Java EasyExcel读写excel如何解决poi读取大文件内存溢出问题
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问题
以前项目使用 poi 读写 excel，但是 excel 中的数据量太大的话，用 poi 读取时就会导致 OOM 异常，这是因为 poi 在读取数据时，是将全部数据一次性都加载到内存中。
如何解决
使用EasyExcel，以下是使用示例。
使用示例
pom
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>easyexcel</artifactId>
<version>3.1.3</version>
</dependency>监听器
public class ProductListener extends AnalysisEventListener<Product> {
private static final int BATCH_COUNT = 1000;
private final List<Product> list = new ArrayList<>();
private int totalCount;
public ProductListener() {}
@Override
public void invoke(Product product, AnalysisContext analysisContext) {
list.add(product);
if(list.size() >= BATCH_COUNT){
saveData();
list.clear();
}
}
@Override
public void doAfterAllAnalysed(AnalysisContext analysisContext) {
saveData();
System.out.printf("数据同步完成,总数量为:%s%n",totalCount);
}
public void saveData(){
if(!list.isEmpty()){
for (Product product : list) {
insertIgnore(product);
}
}
}
public void insertIgnore(Product product) {
try {
// 执行数据库操作
System.out.println(product.getName());
++totalCount;
} catch (Exception e) {
e.printStackTrace();
}
}
}实体类
public class Product {
private Long id;
@ExcelProperty("name")
private String name;
@ExcelProperty("quantity")
private Long quantity;
@ExcelProperty("desc")
private String desc;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Long getQuantity() {
return quantity;
}
public void setQuantity(Long quantity) {
this.quantity = quantity;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
}读写方法
public class MyEasyExcel {
public static void read(String filePath) {
try (InputStream inputStream = Files.newInputStream(Paths.get(filePath))) {
EasyExcel.read(inputStream, Product.class, new ProductListener())
.sheet()
.doRead();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public static void write(List<Product> data, String filePath) {
try (OutputStream outputStream = Files.newOutputStream(Paths.get(filePath))) {
ExcelWriterBuilder writerBuilder = EasyExcel.write(outputStream, Product.class);
writerBuilder.sheet("Data").doWrite(data);
} catch (Exception e) {
// 处理异常
}
}
}测试类
class MyEasyExcelTest {
@Test
void read() {
String filePath = "C:\\Users\\XXX\\Desktop\\excel.xlsx";
MyEasyExcel.read(filePath);
}
@Test
void write() {
List<Product> products = new ArrayList<>();
Product product = new Product();
product.setId(1L);
product.setName("qwe");
product.setDesc("abc");
product.setQuantity(1342L);
products.add(product);
String filePath = "C:\\Users\\XXX\\Desktop\\excel.xlsx";
MyEasyExcel.write(products, filePath);
}
}总结
以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。