java读写CSV文件
起初，我自己连什么叫CSV文件都不知道，这个问题是来自一个网友的问题，他要我帮他做一个对csv文件数据的操作的题目。要求：如果原来数据是“江苏省南京市南京街……”换成“江苏 省 南京 市 南京 街 ……”也就是把出现类似"省","市","区","街","路","里","幢","村","室","园","苑","巷","号"的都在其前面和后面都加上空格。根据他给的一个参考文档做了一下，第一次做的虽然实现了功能，但是代码比较累赘，之后看了一下String类的一些方法，发现有一个replace(str,str)方法可以很快替换掉原来字符串中的字符，就对原来的方法进行了修改，代码显得少了很多。
CSV文件简介：Comma Separated Values，简称CSV，即逗号分隔值，是一种纯文本格式，用来存储数据。在CSV中，数据的字段由逗号分开。CSV文件是一个计算机数据文件用于执行审判和真正的组织工具，逗号分隔的清单。常常被用于移动表格数据之间的两个不同的计算机程序，例如关系数据库程序和电子表格程序。建议用记事本新建一个文件然后修改后缀名，也建议用记事本打开CSV文件。用Excel打开，有时候会报错。
下面是最开始写的比较累赘的代码:
package test;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class OperateCSVfile {
public static void main(String[] args){
String [] str ={"省","市","区","街","路","里","幢","村","室","园","苑","巷","号"};
File inFile = new File("C://in.csv"); // 读取的CSV文件
File outFile = new File("C://out.csv");//写出的CSV文件
String inString = "";
String tmpString = "";
try {
BufferedReader reader = new BufferedReader(new FileReader(inFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(outFile));
while((inString = reader.readLine())!= null){
char [] c = inString.toCharArray();
String [] value = new String[c.length];
String result = "";
for(int i = 0;i < c.length;i++){
value[i] = String.valueOf(c[i]);
for(int j = 0;j < str.length;j++){
if(value[i].equals(str[j])){
String tmp = value[i];
value[i] = "," + tmp + ",";
}
}
result += value[i];
}
writer.write(inString);
writer.newLine();
}
reader.close();
writer.close();
} catch (FileNotFoundException ex) {
System.out.println("没找到文件！");
} catch (IOException ex) {
System.out.println("读写文件出错！");
}
}
}
利用String类的replace()方法之后的代码简化为;
package test;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class OperateCSVfile {
public static void main(String[] args){
String [] str ={"省","市","区","街","路","里","幢","村","室","园","苑","巷","号"};
File inFile = new File("C://in.csv"); // 读取的CSV文件
File outFile = new File("C://out.csv");//写出的CSV文件
String inString = "";
String tmpString = "";
try {
BufferedReader reader = new BufferedReader(new FileReader(inFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(outFile));
while((inString = reader.readLine())!= null){
for(int i = 0;i<str.length;i++){
tmpString = inString.replace(str[i], "," + str[i] + ",");
inString = tmpString;
}
writer.write(inString);
writer.newLine();
}
reader.close();
writer.close();
} catch (FileNotFoundException ex) {
System.out.println("没找到文件！");
} catch (IOException ex) {
System.out.println("读写文件出错！");
}
}
}
效果图;
之后我又在网上查了一下资料，发现java有专门操作CSV文件的类和方法。java开源框架csvreader提供了一个轻量级的、简单方便的统一操作接口可用。要使用CsvReader，CsvWriter需要下载一个javacsv.jar导入到项目中才行，在项目上点击右键--属性--库--添加jar文件，选择javacsv.jar文件即可，然后在程序中用import com.csvreader.CsvReader，import com.csvreader.CsvWriter导入即可。
代码如下:
代码如下:
package test;
import com.csvreader.CsvReader;
import com.csvreader.CsvWriter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class readandwrite {
public static void main(String[] args) throws IOException {
String [] str ={"省","市","区","街","路","里","幢","村","室","园","苑","巷","号"};
String inString = "";
String tmpString = "";
File inFile = new File("C://in.csv"); // 读取的CSV文件
File outFile = new File("C://outtest.csv");//输出的CSV文
try {
BufferedReader reader = new BufferedReader(new FileReader(inFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(outFile));
CsvReader creader = new CsvReader(reader, ',');
CsvWriter cwriter = new CsvWriter(writer,',');
while(creader.readRecord()){
inString = creader.getRawRecord();//读取一行数据
for(int i = 0;i < str.length;i++){
tmpString = inString.replace(str[i], "," + str[i] + ",");
inString = tmpString;
}
//第一个参数表示要写入的字符串数组，每一个元素占一个单元格，第二个参数为true时表示写完数据后自动换行
cwriter.writeRecord(inString.split(","), true);
//注意，此时再用cwriter.write(inString)方法写入数据将会看到只往第一个单元格写入了数据，“，”没起到调到下一个单元格的作用
//如果用cwriter.write(String str)方法来写数据，则要用cwriter.endRecord()方法来实现换行
//cwriter.endRecord();//换行
cwriter.flush();//刷新数据
}
creader.close();
cwriter.close();
} catch (FileNotFoundException ex) {
ex.printStackTrace();
}
}
}
得到同样的效果。