以下是一个简单的Servlet和JSP实现登录注册的例子：
1. 创建用户实体类User.java
```java
public class User {
private String username;
private String password;
public User() {
}
public User(String username, String password) {
this.username = username;
this.password = password;
}
// Getters and Setters
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
```
2. 创建数据库连接工具类DBUtil.java
```java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class DBUtil {
private static final String URL = "
