Android HttpClient、DefaultHttpClient、HttpPost

Question

我如何将字符串数据 (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) 抛出 SomeCustomException

字符串url应该是什么格式

返回的字符串是来自服务器的响应，以 json 数据的字符串表示形式。

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): Error in http connection java.lang.NullPointerException10-16 11:27:27.287: W/System.err(4935): java.lang.NullPointerException10-16 11:27:27.287: W/System.err(4935): at org.apache.http.impl.client.AbstractHttpClient.determineTarget(AbstractHttpClient.java:496)10-16 11:27:27.307: W/System.err(4935): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)10-16 11:27:27.327: W/System.err(4935): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)10-16 11:27:27.327: W/System.err(4935): at in.gharpay.zap.integration.ConnectionUtil.postData(ConnectionUtil.java:92)10-16 11:27:27.327: W/System.err(4935): at in.gharpay.zap.integration.ZapTransaction$1.doInBackground(ZapTransaction.java:54)10-16 11:27:27.327: W/System.err(4935): at in.gharpay.zap.integration.ZapTransaction$1.doInBackground(ZapTransaction.java:1)10-16 11:27:27.327: W/System.err(4935): at android.os.AsyncTask$2.call(AsyncTask.java:185)10-16 11:27:27.327: W/System.err(4935): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)10-16 11:27:27.327: W/System.err(4935): at java.util.concurrent.FutureTask.run(FutureTask.java:138)10-16 11:27:27.327: W/System.err(4935): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)10-16 11:27:27.327: W/System.err(4935): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)10-16 11:27:27.327: W/System.err(4935): at java.lang.Thread.run(Thread.java:1019)10-16 11:27:27.327: V/log_tag(4935): Could not establish network connection

Answer 1

我认为在您的代码中，基本问题是由您使用 StringEntity 将 POST 参数发送到您的 url 的方式引起的。检查以下代码是否有助于使用 StringEntity 将您的数据发布到服务器。

    // 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。