Question

运行此程序时，我得到“IOException：Stream Closed”。该文本包含许多行数据。程序应读取每一行，执行必要的功能并将输出写入新文件。我很困惑哪个作家应该先关闭哪里。

import java.net.*; 
import java.io.*;

public class URLReader {
    public static void main(String[] args) throws Exception {
        BufferedReader br = null;
        try {
            // change this value
            FileInputStream fis = new FileInputStream("C:\\Users\\Rao\\Desktop\\test.txt");
            br = new BufferedReader(new InputStreamReader(fis, "UTF-8"));
            String sCurrentLine;
            while ((sCurrentLine = br.readLine()) != null) {
                processLine(sCurrentLine); //error
            }
        } finally {
            if (br != null)
                br.close();
        }
    }

    public static void processLine(String line) throws IOException {
        String prename = line.substring(22);
        int siz= prename.indexOf(":");
        String name = prename.substring(0, siz);

        URL oracle = new URL("http://ip-api.com/json/"+name);
        BufferedReader in = new BufferedReader(new InputStreamReader(oracle.openStream()));
        String inputLine;
        while ((inputLine = in.readLine()) != null) // error
            // System.out.println(inputLine);
            in.close();  
        String baby = (line + "\t" + inputLine); 

        try {
            FileWriter writer = new FileWriter("C:\\Users\\Rao\\Desktop\\output.txt", true);
            writer.write(baby);
            writer.write("\r\n");   // write new line
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

例外情况如下：

Exception in thread "main" java.io.IOException: Stream closed
    at java.io.BufferedReader.ensureOpen(Unknown Source)
    at java.io.BufferedReader.readLine(Unknown Source)
    at java.io.BufferedReader.readLine(Unknown Source)
    at URLReader.processLine(URLReader.java:31)
    at URLReader.main(URLReader.java:13)

Answer 1

关闭循环中的输入流：

while ((inputLine = in.readLine()) != null) // error

               // System.out.println(inputLine);
in.close();

您应该关闭循环外的流：

while ((inputLine = in.readLine()) != null) // error
{
   //dosomething
   // System.out.println(inputLine);
}
in.close();

Answer 2

你应该在while循环中放入一个函数调用，如：

a System.out.println("Hi, I'm a row!");或
取消注释System.out.println(inputLine);或
在while语句的末尾添加分号

为了让它正确执行。

编写的代码执行（注释省略）：

...
   while ((inputLine = in.readLine()) != null)
     in.close();  
...

所以循环的第一个循环正确执行并运行in.close()。然后第二个循环调用inputLine = in.readLine()失败，因为流已关闭，然后抛出异常。

Java IOException - 流已关闭

2 个答案: