下面列出了java.sql.ResultSetMetaData#getColumnCount ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
/**
* Execute query.
*
* @param query the query
* @return the list
*/
public static List<Map<String, String>> executeQuery(String query) {
List<Map<String, String>> results = new ArrayList<>();
try (Connection conn = getConnection();
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(query);) {
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
Map<String, String> data;
while (rs.next()) {
data = new LinkedHashMap<>();
for (int i = 1; i <= columnCount; i++) {
data.put(rsmd.getColumnName(i), rs.getString(i));
}
results.add(data);
}
} catch (Exception ex) {
ex.printStackTrace();
LOGGER.error("Error Executing Query", Util.getStackTrace(ex));
}
return results;
}
private TypeHandler<?> resolveTypeHandler(ResultSet rs, String column) {
try {
Map<String, Integer> columnIndexLookup;
columnIndexLookup = new HashMap<String, Integer>();
ResultSetMetaData rsmd = rs.getMetaData();
int count = rsmd.getColumnCount();
for (int i = 1; i <= count; i++) {
String name = rsmd.getColumnName(i);
columnIndexLookup.put(name, i);
}
Integer columnIndex = columnIndexLookup.get(column);
TypeHandler<?> handler = null;
if (columnIndex != null) {
handler = resolveTypeHandler(rsmd, columnIndex);
}
if (handler == null || handler instanceof UnknownTypeHandler) {
handler = OBJECT_TYPE_HANDLER;
}
return handler;
} catch (SQLException e) {
throw new TypeException("Error determining JDBC type for column " + column + ". Cause: " + e, e);
}
}
private void compareRowSets(CachedRowSet crs, CachedRowSet crs1) throws Exception {
int rows = crs.size();
assertTrue(rows == crs1.size());
ResultSetMetaData rsmd = crs.getMetaData();
compareMetaData(rsmd, crs1.getMetaData());
int cols = rsmd.getColumnCount();
for (int row = 1; row <= rows; row++) {
crs.absolute((row));
crs1.absolute(row);
for (int col = 1; col <= cols; col++) {
compareColumnValue(JDBCType.valueOf(rsmd.getColumnType(col)),
crs, crs1, col);
}
}
}
public static void dumpResultsetMetadata(ResultSet rst, PrintStream out) {
try {
ResultSetMetaData metaData = rst.getMetaData();
for (int i = 1; i <= metaData.getColumnCount(); i++) {
out.print(metaData.getColumnName(i) + "\t");
}
out.println();
} catch (SQLException e) {
throw new RuntimeSqlException(e);
}
out.println();
}
public void testDataAwareProcedureCallUsingGlobalIndex()
throws SQLException {
setup();
CallableStatement cs = prepareCall("CALL RETRIEVE_DYNAMIC_RESULTS(?) ON TABLE EMP.PARTITIONTESTTABLE1 WHERE SECONDID in (?,?,?) AND THIRDID='3'");
cs.setInt(1, 2);
cs.setInt(2, 3);
cs.setInt(3, 4);
cs.setInt(4, 5);
cs.execute();
String[][] results=new String[2][1];
results[0][0]="1";
results[1][0]="1";
int rsIndex=-1;
do {
++rsIndex;
int rowIndex=0;
ResultSet rs = cs.getResultSet();
ResultSetMetaData metaData = rs.getMetaData();
int rowCount = metaData.getColumnCount();
while (rs.next()) {
String row="";
for (int i = 1; i <=rowCount; ++i) {
Object value = rs.getObject(i);
row+=value.toString();
}
if(rsIndex>1 || rowIndex>1) {
fail("the result is not correct!");
}
if(!row.equals(results[rsIndex][rowIndex])) {
fail("the result is not correct!");
}
++rowIndex;
}
} while (cs.getMoreResults());
}
public List<ReportMetaDataColumn> parseMetaDataColumns(final String sqlText) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
List<ReportMetaDataColumn> columns = null;
try {
this.logger.debug("Parse Report MetaDataColumns SQL:{},", sqlText);
conn = this.getJdbcConnection();
stmt = conn.createStatement();
rs = stmt.executeQuery(this.preprocessSqlText(sqlText));
final ResultSetMetaData rsMataData = rs.getMetaData();
final int count = rsMataData.getColumnCount();
columns = new ArrayList<>(count);
for (int i = 1; i <= count; i++) {
final ReportMetaDataColumn column = new ReportMetaDataColumn();
column.setName(rsMataData.getColumnLabel(i));
column.setDataType(rsMataData.getColumnTypeName(i));
column.setWidth(rsMataData.getColumnDisplaySize(i));
columns.add(column);
}
} catch (final SQLException ex) {
throw new RuntimeException(ex);
} finally {
JdbcUtils.releaseJdbcResource(conn, stmt, rs);
}
return columns;
}
public void testExecuteQueryWithDataAwareProcedureCall()
throws SQLException {
setup();
CallableStatement cs = prepareCall("CALL RETRIEVE_DYNAMIC_RESULTS(?) "
+ "ON TABLE EMP.PARTITIONTESTTABLE WHERE SECONDID in (?,?,?) AND THIRDID='3'");
cs.setInt(1, 2);
cs.setInt(2, 3);
cs.setInt(3, 4);
cs.setInt(4, 5);
cs.execute();
String[][] results=new String[2][1];
results[0][0]="1";
results[1][0]="1";
int rsIndex=-1;
do {
++rsIndex;
int rowIndex=0;
ResultSet rs = cs.getResultSet();
ResultSetMetaData metaData = rs.getMetaData();
int rowCount = metaData.getColumnCount();
while (rs.next()) {
String row="";
for (int i = 1; i <=rowCount; ++i) {
Object value = rs.getObject(i);
row+=value.toString();
}
if(rsIndex>1 || rowIndex>1) {
fail("the result is not correct!");
}
if(!row.equals(results[rsIndex][rowIndex])) {
fail("the result is not correct!");
}
++rowIndex;
}
} while (cs.getMoreResults());
}
private boolean compareColumns(ResultSetMetaData meta1,
ResultSetMetaData meta2) throws SQLException {
final int numColumns = meta1.getColumnCount();
if (meta2.getColumnCount() != numColumns) {
return false;
}
for (int i = 1; i <= numColumns; i++) {
if (meta1.getColumnType(i) != meta2.getColumnType(i)
|| !meta1.getColumnName(i).equals(meta2.getColumnName(i))) {
return false;
}
}
return true;
}
/**
* The following method returns an array of strings containing the column names for a given ResultSetMetaData object.
*/
public static String[] getColumnNames( ResultSetMetaData resultSetMetaData ) throws SQLException {
int columnCount = resultSetMetaData.getColumnCount();
String[] columnNames = new String[columnCount];
for ( int colIndex = 1; colIndex <= columnCount; colIndex++ ) {
columnNames[colIndex - 1] = resultSetMetaData.getColumnName( colIndex );
}
return columnNames;
}
/**
* Print out resultSet in two dimensional array format, for use by
* JDBC.assertFullResultSet(rs,expectedRows) expectedRows argument.
* Useful while converting tests to get output in correct format.
*
* @param rs
* @throws SQLException
*/
public static void showResultSet(ResultSet rs) throws SQLException {
System.out.print("{");
int row = 0;
boolean next = rs.next();
while (next) {
row++;
ResultSetMetaData rsmd = rs.getMetaData();
int nocols = rsmd.getColumnCount();
System.out.print("{");
for (int i = 0; i < nocols; i++)
{
String val = rs.getString(i+1);
if (val == null)
System.out.print("null");
else
System.out.print("\"" + rs.getString(i+1) + "\"");
if (i == (nocols -1))
System.out.print("}");
else
System.out.print(",");
}
next = rs.next();
if (next)
System.out.println(",");
else
System.out.println("};\n");
}
}
private Vector<byte[]> convertToVector(ResultSet rs) throws Exception {
Vector<byte[]> v = new Vector<byte[]>();
ResultSetMetaData rsmd = rs.getMetaData();
while (rs.next()) {
for (int i = 1; i <= rsmd.getColumnCount(); i++) {
v.add(rs.getBytes(i));
}
}
return v;
}
public static String getResultSetStr(ResultSet rs, int colWidths)
throws SQLException {
if (rs == null) {
return "null";
}
ResultSetMetaData rsmd = rs.getMetaData();
int colCount = rsmd.getColumnCount();
StringBuffer sb = new StringBuffer();
for (int i = 1; i <= colCount; i++) {
String label = String.format("%1$#" + colWidths + "s", rsmd.getColumnLabel(i));
sb.append(label + "|");
}
sb.append("\n");
while (rs.next()) {
StringBuffer row = new StringBuffer();
for (int i = 1; i <= colCount; i++) {
String value = rs.getString(i);
if (value == null) {
value = "null";
}
value = value.substring(0, Math.min(20, value.length()));
value = String.format("%1$#" + colWidths + "s", value.trim());
row.append(value + "|");
}
sb.append("\n");
}
return sb.toString();
}
public Map<String, Object> runSelectSingleRow(String query_key, Object... params)
{
HashMap<String, Object> res = new HashMap<>();
try (ResultSet rs = runSelect(query_key, params))
{
if (!rs.next())
{
throw new NoResultException("The query returned zero rows when one was expected.");
}
ResultSetMetaData meta = rs.getMetaData();
for (int i = 1; i <= meta.getColumnCount(); i++)
{
// We take the type as returned, with an exception for small numerics (we do not want long or BigInt which cannot be cast)
Object or;
if (meta.getColumnType(i) == java.sql.Types.NUMERIC && meta.getPrecision(i) <= 10)
{
or = rs.getInt(i);
}
else
{
or = rs.getObject(i);
}
res.put(meta.getColumnName(i).toUpperCase(), or);
}
if (rs.next())
{
throw new NonUniqueResultException("The query returned more than one row when one was expected");
}
}
catch (SQLException e)
{
throw new DatabaseException(e);
}
return res;
}
private void checkReturnedColumnsForBug44451(String stepDescription, String methodName, List<String> expectedFields, ResultSet resultSetToCheck)
throws Exception {
ResultSetMetaData rsMetaData = resultSetToCheck.getMetaData();
int numberOfColumns = rsMetaData.getColumnCount();
assertEquals(stepDescription + ", wrong column count in method '" + methodName + "'.", expectedFields.size(), numberOfColumns);
for (int i = 0; i < numberOfColumns; i++) {
int position = i + 1;
assertEquals(stepDescription + ", wrong column at position '" + position + "' in method '" + methodName + "'.", expectedFields.get(i),
rsMetaData.getColumnName(position));
}
rs.close();
}
/**
*
* @param rs
* @param builder
* @throws SQLException
*/
private void populate(ResultSet rs, Message.Builder builder)
throws SQLException {
ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount();// 列个数
String columnLabel = null;// 列名
Object columnValue = null;// 列值
Descriptors.FieldDescriptor fieldDescriptor = null;
for (int i = 1; i <= columnCount; i++) {
columnLabel = metaData.getColumnLabel(i);
columnValue = rs.getObject(i);
if (columnValue == null)
continue;// 如果为空，继续下一个
fieldDescriptor = descriptor.findFieldByName(columnLabel);
if (fieldDescriptor == null)
continue;// 如果为空，继续下一个
// 转换为相应的类型 ，会自动将 date 类型转换为long
if (fieldDescriptor.getType().equals(FieldDescriptor.Type.ENUM)) {
columnValue = fieldDescriptor.getEnumType().findValueByNumber(
(int) columnValue);
} else {
columnValue = ConvertUtils.convert(columnValue, fieldDescriptor
.getDefaultValue().getClass());
}
builder.setField(fieldDescriptor, columnValue);
}
}
public Record[] handle(ResultSet rSet) throws SQLException {
ResultSetMetaData meta = rSet.getMetaData();
List<Record> recordList = new ArrayList<Record>();
Record record = null;
List<Value> valueList = null;
if (startRow != null && startRow > 0) {
for (int i = 0; i < startRow - 1 && rSet.next(); i++);
}
long nbrRows = 0;
String columnName;
while (rSet.next()) {
record = new Record();
recordList.add(record);
valueList = new ArrayList<Value>();
for (int columnIndex = 1; columnIndex <= meta.getColumnCount(); columnIndex++) {
// TODO Normalize values (e.g. long varchars, etc.
// Alias field impl
columnName=meta.getColumnName(columnIndex);
if (this.getAliasMap().containsKey(columnName)) {
columnName=this.getAliasMap().get(columnName);
}
valueList.add(new Value(columnName, rSet.getObject(columnIndex)));
}
record.setValues(valueList.toArray(new Value[0]));
nbrRows++;
if (maxRows != null && maxRows > 0 && nbrRows >= maxRows) {
break;
}
}
return recordList.toArray(new Record[0]);
}
private Vector<byte[]> convertToVector(ResultSet rs) throws Exception {
Vector<byte[]> v = new Vector<byte[]>();
ResultSetMetaData rsmd = rs.getMetaData();
while (rs.next()) {
for (int i = 1; i <= rsmd.getColumnCount(); i++) {
v.add(rs.getBytes(i));
}
}
return v;
}
private void execCommand(Connection conn, StringBuffer command,
LineNumberReader lineReader) throws SQLException {
boolean hasResults;
try (Statement statement = conn.createStatement(); ResultSet rs = statement.getResultSet()) {
logger.debug(command.toString());
hasResults = false;
try {
hasResults = statement.execute(command.toString());
} catch (SQLException e) {
final String errText = String.format("Error executing '%s' (line %d): %s",
command, lineReader.getLineNumber(), e.getMessage());
logger.debug(errText);
System.err.println(errText);
if (stopOnError) {
throw new SQLException(errText, e);
}
}
if (autoCommit && !conn.getAutoCommit()) {
conn.commit();
}
if (hasResults && rs != null) {
ResultSetMetaData md = rs.getMetaData();
int cols = md.getColumnCount();
for (int i = 1; i <= cols; i++) {
String name = md.getColumnLabel(i);
logger.debug(name + "\t");
}
logger.debug("");
while (rs.next()) {
for (int i = 1; i <= cols; i++) {
String value = rs.getString(i);
logger.debug(value + "\t");
}
logger.debug("");
}
}
}
}
/**************supporting methods *******************/
private void dumpRSOriginal(ResultSet rs, String expectedValue) throws SQLException
{
if (rs == null) return;
ResultSetMetaData rsmd = rs.getMetaData();
int numCols = rsmd.getColumnCount();
if (numCols <= 0) return;
StringBuilder heading = new StringBuilder();
for (int i=1; i<=numCols; i++)
{
if (i > 1) heading.append(",");
heading.append("COL"+i);
heading.append("(datatype : " + rsmd.getColumnTypeName(i));
heading.append(", precision : " + rsmd.getPrecision(i));
heading.append(", scale : " + rsmd.getScale(i) + ")");
}
StringBuilder row = new StringBuilder();
while (rs.next())
{
for (int i=1; i<=numCols; i++)
{
if (i > 1) row.append(",");
row.append(rs.getString(i));
row.append(" ");
}
}
String actualValue = heading.toString() + " " + row.toString();
if ( usingDerbyNetClient() ) {
if ( expectedValue.indexOf("()") != -1 ) {
String actualValue2 = actualValue.replaceAll("CHAR", "CHAR ()");
actualValue = actualValue2;
}
}
assertEquals(expectedValue, actualValue);
rs.close();
}
protected String toJsonString(ResultSet rs) throws SQLException, JSONException {
ResultSetMetaData rsmd = rs.getMetaData();
JSONArray array = new JSONArray();
int numColumns = rsmd.getColumnCount();
while (rs.next()) {
JSONObject obj = new JSONObject();
for (int i = 1; i < numColumns + 1; i++) {
String column_label = rsmd.getColumnLabel(i);
log.debug("Column Name=" + column_label + ",type=" + rsmd.getColumnType(i));
switch (rsmd.getColumnType(i)) {
case Types.ARRAY:
obj.put(column_label, rs.getArray(i));
break;
case Types.BIGINT:
obj.put(column_label, rs.getInt(i));
break;
case Types.BOOLEAN:
obj.put(column_label, rs.getBoolean(i));
break;
case Types.BLOB:
obj.put(column_label, rs.getBlob(i));
break;
case Types.DOUBLE:
obj.put(column_label, rs.getDouble(i));
break;
case Types.FLOAT:
obj.put(column_label, rs.getFloat(i));
break;
case Types.INTEGER:
obj.put(column_label, rs.getInt(i));
break;
case Types.NVARCHAR:
obj.put(column_label, rs.getNString(i));
break;
case Types.VARCHAR:
obj.put(column_label, rs.getString(i));
break;
case Types.TINYINT:
obj.put(column_label, rs.getInt(i));
break;
case Types.SMALLINT:
obj.put(column_label, rs.getInt(i));
break;
case Types.DATE:
obj.put(column_label, rs.getDate(i));
break;
case Types.TIMESTAMP:
obj.put(column_label, rs.getTimestamp(i));
break;
default:
obj.put(column_label, rs.getObject(i));
break;
}
}
array.put(obj);
}
return array.toString();
}