我正在尝试使用将显示数据库内容的 AsyncTask 通过 intent 将我创建的数据库的内容传递给另一个 Activity 。查询将用于指定要使用我的查询按钮显示的数据。我想知道如何将数据库信息传递给其他 Activity 。这是我目前所拥有的。
package com.dwolford.project9;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class Main extends Activity {
Button quit;
Button query;
Button create;
String FILENAME = "";
SQLDatabase db;//possibly use asynctask
String sQuery = "";
EditText queryText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
db = new SQLDatabase(this);//Use asynctask?
create = (Button)findViewById(R.id.create);
create.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
boolean isInserted = db.insertDataS("S01", "Smith", "London" );
if(isInserted == true)
Toast.makeText(Main.this, "Data inserted", Toast.LENGTH_LONG).show();
else
Toast.makeText(Main.this, "Data not inserted", Toast.LENGTH_LONG).show();
new createTask().execute(FILENAME);
}
});
queryText = (EditText)findViewById(R.id.selectQuery);
query = (Button)findViewById(R.id.query);
query.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(Main.this,execute_query.class);
sQuery = queryText.getText().toString();
//intent.putExtra("database", db);
intent.putExtra("queryChoice", sQuery);
startActivity(intent);
}
});
quit = (Button)findViewById(R.id.quit);
quit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
finish();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void AddData()//Add to asynctask?
{
}
public class createTask extends AsyncTask<String, Integer, String>
{
@Override
protected String doInBackground(String... params)
{
return null;
}
}
public class SQLDatabase extends SQLiteOpenHelper{
public static final String SPdb = "SPdb.db";
public static final String s = "s";//First table name
public static final String sno = "sno";
public static final String sname = "sname";
public static final String city = "city";
public static final String p = "p";
public static final String pno = "pno";
public static final String pname = "pname";
public static final String cost = "cost";
public static final String sp = "sp";
public static final String qty = "qty";
public SQLDatabase(Context context) {
super(context, SPdb, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + s + "(sno TEXT PRIMARY KEY COLLATE NOCASE,\n" +
" sname TEXT NOT NULL COLLATE NOCASE,\n" +
" city TEXT NOT NULL COLLATE NOCASE\n)");
db.execSQL("CREATE TABLE " + p + "(pno TEXT NOT NULL COLLATE NOCASE,\n" +
" pname TEXT NOT NULL COLLATE NOCASE,\n" +
" cost REAL NOT NULL,\n" +
" city TEXT NOT NULL COLLATE NOCASE,\n" +
"\n" +
" PRIMARY KEY (pno)\n)");
db.execSQL("CREATE TABLE " + sp + "(sno TEXT NOT NULL REFERENCES s(sno) COLLATE NOCASE,\n" +
" pno TEXT NOT NULL COLLATE NOCASE,\n" +
" qty INTEGER NOT NULL,\n" +
"\n" +
" FOREIGN KEY (pno) REFERENCES p(pno)\n)");
//db.execSQL("create table " = );
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " +s);
db.execSQL("DROP TABLE IF EXISTS " +p);
db.execSQL("DROP TABLE IF EXISTS " +sp);
onCreate(db);//Create table in database
}
public boolean insertDataS(String sno, String sname, String city)
{
SQLiteDatabase db = this.getWritableDatabase();//Maybe readable
ContentValues contentValue = new ContentValues();
contentValue.put(this.sno, sno);
contentValue.put(this.sname, sname);
contentValue.put(this.city, city);
long result = db.insert(s, null, contentValue);
if(result == -1)
{
return false;
}
else
{
return true;
}
}
public Cursor getData()
{
SQLiteDatabase db = this.getWritableDatabase();
Cursor res = db.rawQuery("select * from " + s, null);//* gets all in the query
return res;
}
}
}
主要 xml:
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Create"
android:id="@+id/create"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="55dp"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Query"
android:id="@+id/query"
android:layout_below="@+id/sqlQuery"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="45dp"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="quit"
android:id="@+id/quit"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignRight="@+id/selectQuery"
android:layout_alignEnd="@+id/selectQuery" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="sql query"
android:id="@+id/sqlQuery"
android:textSize="40dp"
android:textStyle="bold"
android:layout_below="@+id/create"
android:layout_centerHorizontal="true"
android:layout_marginTop="41dp" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/selectQuery"
android:text="query"
android:layout_below="@+id/query"
android:layout_marginTop="56dp"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
显示数据库信息的类:
package com.dwolford.project9;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class execute_query extends ActionBarActivity {
Button back;
String query = "";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_execute_query);
Bundle extras = getIntent().getExtras();
if(extras == null)
{
return;
}
query = extras.getString("queryChoice");
//query = getIntent().getDataString();
back = (Button)findViewById(R.id.back);
back.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
finish();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_execute_query, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
查询xml:
<Button
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Back"
android:id="@+id/back"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:height="30dp" />
<HorizontalScrollView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/horizontalScrollView"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_above="@+id/back"
android:fillViewport="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/listView"
android:layout_alignTop="@+id/horizontalScrollView"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_above="@+id/back" />
</HorizontalScrollView>
最佳答案
我认为将数据库连接作为单独的静态类并在需要时从 AsyncTask 中的其他类调用函数是一种很好的做法。在 doInBackground() 中调用您的查询函数，并在需要时从 onPostExecute() 开始您的 Activity 。
例子如下:
create.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// initialize your database here
db = new SQLDatabase(Main.this)
boolean isInserted;
new AsyncTask(){
@Override
protected void onPreExecute() {
// do things you need to do before calling db function
}
@Override
protected Object doInBackground(Object[] params) {
//call db function here
isInserted = db.insertDataS("S01", "Smith", "London" );
//return query resul
return isInserted;
}
@Override
protected void onPostExecute(Object o) {
// you can get returned result here as an object and cast it
isInserted = (boolean)o;
// then start your activity here if you need to or make changes
// to a view or show a toast
Intent i = new Intent(Main.this, otherClass.class);
i.putExtras("result",isInserted);
startActivity(i);
}
}.execute();
希望对你有帮助
关于android - 通过 Intent 将数据库传递给另一个 Activity ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/31592707/