java点菜系统连接数据库
时间: 2023-08-18 20:07:11 浏览: 48
要连接数据库,你需要使用Java的JDBC API。下面是连接数据库并执行查询的基本步骤:
1. 加载数据库驱动程序
```java
Class.forName("com.mysql.jdbc.Driver");
```
2. 创建数据库连接
```java
String url = "jdbc:mysql://localhost:3306/mydatabase";
String user = "root";
String password = "mypassword";
Connection conn = DriverManager.getConnection(url, user, password);
```
3. 创建Statement对象
```java
Statement stmt = conn.createStatement();
```
4. 执行查询语句
```java
ResultSet rs = stmt.executeQuery("SELECT * FROM dishes");
```
5. 处理查询结果
```java
while (rs.next()) {
String name = rs.getString("name");
double price = rs.getDouble("price");
// do something with the data
}
```
完整的代码示例:
```java
import java.sql.*;
public class DishCatalog {
public static void main(String[] args) {
try {
// Load the JDBC driver
Class.forName("com.mysql.jdbc.Driver");
// Connect to the database
String url = "jdbc:mysql://localhost:3306/mydatabase";
String user = "root";
String password = "mypassword";
Connection conn = DriverManager.getConnection(url, user, password);
// Create a statement
Statement stmt = conn.createStatement();
// Execute a query
ResultSet rs = stmt.executeQuery("SELECT * FROM dishes");
// Process the query results
while (rs.next()) {
String name = rs.getString("name");
double price = rs.getDouble("price");
System.out.println(name + ": $" + price);
}
// Close the resources
rs.close();
stmt.close();
conn.close();
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
```
请注意,这只是一个基本示例,实际上你需要根据你的具体情况进行适当的调整。例如,你需要根据你的数据库类型和配置来选择正确的驱动程序,并且你需要根据你的查询语句和数据表结构来处理查询结果。