在Java应用中执行MongoDB Shell查询与聚合：从文件到动态参数

// my_aggregation.js
var collectionName = "myCollection"; // 默认集合名，或通过参数覆盖
var threshold = 100; // 默认阈值，或通过参数覆盖

// 这是一个简单的聚合管道示例
db[collectionName].aggregate([
    { $match: { value: { $gte: threshold } } },
    { $group: { _id: "$category", total: { $sum: "$value" } } },
    { $sort: { total: -1 } }
]);

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.HashMap;

public class MongoShellExecutor {

    private static final String MONGOSH_PATH = "/usr/local/bin/mongosh"; // 根据您的系统修改mongosh路径
    private static final String MONGO_URI = "mongodb://localhost:27017/mydatabase"; // MongoDB连接URI

    /**
     * 从文件中读取MongoDB shell查询内容。
     * @param filePath 查询文件路径
     * @return 查询内容的字符串
     * @throws IOException 如果文件读取失败
     */
    private static String readQueryFromFile(String filePath) throws IOException {
        return new String(Files.readAllBytes(Paths.get(filePath)));
    }

    /**
     * 执行MongoDB shell查询。
     * @param queryContent 要执行的MongoDB shell脚本内容
     * @param params 传递给脚本的参数，键值对形式
     * @return 执行结果的字符串
     * @throws IOException 如果执行过程中发生IO错误
     * @throws InterruptedException 如果进程被中断
     */
    public String executeMongoShellQuery(String queryContent, Map<String, Object> params) throws IOException, InterruptedException {
        // 构建参数字符串，用于在脚本中注入变量
        StringBuilder paramInjection = new StringBuilder();
        for (Map.Entry<String, Object> entry : params.entrySet()) {
            paramInjection.append("var ").append(entry.getKey()).append(" = ");
            if (entry.getValue() instanceof String) {
                paramInjection.append("'").append(entry.getValue()).append("';\n");
            } else {
                paramInjection.append(entry.getValue()).append(";\n");
            }
        }

        // 将参数注入到查询内容之前
        String finalQuery = paramInjection.toString() + queryContent;

        List<String> command = new ArrayList<>();
        command.add(MONGOSH_PATH);
        command.add(MONGO_URI); // 连接到指定的数据库
        command.add("--eval");
        command.add(finalQuery); // 传递包含参数和查询的最终脚本

        ProcessBuilder processBuilder = new ProcessBuilder(command);
        // 合并标准错误流到标准输出流，方便统一读取
        processBuilder.redirectErrorStream(true);

        Process process = processBuilder.start();

        // 读取进程的输出
        BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
        StringBuilder output = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            output.append(line).append("\n");
        }

        int exitCode = process.waitFor(); // 等待进程执行完成
        if (exitCode != 0) {
            // 如果退出码不为0，表示执行失败
            System.err.println("MongoDB shell command failed with exit code: " + exitCode);
            System.err.println("Error output:\n" + output.toString());
            throw new RuntimeException("Failed to execute MongoDB shell query. Output:\n" + output.toString());
        }

        return output.toString();
    }

    public static void main(String[] args) {
        MongoShellExecutor executor = new MongoShellExecutor();
        String queryFilePath = "src/main/resources/my_aggregation.js"; // 您的查询文件路径

        try {
            String query = readQueryFromFile(queryFilePath);

            // 传递动态参数
            Map<String, Object> params = new HashMap<>();
            params.put("collectionName", "orders");
            params.put("threshold", 50);

            String result = executor.executeMongoShellQuery(query, params);
            System.out.println("MongoDB Query Result:\n" + result);

        } catch (IOException | InterruptedException e) {
            System.err.println("Error executing MongoDB shell query: " + e.getMessage());
            e.printStackTrace();
        }
    }
}