在 Android 中发送 JSON POST 请求

Question

我是 Andorid 新手，了解以下发送 post 请求的方法在 Android 22 及更高版本中已弃用。任何人都会有一个使用 URLCONNECTION 方法 seding JSON POST 请求的 Android 代码的工作示例（我猜这是不使用 import org.apache.http.client 的基本模型）。

package com.hmkcode.android;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONObject;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.app.Activity;
import com.hmkcode.android.vo.Person;

public class MainActivity extends Activity implements OnClickListener {

    TextView tvIsConnected;
    EditText etName,etCountry,etTwitter;
    Button btnPost;

    Person person;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // get reference to the views
        tvIsConnected = (TextView) findViewById(R.id.tvIsConnected);
        etName = (EditText) findViewById(R.id.etName);
        etCountry = (EditText) findViewById(R.id.etCountry);
        etTwitter = (EditText) findViewById(R.id.etTwitter);
        btnPost = (Button) findViewById(R.id.btnPost);

        // check if you are connected or not
        if(isConnected()){
            tvIsConnected.setBackgroundColor(0xFF00CC00);
            tvIsConnected.setText("You are conncted");
        }
        else{
            tvIsConnected.setText("You are NOT conncted");
        }

        // add click listener to Button "POST"
        btnPost.setOnClickListener(this);

    }

    public static String POST(String url, Person person){
        InputStream inputStream = null;
        String result = "";
        try {

            // 1. create HttpClient
            HttpClient httpclient = new DefaultHttpClient();

            // 2. make POST request to the given URL
            HttpPost httpPost = new HttpPost(url);

            String json = "";

            // 3. build jsonObject
            JSONObject jsonObject = new JSONObject();
            jsonObject.accumulate("name", person.getName());
            jsonObject.accumulate("country", person.getCountry());
            jsonObject.accumulate("twitter", person.getTwitter());

            // 4. convert JSONObject to JSON to String
            json = jsonObject.toString();

            // ** Alternative way to convert Person object to JSON string usin Jackson Lib 
            // ObjectMapper mapper = new ObjectMapper();
            // json = mapper.writeValueAsString(person); 

            // 5. set json to StringEntity
            StringEntity se = new StringEntity(json);

            // 6. set httpPost Entity
            httpPost.setEntity(se);

            // 7. Set some headers to inform server about the type of the content   
            httpPost.setHeader("Accept", "application/json");
            httpPost.setHeader("Content-type", "application/json");

            // 8. Execute POST request to the given URL
            HttpResponse httpResponse = httpclient.execute(httpPost);

            // 9. receive response as inputStream
            inputStream = httpResponse.getEntity().getContent();

            // 10. convert inputstream to string
            if(inputStream != null)
                result = convertInputStreamToString(inputStream);
            else
                result = "Did not work!";

        } catch (Exception e) {
            Log.d("InputStream", e.getLocalizedMessage());
        }

        // 11. return result
        return result;
    }

    public boolean isConnected(){
        ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Activity.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
            if (networkInfo != null && networkInfo.isConnected()) 
                return true;
            else
                return false;    
    }
    @Override
    public void onClick(View view) {

        switch(view.getId()){
            case R.id.btnPost:
                if(!validate())
                    Toast.makeText(getBaseContext(), "Enter some data!", Toast.LENGTH_LONG).show();
                // call AsynTask to perform network operation on separate thread
                new HttpAsyncTask().execute("http://hmkcode.appspot.com/jsonservlet");
            break;
        }

    }
    private class HttpAsyncTask extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... urls) {

            person = new Person();
            person.setName(etName.getText().toString());
            person.setCountry(etCountry.getText().toString());
            person.setTwitter(etTwitter.getText().toString());

            return POST(urls[0],person);
        }
        // onPostExecute displays the results of the AsyncTask.
        @Override
        protected void onPostExecute(String result) {
            Toast.makeText(getBaseContext(), "Data Sent!", Toast.LENGTH_LONG).show();
       }
    }

    private boolean validate(){
        if(etName.getText().toString().trim().equals(""))
            return false;
        else if(etCountry.getText().toString().trim().equals(""))
            return false;
        else if(etTwitter.getText().toString().trim().equals(""))
            return false;
        else
            return true;    
    }
    private static String convertInputStreamToString(InputStream inputStream) throws IOException{
        BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
        String line = "";
        String result = "";
        while((line = bufferedReader.readLine()) != null)
            result += line;

        inputStream.close();
        return result;

    }   
}

Answer 1

是时候使用 volley bro，android 网络库了 这比 http 请求在性能上更快而且更好。 凌空的一些特点。

1. 请求排队和优先级
2. 有效的请求缓存和内存管理
3. 库的可扩展性和自定义以满足我们的需求
4. 取消请求

在这里你可以用凌空做同样的事情 首先设置依赖项

compile 'com.mcxiaoke.volley:library-aar:1.0.0'

在那之后 创建一个单例类

import com.volley.examples;
import android.app.Application;
import android.text.TextUtils;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.Volley;

public class AppController extends Application {

    public static final String TAG = AppController.class
            .getSimpleName();

    private RequestQueue mRequestQueue;
    private ImageLoader mImageLoader;

    private static AppController mInstance;

    @Override
    public void onCreate() {
        super.onCreate();
        mInstance = this;
    }

    public static synchronized AppController getInstance() {
        return mInstance;
    }

    public RequestQueue getRequestQueue() {
        if (mRequestQueue == null) {
            mRequestQueue = Volley.newRequestQueue(getApplicationContext());
        }

        return mRequestQueue;
    }

    public ImageLoader getImageLoader() {
        getRequestQueue();
        if (mImageLoader == null) {
            mImageLoader = new ImageLoader(this.mRequestQueue,
                    new LruBitmapCache());
        }
        return this.mImageLoader;
    }

    public <T> void addToRequestQueue(Request<T> req, String tag) {
        // set the default tag if tag is empty
        req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
        getRequestQueue().add(req);
    }

    public <T> void addToRequestQueue(Request<T> req) {
        req.setTag(TAG);
        getRequestQueue().add(req);
    }

    public void cancelPendingRequests(Object tag) {
        if (mRequestQueue != null) {
            mRequestQueue.cancelAll(tag);
        }
    }
}

这是因为它只是复制粘贴并命名为 AppController 然后在清单中进行一些更改 将其添加到清单的应用程序标签中

android:name="com.volley.examples.AppController"

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.volley.examples"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />

    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:name="com.volley.examples.AppController"
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <!-- all activities and other stuff -->
    </application>

</manifest>

最后一个是发出一个json请求 这就是你如何做到的。

// Tag used to cancel the request

    String tag_json_obj = "json_obj_req";
     //change the url with your's 
    String url = "http://www.exampleUrl.com/androidVersion.json";

    ProgressDialog pDialog = new ProgressDialog(this);
    pDialog.setMessage("Loading...");
    pDialog.show();     

            JsonObjectRequest jsonObjReq = new JsonObjectRequest(Method.POST,
                    url, null,
                    new Response.Listener<JSONObject>() {

                        @Override
                        public void onResponse(JSONObject response) {
                            Log.d(TAG, response.toString());
                            pDialog.hide();
                        }
                    }, new Response.ErrorListener() {

                        @Override
                        public void onErrorResponse(VolleyError error) {
                            VolleyLog.d(TAG, "Error: " + error.getMessage());
                            pDialog.hide();
                        }
                    }) {

                @Override
                protected Map<String, String> getParams() {
                    Map<String, String> params = new HashMap<String, String>();
                    params.put("name", "Android Volley");
                    params.put("email", "abc@android.com");
                    params.put("password", "password123");

                    return params;
                }

            };

    // Adding request to request queue
    AppController.getInstance().addToRequestQueue(jsonObjReq, tag_json_obj);

使用 volley，您可以通过扩展 volley 类来发出几乎任何类型的请求 但默认情况下我们有

1.StringRequest 2.JsonObjectRequest 3.JsonArrayRequest

在上面我们使用了 JsonObjectRequest

我知道这不是您问题的直接答案，但我希望这对您有所帮助。

谢谢。

Answer 2

这里有：

URL url = new URL("http://yoururl.com");
HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
conn.setReadTimeout(10000);
conn.setConnectTimeout(15000);
conn.setRequestMethod("POST");
conn.setDoInput(true);
conn.setDoOutput(true);

List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("firstParam", paramValue1));
params.add(new BasicNameValuePair("secondParam", paramValue2));
params.add(new BasicNameValuePair("thirdParam", paramValue3));

OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(
        new OutputStreamWriter(os, "UTF-8"));
writer.write(getQuery(params));
writer.flush();
writer.close();
os.close();

conn.connect();

Answer 3

这个 repo 相当不错，并且有各种 http 请求。 https://github.com/loopj/android-async-http

Answer 4

确实，httpClient 已被弃用。

您应该升级到HttpURLConnection 甚至更好的HttpsURLConnection：

public static String httpPost(String urlString, HashMap<String, String> postDataParams) {
    URL url;
    String response = "";
    try {
        url = new URL(urlString);

        HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
        conn.setRequestMethod("POST");
        conn.setDoInput(true);
        conn.setDoOutput(true);

        OutputStream os = conn.getOutputStream();
        BufferedWriter writer = new BufferedWriter(
                new OutputStreamWriter(os, "UTF-8"));
        writer.write(getPostDataString(postDataParams));

        writer.flush();
        writer.close();
        os.close();
        int responseCode = conn.getResponseCode();

        if (responseCode == HttpsURLConnection.HTTP_OK) {
            String line;
            BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            while ((line = br.readLine()) != null) {
                response += line;
            }
        } else {
            response = "";
            //throw new HttpException(responseCode+"");
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    if (BuildConfig.DEBUG) {
        Log.d(LOG_TAG, "response = " + response);
    }


    return response;
}

public static String getPostDataString(HashMap<String, String> params) {
    StringBuilder result = new StringBuilder();

    try {
        boolean first = true;
        for (Map.Entry<String, String> entry : params.entrySet()) {
            if (first)
                first = false;
            else
                result.append("&");

            result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
            result.append("=");
            result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
        }
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }

    return result.toString();
}

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