用Python写一个SQLBuilder。Java版能够从 看到。
附上代码：演示样例代码（一）：
class SQLDirector: @classmethod def buildSQL(cls, builder): sql = "" sql += builder.getCommand() sql += builder.getTable() sql += builder.getWhat() sql += builder.getCriteria() return sqlclass SQLBuilder: def __init__(self): pass def __del__(self): pass def getCommand(self): pass def getTable(self): pass def getWhat(self): pass def getCriteria(self): passclass InsertBuilder(SQLBuilder): def __init__(self): self._table = "" self._columnsAndData = dict() self._criteria = "" def setTable(self, table): self._table = table def getCommand(self): return "INSERT INTO " def getTable(self): return self._table def getWhat(self): columns = list() values = list() what = "" for columnName in self._columnsAndData: columns.append(columnName) values.append(self._columnsAndData[columnName]) columns_str = string.join( map(lambda x: str(x), columns), "," ) values_str = string.join( map(lambda x: str(x), values), "," ) what += " (" what += columns_str what += ") VALUES (" what += values_str what += ") " return what def getCriteria(self): return "" def addColumnAndData(self, columnName, value): if value: self._columnsAndData[columnName] = valuedef main(): builder = InsertBuilder() builder.setTable("employees") builder.addColumnAndData("employee_id", int(221)) builder.addColumnAndData("first_name", "'Shane'") builder.addColumnAndData("last_name", "'Grinnell'") builder.addColumnAndData("email", "'al@yahoo.com'") sql = SQLDirector.buildSQL(builder) print sqlif __name__ == '__main__': main() 更有意思的玩法。
代码演示样例（二）：
#!/usr/bin/env pythonimport stringclass SQLDirector: def __init__(self, builder): self._builder = builder def construct(self): self._builder.buildSQL() return self._builder.getSQL()class SQLBuilder: def __init__(self): self._sql = '' def buildSQL(self): return self def getSQL(self): return self._sqlclass InsertBuilder(SQLBuilder): def __init__(self): self._columns = list() self._values = list() def buildSQL(self): columns_str = string.join( map(lambda x: "`%s`" % str(x), self._columns), "," ) values_str = string.join( map(lambda x: "'%s'" % str(x), self._values), "," ) self._sql = "INSERT INTO " self._sql += self._table self._sql += " (%s) VALUES (%s) " % (columns_str, values_str) return self def table(self, table): self._table = table return self def column(self, columnName, value): self._columns.append(columnName) self._values.append(value) return selfdef main(): insertBuilder = InsertBuilder() insertBuilder.table("dt_process") \ .column("attr_key","foo").column("attr_val", "bar") sqlDirector = SQLDirector(insertBuilder) print sqlDirector.construct()if __name__ == "__main__": main() 演示样例代码（三）：
#!/usr/bin/env pythonimport stringdef main(): insertBuilder = InsertBuilder() insertBuilder.table("dt_process") \ .column("attr_key","foo").column("attr_val", "bar") sqlDirector = SQLDirector(insertBuilder) print sqlDirector.construct() createBuilder = CreateBuilder() createBuilder.table("newTable").ifnotexists() \ .column("id").col_type("INTEGER").col_autoincrement() \ .column("name").col_type("VARCHAR(40)").col_nullable(False).col_default("empty") sqlDirector = SQLDirector(createBuilder) print sqlDirector.construct()# -----------------------------------------------------------------------------# Libraries# -----------------------------------------------------------------------------class SQLDirector: def __init__(self, builder): self._builder = builder def construct(self): self._builder.buildSQL() return self._builder.getSQL()class SQLBuilder: def __init__(self): self._sql = '' def buildSQL(self): return self def getSQL(self): return self._sqlclass CreateBuilder(SQLBuilder): def __init__(self): self._columns = list() # item: dict => 'name', 'nullable', 'default' self._column_context = None self._table = "" self._ifnotexists = "" self._criteria = "" def _map_column(self, column): sql = "" if column.has_key('name'): sql += " `%s`"%column['name'] if column.has_key('type'): sql += " %s"%column['type'] if column.has_key('nullable'): sql += "%s"%column['nullable'] if column.has_key('default'): sql += "%s"%column['default'] if column.has_key('auto_increment'): sql += "%s"%column['auto_increment'] return sql def _reduce_column(self, left, right): return left + ", " + right def buildSQL(self): columns_str = reduce(self._reduce_column, map( self._map_column, self._columns )) self._sql = "CREATE TABLE " self._sql += self._ifnotexists self._sql += self._table self._sql += " (%s)" % columns_str return self def ifnotexists(self): self._ifnotexists = " IF NOT EXISTS " return self def table(self, table): self._table = table return self def column(self, columnName): column = dict() column['name'] = columnName self._columns.append(column) self._column_context = column return self def col_type(self, type): self._column_context['type'] = type return self def col_nullable(self, nullable=True): if nullable: self._column_context['nullable'] = "" else: self._column_context['nullable'] = " NOT NULL" return self def col_default(self, default): self._column_context['default'] = " DEFAULT %s" % default return self def col_autoincrement(self, autoincrement=True): self._column_context['auto_increment'] = " AUTO_INCREMENT" return self def primary(self, primary=True): self._primary_key.append(self._column_context['name']) return self## INSERT INTO#class InsertBuilder(SQLBuilder): def __init__(self): self._columns = list() self._values = list() self._table = "" def buildSQL(self): columns_str = string.join( map(lambda x: "`%s`" % str(x), self._columns), "," ) values_str = string.join( map(lambda x: "'%s'" % str(x), self._values), "," ) self._sql = "INSERT INTO " self._sql += self._table self._sql += " (%s) VALUES (%s) " % (columns_str, values_str) return self def table(self, table): self._table = table return self def column(self, columnName, value): self._columns.append(columnName) self._values.append(value) return selfif __name__ == "__main__": main()