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我有问题在 android 版本 18 上运行我的代码。我使用了 AsyncTask 但仍然出现错误，请帮忙。我是编程菜鸟，所以请原谅我的错误

package com.example.androidhive;

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://10.0.2.2/android_connect/get_product_details.php";

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

    // url to delete product
    private static final String url_delete_product = "http://10.0.2.2/android_connect/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);
                            setContentView(R.layout.edit_product);

                            // 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 updated
            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();

        }

    }
    }

我得到的错误是：

10-27 17:01:52.858: E/AndroidRuntime(2001): FATAL EXCEPTION: main
10-27 17:01:52.858: E/AndroidRuntime(2001): android.os.NetworkOnMainThreadException
10-27 17:01:52.858: E/AndroidRuntime(2001):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1133)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at libcore.io.IoBridge.connect(IoBridge.java:112)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at java.net.Socket.connect(Socket.java:842)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at com.example.androidhive.JSONParser.makeHttpRequest(JSONParser.java:62)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at com.example.androidhive.EditProductActivity$GetProductDetails$1.run(EditProductActivity.java:137)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at android.os.Handler.handleCallback(Handler.java:730)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at android.os.Handler.dispatchMessage(Handler.java:92)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at android.os.Looper.loop(Looper.java:137)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at android.app.ActivityThread.main(ActivityThread.java:5103)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at java.lang.reflect.Method.invokeNative(Native Method)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at java.lang.reflect.Method.invoke(Method.java:525)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-27 17:01:52.858: E/AndroidRuntime(2001):     at dalvik.system.NativeStart.main(Native Method)

布局 xml 布局如下所示：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <!-- Name Label -->

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="10dip"
        android:paddingRight="10dip"
        android:paddingTop="10dip"
        android:text="@string/Product_Name2"
        android:textSize="17sp" />

    <!-- Input Name -->
    <EditText android:id="@+id/inputName"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="@string/inputName2"
        android:layout_margin="5dip"
        android:layout_marginBottom="15dip"
        android:singleLine="true"/>

    <!-- Price Label -->

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="10dip"
        android:paddingRight="10dip"
        android:paddingTop="10dip"
        android:text="@string/Price2"
        android:textSize="17sp" />

    <!-- Input Price -->
    <EditText android:id="@+id/inputPrice"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dip"
        android:layout_marginBottom="15dip"
        android:singleLine="true"
        android:inputType="numberDecimal"/>

    <!-- Description Label -->

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="10dip"
        android:paddingRight="10dip"
        android:paddingTop="10dip"
        android:text="@string/Description2"
        android:textSize="17sp" />

    <!-- Input description -->
    <EditText android:id="@+id/inputDesc"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="@string/inputDesc2"
        android:layout_margin="5dip"
        android:layout_marginBottom="15dip"
        android:lines="4"
        android:gravity="top"/>

    <LinearLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <!-- Button Create Product -->

    <Button
        android:id="@+id/btnSave"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="@string/Save_Changes" />

    <!-- Button Create Product -->

    <Button
        android:id="@+id/btnDelete"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="@string/Delete" />

    </LinearLayout>

</LinearLayout>
4

2 回答 2

3

In the GetProductDetails class use only try catch. remove the runOnUiThread() .

于 2013-10-27T21:33:22.353 回答
2

在doInBackground方法上，您必须将 HTTP 请求保留在后台任务中，并且只需将 UI 更新放在runOnUiThread. 这是“快速”修复：

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

    // 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
            final JSONObject product = productObj.getJSONObject(0);

            // updating UI from Background Thread
            runOnUiThread(new Runnable() {
                public void run() {
                    setContentView(R.layout.edit_product);

                    // 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;
}

推荐的解决方案是更改doInBackground返回请求结果的方法并更新 UI，onPostExecute如下所示：

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

    /**
     * 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 JSONObject doInBackground(String... params) {

        JSONObject product = null;
        // 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
                product = productObj.getJSONObject(0);
            }else{
                // product with pid not found
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return product;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(JSONObject product) {
        if (product != null) {
            setContentView(R.layout.edit_product);

            // 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));

        }
        // dismiss the dialog once got all details
        pDialog.dismiss();
    }
}
于 2013-10-28T03:26:14.490 回答