php - 无法获取值的详细信息

Question

我是 android 编程的新手，我正在使用 eclipse 在 android 中运行一个程序，我试图从数据库中获取对象的详细信息，以便我可以编辑和保存更改。难怪为什么当我单击模拟器中显示的对象时程序会自动停止。 下面是代码。请帮帮我!

 **Edit Product Activity** 

    package com.example.androidhives;

    import java.util.ArrayList;
    import java.util.List;

    import org.apache.http.NameValuePair;
    import org.apache.http.message.BasicNameValuePair;
    import org.json.JSONArray;
    import org.json.JSONException;
    import org.json.JSONObject;

    import android.app.Activity;
    import android.app.ProgressDialog;
    import android.content.Intent;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;

    public class EditProductActivity extends Activity {

        EditText txtName;
        EditText txtPrice;
        EditText txtDesc;
        EditText txtCreatedAt;
        Button btnSave;
        Button btnDelete;

        String pid;

        // Progress Dialog
        private ProgressDialog pDialog;

        // JSON parser class
        JSONParser jsonParser = new JSONParser();

        // single product url
        private static final String url_product_details = "http://10.0.2.2/android/get_product_detail.php";

        // url to update product
        private static final String url_update_product = "http://10.0.2.2/android/update_product.php";

        // url to delete product
        private static final String url_delete_product = "http://10.0.2.2/android/delete_product.php";

        // JSON Node names
        private static final String TAG_SUCCESS = "success";
        private static final String TAG_PRODUCT = "product";
        private static final String TAG_PID = "pid";
        private static final String TAG_NAME = "name";
        private static final String TAG_PRICE = "price";
        private static final String TAG_DESCRIPTION = "description";

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.edit_product);

            // save button
            btnSave = (Button) findViewById(R.id.btnSave);
            btnDelete = (Button) findViewById(R.id.btnDelete);

            // getting product details from intent
            Intent i = getIntent();

            // getting product id (pid) from intent
            pid = i.getStringExtra(TAG_PID);

            // Getting complete product details in background thread
            new GetProductDetails().execute();

            // save button click event
            btnSave.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View arg0) {
                    // starting background task to update product
                    new SaveProductDetails().execute();
                }
            });

            // Delete button click event
            btnDelete.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View arg0) {
                    // deleting product in background thread
                    new DeleteProduct().execute();
                }
            });

        }

        /**
         * Background Async Task to Get complete product details
         * */
        class GetProductDetails extends AsyncTask<String, String, String> {

            /**
             * Before starting background thread Show Progress Dialog
             * */
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pDialog = new ProgressDialog(EditProductActivity.this);
                pDialog.setMessage("Loading product details. Please wait...");
                pDialog.setIndeterminate(false);
                pDialog.setCancelable(true);
                pDialog.show();
            }

            /**
             * Getting product details in background thread
             * */
            protected String doInBackground(String... params) {

                // updating UI from Background Thread
                runOnUiThread(new Runnable() {
                    public void run() {
                        // Check for success tag
                        int success;
                        try {
                            // Building Parameters
                            List<NameValuePair> params = new ArrayList<NameValuePair>();
                            params.add(new BasicNameValuePair("pid", pid));

                            // getting product details by making HTTP request
                            // Note that product details url will use GET request
                            JSONObject json = jsonParser.makeHttpRequest(
                                    url_product_details, "GET", params);

                            // check your log for json response
                            Log.e("Single Product Details", json.toString());

                            // json success tag
                            success = json.getInt(TAG_SUCCESS);
                            if (success == 1) {
                                // successfully received product details
                                JSONArray productObj = json
                                        .getJSONArray(TAG_PRODUCT); // JSON Array

                                // get first product object from JSON Array
                                JSONObject product = productObj.getJSONObject(0);

                                // product with this pid found
                                // Edit Text
                                txtName = (EditText) findViewById(R.id.inputName);
                                txtPrice = (EditText) findViewById(R.id.inputPrice);
                                txtDesc = (EditText) findViewById(R.id.inputDesc);

                                // display product data in EditText
                                txtName.setText(product.getString(TAG_NAME));
                                txtPrice.setText(product.getString(TAG_PRICE));
                                txtDesc.setText(product.getString(TAG_DESCRIPTION));

                            }else{
                                // product with pid not found
                            }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                });

                return null;
            }

            /**
             * After completing background task Dismiss the progress dialog
             * **/
            protected void onPostExecute(String file_url) {
                // dismiss the dialog once got all details
                pDialog.dismiss();
            }
        }

        /**
         * Background Async Task to  Save product Details
         * */
        class SaveProductDetails extends AsyncTask<String, String, String> {

            /**
             * Before starting background thread Show Progress Dialog
             * */
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pDialog = new ProgressDialog(EditProductActivity.this);
                pDialog.setMessage("Saving product ...");
                pDialog.setIndeterminate(false);
                pDialog.setCancelable(true);
                pDialog.show();
            }

            /**
             * Saving product
             * */
            protected String doInBackground(String... args) {

                // getting updated data from EditTexts
                String name = txtName.getText().toString();
                String price = txtPrice.getText().toString();
                String description = txtDesc.getText().toString();

                // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                params.add(new BasicNameValuePair(TAG_PID, pid));
                params.add(new BasicNameValuePair(TAG_NAME, name));
                params.add(new BasicNameValuePair(TAG_PRICE, price));
                params.add(new BasicNameValuePair(TAG_DESCRIPTION, description));

                // sending modified data through http request
                // Notice that update product url accepts POST method
                JSONObject json = jsonParser.makeHttpRequest(url_update_product,
                        "POST", params);

                // check json success tag
                try {
                    int success = json.getInt(TAG_SUCCESS);

                    if (success == 1) {
                        // successfully updated
                        Intent i = getIntent();
                        // send result code 100 to notify about product update
                        setResult(100, i);
                        finish();
                    } else {
                        // failed to update product
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }

                return null;
            }

            /**
             * After completing background task Dismiss the progress dialog
             * **/
            protected void onPostExecute(String file_url) {
                // dismiss the dialog once product uupdated
                pDialog.dismiss();
            }
        }

        /*****************************************************************
         * Background Async Task to Delete Product
         * */
        class DeleteProduct extends AsyncTask<String, String, String> {

            /**
             * Before starting background thread Show Progress Dialog
             * */
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pDialog = new ProgressDialog(EditProductActivity.this);
                pDialog.setMessage("Deleting Product...");
                pDialog.setIndeterminate(false);
                pDialog.setCancelable(true);
                pDialog.show();
            }

            /**
             * Deleting product
             * */
            protected String doInBackground(String... args) {

                // Check for success tag
                int success;
                try {
                    // Building Parameters
                    List<NameValuePair> params = new ArrayList<NameValuePair>();
                    params.add(new BasicNameValuePair("pid", pid));

                    // getting product details by making HTTP request
                    JSONObject json = jsonParser.makeHttpRequest(
                            url_delete_product, "POST", params);

                    // check your log for json response
                    Log.d("Delete Product", json.toString());

                    // json success tag
                    success = json.getInt(TAG_SUCCESS);
                    if (success == 1) {
                        // product successfully deleted
                        // notify previous activity by sending code 100
                        Intent i = getIntent();
                        // send result code 100 to notify about product deletion
                        setResult(100, i);
                        finish();
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }

                return null;
            }

            /**
             * After completing background task Dismiss the progress dialog
             * **/
            protected void onPostExecute(String file_url) {
                // dismiss the dialog once product deleted
                pDialog.dismiss();

            }

        }
    }


    **JSONParser**

    package com.example.androidhives;

    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.io.UnsupportedEncodingException;
    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.json.JSONException;
    import org.json.JSONObject;

    import android.util.Log;

    public class JSONParser {

        static InputStream is = null;
        static JSONObject jObj = null;
        static String json = "";

        // constructor
        public JSONParser() {

        }

        // function get json from url
        // by making HTTP POST or GET mehtod
        public JSONObject makeHttpRequest(String url, String method,
                List<NameValuePair> params) {

            // Making HTTP request
            try {

                // check for request method
                if(method == "POST"){
                    // request method is POST
                    // defaultHttpClient
                    DefaultHttpClient httpClient = new DefaultHttpClient();
                    HttpPost httpPost = new HttpPost(url);
                    httpPost.setEntity(new UrlEncodedFormEntity(params));

                    HttpResponse httpResponse = httpClient.execute(httpPost);
                    HttpEntity httpEntity = httpResponse.getEntity();
                    is = httpEntity.getContent();

                }else if(method == "GET"){
                    // request method is GET
                    DefaultHttpClient httpClient = new DefaultHttpClient();
                    String paramString = URLEncodedUtils.format(params, "utf-8");
                    url += "?" + paramString;
                    HttpGet httpGet = new HttpGet(url);

                    HttpResponse httpResponse = httpClient.execute(httpGet);
                    HttpEntity httpEntity = httpResponse.getEntity();
                    is = httpEntity.getContent();
                }           

            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

            try {
                BufferedReader reader = new BufferedReader(new InputStreamReader(
                        is, "iso-8859-1"), 8);
                StringBuilder sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null) {
                    sb.append(line + "\n");
                }
                is.close();
                json = sb.toString();
            } catch (Exception e) {
                Log.e("Buffer Error", "Error converting result " + e.toString());
            }

            // try parse the string to a JSON object
            try {
                jObj = new JSONObject(json);
            } catch (JSONException e) {
                Log.e("JSON Parser", "Error parsing data " + e.toString());
            }

            // return JSON String
            return jObj;

        }
    }

    **PHP File**


    <?php

    $response=array();

    require_once('db_connect.php');

    $db=new DB_CONNECT();
    $db->construct();
    $db->connect();




    if(isset($_GET['pid']))
    {
        $pid=$_GET['pid'];

        $result=mysql_query("Select * from products where pid='$pid'");

        if(!empty($result))
        {
            if(mysql_num_rows($result)>0)
            {
                $result=mysql_fetch_array($result);

                $product=array();
                $product["pid"]=$response["pid"];
                $product["name"]=$response["name"];
                $product["price"]=$response["price"];
                $product["description"]=$response["description"];
                $product["created_at"]=$response["created_at"];
                $product["updated_at"]=$response["updated_at"];

                $response["product"]=array();

                array_push($response["product"],$product);

                echo json_encode($response);
            }
            else
            {
                $response["success"]=0;
                $response["message"]="No product found.";

                echo json_encode($response);
            }
    }
        else
            {
                $response["success"]=0;
                $response["message"]="No product found.";

                echo json_encode($response);
            }
    }
    else
    {
        $response["success"]=0;
        $response["message"]="Required fields missing.";

        echo json_encode($response);
    }




    ?>

Answer 1

您的 GetProductDetails AsyncTask 在 UI 线程上进行网络调用

        /**
         * Getting product details in background thread
         * */
        protected String doInBackground(String... params) {

            // updating UI from Background Thread
            runOnUiThread(new Runnable() {
...

如果 Asynctask 所做的只是在 UI 线程上做某事，您应该考虑为什么要使用 Asynctask。如果您需要更改用户界面，请在 onPostExecute() 中进行。

如果更改 Asynctask 没有帮助，请考虑添加有关您遇到的错误的更多信息(例如日志)