Android從數據庫錯誤中檢索數據

Question

我對android完全陌生..我正在嘗試一個在線發現的教程。基本目的是從數據庫中檢索數據並顯示它。 我無法執行它。我已經附上了代碼和錯誤日志。如果有人可以糾正錯誤，那將是一個很大的幫助。

<package com.example.androidhive;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
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.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class AllProductsActivity extends ListActivity {

    // Progress Dialog
    private ProgressDialog pDialog;

    // Creating JSON Parser object
    JSONParser jParser = new JSONParser();

    ArrayList<HashMap<String, String>> productsList;

    // url to get all products list
    private static String url_all_products = "192.168.0.1/android_connect/get_all_products.php";

    // JSON Node names
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_PRODUCTS = "products";
    private static final String TAG_PID = "pid";
    private static final String TAG_NAME = "name";

    // products JSONArray
    JSONArray products = null;

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

        // Hashmap for ListView
        productsList = new ArrayList<HashMap<String, String>>();

        // Loading products in Background Thread
        new LoadAllProducts().execute();

        // Get listview
        ListView lv = getListView();

        // on seleting single product
        // launching Edit Product Screen
        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // getting values from selected ListItem
                String pid = ((TextView) view.findViewById(R.id.pid)).getText()
                        .toString();

                // Starting new intent
                Intent in = new Intent(getApplicationContext(),
                        EditProductActivity.class);
                // sending pid to next activity
                in.putExtra(TAG_PID, pid);

                // starting new activity and expecting some response back
                startActivityForResult(in, 100);
            }
        });

    }

    // Response from Edit Product Activity
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        // if result code 100
        if (resultCode == 100) {
            // if result code 100 is received
            // means user edited/deleted product
            // reload this screen again
            Intent intent = getIntent();
            finish();
            startActivity(intent);
        }

    }

    /**
     * Background Async Task to Load all product by making HTTP Request
     * */
    class LoadAllProducts extends AsyncTask<String, String, String> {

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

        /**
         * getting All products from url
         * */
        protected String doInBackground(String... args) {
            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            // getting JSON string from URL
            JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);

            // Check your log cat for JSON reponse
            Log.d("All Products: ", json.toString());

            try {
                // Checking for SUCCESS TAG
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // products found
                    // Getting Array of Products
                    products = json.getJSONArray(TAG_PRODUCTS);

                    // looping through All Products
                    for (int i = 0; i < products.length(); i++) {
                        JSONObject c = products.getJSONObject(i);

                        // Storing each json item in variable
                        String id = c.getString(TAG_PID);
                        String name = c.getString(TAG_NAME);

                        // creating new HashMap
                        HashMap<String, String> map = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        map.put(TAG_PID, id);
                        map.put(TAG_NAME, name);

                        // adding HashList to ArrayList
                        productsList.add(map);
                    }
                } else {
                    // no products found
                    // Launch Add New product Activity
                    Intent i = new Intent(getApplicationContext(),
                            NewProductActivity.class);
                    // Closing all previous activities
                    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(i);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after getting all products
            pDialog.dismiss();
            // updating UI from Background Thread
            runOnUiThread(new Runnable() {
                public void run() {
                    /**
                     * Updating parsed JSON data into ListView
                     * */
                    ListAdapter adapter = new SimpleAdapter(
                            AllProductsActivity.this, productsList,
                            R.layout.list_item, new String[] { TAG_PID,
                                    TAG_NAME},
                            new int[] { R.id.pid, R.id.name });
                    // updating listview
                    setListAdapter(adapter);
                }
            });

        }`

錯誤

07-18 02:55:17.809: D/dalvikvm(2205): GC_FOR_ALLOC freed 56K, 5% free 2815K/2944K, paused 106ms, total 107ms
07-18 02:55:17.839: I/dalvikvm-heap(2205): Grow heap (frag case) to 5.628MB for 2949608-byte allocation
07-18 02:55:17.889: D/dalvikvm(2205): GC_FOR_ALLOC freed <1K, 3% free 5695K/5828K, paused 48ms, total 48ms
07-18 02:55:18.349: D/gralloc_goldfish(2205): Emulator without GPU emulation detected.
07-18 02:55:21.079: D/dalvikvm(2205): GC_FOR_ALLOC freed 19K, 2% free 6529K/6620K, paused 86ms, total 87ms
07-18 02:55:22.309: W/dalvikvm(2205): threadid=12: thread exiting with uncaught exception (group=0xb3a4fb90)
07-18 02:55:22.349: E/AndroidRuntime(2205): FATAL EXCEPTION: AsyncTask #1
07-18 02:55:22.349: E/AndroidRuntime(2205): Process: com.example.androidhive, PID: 2205
07-18 02:55:22.349: E/AndroidRuntime(2205): java.lang.RuntimeException: An error occured while executing doInBackground()
07-18 02:55:22.349: E/AndroidRuntime(2205):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at java.lang.Thread.run(Thread.java:841)
07-18 02:55:22.349: E/AndroidRuntime(2205): Caused by: java.lang.IllegalStateException: Target host must not be null, or set in parameters. scheme=null, host=null, path=192.168.0.1/android_connect/get_all_products.php
07-18 02:55:22.349: E/AndroidRuntime(2205):     at org.apache.http.impl.client.DefaultRequestDirector.determineRoute(DefaultRequestDirector.java:591)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:293)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at com.example.androidhive.JSONParser.makeHttpRequest(JSONParser.java:62)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at com.example.androidhive.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:127)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at com.example.androidhive.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:1)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
07-18 02:55:22.349: E/AndroidRuntime(2205):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
07-18 02:55:22.349: E/AndroidRuntime(2205):     ... 3 more
07-18 02:55:22.819: I/Choreographer(2205): Skipped 362 frames!  The application may be doing too much work on its main thread.
07-18 02:55:25.829: I/Choreographer(2205): Skipped 171 frames!  The application may be doing too much work on its main thread.
07-18 02:55:30.059: E/WindowManager(2205): android.view.WindowLeaked: Activity com.example.androidhive.AllProductsActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{b40ada18 V.E..... R.....ID 0,0-461,175} that was originally added here
07-18 02:55:30.059: E/WindowManager(2205):  at android.view.ViewRootImpl.<init>(ViewRootImpl.java:346)
07-18 02:55:30.059: E/WindowManager(2205):  at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:248)
07-18 02:55:30.059: E/WindowManager(2205):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
07-18 02:55:30.059: E/WindowManager(2205):  at android.app.Dialog.show(Dialog.java:286)
07-18 02:55:30.059: E/WindowManager(2205):  at com.example.androidhive.AllProductsActivity$LoadAllProducts.onPreExecute(AllProductsActivity.java:117)
07-18 02:55:30.059: E/WindowManager(2205):  at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:587)
07-18 02:55:30.059: E/WindowManager(2205):  at android.os.AsyncTask.execute(AsyncTask.java:535)
07-18 02:55:30.059: E/WindowManager(2205):  at com.example.androidhive.AllProductsActivity.onCreate(AllProductsActivity.java:57)
07-18 02:55:30.059: E/WindowManager(2205):  at android.app.Activity.performCreate(Activity.java:5243)
07-18 02:55:30.059: E/WindowManager(2205):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
07-18 02:55:30.059: E/WindowManager(2205):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
07-18 02:55:30.059: E/WindowManager(2205):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
07-18 02:55:30.059: E/WindowManager(2205):  at android.app.ActivityThread.access$700(ActivityThread.java:135)
07-18 02:55:30.059: E/WindowManager(2205):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
07-18 02:55:30.059: E/WindowManager(2205):  at android.os.Handler.dispatchMessage(Handler.java:102)
07-18 02:55:30.059: E/WindowManager(2205):  at android.os.Looper.loop(Looper.java:137)
07-18 02:55:30.059: E/WindowManager(2205):  at android.app.ActivityThread.main(ActivityThread.java:4998)
07-18 02:55:30.059: E/WindowManager(2205):  at java.lang.reflect.Method.invokeNative(Native Method)
07-18 02:55:30.059: E/WindowManager(2205):  at java.lang.reflect.Method.invoke(Method.java:515)
07-18 02:55:30.059: E/WindowManager(2205):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
07-18 02:55:30.059: E/WindowManager(2205):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
07-18 02:55:30.059: E/WindowManager(2205):  at dalvik.system.NativeStart.main(Native Method)
07-18 02:55:30.059: I/Choreographer(2205): Skipped 217 frames!  The application may be doing too much work on its main thread.
07-18 02:55:32.999: I/Process(2205): Sending signal. PID: 2205 SIG: 9

Answer 1

此異常消息：

java.lang.IllegalStateException: Target host must not be n\
ull, or set in parameters. scheme=null, host=null, path=192.168.0.1/android_connect/get_all_products.php

告訴我makeHttpRequest無法識別您傳遞的url中的host參數。 因此，我真的會接受@Titus的建議，並提供帶有http://前綴的完整URL（或任何協議）。 如果錯誤的類型發生變化，那么您可能會遇到多個錯誤。