Android HttpClient、DefaultHttpClient、HttpPost

Question

如何将字符串数据 (JSONObject.toString()) 发送到 url。我想在 util 类中编写一个静态方法来执行此操作。我希望方法签名如下

public static String postData (String url, String postData) throws SomeCustomException

字符串url应该是什么格式

返回字符串是来自服务器的响应，作为 json 数据的字符串表示。

编辑

当前连接工具

package my.package;
import my.package.exceptions.CustomException;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URLDecoder;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;


 public class ConnectionUtil {

 public static String postData(String url, String postData)
        throws CustomException {

    // Create a new HttpClient and Post Header
    InputStream is = null;
    StringBuilder sb = null;
    String result = "";
    HttpClient httpclient = new DefaultHttpClient();

HttpPost httppost = new HttpPost();
    httppost.setHeader("host", url);

    Log.v("ConnectionUtil", "Opening POST connection to URI = " + httppost.getURI() + " url = " + URLDecoder.decode(url));

    try {
        httppost.setEntity(new StringEntity(postData));

        // Execute HTTP Post Request
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        is = entity.getContent();

    } catch (Exception e) {
        Log.e("log_tag", "Error in http connection " + e.toString());
        e.printStackTrace();
        throw new CustomException("Could not establish network connection");
    }
    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "utf-8"), 8);
        sb = new StringBuilder();
        sb.append(reader.readLine() + "\n");
        String line = "0";

        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }

        is.close();
        result = sb.toString();

    } catch (Exception e) {
        Log.e("log_tag", "Error converting result " + e.toString());
        throw new CustomException("Error parsing the response");
    }
    Log.v("ConnectionUtil", "Sent: "+postData);
    Log.v("ConnectionUtil", "Got result "+result);
    return result;

}

}

Logcat 输出

10-16 11:27:27.287：E/log_tag(4935)：http 连接出错 java.lang.NullPointerException 10-16 11:27:27.287: W/System.err(4935): java.lang.NullPointerException 10-16 11:27:27.287: W/System.err(4935): 在 org.apache.http.impl.client.AbstractHttpClient.determineTarget(AbstractHttpClient.java:496) 10-16 11:27:27.307: W/System.err(4935): 在 org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 10-16 11:27:27.327: W/System.err(4935): 在 org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 10-16 11:27:27.327: W/System.err(4935): 在 in.gharpay.zap.integration.ConnectionUtil.postData(ConnectionUtil.java:92) 10-16 11:27:27.327: W/System.err(4935): 在 in.gharpay.zap.integration.ZapTransaction$1.doInBackground(ZapTransaction.java:54) 10-16 11:27:27.327: W/System.err(4935): 在 in.gharpay.zap.integration.ZapTransaction$1.doInBackground(ZapTransaction.java:1) 10-16 11:27:27.327: W/System.err(4935): 在 android.os.AsyncTask$2.call(AsyncTask.java:185) 10-16 11:27:27.327: W/System.err(4935): 在 java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306) 10-16 11:27:27.327: W/System.err(4935): 在 java.util.concurrent.FutureTask.run(FutureTask.java:138) 10-16 11:27:27.327: W/System.err(4935): 在 java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 10-16 11:27:27.327: W/System.err(4935): 在 java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 10-16 11:27:27.327: W/System.err(4935): 在 java.lang.Thread.run(Thread.java:1019) 10-16 11:27:27.327: V/log_tag(4935): 无法建立网络连接

Answer 1

我认为在您的代码中，基本问题是由您在 url 中使用 StringEntity 到 POST 参数的方式引起的。检查以下代码是否有助于使用 StringEntity 将数据发布到服务器。

    // Build the JSON object to pass parameters
    JSONObject jsonObj = new JSONObject();
    jsonObj.put("username", username);
    jsonObj.put("data", dataValue);

    // Create the POST object and add the parameters
    HttpPost httpPost = new HttpPost(url);
    StringEntity entity = new StringEntity(jsonObj.toString(), HTTP.UTF_8);
    entity.setContentType("application/json");
    httpPost.setEntity(entity);

    HttpClient client = new DefaultHttpClient();
    HttpResponse response = client.execute(httpPost);

希望这有助于解决您的问题。谢谢。

Answer 2

嗯，以下是我对你的问题的看法：-

1. 首先，您应该使用POST 方法简单地将数据发送到服务器。它在 Android 中也很容易且绝对可行。发送POST数据的简单代码sn-p可以是这样的：

   HttpClient httpclient = new DefaultHttpClient();
   HttpPost httppost = new HttpPost(
           "http://yourserverIP/postdata.php");
   String serverResponse = null;
   try {
       List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
       nameValuePairs.add(new BasicNameValuePair("datakey1", dataValue1));
       nameValuePairs.add(new BasicNameValuePair("datakey2",
               dataValue2));
   
       httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
       HttpResponse response = httpclient.execute(httppost);
   
       serverResponse = response.getStatusLine().toString();
       Log.e("response", serverResponse);
   } catch (ClientProtocolException e) {
       e.printStackTrace();
   } catch (IOException e) {
       e.printStackTrace();
   }
   

   以上代码将数据发送到您服务器上的 PHP 脚本postdata。

2. 接下来，为了解析服务器发送的JSON数据，您可以使用JSONParser，然后根据您的需要轻松使用它。您可以使用以下代码获取服务器返回的响应：

   String jsonData = EntityUtils.toString(serverResponse.getEntity());
   

希望这会有所帮助。谢谢。

Answer 3

尝试使用此方法，其中 strJsonRequest 是您要发布的 json 字符串，而 strUrl 是您要发布 strJsonRequest 的 url

   public String urlPost(String strJsonRequest, String strURL) throws Exception 
{
    try
    {
        URL objURL = new URL(strURL);
        connection = (HttpURLConnection)objURL.openConnection();
        connection.setDoInput(true);
        connection.setDoOutput(true);
        connection.setAllowUserInteraction(false);
        connection.setUseCaches(false);
        connection.setConnectTimeout(TIMEOUT_CONNECT_MILLIS);
        connection.setReadTimeout(TIMEOUT_READ_MILLIS);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Accept-Charset", "utf-8");
        connection.setRequestProperty("Content-Type", "application/json; charset=utf-8");
        connection.setRequestProperty("Content-Length", ""+strJsonRequest.toString().getBytes("UTF8").length);

        DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());

        byte [] b = strJsonRequest.getBytes("UTF-8");

        outputStream.write(b);
        outputStream.flush();

        inputstreamObj = (InputStream) connection.getContent();//getInputStream();

        if(inputstreamObj != null)
            strResponse = convertStreamToString(inputstreamObj);

    }
    catch(Exception e)
    {
        throw e;
    }
    return strResponse;
}

convertStreamToString()方法如下

private static String convertStreamToString(InputStream is)
{
    /*
     * To convert the InputStream to String we use the BufferedReader.readLine()
     * method. We iterate until the BufferedReader return null which means
     * there's no more data to read. Each line will appended to a StringBuilder
     * and returned as String.
     */
    BufferedReader reader = null;
        try {
            reader = new BufferedReader(new InputStreamReader(is));
        } catch (Exception e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
    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();
}

Answer 4

根据您的服务器端代码的设置方式，您的服务器有一个用于处理 API 调用的 php 页面的 URL 示例格式为：

http://yoururl.com/demo.php?jsondata=postData

如果您使用的是帖子连接，您可以简单地说：

http://yoururl.com/demo.php

并将您的帖子参数传递给它，即 json 字符串

这里有一个很棒的教程，教你如何做到这一点： http://yoururl.com/demo.php?jsondata=postData