getApplicationContext（）问题

Question

我遵循本教程：

http://www.tutos-android.com/importer-ajouter-certificat-ssl-auto-signe-bouncy-castle-android/comment-page-2#comment-2159 （SSl自动签名证书问题）

JsonParserFUnction代码：

    package com.example.androidsupervision;

    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.security.KeyManagementException;
    import java.security.KeyStoreException;
    import java.security.NoSuchAlgorithmException;
    import java.security.UnrecoverableKeyException;
    import java.security.cert.CertificateException;
    import java.util.ArrayList;
    import java.util.List;

    import javax.net.ssl.HostnameVerifier;
    import javax.net.ssl.HttpsURLConnection;

    import org.apache.http.HttpEntity;
    import org.apache.http.HttpResponse;
    import org.apache.http.NameValuePair;
    import org.apache.http.client.HttpClient;
    import org.apache.http.client.entity.UrlEncodedFormEntity;
    import org.apache.http.client.methods.HttpPost;
    import org.apache.http.conn.scheme.Scheme;
    import org.apache.http.conn.scheme.SchemeRegistry;
    import org.apache.http.conn.ssl.SSLSocketFactory;
    import org.apache.http.conn.ssl.X509HostnameVerifier;
    import org.apache.http.impl.client.DefaultHttpClient;
    import org.apache.http.impl.conn.SingleClientConnManager;
    import org.apache.http.message.BasicNameValuePair;
    import org.json.JSONArray;
    import org.json.JSONException;
    import org.json.JSONObject;

    import android.content.Context;
    import android.util.Log;

    public class JsonReaderPost {

        public JsonReaderPost() {

        }

        public void Reader() throws IOException, JSONException, KeyStoreException, NoSuchAlgorithmException, CertificateException, KeyManagementException, UnrecoverableKeyException {



            String ints = "";
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("query","SELECT+AlertId+FROM+Orion.Alerts"));
            //HttpClient client = new DefaultHttpClient();  

    **//Here is the problem**
            HttpClient client =new MyHttpClient(getApplicationContext());

            HttpPost httpPost = new
HttpPost("https://192.168.56.101:17778/SolarWinds/InformationService/v3/Json/Query");
            httpPost.addHeader("content-type", "application/json");
            httpPost.addHeader("Authorization", "Basic YWRtaW46");
            httpPost.setEntity(new UrlEncodedFormEntity(params));


            HttpResponse response;
            String result = null;

            response = client.execute(httpPost);
            HttpEntity entity = response.getEntity();

            if (entity != null) {

                // A Simple JSON Response Read
                InputStream instream = entity.getContent();
                result = convertStreamToString(instream);
                // now you have the string representation of the HTML request
                // System.out.println("RESPONSE: " + result);
                Log.e("Result", "RESPONSE: " + result);
                instream.close();
            }

            // Converting the String result into JSONObject jsonObj and then into
            // JSONArray to get data
            JSONObject jsonObj = new JSONObject(result);
            JSONArray results = jsonObj.getJSONArray("results");
            for (int i = 0; i < results.length(); i++) {
                JSONObject r = results.getJSONObject(i);
                ints = r.getString("AlertId");
                Log.e("Final Result", "RESPONSE: " + ints);
            }

        }


        public static String convertStreamToString(InputStream is) {

            BufferedReader reader = new BufferedReader(new InputStreamReader(is));
            StringBuilder sb = new StringBuilder();

            String line = null;
            try {
                while ((line = reader.readLine()) != null) {
                    sb.append(line + "\n");
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return sb.toString();
        }

    }

我在这行中遇到错误：

HttpClient client =new MyHttpClient(getApplicationContext());

错误是： getApplicationContext()

类型的方法JsonReaderPost未定义

Answer 1

您应该在实例化类时发送活动的上下文：

private Context mContext;

public JsonReaderPost(Context mContext) {
this.mContext = mContext;
}

然后，你应该使用＆＃34; mContext＆＃34;而不是getApplicationContext（）;

Answer 2

这是未知的，因为您的班级没有扩展任何其他Class Context，因此它不知道该方法是什么。例如，这是Activity。

但是，使用getApplicationContext()，除非您真的知道您正在做什么，否则几乎总是错误的。如果处理不当，这会带来Exception之类的不良行为。您应该始终使用您正在处理的课程的Context。

您可以了解哪些类实现Context并获取有关上下文here的更多信息。