阅读URL时没有协议异常

Question

我想读取一个URL，然后将其转换为字符串并将内容写入文本文件，但在编译代码时出现以下异常。这里是我的代码和我的例外：

import java.io.*; 
import java.net.URL; 
import java.net.URLConnection; 

public class Main { 
public static String url = "google.com"; 
public static String fileName= null; 
public static String fileConttent ="Something"; 

public static void main(String[] args) throws Exception { 
     getText(new String(url)); 
} 

public static void getText(String url) throws Exception { 
    URL website = new URL("url\n" + 
      " public static void main(String[] args) throws Exception {\n" + 
      "   getText(new String(url));\n" + 
      " }\n" + 
      "\n" + 
      " public static void getText(String url) throws Exception {\n" + 
      "  URL website = new URL(\"url"); 
    URLConnection connection = website.openConnection(); 
    BufferedReader in = new BufferedReader(
      new InputStreamReader(
        connection.getInputStream())); 

    StringBuilder response = new StringBuilder(); 
    String inputLine; 

    while ((inputLine = in.readLine()) != null) 
     response.append(inputLine); 

    in.close(); 

    String toBeWritten = response.toString(); 
    System.out.println(toBeWritten); 
} 




public static void createFile(String fileName,String fileContent){ 
    Writer writer = null; 

    try { 
     writer = new BufferedWriter(new OutputStreamWriter(
       new FileOutputStream("C:\\Users\\Dell\\Documents\\t"+"fileName"), "utf-8")); 
     writer.write(fileContent); 
    } catch (IOException ex) { 
     // report 
    } finally { 
     try {writer.close();} catch (Exception ex) {} 
    } 

} 



} 

这是我的例外：

Exception in thread "main" java.net.MalformedURLException: no protocol: url 
at java.net.URL.<init>(URL.java:583) 
at java.net.URL.<init>(URL.java:480) 
at java.net.URL.<init>(URL.java:429) 
at Main.getText(Main.java:15) 
at Main.main(Main.java:11) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:601) 
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) 

过程与退出代码完成1

应该做些什么来解决这个问题？提前感谢所有答案。

更新

非常感谢你的回答。我做了你所说的，但我仍然得到同样的错误。

Exception in thread "main" java.net.MalformedURLException: no protocol: url 
public static void main(String[] args) throws Exception { 
     getText(new String(url)); 
} 

public static void getText(String url) throws Exception { 
    URL website = new URL("url 
at java.net.URL.<init>(URL.java:583) 
at java.net.URL.<init>(URL.java:480) 
at java.net.URL.<init>(URL.java:429) 
at Main.getText(Main.java:15) 
at Main.main(Main.java:11) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:601) 
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) 

过程完成，退出代码为1

Answer 1

您需要的协议添加到您的网址：

public static String url = "http://google.com"; 

而且你必须chnage你的代码（以往的结果应该是什么）：

URL website = new URL("url\n" + 
      " public static void main(String[] args) throws Exception {\n" + 
      "   getText(new String(url));\n" + 
      " }\n" + 
      "\n" + 
      " public static void getText(String url) throws Exception {\n" + 
      "  URL website = new URL(\"url"); 

到

URL website = new URL(url); 

Answer 2

public static String url = "google.com";

这是一个域，而不是一个URL（或命名文件的相对URL“google.com”，但我们不要去那里）。网址具有协议，例如HTTP。

Answer 3

你的代码更改为：

import java.io.BufferedReader; 
import java.io.InputStreamReader; 
import java.net.URL; 
import java.net.URLConnection; 

public class Main { 
public static String url = "https://www.google.com"; 
public static String fileName = null; 
public static String fileConttent = "Something"; 

public static void main(String[] args) throws Exception { 
    getText(new String(url)); 
} 

public static void getText(String url) throws Exception { 
    URL website = new URL(url); 
    URLConnection connection = website.openConnection(); 
    BufferedReader in = new BufferedReader(new InputStreamReader(
    connection.getInputStream())); 

    StringBuilder response = new StringBuilder(); 
    String inputLine; 

    while ((inputLine = in.readLine()) != null) 
    response.append(inputLine); 

    in.close(); 

    String toBeWritten = response.toString(); 
    System.out.println(toBeWritten); 
} 
}