我正在构建一个小型应用程序，用于管理用户并在Android Studio中进行转换，并且我将Firebase数据库用作后端。
用户和班次具有M：M关系，因为可以将许多用户分配给同一班次，而一个班次可以有许多用户。
这是我的数据库的结构：
String FROM = "sender@example.com";
String FROMNAME = "Sender Name";
String TO = "recipient@amazon.com";
String SMTP_USERNAME = "smtp_username";
String SMTP_PASSWORD = "smtp_password";
String CONFIGSET = "ConfigSet";
String HOST = "email-smtp.us-west-2.amazonaws.com";
int PORT = 587;
String SUBJECT =
"Amazon SES test (SMTP interface accessed using C#)";
String BODY =
"<h1>Amazon SES Test</h1>" +
"<p>This email was sent through the " +
"<a href='https://aws.amazon.com/ses'>Amazon SES</a> SMTP interface " +
"using the .NET System.Net.Mail library.</p>";
MailMessage message = new MailMessage();
message.IsBodyHtml = true;
message.From = new MailAddress(FROM, FROMNAME);
message.To.Add(new MailAddress(TO));
message.Subject = SUBJECT;
message.Body = BODY;
message.Headers.Add("X-SES-CONFIGURATION-SET", CONFIGSET);
using (var client = new System.Net.Mail.SmtpClient(HOST, PORT))
{
client.Credentials =
new NetworkCredential(SMTP_USERNAME, SMTP_PASSWORD);
client.EnableSsl = true;
try
{
Console.WriteLine("Attempting to send email...");
client.Send(message);
Console.WriteLine("Email sent!");
}
catch (Exception ex)
{
Console.WriteLine("The email was not sent.");
Console.WriteLine("Error message: " + ex.Message);
}
}
}
}
}
构建我的应用程序后，当用户单击日历中的日期时，会打开{
"linking" : {
"shift-assign" : {
"key1" : {
"111" : true,
"222" : true
},
"key2" : {
"111" : true
}
},
"user-assign" : {
"111" : {
"key1" : true,
"key2" : true
},
"222" : {
"key1" : true
}
}
},
"shifts" : {
"20191116" : {
"key1" : {
"endTime" : "00:00",
"name" : "Morning",
"numOfEmps" : 3,
"startTime" : "00:00",
"wage" : 0
},
"key2" : {
"endTime" : "00:00",
"name" : "Night",
"numOfEmps" : 1,
"startTime" : "00:00",
"wage" : 0
}
}
},
"users" : {
"111" : {
"id" : "111",
"password" : "111",
...
},
"222" : {
"id" : "222",
"password" : "222",
...
},
"99999" : {
"id" : "99999",
"password" : "123",
...
}
}
}
，其中列出了与该日期相关的所有班次。
我正在使用一个可扩展列表将数据呈现给用户-标头代表一个班次（在所述日期下），其子级代表当前分配给该班次的所有用户。
但是我很难从Firebase提取数据。
这是我的DateActivity：
DateActivity显示了可扩展列表，但数据全部弄乱了。而不是public class DateActivity extends AppCompatActivity {
private String[] dates; // the chosen date and its prior dates
private List<mShift> shiftList; // parent items of expandable list
private List<mUser> userList; // child items of expandable list
private HashMap<mShift, List<mUser>> collection = new HashMap<>(); // mapping parent-children
private ExpandableListView expListView;
private mUser user; // store the logged-in user ,to be replaced with user's id
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_date);
// get user object from shared preferences
SharedPreferences sp = getSharedPreferences("sp", 0);
String json = sp.getString("user", "");
user = (new Gson()).fromJson(json, mUser.class);
// get dates array
// chosen date in index 0
// yesterday's date in index 1
// and so on
dates = sp.getString("days", "").split(",");
//bind elements here...
expListView = (ExpandableListView) findViewById(R.id.expListView);
// Fetch all shifts for selected date
fetchShifts();
}
private void fetchShifts() {
// root reference
DatabaseReference mDatabase = FirebaseDatabase.getInstance().getReference();
// reference to shifts/dates[0]
mDatabase.child("shifts")
.child(dates[0])
.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
// create a new shift list
shiftList = new ArrayList<>();
// loop through all shift objects
for (DataSnapshot ds : dataSnapshot.getChildren()) {
mShift shift = ds.getValue(mShift.class);
shift.setKey(ds.getKey());
shiftList.add(shift); // add shift to list
// reference to linking/shift-assign/shift-key
mDatabase.child("linking")
.child("shift-assign")
.child(shift.getKey())
.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
// create a new user list
userList = new ArrayList<>();
// loop through all user objects
for(DataSnapshot ds1 : snapshot.getChildren()){
// reference to users/user-id
mDatabase.child("users")
.child(ds1.getKey())
.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot2) {
mUser u = snapshot2.getValue(mUser.class);
userList.add(u); // add user to list
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {}
});
}
// map current shift and its users
collection.put(shiftList.get(0), userList);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {}
});
}
final ExpandableListAdapter expListAdapter = new ExpandableListAdapter(DateActivity.this, shiftList, collection, dates, user);
expListView.setAdapter(expListAdapter);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {}
});
}
下的两个用户，我仅获得第一个（ID为key1的用户，而111下的我应该显示一个用户，但没有一个用户。