Development techniques - import files using easyexcel (simple example)

Catalog

1. Introduce dependencies

2. Entity class

3. Business processing class

4. Monitor class

5.controller

6.postman test

7. explain  

---

1. Introduce dependencies

pom Add to file easyexcel rely on

            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>easyexcel</artifactId>
                <version>2.0.0</version>
            </dependency>

2. Entity class

The fields in the entity class correspond to the columns in the table to be imported one by one .

import com.alibaba.excel.annotation.ExcelProperty;


public class TestImport {
    @ExcelProperty(value = " Serial number ", index = 0)
    private String id;

    @ExcelProperty(value = " full name ", index = 1)
    private String name;

    @ExcelProperty(value = " Age ", index = 2)
    private String age;

    public TestImport() {
    }

    public TestImport(String id, String name, String age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "TestImport{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age='" + age + '\'' +
                '}';
    }
}

3. Business processing class

Interface

import  Your path .TestImport;
import org.springframework.web.multipart.MultipartFile;

import java.util.List;

public interface FileService {
    void dealFile(MultipartFile file);

    void save(List<TestImport> list);

}

Implementation class

import com.alibaba.excel.EasyExcel;
import  Your path .TestImport;
import  Your path .FileListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.multipart.MultipartFile;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;


@Component
public class FileServiceImpl implements FileService {
    private static final Logger LOGGER = LoggerFactory.getLogger(FileServiceImpl.class);
    @Autowired
    private FileService fileService;


    @Override
    public void dealFile(MultipartFile file) {
        InputStream is = null;
        try {
            is = file.getInputStream();
        } catch (IOException e) {
            e.printStackTrace();
        }
        //1. Read the data ,TestImport It is my pojo class ,
        //2.new SorageListener(storageService) This is a monitor , Mainly used to read data , Don't worry. I'll talk about it later 
        //3. Special note storageService This service, I have an injection on it  @Autowired, Remember not to new Will report a mistake 
        EasyExcel.read(is, TestImport.class, new FileListener(fileService)).sheet().doRead();
    }

    @Override
    public void save(List<TestImport> list) {
        LOGGER.info(" Unloading start ------");
        //  Write the drop logic , Omitted here 

    }
}

4. Monitor class

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import  Your path .FileService;
import  Your path .FileServiceImpl;
import  Your path .TestImport;
import org.springframework.stereotype.Component;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.List;


@Component
public class FileListener extends AnalysisEventListener<TestImport> {

    private static final Logger LOGGER = LoggerFactory.getLogger(FileListener.class);
    // Read data initialization value 
    private static final int BATCH_COUNT = 50;
    List<TestImport> list = new ArrayList<>();

    private FileService fileService;


    public FileListener() {
        fileService =new FileServiceImpl();
    }

    public FileListener(FileService fileService) {
        this.fileService = fileService;
    }

    /**
     *  Every data parsing will call , The data is parsed one by one 
     *
     * @param data    one row value. Is is same as {@link AnalysisContext#readRowHolder()}
     * @param context
     */
    @Override
    public void invoke(TestImport data, AnalysisContext context) {
        LOGGER.info("invoke--- Start parsing table data ");
        list.add(data);
        //  achieve BATCH_COUNT 了 , Need to store the database once , Prevent tens of thousands of data in memory , Easy to OOM
        if (list.size() >= BATCH_COUNT) {
            LOGGER.info("invoke--- Over the set value , Import database ");
            saveData();
            //  Storage complete cleaning  list
            list.clear();
        }
    }

    /**
     *  all excel The data analysis in the table is completed   Will call this 
     *  Explain why you want to save data ？
     * The number of initialization reads is 50, The information in the table has been loaded ,,
     *  hypothesis excel At the end of the table, only 30 Row legacy data , So to prevent the existence of legacy data   Try to judge whether the next set is empty ,
     *  It is not empty and is being stored （ This is my logic to judge , If it is not necessary, it can also be judged ）
     * @param context
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
        LOGGER.info("doAfterAllAnalysed--- Start to deal with ");
        if(list.size()==0){
            return;
        }
        saveData();
        LOGGER.info(" All data analysis completed ！");
    }

    /**
     *  Plus the storage database 
     */
    public void saveData() {
        // The code implementation class layer saves data 
        fileService.save(list);
        LOGGER.info(" Storage database success ！");
    }
}

5.controller

    //excel Bulk import data 
    @PostMapping(value = "/import")
    public T storageService(@RequestParam("file") MultipartFile file) {
        T t= new T();
        try {
            fileService.dealFile(file);
        } catch (Exception e) {

            return t;
        }
        return t;
    }
    //  This  T  Is the return type 

6.postman test

7. explain  

See through the output log , Request to come in , Business processing class calls  dealFile() perform  EasyExcel.read , Then enter the listening class , Execute first  invoke() Re execution  doAfterAllAnalysed()

Write this right for record