jdbctemplate 获取数据表结构的方法&注意事项

方法一 直接查询：

SqlRowSet srcSqlRowSet = srcJdbcTemplate.queryForRowSet("SELECT * FROM tablename LIMIT 0"); //注意limit 0更合适
List<ColumnMetaData> columneMetaList = new LinkedList<ColumnMetaData>();
int columnCount;
SqlRowSetMetaData sqlRowSetMetaData = sqlRowSet.getMetaData();
columnCount = sqlRowSetMetaData.getColumnCount();
for (int i = 1; i <= columnCount; i++) {
    columneMetaList.add(new ColumnMetaData(sqlRowSetMetaData.getColumnName(i), sqlRowSetMetaData.getColumnType(i), sqlRowSetMetaData.getColumnTypeName(i))); //获取字段的名称、类型和描述
}
Collections.sort(columneMetaList);

方法一的ColumnMetaData类代码如下：

public class ColumnMetaData implements Comparable<ColumnMetaData> {

    private String name; // 字段名称
    private int type; // 字段类型
    private String typeName; // 字段类型名称
    private Object value; // 值
    
    public ColumnMetaData(String columnName, int valueType, String typeName) {
        this.name = columnName;
        this.type = valueType;
        this.typeName = typeName;
    }
}

方法二 使用RowCountCallbackHandler查询

String sql = "select * from "+ tableName + " limit 0";  
RowCountCallbackHandler rcch = new RowCountCallbackHandler();  
this.jdbcTemplateDao.query(sql, rcch);  
String[] coloumnName = rcch.getColumnNames();  
int[] coloumnType = rcch.getColumnTypes();  

方法二效率高，但麻烦的是拿到了类型是数字，如果要获得字段的描述信息，比如：int还是varchar等，需要一个对照关系类：

public class SqlTypeAdapter {
public static String getTypeName(int type) throws SQLException {
        switch (type) {
            case Types.ARRAY:
                break;
            case Types.BIGINT:
                return "BIGINT";
            case Types.BINARY:
                return "BINARY";
            case Types.BIT:
                return "BIT";
            case Types.BLOB:
                return "BLOB";
            case Types.BOOLEAN:
                return "BOOLEAN";
            //..代码太多就不多写啦default:
                break;
        }
        return "VARCHAR";
    }
}