Add DB Dialects

itsallcode · Dec 16, 2023 · 3f5d9ea · 3f5d9ea
1 parent 75701b2
commit 3f5d9ea
Show file tree

Hide file tree

Showing 18 changed files with 269 additions and 33 deletions.
diff --git a/src/integrationTest/java/org/itsallcode/jdbc/ExasolTypeTest.java b/src/integrationTest/java/org/itsallcode/jdbc/ExasolTypeTest.java
@@ -8,6 +8,7 @@
 import java.time.LocalDate;
 import java.util.stream.Stream;
 
+import org.itsallcode.jdbc.dialect.ExasolDialect;
 import org.itsallcode.jdbc.resultset.SimpleResultSet;
 import org.itsallcode.jdbc.resultset.generic.Row;
 import org.junit.jupiter.api.AfterAll;
@@ -35,7 +36,7 @@ static void stopDb() {
     }
 
     SimpleConnection connect() {
-        return ConnectionFactory.create(Context.builder().build()) //
+        return ConnectionFactory.create(Context.builder().dialect(new ExasolDialect()).build()) //
                 .create(container.getJdbcUrl(), container.getUsername(), container.getPassword());
     }
 

diff --git a/src/main/java/org/itsallcode/jdbc/ConnectionFactory.java b/src/main/java/org/itsallcode/jdbc/ConnectionFactory.java
@@ -13,15 +13,6 @@ private ConnectionFactory(final Context context) {
         this.context = context;
     }
 
-    /**
-     * Create a new connection factory with a default context.
-     * 
-     * @return a new instance
-     */
-    public static ConnectionFactory create() {
-        return create(Context.builder().build());
-    }
-
     /**
      * Create a new connection factory with a custom context.
      * 

diff --git a/src/main/java/org/itsallcode/jdbc/Context.java b/src/main/java/org/itsallcode/jdbc/Context.java
@@ -1,13 +1,25 @@
 package org.itsallcode.jdbc;
 
+import static java.util.stream.Collectors.toList;
+
+import java.sql.ResultSet;
+import java.util.List;
+import java.util.Objects;
+
+import org.itsallcode.jdbc.dialect.DbDialect;
+import org.itsallcode.jdbc.resultset.*;
+import org.itsallcode.jdbc.resultset.generic.SimpleMetaData;
 import org.itsallcode.jdbc.resultset.generic.ValueExtractorFactory;
 
 /**
  * This represents a context with configuration for the Simple JDBC framework.
  */
 public class Context {
 
-    private Context() {
+    private final DbDialect dialect;
+
+    private Context(final ContextBuilder builder) {
+        this.dialect = Objects.requireNonNull(builder.dialect, "dialect");
     }
 
     /**
@@ -28,6 +40,14 @@ public ParameterMapper getParameterMapper() {
         return ParameterMapper.create();
     }
 
+    ResultSet convertingResultSet(final ResultSet resultSet) {
+        final SimpleMetaData metaData = SimpleMetaData.create(resultSet, this);
+        final List<ColumnValueConverter> converters = metaData.getColumns().stream()
+                .map(col -> ColumnValueConverter.simple(dialect.createConverter(col)))
+                .collect(toList());
+        return new ConvertingResultSet(resultSet, ResultSetValueConverter.create(metaData, converters));
+    }
+
     /**
      * Create a new builder for {@link Context} objects.
      * 
@@ -42,16 +62,23 @@ public static ContextBuilder builder() {
      */
     public static class ContextBuilder {
 
+        private DbDialect dialect;
+
         private ContextBuilder() {
         }
 
+        public ContextBuilder dialect(final DbDialect dialect) {
+            this.dialect = dialect;
+            return this;
+        }
+
         /**
          * Build a new context.
          * 
          * @return a new context
          */
         public Context build() {
-            return new Context();
+            return new Context(this);
         }
     }
 }
diff --git a/src/main/java/org/itsallcode/jdbc/SimplePreparedStatement.java b/src/main/java/org/itsallcode/jdbc/SimplePreparedStatement.java
@@ -18,7 +18,8 @@ class SimplePreparedStatement implements AutoCloseable {
 
     <T> SimpleResultSet<T> executeQuery(final RowMapper<T> rowMapper) {
         final ResultSet resultSet = doExecute();
-        return new SimpleResultSet<>(context, resultSet, rowMapper);
+        final ResultSet convertingResultSet = context.convertingResultSet(resultSet);
+        return new SimpleResultSet<>(context, convertingResultSet, rowMapper);
     }
 
     private ResultSet doExecute() {

diff --git a/src/main/java/org/itsallcode/jdbc/dialect/DbDialect.java b/src/main/java/org/itsallcode/jdbc/dialect/DbDialect.java
@@ -0,0 +1,7 @@
+package org.itsallcode.jdbc.dialect;
+
+import org.itsallcode.jdbc.resultset.generic.SimpleMetaData.ColumnMetaData;
+
+public interface DbDialect {
+    Extractor createConverter(final ColumnMetaData column);
+}
diff --git a/src/main/java/org/itsallcode/jdbc/dialect/ExasolDialect.java b/src/main/java/org/itsallcode/jdbc/dialect/ExasolDialect.java
@@ -0,0 +1,20 @@
+package org.itsallcode.jdbc.dialect;
+
+import java.time.LocalDate;
+import java.time.LocalTime;
+
+import org.itsallcode.jdbc.resultset.generic.SimpleMetaData.ColumnMetaData;
+
+public class ExasolDialect implements DbDialect {
+
+    public Extractor createConverter(final ColumnMetaData column) {
+        return switch (column.getType().getJdbcType()) {
+        case TIMESTAMP -> Extractors.timestampToUTCInstant();
+        case CLOB -> Extractors.clobToString();
+        case BLOB -> Extractors.blobToBytes();
+        case TIME -> Extractors.forType(LocalTime.class);
+        case DATE -> Extractors.forType(LocalDate.class);
+        default -> Extractors.generic();
+        };
+    }
+}
diff --git a/src/main/java/org/itsallcode/jdbc/dialect/Extractor.java b/src/main/java/org/itsallcode/jdbc/dialect/Extractor.java
@@ -0,0 +1,11 @@
+package org.itsallcode.jdbc.dialect;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+@FunctionalInterface
+public interface Extractor {
+
+    Object getObject(ResultSet resultSet, int columnIndex) throws SQLException;
+
+}
diff --git a/src/main/java/org/itsallcode/jdbc/dialect/Extractors.java b/src/main/java/org/itsallcode/jdbc/dialect/Extractors.java
@@ -0,0 +1,48 @@
+package org.itsallcode.jdbc.dialect;
+
+import java.sql.*;
+import java.util.Calendar;
+import java.util.TimeZone;
+
+public class Extractors {
+    private static final Calendar UTC_CALENDAR = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
+
+    private Extractors() {
+    }
+
+    static Extractor timestampToUTCInstant() {
+        return nonNull((resultSet, columnIndex) -> resultSet.getTimestamp(columnIndex, UTC_CALENDAR).toInstant());
+    }
+
+    private static Extractor nonNull(final Extractor extractor) {
+        return (resultSet, columnIndex) -> {
+            resultSet.getObject(columnIndex);
+            if (resultSet.wasNull()) {
+                return null;
+            }
+            return extractor.getObject(resultSet, columnIndex);
+        };
+    }
+
+    static Extractor clobToString() {
+        return nonNull((resultSet, columnIndex) -> {
+            final Clob clob = resultSet.getClob(columnIndex);
+            return clob.getSubString(1, (int) clob.length());
+        });
+    }
+
+    static Extractor blobToBytes() {
+        return nonNull((resultSet, columnIndex) -> {
+            final Blob blob = resultSet.getBlob(columnIndex);
+            return blob.getBytes(1, (int) blob.length());
+        });
+    }
+
+    static Extractor forType(final Class<?> type) {
+        return (resultSet, columnIndex) -> resultSet.getObject(columnIndex, type);
+    }
+
+    static Extractor generic() {
+        return ResultSet::getObject;
+    }
+}
diff --git a/src/main/java/org/itsallcode/jdbc/dialect/H2Dialect.java b/src/main/java/org/itsallcode/jdbc/dialect/H2Dialect.java
@@ -0,0 +1,20 @@
+package org.itsallcode.jdbc.dialect;
+
+import java.time.LocalDate;
+import java.time.LocalTime;
+
+import org.itsallcode.jdbc.resultset.generic.SimpleMetaData.ColumnMetaData;
+
+public class H2Dialect implements DbDialect {
+
+    public Extractor createConverter(final ColumnMetaData column) {
+        return switch (column.getType().getJdbcType()) {
+        case TIMESTAMP -> Extractors.timestampToUTCInstant();
+        case CLOB -> Extractors.clobToString();
+        case BLOB -> Extractors.blobToBytes();
+        case TIME -> Extractors.forType(LocalTime.class);
+        case DATE -> Extractors.forType(LocalDate.class);
+        default -> Extractors.generic();
+        };
+    }
+}
diff --git a/src/main/java/org/itsallcode/jdbc/resultset/ColumnValueConverter.java b/src/main/java/org/itsallcode/jdbc/resultset/ColumnValueConverter.java
@@ -0,0 +1,26 @@
+package org.itsallcode.jdbc.resultset;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+import org.itsallcode.jdbc.dialect.Extractor;
+
+@FunctionalInterface
+public interface ColumnValueConverter {
+
+    <T> T getObject(ResultSet resultSet, int columnIndex, Class<T> type) throws SQLException;
+
+    static ColumnValueConverter generic() {
+        return simple(ResultSet::getObject);
+    }
+
+    static ColumnValueConverter simple(final Extractor extractor) {
+        return new ColumnValueConverter() {
+            @Override
+            public <T> T getObject(final ResultSet resultSet, final int columnIndex, final Class<T> type)
+                    throws SQLException {
+                return type.cast(extractor.getObject(resultSet, columnIndex));
+            }
+        };
+    }
+}
diff --git a/src/main/java/org/itsallcode/jdbc/resultset/ConvertingResultSet.java b/src/main/java/org/itsallcode/jdbc/resultset/ConvertingResultSet.java
@@ -3,21 +3,23 @@
 import java.sql.ResultSet;
 import java.sql.SQLException;
 
-class ConvertingResultSet extends DelegatingResultSet {
+public class ConvertingResultSet extends DelegatingResultSet {
     private final ResultSet delegate;
+    private final ResultSetValueConverter converter;
 
-    ConvertingResultSet(final ResultSet delegate) {
+    public ConvertingResultSet(final ResultSet delegate, final ResultSetValueConverter converter) {
         super(delegate);
         this.delegate = delegate;
+        this.converter = converter;
     }
 
     @Override
     public <T> T getObject(final int columnIndex, final Class<T> type) throws SQLException {
-        throw new UnsupportedOperationException();
+        return converter.getObject(delegate, columnIndex, type);
     }
 
     @Override
     public <T> T getObject(final String columnLabel, final Class<T> type) throws SQLException {
-        throw new UnsupportedOperationException();
+        return converter.getObject(delegate, columnLabel, type);
     }
 }
diff --git a/src/main/java/org/itsallcode/jdbc/resultset/ResultSetValueConverter.java b/src/main/java/org/itsallcode/jdbc/resultset/ResultSetValueConverter.java
@@ -0,0 +1,59 @@
+package org.itsallcode.jdbc.resultset;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.*;
+
+import org.itsallcode.jdbc.resultset.generic.SimpleMetaData;
+import org.itsallcode.jdbc.resultset.generic.SimpleMetaData.ColumnMetaData;
+
+public class ResultSetValueConverter {
+
+    private final Map<Integer, ColumnValueConverter> convertersByIndex;
+    private final Map<String, Integer> columnIndexByLabel;
+
+    private ResultSetValueConverter(final Map<Integer, ColumnValueConverter> convertersByIndex,
+            final Map<String, Integer> columnIndexByLabel) {
+        this.convertersByIndex = convertersByIndex;
+        this.columnIndexByLabel = columnIndexByLabel;
+    }
+
+    public static ResultSetValueConverter create(final SimpleMetaData resultSetMetadata,
+            final List<ColumnValueConverter> converters) {
+        final Map<Integer, ColumnValueConverter> convertersByIndex = new HashMap<>();
+        final Map<String, Integer> columnIndexByLabel = new HashMap<>();
+        for (int i = 1; i <= converters.size(); i++) {
+            final ColumnValueConverter converter = converters.get(i - 1);
+            final ColumnMetaData metaData = resultSetMetadata.getColumnByIndex(i);
+            convertersByIndex.put(metaData.getColumnIndex(), converter);
+            columnIndexByLabel.put(metaData.getLabel(), i);
+        }
+        return new ResultSetValueConverter(convertersByIndex, columnIndexByLabel);
+    }
+
+    public <T> T getObject(final ResultSet delegate, final int columnIndex, final Class<T> type) throws SQLException {
+        return getConverter(columnIndex).getObject(delegate, columnIndex, type);
+    }
+
+    public <T> T getObject(final ResultSet delegate, final String columnLabel, final Class<T> type)
+            throws SQLException {
+        final int columnIndex = getIndexForLabel(columnLabel);
+        return getConverter(columnIndex).getObject(delegate, columnIndex, type);
+    }
+
+    private int getIndexForLabel(final String columnLabel) {
+        final Integer index = columnIndexByLabel.get(columnLabel);
+        if (index == null) {
+            throw new IllegalStateException("No index found for column label '" + columnLabel + "'");
+        }
+        return index.intValue();
+    }
+
+    private ColumnValueConverter getConverter(final int columnIndex) {
+        final ColumnValueConverter converter = convertersByIndex.get(columnIndex);
+        if (converter == null) {
+            throw new IllegalStateException("No converter found for column index " + columnIndex);
+        }
+        return converter;
+    }
+}
diff --git a/src/main/java/org/itsallcode/jdbc/resultset/generic/GenericRowMapper.java b/src/main/java/org/itsallcode/jdbc/resultset/generic/GenericRowMapper.java
@@ -32,7 +32,7 @@ public GenericRowMapper(final ColumnValuesConverter<T> converter) {
     @Override
     public T mapRow(final Context context, final ResultSet resultSet, final int rowNum) throws SQLException {
         if (rowBuilder == null) {
-            rowBuilder = new ResultSetRowBuilder(SimpleMetaData.create(resultSet.getMetaData(), context));
+            rowBuilder = new ResultSetRowBuilder(SimpleMetaData.create(resultSet, context));
         }
         final Row row = rowBuilder.buildRow(resultSet, rowNum);
         return converter.mapRow(row);

diff --git a/src/main/java/org/itsallcode/jdbc/resultset/generic/SimpleMetaData.java b/src/main/java/org/itsallcode/jdbc/resultset/generic/SimpleMetaData.java
@@ -1,7 +1,6 @@
 package org.itsallcode.jdbc.resultset.generic;
 
-import java.sql.ResultSetMetaData;
-import java.sql.SQLException;
+import java.sql.*;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -18,7 +17,19 @@ private SimpleMetaData(final List<ColumnMetaData> columns) {
         this.columns = columns;
     }
 
-    static SimpleMetaData create(final ResultSetMetaData metaData, final Context context) {
+    public static SimpleMetaData create(final ResultSet resultSet, final Context context) {
+        return create(getMetaData(resultSet), context);
+    }
+
+    private static ResultSetMetaData getMetaData(final ResultSet resultSet) {
+        try {
+            return resultSet.getMetaData();
+        } catch (final SQLException e) {
+            throw new UncheckedSQLException("Error getting meta data", e);
+        }
+    }
+
+    private static SimpleMetaData create(final ResultSetMetaData metaData, final Context context) {
         try {
             final List<ColumnMetaData> columns = createColumnMetaData(metaData, context);
             return new SimpleMetaData(columns);
@@ -49,6 +60,16 @@ public List<ColumnMetaData> getColumns() {
         return columns;
     }
 
+    /**
+     * Get column metadata for a given index (one based).
+     * 
+     * @param index column index (one based)
+     * @return column metadata
+     */
+    public ColumnMetaData getColumnByIndex(final int index) {
+        return columns.get(index - 1);
+    }
+
     /**
      * Represents the metadata of a single column.
      */