java把从MySQL数据库blog中user表中查询的数据放list中
时间: 2023-03-19 10:24:39 浏览: 84
您可以使用Java中的JDBC(Java Database Connectivity)来连接MySQL数据库并从数据库中查询数据。以下是一个简单的示例代码,它将从MySQL数据库的"blog"数据库中的"user"表中查询数据,并将结果放入一个List中:
```
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
public class Example {
public static void main(String[] args) {
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
List<User> users = new ArrayList<>();
try {
// Connect to the database
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/blog", "username", "password");
// Execute the query
statement = connection.createStatement();
resultSet = statement.executeQuery("SELECT * FROM user");
// Loop through the results and add each user to the list
while (resultSet.next()) {
User user = new User();
user.setId(resultSet.getInt("id"));
user.setUsername(resultSet.getString("username"));
user.setEmail(resultSet.getString("email"));
users.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
// Close the resources
if (resultSet != null) {
resultSet.close();
}
if (statement != null) {
statement.close();
}
if (connection != null) {
connection.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
// Do something with the list of users
for (User user : users) {
System.out.println(user);
}
}
}
// User class
class User {
private int id;
private String username;
private String email;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", email='" + email + '\'' +
'}';
}
}
```
在上面的示例代码中,我们首先建立了一个与MySQL数据库的连接,然后使用一个SQL语句执行查询操作。然后我们使用一个while循环来遍历查询结果,并将每个用户添加到一个List中。最后,我们打印出List中的每个用户。请注意,您需要根据您的MySQL数据库的实际配置更改连接字符串中的数据库名称、用户名和密码。