我必须解析csv文件。 列数可变。 我已经为固定列编写了以下代码。 我使用csvtobean和MappingStrategy apis进行解析。
请帮助我如何动态创建映射。
公共类OpencsvExecutor2 {
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
CsvToBean csv = new CsvToBean();
String csvFilename="C:\\Users\\ersvvwa\\Desktop\\taks\\supercsv\\20160511-0750--MaS_GsmrRel\\20160511-0750--MaS_GsmrRel.txt";
CSVReader csvReader = null;
List objList=new ArrayList<DataBean>();
try {
FileInputStream fis = new FileInputStream(csvFilename);
BufferedReader myInput = new BufferedReader(new InputStreamReader(fis));
csvReader = new CSVReader(new InputStreamReader(new FileInputStream(csvFilename), "UTF-8"), ' ', '\'', 1);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
csvReader.getRecordsRead();
//Set column mapping strategy
List<DataBean> list = csv.parse(setColumMapping(csvReader), csvReader);
for (Object object : list) {
DataBean obj = (DataBean) object;
// System.out.println(obj.Col1);
objList.add(obj);
}
csvReader.close();
System.out.println("list size "+list.size());
System.out.println("objList size "+objList.size());
String outFile="C:\\Users\\ersvvwa\\Desktop\\taks\\supercsv\\20160511-0750--MaS_GsmrRel\\20160511-0750--MaS_GsmrRel.csv";
try {
CSVWriter csvWriter = null;
csvWriter = new CSVWriter(new FileWriter(outFile),CSVWriter.DEFAULT_SEPARATOR,CSVWriter.NO_QUOTE_CHARACTER);
//csvWriter = new CSVWriter(out,CSVWriter.DEFAULT_SEPARATOR,CSVWriter.NO_QUOTE_CHARACTER);
String[] columns = new String[] {"col1","col2","col3","col4"};
// Writer w= new FileWriter(out);
BeanToCsv bc = new BeanToCsv();
List ls;
csvWriter.writeNext(columns);
//bc.write(setColumMapping(), csvWriter, objList);
System.out.println("complete");
csvWriter.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private static MappingStrategy setColumMapping(CSVReader csvReader) throws IOException {
// TODO Auto-generated method stub
ColumnPositionMappingStrategy strategy = new ColumnPositionMappingStrategy();
strategy.setType(DataBean2.class);
String[] columns = new String[] {"col1","col2","col3","col4"};
strategy.setColumnMapping(columns);
return strategy;
}
}
答案 0 :(得分：1)
如果我理解正确，您可以逐行阅读文件并使用split。
示例READ CSV：从mkyong
中提取的示例import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class ReadCVS {
public static void main(String[] args) {
ReadCVS obj = new ReadCVS();
obj.run();
}
public void run() {
String csvFile = "/Users/mkyong/Downloads/GeoIPCountryWhois.csv";
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
try {
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
String[] country = line.split(cvsSplitBy);
System.out.println("Country [code= " + country[4]
+ " , name=" + country[5] + "]");
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
System.out.println("Done");
}
}
写入CSV文件的示例：从mkyong
中提取的示例import java.io.FileWriter;
import java.io.IOException;
public class GenerateCsv
{
public static void main(String [] args)
{
generateCsvFile("c:\\test.csv");
}
private static void generateCsvFile(String sFileName)
{
try
{
FileWriter writer = new FileWriter(sFileName);
writer.append("DisplayName");
writer.append(',');
writer.append("Age");
writer.append('\n');
writer.append("MKYONG");
writer.append(',');
writer.append("26");
writer.append('\n');
writer.append("YOUR NAME");
writer.append(',');
writer.append("29");
writer.append('\n');
//generate whatever data you want
writer.flush();
writer.close();
}
catch(IOException e)
{
e.printStackTrace();
}
}
}
但是，我建议使用库。有许多（例如，opencsv，Apache Commons CSV，Jackson Dataformat CSV等）。你不必重新发明轮子。
希望这会对你有所帮助！
答案 1 :(得分：0)
假设您的代码有效，我会尝试将Generics用于setColumnMapping方法。
方法setType获取参数“类类型”。将此作为您自己的方法setColumnMapping的参数，例如，（CSVReader csvReader，Class type）。这样，您可以将DataBean2.class传递给方法或任何其他类。此外，您需要一个变量列到bean映射，因为{“col1”，“col2”，“col3”，“col4”}对于每个bean来说都不够，如您所知。考虑一下如何使其动态化（例如，您可以将String []传递给setColumnMethod。）
您还需要调整主要内部的列表使用情况。
我建议您在开始编程之前先找一些关于java泛型的简要教程。
答案 2 :(得分：0)
最后，我能够解析csv并以所需的格式编写，如
csvWriter = new CSVWriter(new FileWriter(outFile),CSVWriter.DEFAULT_SEPARATOR,CSVWriter.NO_QUOTE_CHARACTER);
csvReader = new CSVReader(new InputStreamReader(new FileInputStream(csvFilename), "UTF-8"), ' ');
String header = "NW,MSC,BSC,CELL,CELL_0";
List<String> headerList = new ArrayList<String>();
headerList.add(header);
csvWriter.writeNext(headerList.toArray(new String[headerList.size()]));
while ((nextLine = csvReader.readNext()) != null) {
// nextLine[] is an array of values from the line
for(int j=0;j< nextLine.length;j++){
// System.out.println("next " +nextLine[1]+" "+nextLine [2]+ " "+nextLine [2]);
if(nextLine[j].contains("cell")||
nextLine[j].equalsIgnoreCase("NW") ||
nextLine[j].equalsIgnoreCase("MSC") ||
nextLine[j].equalsIgnoreCase("BSC") ||
nextLine[j].equalsIgnoreCase("CELL")){
hm.put(nextLine[j], j);
}
}
break;
}
String[] out=null;
while ((row = csvReader.readNext()) != null) {
String [] arr=new String[4];
outList = new ArrayList<>();
innerList = new ArrayList<>();
finalList=new ArrayList<String[]>();
String[] str=null;
int x=4;
for(int y=0; y<hm.size()-10;y++){
if(!row[x].equalsIgnoreCase("NULL")|| !row[x].equals(" ")){
System.out.println("x "+x);
str=new String[]{row[0],row[1],row[2],row[3],row[x]};
}
finalList.add(str);;
x=x+3;
}
csvWriter.writeAll(finalList);
break;
}
csvReader.close();
csvWriter.close();
}