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How to read data in java

angryTom
angryTomOriginal
2019-11-12 13:18:494322browse

How to read data in java

How to read data in java

1. Read data from the console

Use the Scanner class to read input from the console (Recommended tutorial: java tutorial)

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
  String a = in.nextLine();
  System.out.println(a);
}

2. Read files from local

Use FileInputStream, InputStreamReader, and BufferedReader classes to read local data

 public void readTxtFile(String filePath) {
        try {
            File file = new File(filePath);
            if (file.isFile() && file.exists()) {
                InputStreamReader isr = new InputStreamReader(new FileInputStream(file), "utf-8");
                BufferedReader br = new BufferedReader(isr);
                String lineTxt = null;
                while ((lineTxt = br.readLine()) != null) {
                    System.out.println(lineTxt);
                }
                br.close();
            } else {
                System.out.println("文件不存在!");
            }
        } catch (Exception e) {
            System.out.println("文件读取错误!");
        }
    }

3. Read files from the network

Use URLConnection, InputStreamReader, and BufferedReader to read network data.

public class Main {
    public static void main(String[] args) {
    String url = "http://www.php.cn/test.txt";
    String result = "";
    BufferedReader in = null;
    try {
        //生成URL
        URL realUrl = new URL(url);
        //初始化连接到特定URL的连接通道
        URLConnection connection = realUrl.openConnection();
        //开始实际连接
        connection.connect();
        //数据读取
        in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        
        //临时存储一行数据
        String line;
        while((line = in.readLine()) != null) {
            result += line;
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (in != null) {
                in.close();
            }
        } catch (Exception e2) {
            e2.printStackTrace();
        }
    }
    System.out.println(result);
  }
}

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