将一个Android JSON应用程序迁移到Android中的简单应用程序中

Question

我为android创建了两个基于java的应用程序，它们都是独立工作的。

第一个是一个简单的应用程序，带有一些文本字段和带有onClick功能的框，可以在页面之间切换，

第二个是JSON列表（是的，这就是应用程序中的所有内容）

我正在尝试将JSON列表应用程序放在第一个应用程序的中间，但是当我单击针对我的JSON.java页面的onClick按钮时，它会崩溃，但是当我运行JSON.java页面时它自己的应用程序，运行正常。

很抱歉每个人都把我的代码转储到这里，但我是android的新手，并且不太了解它，所以不确定哪些部分/不相关。

HomePage.Java

package com.example.assent.app;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;

public class HomePage extends Activity {

public void SelectClient(View view) 
{
    Intent intent = new Intent(HomePage.this, AndroidJSONParsingActivity.class);
    startActivity(intent);
}

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

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_home_page, menu);
    return true;
}
}

布局 - activity_home_page.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="top"
android:orientation="vertical" >

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="0dp"
    android:layout_gravity="center_horizontal"
    android:layout_weight="0.08"
    android:text="@string/Home_Text1"
    android:textAppearance="?android:attr/textAppearanceLarge" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:text="@string/Home_Text2"
    android:textAppearance="?android:attr/textAppearanceLarge" />

<EditText
    android:id="@+id/editText3"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPersonName" />

<TableLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="0.06" >

    <TableRow
        android:id="@+id/tableRow1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TableRow>

    <TableRow
        android:id="@+id/tableRow2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TableRow>

    <TableRow
        android:id="@+id/tableRow3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TableRow>

    <TableRow
        android:id="@+id/tableRow4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TableRow>
</TableLayout>

<TextView
    android:id="@+id/textView4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:text="@string/Home_Text3"
    android:textAppearance="?android:attr/textAppearanceLarge" />

<TextView
    android:id="@+id/textView5"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:text="@string/Home_Text4"
    android:textAppearance="?android:attr/textAppearanceSmall" />

<EditText
    android:id="@+id/editText2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="textPassword" />

<TableLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="0.09" >

    <TableRow
        android:id="@+id/TableRow02"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TableRow>

    <TableRow
        android:id="@+id/TableRow01"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TableRow>

    <TableRow
        android:id="@+id/TableRow04"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TableRow>

    <TableRow
        android:id="@+id/TableRow03"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TableRow>
</TableLayout>

<Button
    android:id="@+id/button1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:onClick="SelectClient"
    android:text="@string/Home_Button1" />

</LinearLayout>

MENU - activity_home_page.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/menu_settings"
    android:title="@string/menu_settings"
    android:orderInCategory="100"
    android:showAsAction="never" />
</menu>

JSON JAVA - AndroidJSONParsingActivity.java

package com.example.assent.app;

import java.util.ArrayList;
import java.util.HashMap;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.content.Intent;
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 AndroidJSONParsingActivity extends ListActivity {

// url to make request
private static String url = "http://dcc.assentbc.co.uk/GetClients.aspx?SecureID=*******";

// JSON Node names
private static final String TAG_CONTACTS = "Clients";
private static final String TAG_NAME = "CompanyName";

// contacts JSONArray
JSONArray Clients = null;

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

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

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

    // getting JSON string from URL
    JSONObject json = jParser.getJSONFromUrl(url);

    try {
        // Getting Array of Contacts
        Clients = json.getJSONArray(TAG_CONTACTS);

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

            // Storing each json item in variable
            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_NAME, name);

            // adding HashList to ArrayList
            contactList.add(map);
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }

    /**
     * Updating parsed JSON data into ListView
     * */
    ListAdapter adapter = new SimpleAdapter(this, contactList,
            R.layout.list_item,
            new String[] { TAG_NAME }, new int[] {
                    R.id.name });

    setListAdapter(adapter);

    // selecting single ListView item
    ListView lv = getListView();

    // Launching new screen on Selecting Single ListItem
    lv.setOnItemClickListener(new OnItemClickListener() {

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

            // Starting new intent
            Intent in = new Intent(getApplicationContext(),     SingleMenuItemActivity.class);
            in.putExtra(TAG_NAME, name);
            startActivity(in);
        }
    });
}

}

JSON PARSER JAVA - JSONParser.java

package com.example.assent.app;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
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() {

}

public JSONObject getJSONFromUrl(String url) {

    // Making HTTP request
    try {
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        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;

}
}

JSON项目 - SingleMenuItemActivity.java

package com.example.assent.app;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

public class SingleMenuItemActivity  extends Activity {

// JSON node keys
private static final String TAG_NAME = "CompanyName";
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.single_list_item);

    // getting intent data
    Intent in = getIntent();

    // Get JSON values from previous intent
    String name = in.getStringExtra(TAG_NAME);

    // Displaying all values on the screen
    TextView lblName = (TextView) findViewById(R.id.name_label);

    lblName.setText(name);
}
}

布局列表项 - list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
    <!-- Name Label -->
    <TextView
        android:id="@+id/name"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textColor="#43bd00"
        android:textSize="16sp"
        android:textStyle="bold"
        android:paddingTop="6dip"
        android:paddingBottom="2dip" />

    </LinearLayout>

主要布局 - main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<!-- Main ListView 
     Always give id value as list(@android:id/list)
-->
<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>

</LinearLayout>

单一项目布局 - single_item_list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- Name Label -->
<TextView android:id="@+id/name_label"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="25dip"
        android:textStyle="bold"
        android:paddingTop="10dip"
        android:paddingBottom="10dip"
        android:textColor="#43bd00"/>
<!-- Description Label -->
<TextView android:id="@+id/email_label"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textColor="#acacac"/>
<!-- Price Label -->
<TextView android:id="@+id/mobile_label"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textStyle="bold"/>
</LinearLayout>

MY MANIFEST

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.assent.app"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="15" />

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >

    <activity
        android:name=".HomePage"
        android:label="@string/title_activity_home_page" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".MainActivity"
        android:label="@string/title_activity_main" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.HomePage" />
    </activity>
    <activity
        android:name=".Photos"
        android:label="@string/title_activity_photos" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".AudioNotes"
        android:label="@string/title_activity_audio_notes" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".Notes"
        android:label="@string/title_activity_notes" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".Documents"
        android:label="@string/title_activity_documents" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".PhotosSuccess"
        android:label="@string/title_activity_photos_success" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".PhotosActivity"
        android:label="@string/title_activity_photos" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".Photos_Upload"
        android:label="@string/title_activity_photos__upload" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".ImageUpload"
        android:label="@string/title_activity_image_upload" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".Notes_Upload"
        android:label="@string/title_activity_notes__upload" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.MainActivity" />
    </activity>
    <activity
        android:name=".SelectClient"
        android:label="@string/title_activity_select_client" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.assent.app.HomePage" />
    </activity>
    <activity
        android:label="@string/app_name"
        android:name=".AndroidJSONParsingActivity" >
        <intent-filter >
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <!-- Single List Item View -->
    <activity
        android:label="Single Menu Item"
        android:name=".SingleMenuItemActivity" >
    </activity>
</application>

<uses-permission android:name="android.permission.INTERNET" />
</manifest>

我的ECLIPSE日志

11-22 12:10:56.638: D/dalvikvm(381): GC_FOR_ALLOC freed 88K, 3% free 6478K/6663K, paused 56ms
11-22 12:10:56.648: I/dalvikvm-heap(381): Grow heap (frag case) to 6.872MB for 513744-byte allocation
11-22 12:10:56.738: D/dalvikvm(381): GC_FOR_ALLOC freed 2K, 3% free 6977K/7175K, paused 53ms
11-22 12:10:56.868: D/dalvikvm(381): GC_CONCURRENT freed <1K, 3% free 6977K/7175K, paused 4ms+22ms
11-22 12:10:56.938: D/AndroidRuntime(381): Shutting down VM
11-22 12:10:56.938: W/dalvikvm(381): threadid=1: thread exiting with uncaught exception (group=0x40014760)
11-22 12:10:56.958: E/AndroidRuntime(381): FATAL EXCEPTION: main
11-22 12:10:56.958: E/AndroidRuntime(381): java.lang.RuntimeException: Unable to start activity          ComponentInfo{com.example.assent.app/com.example.assent.app.AndroidJSONParsingActivity}: android.os.NetworkOnMainThreadException
11-22 12:10:56.958: E/AndroidRuntime(381):  at     android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.app.ActivityThread.access$500(ActivityThread.java:122)
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.os.Handler.dispatchMessage(Handler.java:99)
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.os.Looper.loop(Looper.java:132)
11-22 12:10:56.958: E/AndroidRuntime(381):  at     android.app.ActivityThread.main(ActivityThread.java:4123)
11-22 12:10:56.958: E/AndroidRuntime(381):  at java.lang.reflect.Method.invokeNative(Native Method)
11-22 12:10:56.958: E/AndroidRuntime(381):  at java.lang.reflect.Method.invoke(Method.java:491)
11-22 12:10:56.958: E/AndroidRuntime(381):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
11-22 12:10:56.958: E/AndroidRuntime(381):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
11-22 12:10:56.958: E/AndroidRuntime(381):  at dalvik.system.NativeStart.main(Native Method)
11-22 12:10:56.958: E/AndroidRuntime(381): Caused by: android.os.NetworkOnMainThreadException
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1077)
11-22 12:10:56.958: E/AndroidRuntime(381):  at java.net.InetAddress.lookupHostByName(InetAddress.java:477)
11-22 12:10:56.958: E/AndroidRuntime(381):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:277)
11-22 12:10:56.958: E/AndroidRuntime(381):  at java.net.InetAddress.getAllByName(InetAddress.java:249)
11-22 12:10:56.958: E/AndroidRuntime(381):  at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:136)
11-22 12:10:56.958: E/AndroidRuntime(381):  at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
11-22 12:10:56.958: E/AndroidRuntime(381):  at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
11-22 12:10:56.958: E/AndroidRuntime(381):  at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
11-22 12:10:56.958: E/AndroidRuntime(381):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
11-22 12:10:56.958: E/AndroidRuntime(381):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
11-22 12:10:56.958: E/AndroidRuntime(381):  at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
11-22 12:10:56.958: E/AndroidRuntime(381):  at com.example.assent.app.JSONParser.getJSONFromUrl(JSONParser.java:38)
11-22 12:10:56.958: E/AndroidRuntime(381):  at com.example.assent.app.AndroidJSONParsingActivity.onCreate(AndroidJSONParsingActivity.java:46)
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.app.Activity.performCreate(Activity.java:4397)
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
11-22 12:10:56.958: E/AndroidRuntime(381):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
11-22 12:10:56.958: E/AndroidRuntime(381):  ... 11 more
11-22 12:11:00.760: I/Process(381): Sending signal. PID: 381 SIG: 9

再次抱歉代码转储，希望有人可以指出我正确的方向

Answer 1

建议使用AsyncTask进行网络操作。 在Honey Comb之前，它不会给出任何错误，但是从主UI线程上的HoneyComb版本网络操作将导致NetworkOnUIthread异常。

所以调用你的：JSONObject json = jParser.getJSONFromUrl（url）;执行异步任务的doInBackGround（）方法，并使用OnPostExecute方法更新您的UI结果。

Answer 2

来自你的logcat

11-22 12:10:56.958: E/AndroidRuntime(381): java.lang.RuntimeException: Unable to start activity          ComponentInfo{com.example.assent.app/com.example.assent.app.AndroidJSONParsingActivity}: android.os.NetworkOnMainThreadException

你正在主线程上下载你的json，在Android 3.0 +上抛出异常。

具体的一行是：JSONObject json = jParser.getJSONFromUrl(url);。将它移动到另一个线程，它应该解决你的问题。

考虑使用AsyncTask，或查看其他选项here