader;
import org.supercsv.io.ICsvMapReader;
import org.supercsv.prefs.CsvPreference;
import java.io.FileReader;
import java.util.Map;

public class partialReadWithCsvMapReaderTest {

    private static void partialReadWithCsvMapReader() throws Exception {

        ICsvMapReader mapReader = null;
        try {
            mapReader = new CsvMapReader(new FileReader("/partialWriteWithCsvBeanWriter.csv"), CsvPreference.STANDARD_PREFERENCE);

            mapReader.getHeader(true); // skip past the header (we're defining our own)

            // only map the first 3 columns - setting header elements to null means those columns are ignored
            final String[] header = new String[] { "customerNo", "firstName", "lastName", null, "numberOfKids" };

            // apply some constraints to ignored columns (just because we can)
            final CellProcessor[] processors = new CellProcessor[] {
                    new UniqueHashCode(),
                    new NotNull(),
                    new NotNull(),
                    new Optional(),
                    //读取该字段的值的范围，超出报错
                    new LMinMax(0L, LMinMax.MAX_LONG)
                     };

            Map<String, Object> customerMap;
            while( (customerMap = mapReader.read(header, processors)) != null ) {
                System.out.println(String.format("lineNo=%s, rowNo=%s, customerMap=%s", mapReader.getLineNumber(),
                        mapReader.getRowNumber(), customerMap));
            }

        }
        finally {
            if( mapReader != null ) {
                mapReader.close();
            }
        }
    }


    public static void main(String[] args) throws Exception{

        partialReadWithCsvMapReader();

    }}


lineNo=2, rowNo=2, customerMap={firstName=John, lastName=Dunbar, numberOfKids=34, customerNo=1}

lineNo=3, rowNo=3, customerMap={firstName=Bob, lastName=Down, numberOfKids=0, customerNo=2}
```