Java异常处理：常见场景与案例-蒲公英云

Java异常处理：常见场景与案例

原创 Bertha 。 2024-09-24 02:15 378阅读 0赞

在Java编程中，异常处理是防止程序因意外情况而崩溃的重要机制。以下是一些常见的Java异常处理场景和案例：

文件操作：

检查文件是否存在：

File file = new File("path/to/file.txt");
if (!file.exists()) {
    throw new IllegalArgumentException("File does not exist.");
}

读写文件，捕获可能的IOException异常：

BufferedReader br = null;
try {
    br = new BufferedReader(new FileReader("file.txt")));
    // 读取内容
    String content = br.readLine();
    System.out.println(content);
} catch (IOException e) {
    e.printStackTrace();  // 或者使用处理方式，如记录日志等
    if (br != null) {
        try {
            br.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
    throw new RuntimeException("Error reading file.", e);
}
finally {
    if (br != null) {
        try {
            br.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        // 确保文件关闭，即使发生异常
    }
}

网络通信：

发送HTTP请求，捕获可能的Exception：

try {
    URL url = new URL("http://example.com");
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    connection.setRequestMethod("GET");
    int responseCode = connection.getResponseCode();
    if (responseCode == 200) {
        // 请求成功，读取响应内容
        BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()))));
        String content = br.readLine();
        System.out.println(content);
    } else {
        // 请求失败或状态码不为200
        System.out.println("Request failed with response code " + responseCode));
    }
} catch (Exception e) {
    e.printStackTrace();  // 或者使用处理方式，如记录日志等
    System.out.println("An error occurred during request execution.");
}

数据库操作：

连接数据库，捕获可能的SQLException异常：

Connection connection = null;
try {
    // 创建连接对象
    Class.forName("com.mysql.jdbc.Driver");
    connection = DriverManager.getConnection(
        "jdbc//localhost:3306/mydatabase",
        "username",
        "password"
    );
    // 执行SQL语句
    Statement stmt = connection.createStatement();
    ResultSet rs = stmt.executeQuery("SELECT * FROM mytable");
    while (rs.next()) {
        // 处理查询结果
        int id = rs.getInt("id");
        String name = rs.getString("name");
        System.out.println("ID: " + id + ", Name: " + name);
    }
} catch (Exception e) {
    e.printStackTrace();
    System.out.println("An error occurred while executing SQL queries.");
} finally {
    if (connection != null) {
        try {
            connection.close();
        } catch (SQLException se) {
            se.printStackTrace();
            System.out.println("Error closing database connection.");
        }
    }
}