閱讀URL時沒有協議異常

Question

我想讀取一個URL，然後將其轉換爲字符串並將內容寫入文本文件，但在編譯代碼時出現以下異常。這裏是我的代碼和我的例外：

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) {} 
    } 

} 



} 

這是我的例外：

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) 

過程與退出代碼完成1

應該做些什麼來解決這個問題？提前感謝所有答案。

更新

非常感謝你的回答。我做了你所說的，但我仍然得到同樣的錯誤。

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) 

過程完成，退出代碼爲1

Answer 1

您需要的協議添加到您的網址：

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

而且你必須chnage你的代碼（以往的結果應該是什麼）：

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";

這是一個域，而不是一個URL（或命名文件的相對URL「google.com」，但我們不要去那裏）。網址具有協議，例如HTTP。

Answer 3

你的代碼更改爲：

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); 
} 
}