将开发过程经常用的内容片段做个备份，如下内容是关于Android系统下读写Sqlite数据库的的内容。

Licensed under the Apache License, Version 2.0 (the "License");you may not use this file except in compliance with the License.You may obtain a copy of the License atUnless required by applicable law or agreed to in writing, softwaredistributed under the License is distributed on an "AS IS" BASIS,WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.See the License for the specific language governing permissions andlimitations under the License.package com.commonsware.android.constants;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.SQLException;import android.database.sqlite.SQLiteOpenHelper;import android.database.sqlite.SQLiteDatabase;import android.hardware.SensorManager;public class DatabaseHelper extends SQLiteOpenHelper {private static final String DATABASE_NAME="db";public static final String TITLE="title";public static final String VALUE="value";public DatabaseHelper(Context context) {super(context, DATABASE_NAME, null, 1);}@Overridepublic void onCreate(SQLiteDatabase db) {db.execSQL("CREATE TABLE constants (_id INTEGER PRIMARY KEY AUTOINCREMENT, title TEXT, value REAL);");ContentValues cv=new ContentValues();cv.put(TITLE, "Gravity, Death Star I");cv.put(VALUE, SensorManager.GRAVITY_DEATH_STAR_I);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Earth");cv.put(VALUE, SensorManager.GRAVITY_EARTH);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Jupiter");cv.put(VALUE, SensorManager.GRAVITY_JUPITER);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Mars");cv.put(VALUE, SensorManager.GRAVITY_MARS);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Mercury");cv.put(VALUE, SensorManager.GRAVITY_MERCURY);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Moon");cv.put(VALUE, SensorManager.GRAVITY_MOON);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Neptune");cv.put(VALUE, SensorManager.GRAVITY_NEPTUNE);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Pluto");cv.put(VALUE, SensorManager.GRAVITY_PLUTO);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Saturn");cv.put(VALUE, SensorManager.GRAVITY_SATURN);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Sun");cv.put(VALUE, SensorManager.GRAVITY_SUN);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, The Island");cv.put(VALUE, SensorManager.GRAVITY_THE_ISLAND);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Uranus");cv.put(VALUE, SensorManager.GRAVITY_URANUS);db.insert("constants", TITLE, cv);cv.put(TITLE, "Gravity, Venus");cv.put(VALUE, SensorManager.GRAVITY_VENUS);db.insert("constants", TITLE, cv);}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {android.util.Log.w("Constants", "Upgrading database, which will destroy all old data");db.execSQL("DROP TABLE IF EXISTS constants");onCreate(db);}}复制代码ConstantsBrowser.javaLicensed under the Apache License, Version 2.0 (the "License");you may not use this file except in compliance with the License.You may obtain a copy of the License atUnless required by applicable law or agreed to in writing, softwaredistributed under the License is distributed on an "AS IS" BASIS,WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.See the License for the specific language governing permissions andlimitations under the License.package com.commonsware.android.constants;import android.app.AlertDialog;import android.app.ListActivity;import android.content.ContentValues;import android.content.DialogInterface;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.text.method.NumberKeyListener;import android.view.ContextMenu;import android.view.LayoutInflater;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.AdapterView;import android.widget.EditText;import android.widget.ListAdapter;import android.widget.SimpleCursorAdapter;import android.widget.TextView;public class ConstantsBrowser extends ListActivity {private static final int ADD_ID = Menu.FIRST+1;private static final int DELETE_ID = Menu.FIRST+3;private static final int CLOSE_ID = Menu.FIRST+4;private SQLiteDatabase db=null;private Cursor constantsCursor=null;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);db=(new DatabaseHelper(this)).getWritableDatabase();constantsCursor=db.rawQuery("SELECT _ID, title, value "+"FROM constants ORDER BY title",null);ListAdapter adapter=new SimpleCursorAdapter(this,R.layout.row, constantsCursor,new String[] {"title", "value"},new int[] {R.id.title, R.id.value});setListAdapter(adapter);registerForContextMenu(getListView());}@Overridepublic void onDestroy() {super.onDestroy();constantsCursor.close();db.close();}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {menu.add(Menu.NONE, ADD_ID, Menu.NONE, "Add").setIcon(R.drawable.add).setAlphabeticShortcut('a');menu.add(Menu.NONE, CLOSE_ID, Menu.NONE, "Close").setIcon(R.drawable.eject).setAlphabeticShortcut('c');return(super.onCreateOptionsMenu(menu));}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {switch (item.getItemId()) {case ADD_ID:add();return(true);case CLOSE_ID:finish();return(true);}return(super.onOptionsItemSelected(item));}@Overridepublic void onCreateContextMenu(ContextMenu menu, View v,ContextMenu.ContextMenuInfo menuInfo) {menu.add(Menu.NONE, DELETE_ID, Menu.NONE, "Delete").setIcon(R.drawable.delete).setAlphabeticShortcut('d');}@Overridepublic boolean onContextItemSelected(MenuItem item) {switch (item.getItemId()) {case DELETE_ID:AdapterView.AdapterContextMenuInfo info=(AdapterView.AdapterContextMenuInfo)item.getMenuInfo();delete(info.id);return(true);}return(super.onOptionsItemSelected(item));}private void add() {LayoutInflater inflater=LayoutInflater.from(this);View addView=inflater.inflate(R.layout.add_edit, null);final DialogWrapper wrapper=new DialogWrapper(addView);new AlertDialog.Builder(this).setTitle(R.string.add_title).setView(addView).setPositiveButton(R.string.ok,new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog,int whichButton) {processAdd(wrapper);}}).setNegativeButton(R.string.cancel,new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog,int whichButton) {}}).show();}private void delete(final long rowId) {if (rowId>0) {new AlertDialog.Builder(this).setTitle(R.string.delete_title).setPositiveButton(R.string.ok,new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog,int whichButton) {processDelete(rowId);}}).setNegativeButton(R.string.cancel,new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog,int whichButton) {}}).show();}}private void processAdd(DialogWrapper wrapper) {ContentValues values=new ContentValues(2);values.put("title", wrapper.getTitle());values.put("value", wrapper.getValue());db.insert("constants", "title", values);constantsCursor.requery();}private void processDelete(long rowId) {String[] args={String.valueOf(rowId)};db.delete("constants", "_ID=?", args);constantsCursor.requery();}class DialogWrapper {EditText titleField=null;EditText valueField=null;View base=null;DialogWrapper(View base) {this.base=base;valueField=(EditText)base.findViewById(R.id.value);}String getTitle() {return(getTitleField().getText().toString());}float getValue() {return(new Float(getValueField().getText().toString()).floatValue());}private EditText getTitleField() {if (titleField==null) {titleField=(EditText)base.findViewById(R.id.title);}return(titleField);}private EditText getValueField() {if (valueField==null) {valueField=(EditText)base.findViewById(R.id.value);}return(valueField);}}}<?xml version="1.0" encoding="utf-8"?>android:orientation="horizontal"android:layout_width="fill_parent"android:layout_height="fill_parent"><TextViewandroid:id="@+id/title"android:layout_width="wrap_content" android:layout_height="wrap_content"android:layout_alignParentLeft="true"/><TextViewandroid:id="@+id/value"android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true"/></RelativeLayout><?xml version="1.0" encoding="utf-8"?>android:orientation="vertical"android:layout_width="fill_parent"android:layout_height="wrap_content"><LinearLayoutandroid:orientation="horizontal"android:layout_width="fill_parent"android:layout_height="wrap_content"><TextViewandroid:text="Display Name:"android:layout_width="wrap_content" android:layout_height="wrap_content"android:layout_alignParentLeft="true"/><EditTextandroid:id="@+id/title"android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_alignParentRight="true"/></LinearLayout><LinearLayoutandroid:orientation="horizontal"android:layout_width="fill_parent"android:layout_height="wrap_content"><TextViewandroid:text="Value:"android:layout_width="wrap_content" android:layout_height="wrap_content"android:layout_alignParentLeft="true"/><EditTextandroid:id="@+id/value"android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_alignParentRight="true"/></LinearLayout></LinearLayout>