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Android和iOS的数据库都是用SQLite来实现.
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一,SQLite数据库简介:
轻量级:SQLite数据库是一个轻量级的数据库,适用于少量数据的CURD;
文件本质:SQLite数据库支持大部分SQL语法,允许使用SQL语句操作数据库,其本质是一个文件,不需要安装启动。
数据读写:SQLite数据库打开只是一个文件的读写流。
二.简单的数据库语句知识
在android平台上,集成了一个嵌入式关系型数据库—SQLite,SQLite3支持NULL,INTEGER,REAL(浮点数字),TEXT(字符串文本)和BLOB(二进制对象)数据类型,实际上sqlite3也接受varchar(n),char(n),decimal(p,s)等数据类型,只不过在运算或保存时会转成对应的五种数据类型.
SQLite最大的特点是你可以把各种类型的数据保存到任何字段中,而不用关心字段声明的数据类型是什么。
今天我就用一个简单的列子来说明来实现SQLite。
实例代码:
import java.util.ArrayList; import java.util.Iterator; import com.hucc.huccgps.R; import android.app.Activity; import android.app.Dialog; import android.content.Context; import android.content.Intent; import android.content.SharedPreferences; import android.net.Uri; import android.os.Bundle; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.View.OnClickListener; import android.view.ViewGroup; import android.view.Window; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ImageView; import android.widget.ListView; import android.widget.TextView; import android.widget.Toast; public class MainActivity extends Activity { private static final String TAG = "JGPS/MainActivity"; private TextView mAdd_white = null; private ListView mWhiteListView = null; private Context mContext = null; private int mPosition; private DBHelper mDBHelper = null; private WhiteListAdapter mAdapter = null; private ArrayList- mWhiteListItem = new ArrayList
- (); @Override protected void onCreate(Bundle savedInstanceState) { Log.d("JGPS/Start", "onCreate"); super.onCreate(savedInstanceState); setContentView(R.layout.relative_main); this.mDBHelper = new DBHelper(this); this.mContext = this; this.mWhiteListItem = new ArrayList
- (); this.mWhiteListView = (ListView)findViewById(R.id.list_view); initData(); this.mWhiteListView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> paramAdapterView, View paramView, int paramInt, long paramLong) { Log.d("JGPS/MainActivity", ""+paramInt); MainActivity.this.updateWhiteList((Item)MainActivity.this.mWhiteListItem.get(paramInt)); } }); if (this.mAdd_white == null) return; mAdd_white.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { MainActivity.this.addContactList(); } }); Log.d("JGPS/end", "onCreate"); } private void initData() { this.mWhiteListItem = this.mDBHelper.getRelativesList(); if (this.mWhiteListItem.size() != 3) { for (int i = 1; i < 4; i++) { Log.d("JGPS/MainActivity", "initData,id=" + i); Item localItem1 = new Item(); localItem1.setName(""); localItem1.setNumber(""); addItemToList(localItem1); updateSetting(i,""); } this.mWhiteListItem = this.mDBHelper.getRelativesList(); } Iterator localIterator = this.mWhiteListItem.iterator(); while (localIterator.hasNext()) { Item localItem2 = (Item) localIterator.next(); Log.d("JGPS/MainActivity", "initData,id=" + localItem2.getId() + ",name = " + localItem2.getName() + ",number=" + localItem2.getNumber()); } this.mAdapter = new WhiteListAdapter(this, this.mWhiteListItem); this.mWhiteListView.setAdapter(mAdapter); } private void updateSetting(int id, String phoneNum) { switch (id) { case 1: putSting("phone_num1",phoneNum); break; case 2: putSting("phone_num2",phoneNum); break; case 3: putSting("phone_num3",phoneNum); break; default: Log.d("JGPS/MainActivity", "Wrong relative number id"); } } private void putSting(String paramString1, String paramString2) { SharedPreferences.Editor localEditor = getSharedPreferences("sos_config", 0).edit(); localEditor.putString(paramString1, paramString2); localEditor.apply(); } protected void updateWhiteList(Item paramItem) { final Item item = paramItem; Log.d("JGPS/MainActivity", "updateWhiteList------" + item.getId()); final Dialog localDialog = new Dialog(this, R.style.dialog); localDialog.show(); Window localWindow = localDialog.getWindow(); localWindow.setContentView(R.layout.dialog_editor); Button localButton1 = (Button) localWindow.findViewById(R.id.btn_ok); Button localButton2 = (Button) localWindow.findViewById(R.id.btn_cancel); final EditText phone = (EditText)localWindow.findViewById(R.id.phone); final EditText name = (EditText)localWindow.findViewById(R.id.name); name.setText(item.getName()); phone.setText(item.getNumber()); ((TextView)localWindow.findViewById(R.id.title)).setText(R.string.edit_white); localButton1.setOnClickListener(new OnClickListener() { @Override public void onClick(View paramView) { if (phone.getText().toString().trim().length() == 0) { Toast.makeText(mContext, R.string.toast_tel, 2000).show(); return; } if (name.getText().toString().trim().length() == 0) { Toast.makeText(mContext, R.string.name_null, 2000).show(); return; } MainActivity.this.updateContactInDB(item.getId(), name.getText().toString(), phone.getText().toString()); int id = Integer.parseInt(item.getId()); updateSetting(id, phone.getText().toString()); Toast.makeText(mContext, R.string.edit_success, 2000).show(); localDialog.cancel(); } }); localButton2.setOnClickListener(new OnClickListener() { @Override public void onClick(View paramView) { localDialog.cancel(); } }); } protected void updateContactInDB(String paramString1, String paramString2, String paramString3) { Item localItem = new Item(); localItem.setId(paramString1); localItem.setName(paramString2); localItem.setNumber(paramString3); updateItemList(localItem); } private void updateItemList(Item paramItem) { Item localItem2; Iterator localIterator1 = this.mWhiteListItem.iterator(); while (localIterator1.hasNext()) { localItem2 = (Item) localIterator1.next(); if (localItem2.getId().equals(paramItem.getId())) { localItem2.setName(paramItem.getName()); localItem2.setNumber(paramItem.getNumber()); this.mDBHelper.updateRelativesItem(paramItem); } } Log.d("JGPS/MainActivity", "updateItemInList ---------"); this.mAdapter = new WhiteListAdapter(this, this.mWhiteListItem); this.mWhiteListView.setAdapter(mAdapter); } private void addContactList() { final Dialog dialog = new Dialog(this, R.style.dialog); dialog.show(); Window window = dialog.getWindow(); window.setContentView(R.layout.dialog_editor); Button btn1 = (Button)window.findViewById(R.id.btn_ok); Button btn2 = (Button)window.findViewById(R.id.btn_cancel); final EditText phone = (EditText)window.findViewById(R.id.phone); final EditText name = (EditText)window.findViewById(R.id.name); btn1.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { if (phone.getText().toString().trim().length() == 0) { Toast.makeText(mContext, R.string.toast_tel, 2000).show(); return; } if (name.getText().toString().trim().length() == 0) { Toast.makeText(mContext, R.string.name_null, 2000).show(); return; } if (MainActivity.this.mWhiteListItem.size()>3) { String str = MainActivity.this.getResources().getString(R.string.full1)+ " " + 3 + " " + MainActivity.this.getResources().getString(R.string.full2); Toast.makeText(mContext, str, 2000).show(); dialog.cancel(); return; } MainActivity.this.addContactToDB(name.getText().toString(),phone.getText().toString()); dialog.cancel(); } }); btn2.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { dialog.cancel(); } }); } protected void deleteContactFromDB(String paramString) { updateContactInDB(paramString, "", ""); Log.d("JGPS/MainActivity", "===addItemToList = "+paramString); int id = Integer.parseInt(paramString); updateSetting(id, paramString); Toast.makeText(this.mContext, R.string.delete_success, 2000).show(); } @Override protected void onStart() { Log.d("JGPS/MainActivity", "onStart()"); super.onStart(); } protected void startContactIntent(int paramInt) { Log.d("JGPS/MainActivity", "onClick " + paramInt); this.mPosition = paramInt; Intent localIntent = new Intent("android.intent.action.PICK"); localIntent.setType("vnd.android.cursor.dir/phone_v2"); startActivityForResult(localIntent, 100); } protected void addContactToDB(String paramString1, String paramString2) { Iterator localIterator = this.mWhiteListItem.iterator(); while (localIterator.hasNext()) { if(((Item)localIterator.next()).getNumber().equals(paramString2)){ Toast.makeText(mContext, R.string.replace, 2000).show(); return; } } Item localItem = new Item(); localItem.setName(paramString1); localItem.setNumber(paramString2); addItemToList(localItem); Toast.makeText(mContext, R.string.replace, 2000).show(); } private void addItemToList(Item localItem) { Log.d("JGPS/MainActivity", "addItemToList,name = " + localItem.getName() + ",number=" + localItem.getNumber()); this.mDBHelper.addRelativesItem(localItem); this.mWhiteListItem = this.mDBHelper.getRelativesList(); this.mAdapter = new WhiteListAdapter(this, this.mWhiteListItem); this.mWhiteListView.setAdapter(mAdapter); } public void startActivityForResult(Intent paramIntent, int paramInt) { super.startActivityForResult(paramIntent, paramInt); } private class WhiteListAdapter extends BaseAdapter{ private Context context; private LayoutInflater mInflater; private ArrayList
- listItem; public WhiteListAdapter(Context context1, ArrayList
- whiteListItem) { this.context = context1; this.listItem = whiteListItem; this.mInflater = LayoutInflater.from(context); } public int getCount() { if ((this.listItem !=null) && (this.listItem.size() > 0)) { return 3; } return 0; } public Object getItem(int paramInt) { if ((this.listItem != null) && (this.listItem.size() > 0)) return this.listItem.get(paramInt); return null; } public long getItemId(int paramInt) { return 0L; } @Override public View getView(int paramInt, View paramView, ViewGroup paramViewGroup) { Log.d("JGPS/MainActivity", "getView,position=" + paramInt + ",name=" + ((Item)this.listItem.get(paramInt)).getName() + ",num=" + ((Item)this.listItem.get(paramInt)).getNumber()); if (paramView == null) { final ViewHolder localViewHolder = new ViewHolder(); paramView = this.mInflater.inflate(R.layout.relative_list_item, null); localViewHolder.ivCall = (ImageView)paramView.findViewById(R.id.imageView_call); localViewHolder.ivDelete = (ImageView)paramView.findViewById(R.id.imageView_delete); localViewHolder.ivSelect = (ImageView)paramView.findViewById(R.id.recipients_picker); localViewHolder.txtView_name = (TextView)paramView.findViewById(R.id.txtView_name); localViewHolder.txtView_tel = (TextView)paramView.findViewById(R.id.txtView_number); paramView.setTag(localViewHolder); localViewHolder.position = paramInt; localViewHolder.ivSelect.setTag(localViewHolder); if ((this.listItem.get(paramInt)== null)|| (((Item)this.listItem.get(paramInt)).getNumber() == null) || (((Item)this.listItem.get(paramInt)).getNumber().equals(""))) { localViewHolder.ivCall.setVisibility(View.GONE); localViewHolder.ivSelect.setVisibility(View.VISIBLE); String str1 = MainActivity.this.getString(R.string.family_string); String str2 = str1 + (paramInt + 1) + ":"; localViewHolder.txtView_name.setText(str2); localViewHolder.txtView_tel.setText(R.string.click_to_add); }else { localViewHolder.ivCall.setVisibility(View.VISIBLE); localViewHolder.ivSelect.setVisibility(View.GONE); localViewHolder.txtView_name.setText(((Item)this.listItem.get(paramInt)).getName()); localViewHolder.txtView_tel.setText(((Item)this.listItem.get(paramInt)).getNumber()); } localViewHolder.ivSelect.setOnClickListener(new OnClickListener() { @Override public void onClick(View paramView) { MainActivity.WhiteListAdapter.ViewHolder localViewHolder = (MainActivity.WhiteListAdapter.ViewHolder)paramView.getTag(); Log.d("JGPS/MainActivity", "getView,mPosition=" + MainActivity.this.mPosition); MainActivity.this.startContactIntent(localViewHolder.position); } }); if ((!(((Item)this.listItem.get(paramInt)).getName().equals(""))) || (!(((Item)this.listItem.get(paramInt)).getNumber().equals("")))) { localViewHolder.ivDelete.setVisibility(View.VISIBLE); }else { localViewHolder.ivDelete.setVisibility(View.GONE); } localViewHolder.ivCall.setOnClickListener(new OnClickListener() { @Override public void onClick(View paramView) { Intent localIntent = new Intent("android.intent.action.CALL", Uri.parse("tel:" + ((Item)MainActivity.WhiteListAdapter.this.listItem.get(localViewHolder.position)).getNumber())); MainActivity.WhiteListAdapter.this.context.startActivity(localIntent); } }); localViewHolder.ivDelete.setOnClickListener(new OnClickListener() { @Override public void onClick(View paramView) { if(paramView.getId() != R.id.imageView_delete) return; final String str = ((Item)MainActivity.WhiteListAdapter.this.listItem.get(localViewHolder.position)).getId(); Log.d("JGPS/MainActivity", "delete item onClick,strId=" + str + ",position=" + localViewHolder.position); final Dialog localDialog = new Dialog(MainActivity.WhiteListAdapter.this.context, R.style.dialog); localDialog.show(); Window localWindow = localDialog.getWindow(); localWindow.setContentView(R.layout.dialog_delete); ((TextView)localWindow.findViewById(R.id.txtView_delete)).setText(MainActivity.WhiteListAdapter.this.context.getResources().getString(R.string.delete_one) + "'" + ((Item)MainActivity.WhiteListAdapter.this.listItem.get(localViewHolder.position)).getName() + "'" + MainActivity.WhiteListAdapter.this.context.getResources().getString(R.string.delete_two)); Button localButton1 = (Button) localWindow.findViewById(R.id.btn_ok); Button localButton2 = (Button) localWindow.findViewById(R.id.btn_cancel); localButton1.setOnClickListener(new OnClickListener() { @Override public void onClick(View paramView) { MainActivity.this.deleteContactFromDB(str); localDialog.cancel(); } }); localButton2.setOnClickListener(new OnClickListener() { @Override public void onClick(View paramView) { localDialog.cancel(); } }); } }); }else { } return paramView; } public class ViewHolder{ public ImageView ivCall; public ImageView ivDelete; public ImageView ivSelect; public int position; public TextView txtView_name; public TextView txtView_tel; } } } import java.util.ArrayList; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; public class DBHelper extends SQLiteOpenHelper { public static final String TABLE_RELATIVES_CONTENT = "RelativesContent"; public static final int VERSION = 1; //版本 public static final String dbName = "SosDB"; //数据库的名字 public static Context mContext = null; public SQLiteDatabase db = null; public DBHelper(Context paramContext) { super(paramContext, "SosDB", null, 1); mContext = paramContext; } // 创建数据库表 @Override public void onCreate(SQLiteDatabase paramSQLiteDatabase) { paramSQLiteDatabase.execSQL("create table RelativesContent(id integer primary key autoincrement,name text , number text)"); closeDatabase(); } private void closeDatabase() { if (this.db == null) return; this.db.close(); } @Override public void onUpgrade(SQLiteDatabase paramSQLiteDatabase, int paramInt1, int paramInt2) { onCreate(paramSQLiteDatabase); } //查询方法 public ArrayList
- getRelativesList() { String idf = null; String namef = null; String numf = null; ArrayList localArrayList = new ArrayList(); openDatabase(); Cursor localCursor = this.db.query("RelativesContent", null, null, null, null, null, null); if(localCursor == null) return localArrayList; while (localCursor.moveToNext()) { Item localItem = new Item(); idf = localCursor.getString(localCursor.getColumnIndex("id")); namef = localCursor.getString(localCursor.getColumnIndex("name")); numf = localCursor.getString(localCursor.getColumnIndex("number")); localItem.setId(idf); Log.d("JGPS/MainActivity", "dbid=" + idf); if ((namef == null) || ("".equals(namef))) { localItem.setName(""); }else { localItem.setName(namef); } if ((numf == null) || ("".equals(numf))) { localItem.setNumber(""); }else { localItem.setNumber(numf); } localArrayList.add(localItem); } return localArrayList; } //写入数据 private void openDatabase() { this.db = super.getWritableDatabase(); } //添加数据 public boolean addRelativesItem(Item localItem) { openDatabase(); ContentValues localContentValues = new ContentValues(); localContentValues.put("name", localItem.getName()); localContentValues.put("number", localItem.getNumber()); long l = this.db.insert("RelativesContent", null, localContentValues); closeDatabase(); return (1<=0L); } //更新数据 public boolean updateRelativesItem(Item paramItem) { openDatabase(); ContentValues localContentValues = new ContentValues(); localContentValues.put("name", paramItem.getName()); localContentValues.put("number", paramItem.getNumber()); SQLiteDatabase localSQLiteDatabase = this.db; String[] arrayOfString = new String[1]; arrayOfString[0] = paramItem.getId(); long l = localSQLiteDatabase.update("RelativesContent", localContentValues, "id=?", arrayOfString); closeDatabase(); return (1 <= 0L); } } import java.io.Serializable; public class Item implements Serializable{ private String _id; private String name; private String number; public Item() { // TODO Auto-generated constructor stub } public void Item(String paramString1, String paramString2, String paramString3) { this._id = paramString1; this.name = paramString2; this.number = paramString3; } public String getId() { return _id; } public void setId(String paramString) { this._id = paramString; } public String getName() { return name; } public void setName(String paramString) { this.name = paramString; } public String getNumber() { return number; } public void setNumber(String paramString) { this.number = paramString; } }
这是基本的数据程序。
XML
relative_main
dialog_editor <?xml version="1.0" encoding="utf-8"?>
relative_list_item
"
dialog_delete
这是一个简单的demo,我这里就不详细说明数据库的细节了,对于已经很熟悉数据库的,可以查看android官网有说明的,
感谢阅读,希望能帮助到大家,谢谢大家对本站的支持!