php - Android 应用程序 - 网络任务出错

Question

我正在开发一个 Android 应用程序。我有一个包含多个元素的 ListView 。我正在使用 php 脚本从 mysql 数据库中获取列表的元素。但是在获取项目时，我的应用程序崩溃并且日志 cat 显示以下错误。这里有什么问题？

这是我的 logcat 输出。

12-22 16:03:30.440: D/dalvikvm(1431): GC_FOR_ALLOC freed 233K, 8% free 3989K/4296K, paused 85ms, total 99ms
12-22 16:03:32.070: I/Choreographer(1431): Skipped 219 frames!  The application may be doing too much work on its main thread.
12-22 16:03:32.610: D/AndroidRuntime(1431): Shutting down VM
12-22 16:03:32.610: W/dalvikvm(1431): threadid=1: thread exiting with uncaught exception (group=0xb3a55ba8)
12-22 16:03:32.690: E/AndroidRuntime(1431): FATAL EXCEPTION: main
12-22 16:03:32.690: E/AndroidRuntime(1431): Process: com.example.orders, PID: 1431
12-22 16:03:32.690: E/AndroidRuntime(1431): android.os.NetworkOnMainThreadException
12-22 16:03:32.690: E/AndroidRuntime(1431):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1145)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at libcore.io.IoBridge.connect(IoBridge.java:112)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at java.net.Socket.connect(Socket.java:843)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at com.example.orders.JSONParser.makeHttpRequest(JSONParser.java:62)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at com.example.orders.EditProductActivity$GetProductDetails$1.run(EditProductActivity.java:132)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at android.os.Handler.handleCallback(Handler.java:733)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at android.os.Handler.dispatchMessage(Handler.java:95)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at android.os.Looper.loop(Looper.java:136)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at android.app.ActivityThread.main(ActivityThread.java:5001)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at java.lang.reflect.Method.invokeNative(Native Method)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at java.lang.reflect.Method.invoke(Method.java:515)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
12-22 16:03:32.690: E/AndroidRuntime(1431):     at dalvik.system.NativeStart.main(Native Method)
12-22 16:03:41.360: I/Process(1431): Sending signal. PID: 1431 SIG: 9
12-22 16:03:42.990: D/gralloc_goldfish(1457): Emulator without GPU emulation detected.

这是我的 EditProductActivity

package com.example.orders;


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_detials = "http://192.168.1.31/test/get_product_details.php";

    // url to update product
    private static final String url_update_product  = "http://192.168.1.31/test/update_product.php";

    // url to delete product
    private static final String url_delete_product  = "http://192.168.1.31/test/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_detials, "GET", params);

                        // check your log for json response
                        Log.d("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();

        }

    }
}

Answer 1

使用 AsyncTask 或 Thread 来使用任何与网络相关的操作。这是因为某些网络操作可能会被阻止，您的应用程序将无响应。如果您的互联网连接速度较慢，请将其乘以几次。

查看此 post关于服务、线程和异步任务之间的区别。

看看这个link关于异步任务文档。

编辑:我看到您在 asyncTask 中使用线程，但您还指定了 runOnUiThread，这违背了使用 asynctask 的目的。此外，AsyncTask 已经是一个线程，因此不建议指定一个新的 runnable。

//从后台线程更新 UI
runOnUiThread(新的 Runnable(){

如果您查看规范，onPreExecute、onProgressUpdate 和 onPostExecute 已经在主线程上，因此您可以在那里访问您的产品详细信息并发布更新。只要确保你只在那里检索信息并在 doInBackground

中进行网络操作