table of Contents
Java quickly realizes export to generate csv file (including comment code)
In java, we generally use poi to import and export excel, but poi consumes memory, especially when exporting. At this time, we can actually choose to export to generate a csv file, because csv is essentially a text file, so it is very efficient.
Text file -> csv
csv, which is a comma separated file. To generate a csv file, just 生成逗号分隔的txtfile and then 修改后缀名为.csv.
Generated text file:
The .csv file after modifying the suffix:
Implementation code
Implementation class
/**
* 导出生成csv格式的文件
* @author https://www.jb51.net/article/102607.htm
* @param titles csv格式头文
* @param propertys 需要导出的数据实体的属性，注意与title一一对应
* @param list 需要导出的对象集合
* @return
* @throws IOException
* Created 2017年1月5日 上午10:51:44
* @throws IllegalAccessException
* @throws IllegalArgumentException
*/
public static <T> String exportCsv(String[] titles,String[] propertys,List<T> list) throws IOException, IllegalArgumentException, IllegalAccessException{
File file = new File("d:\\test.csv");
//构建输出流，同时指定编码
OutputStreamWriter ow = new OutputStreamWriter(new FileOutputStream(file), "gbk");
//csv文件是逗号分隔，除第一个外，每次写入一个单元格数据后需要输入逗号
for(String title : titles){
ow.write(title);
ow.write(",");
}
//写完文件头后换行
ow.write("\r\n");
//写内容
for(Object obj : list){
//利用反射获取所有字段
Field[] fields = obj.getClass().getDeclaredFields();
for(String property : propertys){
for(Field field : fields){
//设置字段可见性
field.setAccessible(true);
if(property.equals(field.getName())){
ow.write(field.get(obj).toString());
ow.write(",");
continue;
}
}
}
//写完一行换行
ow.write("\r\n");
}
ow.flush();
ow.close();
return "0";
}
Test class
public void test() throws IOException, IllegalArgumentException, IllegalAccessException{
String[] titles = new String[]{
"ID","姓名"};
String[] propertys = new String[]{
"id","name"};
List<User> list = new ArrayList<User>();
User user;
user = new User();
user.setId(1L);
user.setName("张三");
list.add(user);
user = new User();
user.setId(2L);
user.setName("李四");
list.add(user);
CsvUtil.getInstance().exportCsv(titles,propertys, list);
}
The generated files are the two pictures above .