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DSL Platform compatible Java JSON library (https://dsl-platform.com)
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package com.dslplatform.json;
import java.math.BigDecimal;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.sql.*;
import java.time.OffsetDateTime;
import java.time.OffsetTime;
import java.time.ZoneId;
public class ResultSetConverter implements JsonWriter.WriteObject {
private final DslJson dslJson;
private final boolean writeNames;
private final boolean writeTypes;
private final ZoneId zone;
public ResultSetConverter(DslJson dslJson) {
this(dslJson, true, true, ZoneId.systemDefault());
}
public ResultSetConverter(DslJson dslJson, boolean writeNames, boolean writeTypes, ZoneId zone) {
this.dslJson = dslJson;
this.writeNames = writeNames;
this.writeTypes = writeTypes;
this.zone = zone;
}
public void write(JsonWriter writer, @Nullable ResultSet rs) {
if (rs == null) writer.writeNull();
else {
try {
final ResultSetMetaData metadata = rs.getMetaData();
final int columns = metadata.getColumnCount();
if (columns == 0) throw new ConfigurationException("No columns found in ResultSet");
final Writer[] writers = new Writer[columns];
for (int i = 0; i < writers.length; i++) {
final Writer wrt = writers[i] = createWriter(metadata, i + 1);
if (wrt == null) throw new ConfigurationException("Unable to find Writer for column " + (i + 1) + "(" + metadata.getColumnName(i + 1) + ") of type :" + getColumnType(metadata.getColumnType(i + 1)));
}
serialize(rs, writer, writers);
} catch (SQLException e) {
throw new SerializationException(e);
}
}
}
private static byte[] NextRow = "],[".getBytes(StandardCharsets.UTF_8);
private static byte[] DoubleEnd = "]]".getBytes(StandardCharsets.UTF_8);
private void serialize(
final ResultSet rs,
final JsonWriter buffer,
final Writer[] writers) throws SQLException {
final ResultSetMetaData metadata = rs.getMetaData();
if (metadata.getColumnCount() != writers.length) {
throw new ConfigurationException("Result set metadata column count mismatch. Expecting " + metadata.getColumnCount() + " writers");
}
buffer.writeByte(JsonWriter.ARRAY_START);
if (writeNames) {
buffer.writeByte(JsonWriter.ARRAY_START);
if (writers.length > 0) {
buffer.writeString(metadata.getColumnLabel(1));
for (int i = 1; i < writers.length; i++) {
buffer.writeByte(JsonWriter.COMMA);
buffer.writeString(metadata.getColumnLabel(i + 1));
}
}
buffer.writeByte(JsonWriter.ARRAY_END);
}
if (writeTypes) {
if (writeNames) {
buffer.writeByte(JsonWriter.COMMA);
}
buffer.writeByte(JsonWriter.ARRAY_START);
if (writers.length > 0) {
buffer.writeString(getColumnType(metadata.getColumnType(1)));
for (int i = 1; i < writers.length; i++) {
buffer.writeByte(JsonWriter.COMMA);
buffer.writeString(getColumnType(metadata.getColumnType(i + 1)));
}
}
buffer.writeByte(JsonWriter.ARRAY_END);
}
if (rs.next()) {
if (writeNames || writeTypes) {
buffer.writeByte(JsonWriter.COMMA);
}
buffer.writeByte(JsonWriter.ARRAY_START);
writers[0].write(rs, buffer);
for (int i = 1; i < writers.length; i++) {
buffer.writeByte(JsonWriter.COMMA);
writers[i].write(rs, buffer);
}
} else {
buffer.writeByte(JsonWriter.ARRAY_END);
return;
}
while (rs.next()) {
buffer.writeAscii(NextRow);
writers[0].write(rs, buffer);
for (int i = 1; i < writers.length; i++) {
buffer.writeByte(JsonWriter.COMMA);
writers[i].write(rs, buffer);
}
}
buffer.writeAscii(DoubleEnd);
}
public interface Writer {
void write(ResultSet rs, JsonWriter buffer) throws SQLException;
}
private JsonWriter.WriteObject DecimalConverter;
@Nullable
public Writer createWriter(
final ResultSetMetaData metaData,
final int index) throws SQLException {
switch (metaData.getColumnType(index)) {
case Types.ARRAY:
return (rs, buffer) -> {
final Array value = rs.getArray(index);
if (value == null) buffer.writeNull();
else {
try {
final Object instance = value.getArray();
if (instance == null) buffer.writeNull();
else {
final Class manifest = instance.getClass();
if (!dslJson.serialize(buffer, manifest, instance)) {
throw new SerializationException("Unable to serialize result set for column " + index);
}
}
} finally {
value.free();
}
}
};
case Types.BIGINT:
return (rs, buffer) -> {
final long value = rs.getLong(index);
if (rs.wasNull()) buffer.writeNull();
else NumberConverter.serialize(value, buffer);
};
case Types.VARBINARY:
case Types.BINARY:
case Types.LONGVARBINARY:
case Types.BLOB:
return (rs, buffer) -> {
final byte[] value = rs.getBytes(index);
if (value == null) buffer.writeNull();
else buffer.writeBinary(value);
};
case Types.BIT:
case Types.BOOLEAN:
return (rs, buffer) -> {
final boolean value = rs.getBoolean(index);
if (rs.wasNull()) buffer.writeNull();
else BoolConverter.serialize(value, buffer);
};
case Types.DATALINK:
return (rs, buffer) -> {
final URL url = rs.getURL(index);
if (url == null) buffer.writeNull();
else buffer.writeString(url.toExternalForm()); //TODO: optimize
};
case Types.DATE:
return (rs, buffer) -> {
java.sql.Date date = rs.getDate(index);
if (date == null) buffer.writeNull();
else JavaTimeConverter.serialize(date.toLocalDate(), buffer);
};
case Types.DECIMAL:
case Types.NUMERIC:
if (DecimalConverter == null) {
DecimalConverter = dslJson.tryFindWriter(BigDecimal.class);
}
return (rs, buffer) -> DecimalConverter.write(buffer, rs.getBigDecimal(index));
case Types.DOUBLE:
return (rs, buffer) -> {
final double value = rs.getDouble(index);
if (rs.wasNull()) buffer.writeNull();
else NumberConverter.serialize(value, buffer);
};
case Types.REAL:
case Types.FLOAT:
return (rs, buffer) -> {
final float value = rs.getFloat(index);
if (rs.wasNull()) buffer.writeNull();
else NumberConverter.serialize(value, buffer);
};
case Types.TINYINT:
case Types.SMALLINT:
return (rs, buffer) -> {
final int value = rs.getShort(index);
if (rs.wasNull()) buffer.writeNull();
else NumberConverter.serialize(value, buffer);
};
case Types.INTEGER:
return (rs, buffer) -> {
final int value = rs.getInt(index);
if (rs.wasNull()) buffer.writeNull();
else NumberConverter.serialize(value, buffer);
};
case Types.NULL:
return (rs, buffer) -> buffer.writeNull();
case Types.NCLOB:
case Types.LONGNVARCHAR:
case Types.NCHAR:
case Types.NVARCHAR:
return (rs, buffer) -> StringConverter.serializeNullable(rs.getNString(index), buffer);
case Types.CLOB:
case Types.LONGVARCHAR:
case Types.CHAR:
case Types.VARCHAR:
return (rs, buffer) -> StringConverter.serializeNullable(rs.getString(index), buffer);
case Types.DISTINCT:
case Types.JAVA_OBJECT:
case Types.OTHER:
case Types.STRUCT:
return (rs, buffer) -> {
final Object value = rs.getObject(index);
buffer.serializeObject(value);
};
case Types.REF:
return (rs, buffer) -> {
final Ref value = rs.getRef(index);
if (value == null) buffer.writeNull();
else {
final Object instance = value.getObject();
if (instance == null) buffer.writeNull();
else buffer.serializeObject(instance);
}
};
case Types.REF_CURSOR:
return null;
case Types.ROWID:
return (rs, buffer) -> {
final RowId value = rs.getRowId(index);
if (value == null) buffer.writeNull();
else StringConverter.serialize(value.toString(), buffer);
};
case Types.SQLXML:
return (rs, buffer) -> {
final SQLXML xml = rs.getSQLXML(index);
if (xml == null) buffer.writeNull();
else {
try {
StringConverter.serialize(xml.getString(), buffer);
} finally {
xml.free();
}
}
};
case Types.TIME:
return (rs, buffer) -> {
final Time time = rs.getTime(index);
if (time == null) buffer.writeNull();
else JavaTimeConverter.serialize(time.toLocalTime(), buffer);
};
case Types.TIME_WITH_TIMEZONE:
return (rs, buffer) -> {
final Time time = rs.getTime(index);
if (time == null) buffer.writeNull();
else JavaTimeConverter.serialize(OffsetTime.ofInstant(time.toInstant(), zone), buffer);
};
case Types.TIMESTAMP:
return (rs, buffer) -> {
Timestamp timestamp = rs.getTimestamp(index);
if (timestamp == null) buffer.writeNull();
else JavaTimeConverter.serialize(timestamp.toLocalDateTime(), buffer);
};
case Types.TIMESTAMP_WITH_TIMEZONE:
return (rs, buffer) -> {
Timestamp timestamp = rs.getTimestamp(index);
if (timestamp == null) buffer.writeNull();
else JavaTimeConverter.serialize(OffsetDateTime.ofInstant(timestamp.toInstant(), zone), buffer);
};
default:
return (rs, buffer) -> {
final Object value = rs.getObject(index);
buffer.serializeObject(value);
};
}
}
public static String getColumnType(int sqlType) {
switch (sqlType) {
case Types.ARRAY:
return "Array";
case Types.BIGINT:
return "Long";
case Types.VARBINARY:
case Types.BINARY:
case Types.LONGVARBINARY:
case Types.BLOB:
return "Binary";
case Types.BIT:
case Types.BOOLEAN:
return "Boolean";
case Types.DATE:
return "Date";
case Types.DECIMAL:
case Types.NUMERIC:
return "Decimal";
case Types.DOUBLE:
return "Double";
case Types.REAL:
case Types.FLOAT:
return "Float";
case Types.TINYINT:
case Types.SMALLINT:
return "Short";
case Types.INTEGER:
return "Int";
case Types.NULL:
return "Null";
case Types.NCLOB:
case Types.LONGNVARCHAR:
case Types.NCHAR:
case Types.NVARCHAR:
case Types.CLOB:
case Types.LONGVARCHAR:
case Types.CHAR:
case Types.VARCHAR:
return "String";
case Types.JAVA_OBJECT:
case Types.OTHER:
case Types.STRUCT:
return "Unknown";
case Types.REF:
case Types.DISTINCT:
case Types.REF_CURSOR:
case Types.ROWID:
return "Unknown";
case Types.DATALINK:
return "Url";
case Types.SQLXML:
return "SQL";
case Types.TIME:
case Types.TIME_WITH_TIMEZONE:
return "Time";
case Types.TIMESTAMP:
case Types.TIMESTAMP_WITH_TIMEZONE:
return "Timestamp";
default:
return "Unknown";
}
}
}