mybatis-flex/mybatis-flex-codegen/src/main/java/com/mybatisflex/codegen/dialect/JdbcDialect.java

/**
 * Copyright (c) 2022-2023, Mybatis-Flex (fuhai999@gmail.com).
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.mybatisflex.codegen.dialect;

import com.mybatisflex.codegen.config.GlobalConfig;
import com.mybatisflex.codegen.entity.Column;
import com.mybatisflex.codegen.entity.Table;

import java.sql.*;
import java.util.HashMap;
import java.util.Map;

public abstract class JdbcDialect implements IDialect {

    @Override
    public void buildTableColumns(Table table, GlobalConfig globalConfig, DatabaseMetaData dbMeta, Connection conn) throws SQLException {
        Map<String, String> columnRemarks = buildColumnRemarks(table, dbMeta, conn);

        String sql = forBuildColumnsSql(table.getName());
        try (Statement stm = conn.createStatement(); ResultSet rs = stm.executeQuery(sql)) {

            ResultSetMetaData columnMetaData = rs.getMetaData();
            int columnCount = columnMetaData.getColumnCount();

            for (int i = 1; i <= columnCount; i++) {
                Column column = new Column();
                column.setName(columnMetaData.getColumnName(i));

                String jdbcType = columnMetaData.getColumnClassName(i);
                column.setPropertyType(JdbcTypeMapping.getType(jdbcType));

                column.setAutoIncrement(columnMetaData.isAutoIncrement(i));

                //注释
                column.setRemarks(columnRemarks.get(column.getName()));

                table.addColumn(column);
            }
        }
    }


    private Map<String, String> buildColumnRemarks(Table table, DatabaseMetaData dbMeta, Connection conn) {
        Map<String, String> columnRemarks = new HashMap<>();
        try (ResultSet colRs = dbMeta.getColumns(conn.getCatalog(), null, table.getName(), null)) {
            while (colRs.next()) {
                columnRemarks.put(colRs.getString("COLUMN_NAME"), colRs.getString("REMARKS"));
            }
        } catch (Exception e) {
            System.err.println("无法获取字段的备注内容：" + e.getMessage());
        }
        return columnRemarks;
    }


    @Override
    public ResultSet getTablesResultSet(DatabaseMetaData dbMeta, Connection conn, String[] types) throws SQLException {
        return dbMeta.getTables(conn.getCatalog(), null, null, types);
    }


    abstract String forBuildColumnsSql(String tableName);
}