微服务架构：用户管理模块定义

### 用户管理模块的Java实现 以下是基于微服务架构中用户管理模块的一个简单示例。假设我们有一个Python代码片段用于创建和验证用户的操作，下面将其转换为等效的Java代码。 #### Python 示例代码（假设） ```python class UserManager: def __init__(self, db_connection): self.db_connection = db_connection def create_user(self, username, password): query = f"INSERT INTO users (username, password) VALUES ('{username}', '{password}')" with self.db_connection.cursor() as cursor: cursor.execute(query) self.db_connection.commit() print(f"User {username} created successfully.") def authenticate_user(self, username, password): query = f"SELECT * FROM users WHERE username='{username}' AND password='{password}'" with self.db_connection.cursor() as cursor: cursor.execute(query) result = cursor.fetchone() if result: print("Authentication successful.") return True else: print("Authentication failed.") return False ``` #### Java 实现 下面是等价功能的Java版本： ```java import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; public class UserManager { private Connection dbConnection; public UserManager(Connection dbConnection) { this.dbConnection = dbConnection; } public void createUser(String username, String password) throws Exception { String query = "INSERT INTO users (username, password) VALUES (?, ?)"; try (PreparedStatement statement = dbConnection.prepareStatement(query)) { statement.setString(1, username); statement.setString(2, password); statement.executeUpdate(); System.out.println("User " + username + " created successfully."); } } public boolean authenticateUser(String username, String password) throws Exception { String query = "SELECT * FROM users WHERE username=? AND password=?"; try (PreparedStatement statement = dbConnection.prepareStatement(query)) { statement.setString(1, username); statement.setString(2, password); ResultSet resultSet = statement.executeQuery(); if (resultSet.next()) { System.out.println("Authentication successful."); return true; } else { System.out.println("Authentication failed."); return false; } } } } ``` --- ### 关键点说明 1. **数据库连接** 在Java中，`Connection`对象通常由外部提供给类实例化时注入[^3]。这类似于Python中的`db_connection`参数传递方式。 2. **SQL查询的安全性** 使用`PreparedStatement`代替字符串拼接来构建SQL语句，从而防止SQL注入攻击[^4]。 3. **资源管理** 利用`try-with-resources`语法自动关闭`PreparedStatement`和`ResultSet`，确保资源释放[^1]。 4. **异常处理** 方法声明抛出`Exception`以便调用者能够捕获并处理可能发生的错误，例如数据库连接失败或SQL执行错误。 --- ###