Export and generate csv files in java, and export csv files in java

Export and generate csv files in java, and export csv files in java

First, we need to have a basic understanding of csv files. csv files are similar to excel and can be opened in excel. However, csv files are essentially separated by commas (,). For example:

Txt:

After the file suffix is changed to csv, the following information is displayed:

In java, we generally use poi to Operate excel, import, and export, but poi consumes a lot of memory. Especially when exporting, we can choose to export and generate csv files, because it is similar to text, it is very efficient.

A simple implementation class is written. The Code is as follows:

1/** 2*3 * export the attributes of the data entity to be exported to generate a csv file 4 * @ author ccg 5 * @ param titles csv format header 6 * @ param propertys, note that the title corresponds to a set of 7 * @ param list objects to be exported 8 * @ return 9 * @ throws IOException10 * Created January 5, 2017 * @ throws IllegalAccessException 12 * @ throws IllegalArgumentException 13*/14 public static <T> String exportCsv (String [] titles, string [] propertys, List <T> list) throws IOException, IllegalArgumentException, IllegalAccessException {15 File file = new File ("d: \ test.csv "); 16 // construct the output stream and specify the encoding 17 OutputStreamWriter ow = new OutputStreamWriter (new FileOutputStream (file), "gbk"); 18 19 // csv files are separated by commas, except for the first one, each time you write a cell data, you must enter a comma of 20 for (String title: titles) {21 ow. write (title); 22 ow. write (","); 23} 24 // wrap the line after the file header is written 25 ow. write ("\ r \ n"); 26 // write content 27 for (Object obj: list) {28 // obtain all fields Using Reflection 29 Field [] fields = obj. getClass (). getDeclaredFields (); 30 for (String property: propertys) {31 for (Field field: fields) {32 // set Field visibility 33 field. setAccessible (true); 34 if (property. equals (field. getName () {35 ow. write (field. get (obj ). toString (); 36 ow. write (","); 37 continue; 38} 39} 40} 41 // write a line wrap 42 ow. write ("\ r \ n"); 43} 44 ow. flush (); 45 ow. close (); 46 return "0"; 47}

The test class is as follows:

1 public void test () throws IOException, IllegalArgumentException, IllegalAccessException {2 String [] titles = new String [] {"ID", "name "}; 3 String [] propertys = new String [] {"id", "name"}; 4 List <User> list = new ArrayList <User> (); 5 User user; 6 user = new User (); 7 user. setId (1L); 8 user. setName ("Zhang San"); 9 list. add (user); 10 user = new User (); 11 user. setId (2L); 12 user. setName ("Li Si"); 13 list. add (user); 14 CsvUtil. getInstance (). exportCsv (titles, propertys, list); 15}

The file generated after export is the same. It is an encapsulation. You can import the table header and the attributes of the object corresponding to the table header.