Implement HW5 stubs, API helpers, optional SQL/MQ helpers, and test coverage

src/main/java/ru/otus/stub/helper/SqlHelper.java

@@ -0,0 +1,63 @@
+package ru.otus.stub.helper;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+public class SqlHelper {
+
+    private final String jdbcUrl;
+    private final String username;
+    private final String password;
+
+    public SqlHelper(String jdbcUrl, String username, String password) {
+        this.jdbcUrl = jdbcUrl;
+        this.username = username;
+        this.password = password;
+    }
+
+    public int executeUpdate(String sql) {
+        try (Connection connection = openConnection();
+             PreparedStatement statement = connection.prepareStatement(sql)) {
+            return statement.executeUpdate();
+        } catch (SQLException exception) {
+            throw new IllegalStateException("SQL update failed: " + sql, exception);
+        }
+    }
+
+    public List<Map<String, Object>> selectRows(String sql) {
+        try (Connection connection = openConnection();
+             PreparedStatement statement = connection.prepareStatement(sql);
+             ResultSet resultSet = statement.executeQuery()) {
+            return mapRows(resultSet);
+        } catch (SQLException exception) {
+            throw new IllegalStateException("SQL query failed: " + sql, exception);
+        }
+    }
+
+    private Connection openConnection() throws SQLException {
+        return DriverManager.getConnection(jdbcUrl, username, password);
+    }
+
+    private List<Map<String, Object>> mapRows(ResultSet resultSet) throws SQLException {
+        final List<Map<String, Object>> rows = new ArrayList<>();
+        final ResultSetMetaData metaData = resultSet.getMetaData();
+        final int columnsCount = metaData.getColumnCount();
+
+        while (resultSet.next()) {
+            final Map<String, Object> row = new LinkedHashMap<>();
+            for (int column = 1; column <= columnsCount; column++) {
+                row.put(metaData.getColumnLabel(column), resultSet.getObject(column));
+            }
+            rows.add(row);
+        }
+        return rows;
+    }
+}