当前位置：首页 > news >正文

错误处理最佳实践

news 2025/10/28 8:59:50

Rust 错误处理最佳实践

概述

Rust 的错误处理机制通过类型系统强制开发者显式处理错误。主要使用 Result<T, E> 和 Option<T> 类型来表示可能的失败情况。

错误处理基础

Rust 将错误分为两类：

可恢复错误 - 使用 Result<T, E>
不可恢复错误 - 使用 panic!

基本示例

use std::fs::File;
use std::io::{self, Read};fn read_file_basic(path: &str) -> Result<String, io::Error> {let mut file = File::open(path)?;let mut contents = String::new();file.read_to_string(&mut contents)?;Ok(contents)
}

复杂案例：构建一个配置管理系统

实现一个完整的配置管理系统，展示高级错误处理技术：

use std::fmt;
use std::fs;
use std::io;
use std::num::ParseIntError;
use std::path::Path;// 自定义错误类型
#[derive(Debug)]
enum ConfigError {IoError(io::Error),ParseError(String),ValidationError(String),MissingField(String),InvalidValue { field: String, reason: String },
}impl fmt::Display for ConfigError {fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {match self {ConfigError::IoError(e) => write!(f, "IO 错误: {}", e),ConfigError::ParseError(msg) => write!(f, "解析错误: {}", msg),ConfigError::ValidationError(msg) => write!(f, "验证错误: {}", msg),ConfigError::MissingField(field) => write!(f, "缺少字段: {}", field),ConfigError::InvalidValue { field, reason } => {write!(f, "字段 '{}' 的值无效: {}", field, reason)}}}
}impl std::error::Error for ConfigError {}impl From<io::Error> for ConfigError {fn from(error: io::Error) -> Self {ConfigError::IoError(error)}
}impl From<ParseIntError> for ConfigError {fn from(_error: ParseIntError) -> Self {ConfigError::ParseError("无法解析整数".to_string())}
}// 配置结构
#[derive(Debug, Clone)]
struct ServerConfig {host: String,port: u16,max_connections: usize,timeout_seconds: u64,enable_logging: bool,
}impl ServerConfig {fn new(host: String,port: u16,max_connections: usize,timeout_seconds: u64,enable_logging: bool,) -> Result<Self, ConfigError> {let config = ServerConfig {host,port,max_connections,timeout_seconds,enable_logging,};config.validate()?;Ok(config)}fn validate(&self) -> Result<(), ConfigError> {// 验证主机名if self.host.is_empty() {return Err(ConfigError::ValidationError("主机名不能为空".to_string()));}// 验证端口if self.port < 1024 {return Err(ConfigError::InvalidValue {field: "port".to_string(),reason: "端口号必须大于等于 1024".to_string(),});}// 验证最大连接数if self.max_connections == 0 {return Err(ConfigError::InvalidValue {field: "max_connections".to_string(),reason: "最大连接数必须大于 0".to_string(),});}// 验证超时时间if self.timeout_seconds == 0 {return Err(ConfigError::InvalidValue {field: "timeout_seconds".to_string(),reason: "超时时间必须大于 0".to_string(),});}Ok(())}fn from_str(config_str: &str) -> Result<Self, ConfigError> {let mut host = None;let mut port = None;let mut max_connections = None;let mut timeout_seconds = None;let mut enable_logging = None;for line in config_str.lines() {let line = line.trim();if line.is_empty() || line.starts_with('#') {continue;}let parts: Vec<&str> = line.split('=').collect();if parts.len() != 2 {return Err(ConfigError::ParseError(format!("无效的配置行: {}", line)));}let key = parts[0].trim();let value = parts[1].trim();match key {"host" => host = Some(value.to_string()),"port" => port = Some(value.parse()?),"max_connections" => max_connections = Some(value.parse()?),"timeout_seconds" => timeout_seconds = Some(value.parse()?),"enable_logging" => {enable_logging = Some(value.to_lowercase() == "true")}_ => {return Err(ConfigError::ParseError(format!("未知的配置键: {}", key)))}}}ServerConfig::new(host.ok_or_else(|| ConfigError::MissingField("host".to_string()))?,port.ok_or_else(|| ConfigError::MissingField("port".to_string()))?,max_connections.ok_or_else(|| {ConfigError::MissingField("max_connections".to_string())})?,timeout_seconds.ok_or_else(|| {ConfigError::MissingField("timeout_seconds".to_string())})?,enable_logging.ok_or_else(|| {ConfigError::MissingField("enable_logging".to_string())})?,)}fn from_file(path: &Path) -> Result<Self, ConfigError> {let contents = fs::read_to_string(path)?;Self::from_str(&contents)}fn to_string(&self) -> String {format!("host={}\nport={}\nmax_connections={}\ntimeout_seconds={}\nenable_logging={}",self.host,self.port,self.max_connections,self.timeout_seconds,self.enable_logging)}fn save_to_file(&self, path: &Path) -> Result<(), ConfigError> {fs::write(path, self.to_string())?;Ok(())}
}// 配置管理器
struct ConfigManager {config: Option<ServerConfig>,config_path: String,
}impl ConfigManager {fn new(config_path: String) -> Self {ConfigManager {config: None,config_path,}}fn load(&mut self) -> Result<&ServerConfig, ConfigError> {let config = ServerConfig::from_file(Path::new(&self.config_path))?;self.config = Some(config);Ok(self.config.as_ref().unwrap())}fn load_or_default(&mut self) -> Result<&ServerConfig, ConfigError> {match self.load() {Ok(config) => Ok(config),Err(ConfigError::IoError(_)) => {// 文件不存在，使用默认配置let default_config = ServerConfig::new("localhost".to_string(),8080,100,30,true,)?;// 保存默认配置default_config.save_to_file(Path::new(&self.config_path))?;self.config = Some(default_config);Ok(self.config.as_ref().unwrap())}Err(e) => Err(e),}}fn update<F>(&mut self, updater: F) -> Result<(), ConfigError>whereF: FnOnce(&mut ServerConfig),{if let Some(ref mut config) = self.config {updater(config);config.validate()?;config.save_to_file(Path::new(&self.config_path))?;Ok(())} else {Err(ConfigError::ValidationError("配置未加载".to_string()))}}fn get(&self) -> Option<&ServerConfig> {self.config.as_ref()}
}// 演示错误处理
fn demonstrate_config_management() {let mut manager = ConfigManager::new("server_config.txt".to_string());// 尝试加载或使用默认配置match manager.load_or_default() {Ok(config) => {println!("配置加载成功:");println!("  主机: {}", config.host);println!("  端口: {}", config.port);println!("  最大连接数: {}", config.max_connections);println!("  超时: {} 秒", config.timeout_seconds);println!("  日志: {}", config.enable_logging);}Err(e) => {eprintln!("配置加载失败: {}", e);return;}}// 更新配置match manager.update(|config| {config.port = 9090;config.max_connections = 200;}) {Ok(_) => println!("\n配置更新成功"),Err(e) => eprintln!("配置更新失败: {}", e),}// 尝试设置无效值let result = manager.update(|config| {config.port = 80; // 无效端口});match result {Ok(_) => println!("更新成功"),Err(e) => println!("预期的验证错误: {}", e),}
}// 使用 ? 操作符链式调用
fn process_config_chain(path: &str) -> Result<ServerConfig, ConfigError> {let config = ServerConfig::from_file(Path::new(path))?;config.validate()?;Ok(config)
}// 使用 map_err 转换错误
fn read_port_from_file(path: &str) -> Result<u16, ConfigError> {let contents = fs::read_to_string(path).map_err(|e| ConfigError::IoError(e))?;contents.trim().parse::<u16>().map_err(|_| ConfigError::ParseError("无效的端口号".to_string()))
}// Option 与 Result 的转换
fn get_config_value(config: &ServerConfig, key: &str) -> Option<String> {match key {"host" => Some(config.host.clone()),"port" => Some(config.port.to_string()),_ => None,}
}fn main() {demonstrate_config_management();// 清理测试文件let _ = fs::remove_file("server_config.txt");
}

Result 组合器

fn combinator_examples() {let result: Result<i32, &str> = Ok(10);// map: 转换成功值let doubled = result.map(|x| x * 2);println!("Doubled: {:?}", doubled);// and_then: 链式调用let result = Ok(5).and_then(|x| Ok(x * 2)).and_then(|x| Ok(x + 3));println!("Chained: {:?}", result);// or_else: 处理错误let result: Result<i32, &str> = Err("错误");let recovered = result.or_else(|_| Ok(0));println!("Recovered: {:?}", recovered);
}