Java バッチを1つの JAR にまとめるディスパッチャーの実装

import java.io.FileInputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

interface BatchJob {
    void initialize(JobContext context) throws Exception;
    ExitCode execute(JobContext context) throws Exception;
    void terminate(JobContext context);
}

enum ExitCode {
    SUCCESS(0), WARNING(1), ERROR(2);
    private final int code;
    ExitCode(int code) { this.code = code; }
    public int getCode() { return code; }
}

class JobContext {
    private final String jobName;
    private final Properties properties;
    private final Map<String, Object> attributes = new HashMap<String, Object>();
    private long startTimeMillis;

    public JobContext(String jobName, Properties properties) {
        this.jobName = jobName;
        this.properties = properties;
    }
    public String getJobName() { return jobName; }
    public String getProperty(String key, String defaultValue) {
        return properties.getProperty(key, defaultValue);
    }
    public void setAttribute(String key, Object value) { attributes.put(key, value); }
    @SuppressWarnings("unchecked")
    public <T> T getAttribute(String key, Class<T> type) {
        Object v = attributes.get(key);
        return (v != null && type.isInstance(v)) ? (T) v : null;
    }
    public long getStartTimeMillis() { return startTimeMillis; }
    public void setStartTimeMillis(long v) { this.startTimeMillis = v; }
}

class SimpleBatchRunner {
    private static final Logger LOGGER = Logger.getLogger(SimpleBatchRunner.class.getName());

    public ExitCode run(BatchJob job, JobContext context) {
        ExitCode exitCode = ExitCode.ERROR;
        context.setStartTimeMillis(System.currentTimeMillis());
        LOGGER.info("[" + context.getJobName() + "] ジョブ開始");
        try {
            job.initialize(context);
            exitCode = job.execute(context);
        } catch (Exception e) {
            LOGGER.log(Level.SEVERE, "[" + context.getJobName() + "] エラー", e);
        } finally {
            try { job.terminate(context); } catch (Exception e) {
                LOGGER.log(Level.WARNING, "後処理エラー", e);
            }
            long elapsed = System.currentTimeMillis() - context.getStartTimeMillis();
            LOGGER.info("[" + context.getJobName() + "] 終了 ("
                + elapsed + "ms) コード: " + exitCode.getCode());
        }
        return exitCode;
    }
}

// ===== サンプルジョブ 1: CSV取込 =====
class CsvImportJob implements BatchJob {
    @Override
    public void initialize(JobContext ctx) throws Exception {
        String inputFile = ctx.getProperty("input.file", "");
        if (inputFile.isEmpty()) {
            throw new IllegalArgumentException("input.file が設定されていません");
        }
        ctx.setAttribute("inputFile", inputFile);
    }

    @Override
    public ExitCode execute(JobContext ctx) throws Exception {
        String inputFile = ctx.getAttribute("inputFile", String.class);
        int count = 0;
        java.io.BufferedReader reader = new java.io.BufferedReader(
            new java.io.FileReader(inputFile));
        try {
            while (reader.readLine() != null) { count++; }
        } finally { reader.close(); }
        ctx.setAttribute("processedCount", Integer.valueOf(count));
        return ExitCode.SUCCESS;
    }

    @Override
    public void terminate(JobContext ctx) {
        Integer count = ctx.getAttribute("processedCount", Integer.class);
        System.out.println("CSV取込完了: " + (count != null ? count : 0) + " 件");
    }
}

// ===== サンプルジョブ 2: レポート出力 =====
class ReportExportJob implements BatchJob {
    @Override
    public void initialize(JobContext ctx) throws Exception {
        ctx.setAttribute("outputDir", ctx.getProperty("output.dir", "."));
    }

    @Override
    public ExitCode execute(JobContext ctx) throws Exception {
        String outputDir = ctx.getAttribute("outputDir", String.class);
        String path = outputDir + "/report_" + System.currentTimeMillis() + ".txt";
        java.io.FileWriter writer = new java.io.FileWriter(path);
        try {
            writer.write("日次売上レポート\n");
            writer.write("生成日時: " + new java.util.Date() + "\n");
        } finally { writer.close(); }
        ctx.setAttribute("reportPath", path);
        return ExitCode.SUCCESS;
    }

    @Override
    public void terminate(JobContext ctx) {
        String path = ctx.getAttribute("reportPath", String.class);
        System.out.println("レポート出力完了: " + (path != null ? path : "未生成"));
    }
}

// ===== ディスパッチャー本体 =====
public class BatchDispatcher {
    private static final Logger LOGGER = Logger.getLogger(BatchDispatcher.class.getName());

    public static void main(String[] args) {
        if (args.length < 1) {
            System.err.println("使い方: java -jar batch.jar <properties-file-path>");
            System.err.println("例: java -jar batch.jar config/csv-import.properties");
            System.exit(ExitCode.ERROR.getCode());
            return;
        }

        // 1. Properties ファイル読み込み
        String propsPath = args[0];
        Properties props = new Properties();
        FileInputStream fis = null;
        try {
            fis = new FileInputStream(propsPath);
            props.load(fis);
        } catch (IOException e) {
            System.err.println("設定ファイル読込失敗: " + propsPath);
            e.printStackTrace();
            System.exit(ExitCode.ERROR.getCode());
            return;
        } finally {
            if (fis != null) { try { fis.close(); } catch (IOException ignored) {} }
        }

        // 2. ジョブクラス名と表示名を取得
        String jobClassName = props.getProperty("job.class");
        String jobName = props.getProperty("job.name", "unknown");

        if (jobClassName == null || jobClassName.trim().isEmpty()) {
            System.err.println("job.class が未定義: " + propsPath);
            System.exit(ExitCode.ERROR.getCode());
            return;
        }

        LOGGER.info("ディスパッチ: job.class=" + jobClassName + ", job.name=" + jobName);

        // 3. リフレクションで BatchJob インスタンスを生成
        BatchJob job;
        try {
            Class<?> clazz = Class.forName(jobClassName.trim());
            Object instance = clazz.getDeclaredConstructor().newInstance();
            if (!(instance instanceof BatchJob)) {
                System.err.println(jobClassName + " は BatchJob を実装していません");
                System.exit(ExitCode.ERROR.getCode());
                return;
            }
            job = (BatchJob) instance;
        } catch (ClassNotFoundException e) {
            System.err.println("クラスが見つかりません: " + jobClassName);
            System.exit(ExitCode.ERROR.getCode());
            return;
        } catch (NoSuchMethodException e) {
            System.err.println("引数なしコンストラクタがありません: " + jobClassName);
            System.exit(ExitCode.ERROR.getCode());
            return;
        } catch (Exception e) {
            System.err.println("インスタンス化失敗: " + jobClassName);
            e.printStackTrace();
            System.exit(ExitCode.ERROR.getCode());
            return;
        }

        // 4. ジョブ実行
        JobContext context = new JobContext(jobName, props);
        SimpleBatchRunner runner = new SimpleBatchRunner();
        ExitCode exitCode = runner.run(job, context);

        LOGGER.info("ディスパッチ完了: " + jobName + " -> " + exitCode.name());
        System.exit(exitCode.getCode());
    }
}

/*
 * === Properties ファイル例 ===
 *
 * --- config/csv-import.properties ---
 * job.class=CsvImportJob
 * job.name=日次CSV取込
 * input.file=/data/import/daily_sales.csv
 *
 * --- config/report-export.properties ---
 * job.class=ReportExportJob
 * job.name=日次レポート出力
 * output.dir=/data/reports
 *
 * === 起動例 ===
 * java -jar batch.jar config/csv-import.properties
 * java -jar batch.jar config/report-export.properties
 *
 * === cron 設定例 ===
 * 0 2 * * * cd /opt/batch && java -jar batch.jar config/csv-import.properties
 * 0 6 * * * cd /opt/batch && java -jar batch.jar config/report-export.properties
 */