java怎么连接数据库
时间: 2024-05-10 12:20:57 浏览: 4
Java可以通过JDBC(Java Database Connectivity)连接数据库。
以下是连接MySQL数据库的示例代码:
1. 导入JDBC相关的包:
```
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
```
2. 加载MySQL的JDBC驱动:
```
Class.forName("com.mysql.jdbc.Driver");
```
3. 建立数据库连接:
```
String url = "jdbc:mysql://localhost:3306/test"; // 数据库URL
String user = "root"; // 数据库用户名
String password = "123456"; // 数据库密码
Connection conn = DriverManager.getConnection(url, user, password);
```
其中,URL格式为“jdbc:mysql://<hostname>:<port>/<database_name>”。
4. 执行SQL语句:
```
Statement stmt = conn.createStatement();
String sql = "SELECT * FROM users";
ResultSet rs = stmt.executeQuery(sql);
while (rs.next()) {
int id = rs.getInt("id");
String name = rs.getString("name");
System.out.println("id=" + id + ", name=" + name);
}
```
5. 关闭数据库连接:
```
rs.close();
stmt.close();
conn.close();
```
完整代码示例:
```
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class JdbcDemo {
public static void main(String[] args) {
Connection conn = null;
try {
// 加载MySQL的JDBC驱动
Class.forName("com.mysql.jdbc.Driver");
// 建立数据库连接
String url = "jdbc:mysql://localhost:3306/test";
String user = "root";
String password = "123456";
conn = DriverManager.getConnection(url, user, password);
// 执行SQL语句
Statement stmt = conn.createStatement();
String sql = "SELECT * FROM users";
ResultSet rs = stmt.executeQuery(sql);
while (rs.next()) {
int id = rs.getInt("id");
String name = rs.getString("name");
System.out.println("id=" + id + ", name=" + name);
}
// 关闭数据库连接
rs.close();
stmt.close();
conn.close();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
```