In many cases in the project, you will encounter the need to export data to the csv file. The code is as follows:
package ;
import ;
import .*;
import ;
import ;
public class CSVUtil {
/**
* Export csv file
* @param response The settings required for exporting files are set in the response
* @param head English comma separated data table header
* @param dataList English comma separated data
* @param filename Exported file name
*/
public static void createCSVFile(HttpServletResponse response, List<String> head, List<String> dataList,
String filename) {
File csvFile = null;
BufferedWriter csvWtriter = null;
InputStream in = null;
OutputStream out = null;
try {
csvFile=new File(filename);
// GB2312 enables the delimiter "," FileOutputStream fileOutputStream=new FileOutputStream(csvFile);
OutputStreamWriter outputStreamWriter=new OutputStreamWriter(fileOutputStream);
// (new String(new byte[]{(byte) 0xEF, (byte) 0xBB, (byte) 0xBF}));
csvWtriter = new BufferedWriter(outputStreamWriter);
// Write to the header of the file if (()>0){
((0));
();
}
// Write file contents for (String item:dataList){
(item);
();
}
();
in = new FileInputStream(csvFile);
int len = 0;
byte[] buffer = new byte[1024*1024*5];
out = ();
// Set this response to the file download response ("application/csv;charset=UTF-8");
("Content-Disposition",
"attachment; filename=" + ((), "UTF-8"));
("UTF-8");
// Write the UTF-8 file logo header first (new byte[] { (byte) 0xEF, (byte) 0xBB, (byte) 0xBF });
while ((len = (buffer)) > 0) {
(buffer, 0, len);
}
();
} catch (Exception e) {
();
} finally {
try {
if (in != null) {
();
}
if (out != null) {
();
}
if (csvFile != null) {
();
}
if (csvWtriter != null) {
();
}
} catch (IOException e) {
();
}
}
}
/**
* Save to csv file, not export
* @param fileName Saved filename
* @param tempDir file save path
* @param head English comma separated data table header
* @param dataList English comma separated data
*/
public static void SaveTxtFile(String fileName, String tempDir,List<String> head,List<String> dataList) {
String filePath=tempDir+"/"+fileName;
try{
FileOutputStream fileOutputStream=new FileOutputStream(filePath);
OutputStreamWriter outputStreamWriter=new OutputStreamWriter(fileOutputStream);
(new String(new byte[]{(byte) 0xEF, (byte) 0xBB, (byte) 0xBF}));
BufferedWriter writer=new BufferedWriter(outputStreamWriter);
((0));
();
for (String item:dataList){
(item));
();
}
();
}
catch (IOException e){
(());
}
}
}Method supplement
Export csv format file
The essence of exporting csv format files is to export commas-separated text data
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
/**
* File operation
*/
public class CSVUtils {
/**
* Function description: Get the BOM signature at the beginning of the UTF-8 encoded text file.
* BOM (Byte Order Mark) is a standard mark used in UTF encoding schemes to identify encoding. Example: When the receiver receives a byte stream starting with EF BB BF, he knows it is UTF-8 encoding.
* @return BOM signature at the beginning of UTF-8 encoded text file
*/
public static String getBOM() {
byte b[] = {(byte)0xEF, (byte)0xBB, (byte)0xBF};
return new String(b);
}
/**
* Generate CVS files
* @param exportData
* Source Data List
* @param map
* csv file list header map
* @param outPutPath
* File path
* @param fileName
* File name
* @return
*/
@SuppressWarnings("rawtypes")
public static File createCSVFile(List exportData, LinkedHashMap map, String outPutPath,
String fileName) {
File csvFile = null;
BufferedWriter csvFileOutputStream = null;
try {
File file = new File(outPutPath);
if (!()) {
();
}
//Define the file name format and create csvFile =new File(outPutPath+fileName+".csv");
();
// UTF-8 enables the delimiter "," //If the production file is garbled, use gbk in Windows and use UTF-8 in Linux csvFileOutputStream = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(
csvFile), "UTF-8"), 1024);
//Write the first byte stream to prevent garbled code (getBOM());
// Write to the header of the file for (Iterator propertyIterator = ().iterator(); ();) {
propertyEntry = () ();
((String) () != null ? (String) () : "" );
if (()) {
(",");
}
}
();
// Write file contents for (Iterator iterator = (); ();) {
Object row = (Object) ();
for (Iterator propertyIterator = ().iterator(); propertyIterator
.hasNext();) {
propertyEntry = () propertyIterator
.next();
String str=row!=null?((String)((Map)row).get( ())):"";
if((str)){
str="";
}else{
str=("\"","\"\"");
if((",")>=0){
str="\""+str+"\"";
}
}
(str);
if (()) {
(",");
}
}
if (()) {
();
}
}
();
} catch (Exception e) {
();
} finally {
try {
();
} catch (IOException e) {
();
}
}
return csvFile;
}
/**
* Generate and download the csv file
* @param response
* @param exportData
* @param map
* @param outPutPath
* @param fileName
* @throws IOException
*/
@SuppressWarnings("rawtypes")
public static void exportDataFile(HttpServletResponse response,List exportData, LinkedHashMap map, String outPutPath,String fileName) throws IOException{
File csvFile = null;
BufferedWriter csvFileOutputStream = null;
try {
File file = new File(outPutPath);
if (!()) {
();
}
//Define the file name format and create csvFile =new File(outPutPath+fileName+".csv");
if(()){
();
}
();
// UTF-8 enables the delimiter "," //If the production file is garbled, use gbk in Windows and use UTF-8 in Linux csvFileOutputStream = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(csvFile), "UTF-8"), 1024);
//Write the first byte stream to prevent garbled code (getBOM());
// Write to the header of the file for (Iterator propertyIterator = ().iterator(); ();) {
propertyEntry = () ();
((String) () != null ? (String) () : "" );
if (()) {
(",");
}
}
();
// Write file contents for (Iterator iterator = (); ();) {
Object row = (Object) ();
for (Iterator propertyIterator = ().iterator(); propertyIterator
.hasNext();) {
propertyEntry = () propertyIterator
.next();
String str=row!=null?((String)((Map)row).get( ())):"";
if((str)){
str="";
}else{
str=("\"","\"\"");
if((",")>=0){
str="\""+str+"\"";
}
}
(str);
if (()) {
(",");
}
}
if (()) {
();
}
}
();
} catch (Exception e) {
();
} finally {
try {
();
} catch (IOException e) {
();
}
}
InputStream in = null;
try {
in = new FileInputStream(outPutPath+fileName+".csv");
int len = 0;
byte[] buffer = new byte[1024];
OutputStream out = ();
();
("application/csv;charset=UTF-8");
("Content-Disposition","attachment; filename=" + (fileName+".csv", "UTF-8"));
("UTF-8");
while ((len = (buffer)) > 0) {
(new byte[] { (byte) 0xEF, (byte) 0xBB, (byte) 0xBF });
(buffer, 0, len);
}
();
} catch (FileNotFoundException e) {
} finally {
if (in != null) {
try {
();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
}
/**
* Delete all files under filePath in this directory
* @param filePath
* File directory path
*/
public static void deleteFiles(String filePath) {
File file = new File(filePath);
if (()) {
File[] files = ();
for (int i = 0; i < ; i++) {
if (files[i].isFile()) {
files[i].delete();
}
}
}
}
/**
* Delete a single file
* @param filePath
* File directory path
* @param fileName
* File name
*/
public static void deleteFile(String filePath, String fileName) {
File file = new File(filePath);
if (()) {
File[] files = ();
for (int i = 0; i < ; i++) {
if (files[i].isFile()) {
if (files[i].getName().equals(fileName)) {
files[i].delete();
return;
}
}
}
}
}
/**
* Test data
* @param args
*/
@SuppressWarnings({ "rawtypes", "unchecked" })
public static void main(String[] args) {
List exportData = new ArrayList<Map>();
Map row1 = new LinkedHashMap<String, String>();
("1", "11");
("2", "12");
("3", "13");
("4", "14");
(row1);
row1 = new LinkedHashMap<String, String>();
("1", "21");
("2", "22");
("3", "23");
("4", "24");
(row1);
LinkedHashMap map = new LinkedHashMap();
//Set the column name ("1", "First Column Name");
("2", "Second Column Name");
("3", "Third Column Name");
("4", "Fourth Column Name");
//This file is uploaded to the path and can be configured to read from the database in the database, which is more convenient! String path = "E:/";
//File name = Production file name + timestamp String fileName = "File Export";
File file = (exportData, map, path, fileName);
String fileName2 = ();
("File Name:" + fileName2);
}
} Implement Csv file import and export
Import
/**
* Read the crv file and convert it to List
*
* @param separator crv file separator
* @param file file to be read
* @return crv object list
*/
public static <T> List<T> read(String separator, File file, Class<T> clazz) {
List<T> result = ();
try {
BeanListProcessor<T> rowProcessor = new BeanListProcessor<>(clazz);
//Set the separator CsvFormat csvFormat = new CsvFormat();
(separator);
CsvParserSettings parserSettings = new CsvParserSettings();
(rowProcessor);
(csvFormat);
CsvParser parser = new CsvParser(parserSettings);
InputStream in = (());
(in);
//Read line by line result = ();
} catch (Exception e) {
("Import csv file failed. message: ", e);
}
return result;
}
test
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString
public static class User implements Serializable {
@Parsed(filed = "name")
private String name;
@Parsed(filed = "age")
private Integer age;
}
public static void main(String[] args) {
File file = new File("E:\\");
List<User> users = (",", file, );
(::println);
}
Export
Create a tool class to use, paste the import and export method in and use it
/**
* csv file export
*
* @param data Export data
* @param file Export the destination file
* @param separator splitter
* @param clazz Export object
* @param <T> Data object generics
*/
public static <T> void export(Collection<T> data, File file, String separator, Class<T> clazz) {
try {
CsvWriterSettings settings = new CsvWriterSettings();
//Set the separator CsvFormat csvFormat = new CsvFormat();
(separator);
(csvFormat);
(false);
(new BeanWriterProcessor<>(clazz));
CsvWriter writer = new CsvWriter((()), "utf-8", settings);
// Write to the header (());
(writer::processRecord);
();
} catch (Exception e) {
("export .csv file failed. message.", e);
}
}
test
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@ToString
public static class User implements Serializable {
@Parsed(filed = "name")
private String name;
@Parsed(filed = "age")
private Integer age;
}
public static void main(String[] args) {
User user1 = new User("Zhang San", 18);
User user2 = new User("Li Si", 19);
List<User> users = (user1, user2);
File file = new File("E:\\");
(users, file, ",", );
}
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