如何在Java中处理异常，包括IO、网络等实例

原创 Love The Way You Lie 2024-12-07 13:36 10阅读 0赞

在Java中，处理异常主要通过try-catch-finally语句块来实现。以下是一些IO和网络异常的处理示例：

1. IO异常：如文件不存在、读写错误等。

```java
import java.io.File;
import java.io.IOException;

public class FileIOException {
    public static void main(String[] args) {
        // 创建一个不存在的文件
        try (File file = new File("non_existent_file.txt")) {
            // 试图读取这个文件，会抛出FileNotFoundException
            System.out.println(file.exists());  // 输出：false
            try (InputStream in = file.newInputStream()) {  // 这里是尝试读取的代码，也会抛出IOException
                // ...
            } catch (IOException e) {
                System.err.println("Error reading file: " + e.getMessage());
            }
        } catch (FileNotFoundException fnfException) {
            System.err.println("Error creating file: " + fnfException.getMessage());
        }
    }
}
```

2. 网络异常：如Socket关闭、HTTP请求错误等。

```java
import java.io.IOException;
import java.net.SocketException;
import java.net.HttpURLConnection;

public class NetworkingException {
    public static void main(String[] args) {
        // 创建一个Socket并尝试关闭它，会抛出SocketException
        try (Socket socket = new Socket("localhost", 8080)) {
            System.out.println("Connected to server.");
            // 关闭Socket，会抛出SocketException
            socket.close();
            System.out.println("Disconnected from server.");
        } catch (SocketException se) {
            System.err.println("Error closing socket: " + se.getMessage());
        }
        
        // 发送一个HTTP请求，如果服务器返回错误的响应，会抛出IOException
        try (HttpURLConnection urlConnection = (HttpURLConnection) new URL("http://example.com").openConnection())) {
            if (!urlConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                System.err.println("Error fetching response from server: " + urlConnection.getResponseMessage()));
                throw new IOException("Failed to fetch response from server.");
            }
        } catch (IOException ioe) {
            System.err.println("Error sending HTTP request: " + ioe.getMessage());
        }
    }
}
```

注意：在实际开发中，通常会将可能抛出异常的代码放在try块内，然后在catch块中处理对应的异常。