我希望有一个Sqlite数据库，它有点像我用来存储信息的MySql数据库。在Sqlite中，默认情况下禁用外键。
当我尝试使用＆＃34; setForeignKeyConstraintsEnabled（）＆＃34;命令我收到以下错误。
java.lang.IllegalStateException：当正在进行事务时，无法启用或禁用外键约束。完成所有事务并首先释放所有活动数据库连接。
我该如何解决这个问题？
RegisterActivity
package e.adin_pc.spark;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import java.util.HashMap;
import java.util.Map;
public class Register extends AppCompatActivity {
EditText Username,Password,Email,Birthday;
Button Register;
String insertURL = "http://10.0.2.2/skripte/insert_user.php";
RequestQueue requestQueue;
private DatabaseHandler db;
private static final String TAG = "RegisterActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_register);
Username=findViewById(R.id.UserNameReg_EditText);
Password=findViewById(R.id.PasswordReg_EditText);
Email=findViewById(R.id.EmailReg_EditText);
Birthday=findViewById(R.id.BirthdayReg_EditText);
Register=findViewById(R.id.register_Button);
db=new DatabaseHandler(this);
requestQueue = Volley.newRequestQueue(getApplicationContext());
Register.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
StringRequest stringRequest = new StringRequest(Request.Method.POST,
insertURL, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Toast.makeText(Register.this,response,Toast.LENGTH_LONG).show();
//Make object
Users user=new Users();
user.setId(Integer.parseInt(
user.setUserName(Username.toString());
user.setPassword(Password.toString());
user.setEmail(Email.toString());
user.setBirthday(Birthday.toString());
user.setIs_Admin(false);
//INSERT IS CALLED HERE
boolean insert = db.InsertUser(user);
Log.i(TAG,"Uspjelo je valjda ",null);
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(Register.this,error.toString(),Toast.LENGTH_LONG).show();
}
}) {
@Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> parameters = new HashMap<String, String>();
parameters.put("USERNAME", Username.getText().toString());
parameters.put("PASSWORD", Password.getText().toString());
parameters.put("EMAIL", Email.getText().toString());
parameters.put("BIRTHDAY", Birthday.getText().toString());
return parameters;
}
};
requestQueue.add(stringRequest);
}
});
}
}
数据库处理程序代码
package e.adin_pc.spark;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
/**
* Created by Adin-PC on 3/30/2018.
*/
public class DatabaseHandler extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "Spark.db";
private static final int VERSION = 1;
//Tabela1
private static final String table1_name="Users";
private static final String Users_id = "Users_id";
private static final String user_name = "user_name";
private static final String password = "password";
private static final String email = "email";
private static final String birthday = "birthday";
private static final String is_admin = "is_admin";
//Table 2
private static final String table2_name="Flights";
private static final String Flights_id = "Flights_id";
private static final String start_destination = "start_destination";
private static final String end_destination = "end_destination";
private static final String flight_start_time = "flight_start_time";
private static final String Flight_end_time = "Flight_end_time";
private static final String Price = "Price";
//Table 3
private static final String table3_name="User_flights";
private static final String User_flights_id = "User_flights_id";
private static final String User_fk = "User_fk";
private static final String Flight_fk = "Flight_fk";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String Tb1Sql="CREATE TABLE "+table1_name+" ("+
Users_id+" integer primary key , "+
user_name+" text not null,"+
password+" text not null,"+
email+" text not null,"+
birthday+" text not null,"+
is_admin+" text not null"+" )";
String Tb2Sql="CREATE TABLE "+table2_name+" ("+
Flights_id+" integer primary key , "+
start_destination+" text not null,"+
end_destination+" text not null,"+
flight_start_time+" text not null,"+
Flight_end_time+" text not null,"+
Price+" text not null"+" )";
String Tb3Sql="CREATE TABLE "+table3_name+" ("+
User_flights_id+" integer primary key , "+
User_fk+" integer not null, "+
"FOREIGN KEY ("+User_fk+") REFERENCES "+table1_name+"("+Users_id+"), "+
Flight_fk+" integer not null, "+
"FOREIGN KEY ("+Flight_fk+") REFERENCES "+table2_name+"("+Flights_id+")"+
" )";
db.setForeignKeyConstraintsEnabled(true); //ERROR IS HERE
//db.execSQL("PRAGMA foreign_keys=ON"); //THIS ALSO DOESNT WORK
db.execSQL(Tb1Sql);
db.execSQL(Tb2Sql);
db.execSQL(Tb3Sql);
}
@Override
public void onOpen(SQLiteDatabase db) {
super.onOpen(db);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + table3_name);
db.execSQL("DROP TABLE IF EXISTS " + table1_name);
db.execSQL("DROP TABLE IF EXISTS " + table2_name);
onCreate(db);
}
//*---------------------------USER COMMANDS-------------------------------------------------------
public boolean InsertUser(Users New_User){
SQLiteDatabase db=this.getWritableDatabase();
ContentValues values=new ContentValues();
values.put(Users_id,New_User.getId());
values.put(user_name,New_User.getUserName());
values.put(password,New_User.getPassword());
values.put(email,New_User.getEmail());
values.put(birthday,New_User.getBirthday());
values.put(is_admin,New_User.getIs_Admin());
long result=db.insert(table1_name,null,values);
db.close();
if (result == -1) {
return false;
} else {
return true;
}
}
public Users GetUser(String UserName, String Password){
SQLiteDatabase db=this.getReadableDatabase();
String Query="SELECT * FROM "+ table1_name+" WHERE "+user_name+" = "+UserName+" AND "+
password+" = "+Password;
Cursor c = db.rawQuery(Query, null);
if (c != null)
c.moveToFirst();
Users user= new Users();
user.setId(c.getInt(c.getColumnIndex(Users_id)));
user.setUserName(c.getString(c.getColumnIndex(user_name)));
user.setPassword(c.getString(c.getColumnIndex(password)));
user.setEmail(c.getString(c.getColumnIndex(email)));
user.setBirthday(c.getString(c.getColumnIndex(birthday)));
String IsAdmin=c.getString(c.getColumnIndex(is_admin));
String validation;
if (IsAdmin=="true")
user.setIs_Admin(true);
else
user.setIs_Admin(false);
db.close();
return user;
}
//*---------------------------FLIGTS COMMANDS-------------------------------------------------------
public boolean InsertFlights(Flights New_flight){
SQLiteDatabase db=this.getWritableDatabase();
ContentValues values=new ContentValues();
values.put(start_destination,New_flight.getStart_destination());
values.put(end_destination,New_flight.getEnd_destination());
values.put(flight_start_time,New_flight.getFlight_start_time());
values.put(Flight_end_time,New_flight.getFlight_end_time());
values.put(Price,New_flight.getPrice());
long result=db.insert(table2_name,null,values);
db.close();
if (result == -1) {
return false;
} else {
return true;
}
}
/*
* getting all flights under single user
* */
public List<Flights> getAllUSersFlights(long user_id) {
List<Flights> flights = new ArrayList<Flights>();
String selectQuery = "SELECT * FROM " + table2_name +" INNER JOIN "+ table3_name+" ON "
+ table2_name+"."+Flights_id+" = "+table3_name+"."+Flight_fk+" WHERE "+table3_name+"."+User_fk+"="+user_id;
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (c.moveToFirst()) {
do {
Flights td = new Flights();
td.setId(c.getInt((c.getColumnIndex(Flights_id))));
td.setStart_destination(c.getString(c.getColumnIndex(start_destination)));
td.setEnd_destination(c.getString(c.getColumnIndex(end_destination)));
td.setFlight_start_time(c.getString(c.getColumnIndex(flight_start_time)));
td.setFlight_end_time(c.getString(c.getColumnIndex(Flight_end_time)));
td.setPrice(c.getFloat(c.getColumnIndex(Price)));
flights.add(td);
} while (c.moveToNext());
}
db.close();
return flights;
}
//*---------------------------USerFlights COMMANDS-------------------------------------------------------
public boolean InsertUSerFlights(long user_id,long flight_id ){
SQLiteDatabase db=this.getWritableDatabase();
ContentValues values=new ContentValues();
values.put(User_fk, user_id);
values.put(Flight_fk, flight_id);
long result=db.insert(table3_name,null,values);
if (result == -1) {
return false;
} else {
return true;
}
}
}
答案 0 :(得分：1)
使用onConfigure()回调来呼叫setForeignKeyConstraintsEnabled()。
onCreate()运行在事务中执行。它也只运行一次而不是以后的应用程序调用，所以它不适合设置外键pragma。