-1
我正在搜索和檢索我的數據庫中的數據我正在使用android asynctask和php的網絡服務 但是當我執行它時我得到一個異常，在這裏我的代碼：從數據庫檢索數據使用Asynctask和PHP的網絡服務
AsynctaskListViewLoader類：
package com.hassen.testannonceasyntask;
import android.app.Application;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
class AsyncListViewLoader extends AsyncTask<String, Void, List<Contact>> {
// private ProgressDialog dialog = new ProgressDialog();
SimpleAdapter adpt;
AsyncListViewLoader() {
}
@Override
protected void onPostExecute(List<Contact> result) {
super.onPostExecute(result);
// dialog.dismiss();
adpt.setItemList(result);
adpt.notifyDataSetChanged();
}
@Override
protected void onPreExecute() {
super.onPreExecute();
// dialog.setMessage("Downloading contacts...");
// dialog.show();
}
@Override
protected List<Contact> doInBackground(String... params) {
List<Contact> result = new ArrayList<Contact>();
try {
URL u = new URL(params[0]);
HttpURLConnection conn = (HttpURLConnection) u.openConnection();
conn.setRequestMethod("GET");
conn.connect();
InputStream is = conn.getInputStream();
// Read the stream
byte[] b = new byte[1024];
ByteArrayOutputStream baos = new ByteArrayOutputStream();
while (is.read(b) != -1)
baos.write(b);
String JSONResp = new String(baos.toByteArray());
JSONArray arr = new JSONArray(JSONResp);
for (int i=0; i < arr.length(); i++) {
result.add(convertContact(arr.getJSONObject(i)));
}
return result;
}
catch(Throwable t) {
t.printStackTrace();
}
return null;
}
private Contact convertContact(JSONObject obj) throws JSONException {
String name = obj.getString("name");
String surname = obj.getString("surname");
String email = obj.getString("email");
String phoneNum = obj.getString("phoneNum");
return new Contact(name, surname, email, phoneNum);
}
}
SimpleAdapter類：
package com.hassen.testannonceasyntask;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import java.util.List;
class SimpleAdapter extends ArrayAdapter<Contact> {
private List<Contact> itemList;
private Context context;
public SimpleAdapter(List<Contact> itemList, Context ctx) {
super(ctx, android.R.layout.simple_list_item_1, itemList);
this.itemList = itemList;
this.context = ctx;
}
public int getCount() {
if (itemList != null)
return itemList.size();
return 0;
}
public Contact getItem(int position) {
if (itemList != null)
return itemList.get(position);
return null;
}
public long getItemId(int position) {
if (itemList != null)
return itemList.get(position).hashCode();
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = inflater.inflate(R.layout.list_item, null);
}
Contact c = itemList.get(position);
TextView text = (TextView) v.findViewById(R.id.name);
text.setText(c.getName());
TextView text1 = (TextView) v.findViewById(R.id.surname);
text1.setText(c.getSurname());
TextView text2 = (TextView) v.findViewById(R.id.email);
text2.setText(c.getEmail());
TextView text3 = (TextView) v.findViewById(R.id.phone);
text3.setText(c.getPhoneNum());
return v;
}
public List<Contact> getItemList() {
return itemList;
}
public void setItemList(List<Contact> itemList) {
this.itemList = itemList;
}
}
我跟類：
package com.hassen.testannonceasyntask;
import java.io.Serializable;
public class Contact implements Serializable {
private String name;
private String surname;
private String email;
private String phoneNum;
public Contact(String name, String surname, String email, String phoneNum) {
super();
this.name = name;
this.surname = surname;
this.email = email;
this.phoneNum = phoneNum;
}
// get and set methods
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getPhoneNum() {
return phoneNum;
}
public void setPhoneNum(String phoneNum) {
this.phoneNum = phoneNum;
}
}
MainActivity類別：
package com.hassen.testannonceasyntask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
SimpleAdapter adpt;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
adpt = new SimpleAdapter(new ArrayList(), this);
ListView lView = (ListView) findViewById(R.id.myList);
lView.setAdapter(adpt);
// Exec async load task
(new AsyncListViewLoader()).execute("http://192.168.83.2/AndroidPhpDemo/user.php");
}
}
LIST_ITEM佈局：
<?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">
<TextView
android:layout_width="390dp"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Name"
android:id="@+id/name"
android:layout_gravity="center_horizontal" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="SurName"
android:id="@+id/surname" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Email"
android:id="@+id/email" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Phone"
android:id="@+id/phone" />
</LinearLayout>
activity_main佈局：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/myList"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
我得到這個錯誤：
09-07 13:02:19.400 1629-1629/com.hassen.testannonceasyntask E/OpenGLRenderer: Getting MAX_TEXTURE_SIZE from GradienCache
09-07 13:02:19.412 1629-1629/com.hassen.testannonceasyntask E/OpenGLRenderer: Getting MAX_TEXTURE_SIZE from Caches::initConstraints()
09-07 13:02:20.872 1629-1629/com.hassen.testannonceasyntask E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.NullPointerException
at com.hassen.testannonceasyntask.AsyncListViewLoader.onPostExecute(AsyncListViewLoader.java:29)
at com.hassen.testannonceasyntask.AsyncListViewLoader.onPostExecute(AsyncListViewLoader.java:18)
at android.os.AsyncTask.finish(AsyncTask.java:631)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
請幫忙!!!!