import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.Chunk;

/**
 * ItemWriter核心接口
 */
public interface ItemWriter<T> {
    /**
     * 批量寫入數(shù)據(jù)項
     * @param items 待寫入的數(shù)據(jù)項列表
     */
    void write(Chunk<? extends T> items) throws Exception;
}

/**
 * 簡單的日志ItemWriter實現(xiàn)
 */
public class LoggingItemWriter implements ItemWriter<Object> {
    
    private static final Logger logger = LoggerFactory.getLogger(LoggingItemWriter.class);
    
    @Override
    public void write(Chunk<? extends Object> items) throws Exception {
        // 記錄數(shù)據(jù)項
        for (Object item : items) {
            logger.info("Writing item: {}", item);
        }
    }
}

import org.springframework.batch.item.database.JdbcBatchItemWriter;
import org.springframework.batch.item.database.builder.JdbcBatchItemWriterBuilder;
import javax.sql.DataSource;

/**
 * 配置JDBC批處理寫入器
 */
@Bean
public JdbcBatchItemWriter<Customer> jdbcCustomerWriter(DataSource dataSource) {
    return new JdbcBatchItemWriterBuilder<Customer>()
            .dataSource(dataSource)
            .sql("INSERT INTO customers (id, name, email, created_date) " +
                 "VALUES (:id, :name, :email, :createdDate)")
            .itemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<>())
            .build();
}

import org.springframework.batch.item.database.JpaItemWriter;
import javax.persistence.EntityManagerFactory;

/**
 * 配置JPA寫入器
 */
@Bean
public JpaItemWriter<Product> jpaProductWriter(EntityManagerFactory entityManagerFactory) {
    JpaItemWriter<Product> writer = new JpaItemWriter<>();
    writer.setEntityManagerFactory(entityManagerFactory);
    return writer;
}

import org.springframework.batch.item.file.FlatFileItemWriter;
import org.springframework.batch.item.file.builder.FlatFileItemWriterBuilder;
import org.springframework.core.io.FileSystemResource;

/**
 * 配置CSV文件寫入器
 */
@Bean
public FlatFileItemWriter<ReportData> csvReportWriter() {
    return new FlatFileItemWriterBuilder<ReportData>()
            .name("reportItemWriter")
            .resource(new FileSystemResource("output/reports.csv"))
            .delimited()
            .delimiter(",")
            .names("id", "name", "amount", "date")
            .headerCallback(writer -> writer.write("ID,Name,Amount,Date"))
            .footerCallback(writer -> writer.write("End of Report"))
            .build();
}

import org.springframework.batch.item.json.JacksonJsonObjectMarshaller;
import org.springframework.batch.item.json.builder.JsonFileItemWriterBuilder;

/**
 * 配置JSON文件寫入器
 */
@Bean
public JsonFileItemWriter<Customer> jsonCustomerWriter() {
    return new JsonFileItemWriterBuilder<Customer>()
            .name("customerJsonWriter")
            .resource(new FileSystemResource("output/customers.json"))
            .jsonObjectMarshaller(new JacksonJsonObjectMarshaller<>())
            .build();
}

import org.springframework.batch.item.support.CompositeItemWriter;
import org.springframework.batch.item.support.ClassifierCompositeItemWriter;
import org.springframework.classify.Classifier;
import java.util.Arrays;

/**
 * 配置組合寫入器
 */
@Bean
public CompositeItemWriter<Customer> compositeCustomerWriter(
        JdbcBatchItemWriter<Customer> databaseWriter,
        JsonFileItemWriter<Customer> jsonWriter) {
    
    CompositeItemWriter<Customer> writer = new CompositeItemWriter<>();
    writer.setDelegates(Arrays.asList(databaseWriter, jsonWriter));
    return writer;
}

/**
 * 配置分類寫入器
 */
@Bean
public ClassifierCompositeItemWriter<Transaction> classifierTransactionWriter(
        ItemWriter<Transaction> highValueWriter,
        ItemWriter<Transaction> regularWriter) {
    
    ClassifierCompositeItemWriter<Transaction> writer = new ClassifierCompositeItemWriter<>();
    writer.setClassifier(new TransactionClassifier(highValueWriter, regularWriter));
    return writer;
}

/**
 * 交易分類器
 */
public class TransactionClassifier implements Classifier<Transaction, ItemWriter<? super Transaction>> {
    
    private final ItemWriter<Transaction> highValueWriter;
    private final ItemWriter<Transaction> regularWriter;
    
    public TransactionClassifier(
            ItemWriter<Transaction> highValueWriter,
            ItemWriter<Transaction> regularWriter) {
        this.highValueWriter = highValueWriter;
        this.regularWriter = regularWriter;
    }
    
    @Override
    public ItemWriter<? super Transaction> classify(Transaction transaction) {
        return transaction.getAmount() > 10000 ? highValueWriter : regularWriter;
    }
}

import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.item.ItemStream;
import org.springframework.batch.item.ExecutionContext;
import org.springframework.kafka.core.KafkaTemplate;

/**
 * 自定義Kafka消息寫入器
 */
@Component
public class KafkaItemWriter<T> implements ItemWriter<T>, ItemStream {
    
    private final KafkaTemplate<String, T> kafkaTemplate;
    private final String topic;
    private final Function<T, String> keyExtractor;
    
    public KafkaItemWriter(
            KafkaTemplate<String, T> kafkaTemplate,
            String topic,
            Function<T, String> keyExtractor) {
        this.kafkaTemplate = kafkaTemplate;
        this.topic = topic;
        this.keyExtractor = keyExtractor;
    }
    
    @Override
    public void write(Chunk<? extends T> items) throws Exception {
        for (T item : items) {
            String key = keyExtractor.apply(item);
            kafkaTemplate.send(topic, key, item);
        }
        // 確保消息發(fā)送完成
        kafkaTemplate.flush();
    }
    
    @Override
    public void open(ExecutionContext executionContext) throws ItemStreamException {
        // 初始化資源
    }
    
    @Override
    public void update(ExecutionContext executionContext) throws ItemStreamException {
        // 更新狀態(tài)
    }
    
    @Override
    public void close() throws ItemStreamException {
        // 釋放資源
    }
}

import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.interceptor.DefaultTransactionAttribute;

/**
 * 配置事務(wù)管理的Step
 */
@Bean
public Step transactionalStep(
        StepBuilderFactory stepBuilderFactory,
        ItemReader<InputData> reader,
        ItemProcessor<InputData, OutputData> processor,
        ItemWriter<OutputData> writer,
        PlatformTransactionManager transactionManager) {
    
    DefaultTransactionAttribute attribute = new DefaultTransactionAttribute();
    attribute.setIsolationLevel(DefaultTransactionAttribute.ISOLATION_READ_COMMITTED);
    attribute.setTimeout(30); // 30秒超時
    
    return stepBuilderFactory.get("transactionalStep")
            .<InputData, OutputData>chunk(100)
            .reader(reader)
            .processor(processor)
            .writer(writer)
            .transactionManager(transactionManager)
            .transactionAttribute(attribute)
            .build();
}

import org.springframework.jdbc.core.namedparam.SqlParameterSourceUtils;
import org.springframework.jdbc.core.JdbcTemplate;
import javax.sql.DataSource;

/**
 * 高性能批量插入寫入器
 */
@Component
public class OptimizedBatchWriter<T> implements ItemWriter<T> {
    
    private final JdbcTemplate jdbcTemplate;
    private final String insertSql;
    private final Function<List<T>, Object[][]> parameterExtractor;
    
    public OptimizedBatchWriter(
            DataSource dataSource,
            String insertSql,
            Function<List<T>, Object[][]> parameterExtractor) {
        this.jdbcTemplate = new JdbcTemplate(dataSource);
        this.insertSql = insertSql;
        this.parameterExtractor = parameterExtractor;
    }
    
    @Override
    public void write(Chunk<? extends T> items) throws Exception {
        List<T> itemList = new ArrayList<>(items);
        Object[][] batchParams = parameterExtractor.apply(itemList);
        
        // 執(zhí)行批量插入
        jdbcTemplate.batchUpdate(insertSql, batchParams);
    }
}