Java 使用web服务时出现未知主机异常

我正在尝试使用一个web服务并在该api上发表文章。我和邮递员试过了，一切都很好。但是，一旦我编写了一个java客户机来使用该web服务，我就会得到以下错误

java.net.UnknownHostException: www.api.com
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
    at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
    at java.net.InetAddress.getAllByName0(InetAddress.java:1276)
    at java.net.InetAddress.getAllByName(InetAddress.java:1192)
    at java.net.InetAddress.getAllByName(InetAddress.java:1126)
    at org.apache.http.impl.conn.SystemDefaultDnsResolver.resolve(SystemDefaultDnsResolver.java:44)
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.resolveHostname(DefaultClientConnectionOperator.java:259)
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:159)
    at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:304)
    at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:611)
    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:446)
    at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:863)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:106)

Java客户端代码：

public static void sendPost() throws ClientProtocolException, IOException {

    try {
        HttpClient client = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(_api.trim());
        List<NameValuePair> postParameters = new ArrayList<NameValuePair>();
        postParameters.add(new BasicNameValuePair("parm_1", "dgs"));
        postParameters.add(new BasicNameValuePair("parm_2", "ab"));
        postParameters.add(new BasicNameValuePair("parm_3", "4hdiin"));
        httpPost.setHeader("Content-type", "application/x-www-form-urlencoded");

        httpPost.setEntity(new UrlEncodedFormEntity(postParameters));

        HttpResponse response = client.execute(httpPost);
    } catch (Exception e) {
        e.printStackTrace();
    }

public static void sendPost（）抛出ClientProtocolException，IOException{
试一试{
HttpClient=new DefaultHttpClient（）；
HttpPost-HttpPost=新的HttpPost（_api.trim（））；
List postParameters=new ArrayList（）；
后参数。添加（新的BasicNameValuePair（“parm_1”、“dgs”）；
后参数。添加（新的BasicNameValuePair（“parm_2”，“ab”）；
后参数。添加（新的BasicNameValuePair（“parm_3”、“4hdiin”）；
setHeader（“内容类型”，“应用程序/x-www-form-urlencoded”）；
setEntity（新的UrlEncodedFormEntity（后参数））；
HttpResponse response=client.execute（httpPost）；
}捕获（例外e）{
e、 printStackTrace（）；
}

来自

抛出UnknownHostException以指示无法确定主机的IP地址

您是否尝试在url www.api.com之前添加http或https