所以我有一个包含2个表的数据库 - 工作流和WorkflowSteps我想使用存储在那里的行来创建java中的对象但是我想要将我的数据库代码与我的应用程序代码分开。从一点开始 - 当创建Workflow / WorkflowSteps对象时,应用程序的其余部分将不必担心数据库访问。所以这就是我所拥有的:
public Workflow getPendingWorkflowId() {
int workflowid = -1;
Statement statement = null;
ResultSet rs = null;
try {
statement = con.createStatement();
rs = statement.executeQuery("SELECT id FROM xxx.workflows WHERE status = 'NOT-YET-STARTED' LIMIT 1");
while (rs.next()) {
workflowid = rs.getInt("id");
}
statement.close();
rs.close();
} catch (SQLException ex) {
Logger.getLogger(DBAccessor.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Error fetching workflows id");
}
return new Workflow(workflowid);
}
每个工作流对象都有一个List,用于存储与特定工作流有关的步骤,然后每个WorkflowStep都有一个Map,用于存储从第3个表中获取的数据:
public List<WorkflowStep> getUnworkedStepsByWFId(int id) {
//can be changed
ArrayList<WorkflowStep> steps = new ArrayList<WorkflowStep>();
Statement statement = null;
ResultSet rs = null;
try {
statement = con.createStatement();
rs = statement.executeQuery("SELECT * FROM `workflow_steps` WHERE `workflow_id` =" + id + " AND status = 'NOT-YET-STARTED'");
while (rs.next()) {
steps.add(new WorkflowStep(rs.getInt(1), rs.getInt(3), rs.getInt(4)));
}
statement.close();
rs.close();
} catch (SQLException ex) {
Logger.getLogger(DBAccessor.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Error fetching workflows id");
}
return steps;
}
这是第3个表的查询: public Map getParametersForStep(int workflowId,int workstepPos){
Statement statement = null;
ResultSet rs = null;
Map<String, String> hMap = new HashMap<String, String>();
try {
statement = con.createStatement();
//MIGHT BE WRONG
rs = statement.executeQuery("SELECT wf.id AS workflowID, ws_steps.id AS workflowStepsID, name, param_value, pathname FROM workflows AS wf INNER JOIN workflow_steps AS ws_steps ON wf.id = ws_steps.workflow_id INNER JOIN ws_parameters ON ws_parameters.ws_id = ws_steps.id INNER JOIN submodule_params ON submodule_params.id = ws_parameters.sp_id AND wf.id =" + workflowId + " AND ws_steps.workflow_position =" + workstepPos);
String paramName = null;
String paramValue = null;
while (rs.next()) {
paramName = rs.getString("name");
if (rs.getString("param_value") == null) {
paramValue = rs.getString("pathname");
} else {
paramValue = rs.getString("param_value");
}
hMap.put(paramName, paramValue);
}
statement.close();
rs.close();
return hMap;
} catch (SQLException ex) {
Logger.getLogger(DBAccessor.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Error fetching workflow step parameters names");
}
return Collections.emptyMap();
}
记住这些代码后,我最终使用以下“过程”来初始化工作流及其所有WorkflowSteps及其参数:
Workflow wf = db.getPendingWorkflowId();
wf.initSteps(db.getUnworkedStepsByWFId(wf.getId()));
Iterator<WorkflowStep> it = wf.getSteps();
while(it.hasNext()) {
WorkflowStep step = it.next();
step.setParameters(db.getParametersForStep(wf.getId(), step.getPosInWorkflow()));
}
我认为我有很好的解耦程度,但我想知道这是否可以以某种方式重构 - 例如,可能将step.setParameters移动到WorkflowStep类的方法但是我必须传递对数据库连接的引用(db)到WorkflowStep对象,但在我的视图中,这将破坏解耦?那么你们如何重构这段代码呢?
答案 0 :(得分:2)
答案 1 :(得分:0)
这是Object Relational Mapper的功能。它用于从您的业务模型中抽象出您的数据库访问。实际上,使用得当,ORM库允许您根本不编写数据库代码。