我正在使用httpClient进行android编码并发送http POST请求。它在行
给我一个零点指示错误 httpEntity = httpResponse.getEntity();
我使用了log cat，发现我的代码停在了上面提到的那一行。请帮帮我。提前谢谢。
我的代码是用于建立http客户端的文件serviceHandler：
package com.example.manumaheshwari.vigo;
/**
* Created by ManuMaheshwari on 30/06/15.
*/
import android.util.Log;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
public class ServiceHandler {
static String response = null;
public final static int GET = 1;
public final static int POST = 2;
StringBuilder sb;
public ServiceHandler() {
}
/**
* Making service call
* @url - url to make request
* @method - http request method
* */
public String makeServiceCall(String url, int method) {
return this.makeServiceCall(url, method, null);
}
/**
* Making service call
* @url - url to make request
* @method - http request method
* @params - http request params
* */
public String makeServiceCall(String url, int method, List<NameValuePair> params) {
try {
// http client
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpEntity httpEntity = null;
HttpResponse httpResponse = null;
// Checking http request method type
if (method == POST) {
HttpPost httpPost = new HttpPost(url);
httpPost.setHeader(HTTP.CONTENT_TYPE, "application/x-www-form-urlencoded ");
if (params != null) {
try {
httpPost.setEntity(new UrlEncodedFormEntity(params, "utf-8"));
}
catch (UnsupportedEncodingException e) {
// writing error to Log
e.printStackTrace();
}
// Making HTTP Request
try {
HttpResponse response = httpClient.execute(httpPost);
// writing response to log
Log.d("Http Response: ", response.toString());
} catch (ClientProtocolException e) {
// writing exception to log
e.printStackTrace();
} catch (IOException e) {
// writing exception to log
e.printStackTrace();
}
}
} else if (method == GET) {
// appending params to url
if (params != null) {
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
}
HttpGet httpGet = new HttpGet(url);
httpResponse = httpClient.execute(httpGet);
}
httpEntity = httpResponse.getEntity();
response = EntityUtils.toString(httpEntity);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return response;
}
}
我主要活动的代码如下：
package com.example.manumaheshwari.vigo;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class MainActivity extends ListActivity {
private ProgressDialog pDialog;
// URL to get pending rides JSON
private static String url = "http://128.199.206.145/vigo/v1/displayalldrivers";
// JSON Node names
private static final String TAG_SOURCE = "source";
private static final String TAG_DESTINATION = "destination";
private static final String TAG_DRIVER_ID = "driver_id";
private static final String TAG_NAME = "name";
// pending rides JSONArray
JSONArray pendingRides = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> pendingRidesList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pendingRidesList = new ArrayList<HashMap<String, String>>();
ListView lv = getListView();
// Calling async task to get json
new GetRides().execute();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* Async task class to get json by making HTTP call
* */
private class GetRides extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("contractor_id", "1"));
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.POST, nameValuePairs);
Log.d("Response: " , "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
pendingRides = jsonObj.getJSONArray("driver");
// looping through All Contacts
for (int i = 0; i < pendingRides.length(); i++) {
JSONObject c = pendingRides.getJSONObject(i);
String source = c.getString(TAG_NAME);
String destination = c.getString(TAG_DRIVER_ID);
// tmp hashmap for single contact
HashMap<String, String> pendingRide = new HashMap<String, String>();
// adding each child node to HashMap key => value
pendingRide.put(TAG_NAME, source);
pendingRide.put(TAG_DRIVER_ID, destination);
// adding pending ride to pending ride list
pendingRidesList.add(pendingRide);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, pendingRidesList,
R.layout.list_view, new String[] { TAG_SOURCE, TAG_DESTINATION,}, new int[] { R.id.source,R.id.destination});
setListAdapter(adapter);
}
}
}
答案 0 :(得分：1)
似乎httpResponse为空，因为在POST方法中你没有为它赋值。所以在POST方法中，改变
HttpResponse response = httpClient.execute(httpPost);
// writing response to log
Log.d("Http Response: ", response.toString());
到
httpResponse = httpClient.execute(httpPost);
// writing response to log
Log.d("Http Response: ", httpResponse.toString());