Created
March 20, 2012 16:35
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Auto Mapping a JDBC ResultSet to JSON
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// convenient Spring JDBC RowMapper for when you want the flexibility of Jackson's TreeModel API | |
// Note: Jackson can also serialize standard Java Collections (Maps and Lists) to JSON: if you don't need JsonNode, | |
// it's simpler and more portable to have Spring JDBC simply return a Map or List<Map>. | |
package org.springframework.jdbc.core; | |
import java.math.BigDecimal; | |
import java.sql.ResultSet; | |
import java.sql.ResultSetMetaData; | |
import java.sql.SQLException; | |
import java.util.Date; | |
import org.codehaus.jackson.JsonNode; | |
import org.codehaus.jackson.map.ObjectMapper; | |
import org.codehaus.jackson.node.ObjectNode; | |
import org.springframework.jdbc.core.RowMapper; | |
import org.springframework.jdbc.support.JdbcUtils; | |
public class JsonNodeRowMapper implements RowMapper<JsonNode> { | |
private final ObjectMapper mapper; | |
public JsonNodeRowMapper(ObjectMapper mapper) { | |
this.mapper = mapper; | |
} | |
@Override | |
public JsonNode mapRow(ResultSet rs, int rowNum) throws SQLException { | |
ObjectNode objectNode = mapper.createObjectNode(); | |
ResultSetMetaData rsmd = rs.getMetaData(); | |
int columnCount = rsmd.getColumnCount(); | |
for (int index = 1; index <= columnCount; index++) { | |
String column = JdbcUtils.lookupColumnName(rsmd, index); | |
Object value = rs.getObject(column); | |
if (value == null) { | |
objectNode.putNull(column); | |
} else if (value instanceof Integer) { | |
objectNode.put(column, (Integer) value); | |
} else if (value instanceof String) { | |
objectNode.put(column, (String) value); | |
} else if (value instanceof Boolean) { | |
objectNode.put(column, (Boolean) value); | |
} else if (value instanceof Date) { | |
objectNode.put(column, ((Date) value).getTime()); | |
} else if (value instanceof Long) { | |
objectNode.put(column, (Long) value); | |
} else if (value instanceof Double) { | |
objectNode.put(column, (Double) value); | |
} else if (value instanceof Float) { | |
objectNode.put(column, (Float) value); | |
} else if (value instanceof BigDecimal) { | |
objectNode.put(column, (BigDecimal) value); | |
} else if (value instanceof Byte) { | |
objectNode.put(column, (Byte) value); | |
} else if (value instanceof byte[]) { | |
objectNode.put(column, (byte[]) value); | |
} else { | |
throw new IllegalArgumentException("Unmappable object type: " + value.getClass()); | |
} | |
} | |
return objectNode; | |
} | |
} |
It's required to implement RowMapper
from Spring JDBC.
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Hi there,
What is the purpose of the
int rowNum
attribute if you don't mind me asking, it seems to be redundant in this snippet?