Simple read operation of EasyExcel

EasyExcel's Simple Read Operation

• The well-known frameworks for parsing and generating Excel in the Java field include Apache poi, jxl, etc.But they all have a serious problem that
  consumes a lot of memory.If your system has a small amount of concurrency, it may be ok, but once the concurrency is up, it will definitely be OOM or
  or the JVM will frequently perform full gc.
• EasyExcel is an excel processing framework open sourced by Alibaba. It is famous for its simplicity of use and memory saving. The main reason why EasyExcel can greatly reduce
  memory usage is that when parsing Excel, it does not load all file data into memory at one time, but reads data line by line
  from the disk, one by one.Parse.
• EasyExcel adopts a line-by-line analysis mode, and notifies the processing
  (AnalysisEventListener) of the analysis result of a line in an observer mode.

From official website

Import dependencies

There is a correspondence between this version, otherwise an error will be reported.

 org.apache.poipoi3.17org.apache.poipoi-ooxml3.17com.alibabaeasyexcel2.1.1

Create entity class

@[email protected][email protected] class DemoData {// Set the header name, index represents the index of the [email protected](value = "student number", index = 0)private Integer sno;@ExcelProperty(value = "student name", index = 1)private String sname;}

Write Test with EasyExcel

/*** easyExcel write operation test*/@Testpublic void write() {String outputFile = "E:\write11.xlsx";EasyExcel.write(outputFile, DemoData.class).sheet("student list").doWrite(TestEasyExcel.getData());}private static List getData() {List list = new ArrayList<>();for (int i = 0; i < 10; i++) {String name = UUID.randomUUID().toString().replace("-", "").substring(0, 5);list.add(new DemoData(i, name));}return list;}

Read with EasyExcel

The ExcelListener is required when reading.

Create an ExcelListener class to inherit AnalysisEventListener and bring the objects in the excel table

/*** Created with IntelliJ IDEA.* @Author: pzx* @Date: 2022/01/30 15:46* @Version:1.0*/public class ExcelListener extends AnalysisEventListener {// Read the content in excel line by line (the header will not be read)@Overridepublic void invoke(DemoData data, AnalysisContext context) {System.out.println("********" + data);}// read the contents of the [email protected] void invokeHeadMap(Map headMap, AnalysisContext context) {System.out.println("Header " + headMap);}// what to do after [email protected] void doAfterAllAnalysed(AnalysisContext context) {}}

Code Test

/*** easyExcel read operation test*/@Testpublic void read() {String outputFile = "E:\write11.xlsx";// Add a listener that inherits the AnalysisEventListener classExcelListener excelListener = new ExcelListener();EasyExcel.read(outputFile,DemoData.class, excelListener).sheet().doRead();}

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