我是一个Android编程的新手，我正在使用eclipse在android中运行程序，我正在尝试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。难怪为什么程序会在我点击模拟器中显示的对象时自动停止。 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);
}
?>
答案 0 :(得分：0)
您的GetProductDetails AsyncTask在UI线程上执行网络调用
public ##
#if($field.modifierStatic)
static ##
#end
$field.type ##
#set($name = $StringUtil.capitalizeWithJavaBeanConvention($StringUtil.sanitizeJavaIdentifier($helper.getPropertyName($field, $project))))
#if ($field.boolean && $field.primitive)
#if ($StringUtil.startsWithIgnoreCase($name, 'is'))
#set($name = $StringUtil.decapitalize($name))
#else
is##
#end
#else
get##
#end
${name}() {
return $field.name;
}
你应该考虑为什么要使用Asynctask，如果它只是在UI线程上做某事。 如果您需要更改用户界面，请在onPostExecute（）中进行。
如果更改您的Asynctask没有帮助，请考虑添加有关您获得的错误的更多信息（例如日志）