我正在制作一个使用MySQL的Android登录应用程序。我创建了一个DatabaseHandler类,其中包含两个私有类,这些类扩展了AsyncTask。
代码:
为了查明为什么它不起作用,我添加了以
问题:我该怎么修复这个问题?
代码:
package me.martinwiesner.cpad;
import android.os.AsyncTask;
import android.support.annotation.Nullable;
import android.util.Log;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
public class UserDatabaseHandler {
private static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
private static final String DB_URL = "sql7.freemysqlhosting.net";
private static final String USER = "**********";
private static final String PASS = "**********";
private static Get get;
private static Set set;
public static void onCreate() {
get = new Get();
set = new Set();
}
static List<User> getAllUsers() {
return get.doInBackground(new String[]{""});
}
@Nullable
static User getUser(String email) {
for (User user : getAllUsers()) {
if (user.getEmail().equals(email))
return user;
}
return null;
}
@Nullable
static User getUser(int id) {
for (User user : getAllUsers()) {
if (user.getId() == id)
return user;
}
return null;
}
static void setAllUsers(List<User> users) {
set.doInBackground(users);
}
static void addUser(User user) {
List<User> users = getAllUsers();
users.add(user);
setAllUsers(users);
}
static User addUser(String name, String email, String password, boolean isAdmin) {
Log.e("UDH", "Adding User");
int id = 0;
for (User user : getAllUsers()) {
if (user.getId() != id) {
break;
} else {
id++;
}
}
User user = new User(id, name, email, password, isAdmin);
addUser(user);
return user;
}
private static class Get extends AsyncTask<String, Void, List<User>> {
@Override
protected List<User> doInBackground(String... strings) {
Log.e("UDH", "Getting in Background");
Connection connection = null;
Statement statement = null;
List<User> allUsers = new ArrayList<>();
try {
Log.e("UDH", "Getting in Background - Trying");
Class.forName(JDBC_DRIVER);
connection = DriverManager.getConnection(DB_URL, USER, PASS);
statement = connection.createStatement();
String sql = "SELECT * FROM users";
ResultSet rs = statement.executeQuery(sql);
while (rs.next()) {
int id = rs.getInt("ID");
String name = rs.getString("NAME");
String email = rs.getString("EMAIL");
String password = rs.getString("PASSWORD");
boolean isAdmin = rs.getBoolean("ISADMIN");
Log.e("Getting", id + "");
Log.e("Getting", name);
Log.e("Getting", email);
Log.e("Getting", password);
Log.e("Getting", isAdmin + "");
User user = new User(id, name, email, password, isAdmin);
allUsers.add(user);
}
rs.close();
statement.close();
connection.close();
} catch (SQLException se) {
se.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (statement != null)
statement.close();
} catch (SQLException se2) {
}
try {
if (connection != null)
connection.close();
} catch (SQLException se) {
se.printStackTrace();
}
}
return allUsers;
}
}
private static class Set extends AsyncTask<List<User>, Void, String> {
@Override
protected String doInBackground(List<User>... users) {
Log.e("UDH", "Setting in Background");
Connection connection = null;
Statement statement = null;
for (User user : users[0]) {
try {
connection = DriverManager.getConnection(DB_URL, USER, PASS);
statement = connection.createStatement();
String query = "INSERT INTO `users`(`ID`, `NAME`, `EMAIL`, `PASSWORD`, `ISADMIN`) VALUES ("
+ user.getId() + "," + user.getName() + "," + user.getEmail() + "," + user.getPassword()
+ "," + user.isAdmin() + ")";
ResultSet rs = statement.executeQuery(query);
rs.close();
connection.close();
statement.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (statement != null)
statement.close();
} catch (SQLException se2) {
}
try {
if (connection != null)
connection.close();
} catch (SQLException se) {
se.printStackTrace();
}
}
}
return "";
}
}
}
为了查明为什么它不起作用,我添加了以
Log.e
开头的代码行。每次我写Log.e
时都会记录日志,但它不起作用。问题:我该怎么修复这个问题?