【发布时间】：2014-09-17 08:35:56
【问题描述】：
我得到以下代码，我不知道为什么主 ui 阻塞（等待 DoaJsonReader 完成）。是的，我已经阅读了所有其他问题，通常问题是滥用 .get() 方法。但我不会在任何地方使用它。
程序运行良好，但布局未加载，只要执行 DoaJsonReader，它只会显示带有标题的空白活动，并在 ASyncTask 完成后显示布局的一瞥（大约 0.5 秒）。
这里是我的代码：
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Toast;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
public class Loading extends Activity {
private Thread thread;
DoaData DD;
@Override
protected void onCreate(Bundle savedInstanceState) {
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_loading);
DD = new DoaData(this);
Toast.makeText(getApplicationContext(), "Loading app resources ...", Toast.LENGTH_LONG).show();
DoaJsonReader jr = new DoaJsonReader();
jr.execute("http://myweb.id/APPS/DOA/?i=index.json");
}
private class DoaJsonReader extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
String response = "";
for (String url : urls) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse execute = client.execute(httpGet);
InputStream content = execute.getEntity().getContent();
BufferedReader buffer = new BufferedReader(
new InputStreamReader(content));
String s = "";
while ((s = buffer.readLine()) != null) {
response += s;
}
} catch (Exception e) {
e.printStackTrace();
}
}
return response;
}
@Override
protected void onPostExecute(String result) {
ArrayList<String> stringArray = new ArrayList<String>();
JSONArray jsonArray = null;
JSONObject jsonObject = null;
String lastupdate="";
try {
//jsonArray = new JSONArray(result);
jsonObject= new JSONObject(result);
lastupdate=jsonObject.get("lastupdate").toString();
jsonArray=new JSONArray(jsonObject.get("index").toString());
} catch (Exception e) {
e.printStackTrace();
}
DD.truncateIndex();
for(int i = 0, count = jsonArray.length(); i< count; i++)
{
try {
jsonObject = jsonArray.getJSONObject(i);
DD.insertIndex(jsonObject.getString("title").toString(),jsonObject.getString("file").toString(),jsonObject.getString("tags").toString());
}
catch (JSONException e) {
e.printStackTrace();
}finally {
DD.insertParam("lastupdate",lastupdate);
}
}
finish();
}
}
}
public class DoaData extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "DOA.db";
public static final String TABLE_DOA = "DOA_INDEX";
public static final String TABLE_PARAM = "DOA_PARAM";
public DoaData(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS "+TABLE_DOA);
db.execSQL("DROP TABLE IF EXISTS "+TABLE_PARAM);
onCreate(db);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE "+TABLE_DOA+" (title TEXT,file TEXT, tags TEXT);");
db.execSQL("CREATE TABLE "+TABLE_PARAM+" (key TEXT,value TEXT);");
}
public void insertIndex(String title, String file, String tags){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put("title",title);
cv.put("file",file);
cv.put("tags",tags);
db.insert(TABLE_DOA,null,cv);
db.close(); // Closing database connection
}
public List<DoaIndex> getIndexes() {
List<DoaIndex> DoaIndexList = new ArrayList<DoaIndex>();
String selectQuery = "Select * From " + TABLE_DOA +";";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
int i = 0;
if (cursor.moveToFirst()) {
do {
DoaIndex idx = new DoaIndex(i, cursor.getString(0), cursor.getString(1), cursor.getString(2));
// Adding contact to list
DoaIndexList.add(idx);
} while (cursor.moveToNext());
db.close();
}
return DoaIndexList;
}
public void truncateIndex(){
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("DELETE FROM "+TABLE_DOA+";");
db.execSQL("VACUUM;");
db.close();
}
public void insertParam(String key, String value){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put("key",key);
cv.put("value",value);
db.insert(TABLE_PARAM, null, cv);
db.close();
}
}
【问题讨论】：
-
你调试过 onPostExecute() 吗？
-
是的，我有，它运行正常。你想知道什么？
-
为什么调用finish();在 onPostExecute() 中？什么是 DoaData？
-
因为我想在来自网络的数据加载完成后返回到 MainActivity。我从 MainActivity 调用 Loading (Activity)，我已经尝试将启动活动更改为 Loading 并调用 MainActivity 之后，但它没有改变任何东西（用户界面仍然被阻止）。 Doa 数据是我的 SQLiteOpenHelper
-
您能否尝试将您的DD相关代码在JSONArray初始化后放入runOnUiThread()中。
标签： android multithreading android-layout android-activity android-asynctask