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CompletableFuture+线程池使用案列

news 2025/6/9 7:21:54

案例一

@RestController
@RequestMapping("/export")
public class ExportController {private final ExecutorService executor = Executors.newFixedThreadPool(5);@GetMapping("/multiSheet")public void exportMultiSheet(HttpServletResponse response) throws Exception {// 构造5个CompletableFuture，每个处理自己的表和业务逻辑CompletableFuture<SheetData> future1 = CompletableFuture.supplyAsync(() -> handleUsers(), executor);CompletableFuture<SheetData> future2 = CompletableFuture.supplyAsync(() -> handleOrders(), executor);CompletableFuture<SheetData> future3 = CompletableFuture.supplyAsync(() -> handleProducts(), executor);CompletableFuture<SheetData> future4 = CompletableFuture.supplyAsync(() -> handleLogs(), executor);CompletableFuture<SheetData> future5 = CompletableFuture.supplyAsync(() -> handleCustomers(), executor);// 等待所有处理完成CompletableFuture<Void> allDone = CompletableFuture.allOf(future1, future2, future3, future4, future5);allDone.thenRun(() -> {try {response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");response.setCharacterEncoding("utf-8");String fileName = URLEncoder.encode("multi_sheet_export", "UTF-8");response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xlsx");ExcelWriter excelWriter = EasyExcel.write(response.getOutputStream()).build();// 依次写入每个Sheet（join获取数据）List<CompletableFuture<SheetData>> futures = Arrays.asList(future1, future2, future3, future4, future5);for (int i = 0; i < futures.size(); i++) {SheetData data = futures.get(i).join();WriteSheet sheet = EasyExcel.writerSheet(i, data.getSheetName()).head(data.getHead()).build();excelWriter.write(data.getRows(), sheet);}excelWriter.finish();} catch (Exception e) {e.printStackTrace();} finally {executor.shutdown(); // 一定要关闭线程池}}).join(); // 等待导出完成}// 示例方法，每个表处理逻辑不同private SheetData handleUsers() {// 查询 users 表，并处理逻辑（脱敏、计算、筛选等）return queryAndBuildSheet("users", "用户信息");}private SheetData handleOrders() {// 查询 orders 表，自定义业务逻辑处理return queryAndBuildSheet("orders", "订单信息");}private SheetData handleProducts() {return queryAndBuildSheet("products", "商品列表");}private SheetData handleLogs() {return queryAndBuildSheet("logs", "操作日志");}private SheetData handleCustomers() {return queryAndBuildSheet("customers", "客户信息");}// 通用方法：查询数据库并生成 SheetDataprivate SheetData queryAndBuildSheet(String tableName, String sheetName) {List<List<String>> headers = new ArrayList<>();List<List<String>> rows = new ArrayList<>();try (Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/your_db", "user", "password");PreparedStatement stmt = conn.prepareStatement("SELECT * FROM " + tableName);ResultSet rs = stmt.executeQuery()) {ResultSetMetaData meta = rs.getMetaData();int columnCount = meta.getColumnCount();List<String> headerRow = new ArrayList<>();for (int i = 1; i <= columnCount; i++) {headerRow.add(meta.getColumnLabel(i));}headers.add(headerRow);while (rs.next()) {List<String> row = new ArrayList<>();for (int i = 1; i <= columnCount; i++) {Object val = rs.getObject(i);// 可以在这里做字段处理，比如脱敏、格式转换等row.add(val != null ? val.toString() : "");}rows.add(row);}} catch (SQLException e) {e.printStackTrace();}return new SheetData(sheetName, headers, rows);}// SheetData结构，用于封装每个 Sheet 页的数据static class SheetData {private final String sheetName;private final List<List<String>> head;private final List<List<String>> rows;public SheetData(String sheetName, List<List<String>> head, List<List<String>> rows) {this.sheetName = sheetName;this.head = head;this.rows = rows;}public String getSheetName() { return sheetName; }public List<List<String>> getHead() { return head; }public List<List<String>> getRows() { return rows; }}
}

案例二

import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.write.metadata.WriteSheet;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;import java.net.URLEncoder;
import java.util.List;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;@RestController
public class ExportController {private final UserService userService;private final OrderService orderService;private final ProductService productService;private final CustomerService customerService;private final InvoiceService invoiceService;public ExportController(UserService userService,OrderService orderService,ProductService productService,CustomerService customerService,InvoiceService invoiceService) {this.userService = userService;this.orderService = orderService;this.productService = productService;this.customerService = customerService;this.invoiceService = invoiceService;}@GetMapping("/export")public void exportExcel(HttpServletResponse response) throws Exception {ExecutorService executor = Executors.newFixedThreadPool(5);try {CompletableFuture<List<User>> userFuture = CompletableFuture.supplyAsync(userService::list, executor);CompletableFuture<List<Order>> orderFuture = CompletableFuture.supplyAsync(orderService::list, executor);CompletableFuture<List<Product>> productFuture = CompletableFuture.supplyAsync(productService::list, executor);CompletableFuture<List<Customer>> customerFuture = CompletableFuture.supplyAsync(customerService::list, executor);CompletableFuture<List<Invoice>> invoiceFuture = CompletableFuture.supplyAsync(invoiceService::list, executor);CompletableFuture<Void> all = CompletableFuture.allOf(userFuture, orderFuture, productFuture, customerFuture, invoiceFuture);all.join(); // 等待全部完成List<User> users = userFuture.join();List<Order> orders = orderFuture.join();List<Product> products = productFuture.join();List<Customer> customers = customerFuture.join();List<Invoice> invoices = invoiceFuture.join();// 设置响应头response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");response.setCharacterEncoding("utf-8");String fileName = URLEncoder.encode("数据导出", "UTF-8");response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");// 写入多个 sheetExcelWriter writer = EasyExcel.write(response.getOutputStream()).build();writer.write(users, EasyExcel.writerSheet(0, "用户").head(User.class).build());writer.write(orders, EasyExcel.writerSheet(1, "订单").head(Order.class).build());writer.write(products, EasyExcel.writerSheet(2, "产品").head(Product.class).build());writer.write(customers, EasyExcel.writerSheet(3, "客户").head(Customer.class).build());writer.write(invoices, EasyExcel.writerSheet(4, "发票").head(Invoice.class).build());writer.finish();} finally {executor.shutdown();}}
}// 假设以下是实体类，省略 Getter/Setter
class User { private Long id; private String name; }
class Order { private Long id; private String number; }
class Product { private Long id; private String title; }
class Customer { private Long id; private String name; }
class Invoice { private Long id; private String invoiceNo; }// 假设以下是 Service 接口
interface UserService { List<User> list(); }
interface OrderService { List<Order> list(); }
interface ProductService { List<Product> list(); }
interface CustomerService { List<Customer> list(); }
interface InvoiceService { List<Invoice> list(); }
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