指定默认值

Question

        URL test = null;
        String inputLine = null;
        BufferedReader in = null;
        try {
            test = new URL("http://localhost/out.php"); // if connection down
        } catch (MalformedURLException e) {
            inputLine = "test_synntax";
        }
        try {
        in = new BufferedReader(new InputStreamReader(test.openStream()));
        ...

  

如果默认情况下URL分辨率失败，如何为输入行指定值   在示例上下文中没有wifi / 3g连接可用，谢谢大家好日子

Answer 1

try {
  test = new URL("http://localhost/out.php");
  //I believe you need this and it throws IOException on timeout. 
  //Though it's still unclear to me what you mean by 'resolution' and 'disponible wifi/3g`?
  test.openConnection(); 
} catch (MalformedURLException | IOException e) { 
  inputLine = "test_synntax";
}

这是java的7多重语法，请注意。

Answer 2

- 如果 wifi / 3g 失败，则会提供UnknownHostException。

所以你可以像这样处理它们......

try {
            test = new URL("http://localhost/out.php");

        } catch (UnknownHostException e) {

            inputLine = "Connection error";
   }

Answer 3

您需要先调用URL.openConnection，然后将默认值放在IOException块中：

try {
   test = new URL("http://localhost/out.php");
   URLConnection urlConn = test.openConnection();
   in = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));
} catch (MalformedURLException e) {
    inputLine = "test_synntax";
} catch (IOException e) {
    inputLine = "test_synntax";
}