要使用Apache Calcite查询JSON嵌套数据，您可以按照以下步骤进行操作：

1. 添加依赖项：首先，您需要在项目中添加Calcite的依赖项。您可以在您的构建工具中添加以下Maven依赖项：

    org.apache.calcite
    calcite-core
    1.26.0


    org.apache.calcite
    calcite-avatica
    1.26.0

2. 创建Schema：接下来，您需要创建一个Calcite的Schema对象来表示嵌套的JSON数据。您可以使用JsonSchemaFactory类来创建Schema对象，并指定JSON数据的位置和结构。

import org.apache.calcite.adapter.java.JavaTypeFactory;
import org.apache.calcite.schema.Schema;
import org.apache.calcite.schema.SchemaFactory;
import org.apache.calcite.schema.SchemaPlus;
import org.apache.calcite.schema.Table;
import org.apache.calcite.schema.impl.AbstractSchema;

public class JsonSchema extends AbstractSchema {

    private final String jsonFilePath;

    public JsonSchema(String jsonFilePath) {
        this.jsonFilePath = jsonFilePath;
    }

    @Override
    protected Map getTableMap() {
        // Create the JSON table
        Map tableMap = new HashMap<>();
        tableMap.put("jsonTable", new JsonTable(jsonFilePath));
        return tableMap;
    }

    public static SchemaFactory factory() {
        return new SchemaFactory() {
            @Override
            public Schema create(SchemaPlus parentSchema, String name, Map operand) {
                String jsonFilePath = (String) operand.get("jsonFilePath");
                return new JsonSchema(jsonFilePath);
            }
        };
    }
}

3. 创建Table：接下来，您需要创建一个Calcite的Table对象来表示JSON数据中的表格。您可以使用JsonTable类来加载JSON数据并提供查询接口。

import org.apache.calcite.DataContext;
import org.apache.calcite.linq4j.AbstractEnumerable;
import org.apache.calcite.linq4j.Enumerable;
import org.apache.calcite.linq4j.Enumerator;
import org.apache.calcite.plan.RelOptTable;
import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.rel.type.RelDataTypeFactory;
import org.apache.calcite.schema.ScannableTable;
import org.apache.calcite.schema.impl.AbstractTable;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;

public class JsonTable extends AbstractTable implements ScannableTable {

    private final String jsonFilePath;

    public JsonTable(String jsonFilePath) {
        this.jsonFilePath = jsonFilePath;
    }

    @Override
    public RelDataType getRowType(RelDataTypeFactory typeFactory) {
        // Define the row type based on the JSON structure
        // For example, if JSON has fields "id" and "name", the row type will be (INTEGER, VARCHAR)
        return typeFactory.builder()
                .add("id", typeFactory.createJavaType(Integer.class))
                .add("name", typeFactory.createJavaType(String.class))
                .build();
    }

    @Override
    public Enumerable scan(DataContext root) {
        return new AbstractEnumerable() {
            @Override
            public Enumerator enumerator() {
                try {
                    // Read the JSON file and convert it into a List of Object arrays
                    List rows = new ArrayList<>();
                    String jsonString = new String(Files.readAllBytes(Paths.get(jsonFilePath)), StandardCharsets.UTF_8);
                    JSONArray jsonArray = new JSONArray(jsonString);
                    for (int i = 0; i < jsonArray.length(); i++) {
                        JSONObject jsonObject = jsonArray.getJSONObject(i);
                        Object[] row = new Object[]{
                                jsonObject.getInt("id"),
                                jsonObject.getString("name")
                                // Add more fields as per the JSON structure
                        };
                        rows.add(row);
                    }
                    return new JsonEnumerator(rows);
                } catch (IOException e) {
                    throw new RuntimeException("Error while reading JSON file", e);
                }
            }
        };
    }

    private static class JsonEnumerator implements Enumerator {
        private final Iterator iterator;

        public JsonEnumerator(List rows) {
            this.iterator = rows.iterator();
        }

        @Override
        public Object[] current() {
            return iterator.next();
        }

        @Override
        public boolean move