android sqlite

在Android中使用SQLite,ContentProvider
数据库支持(SQLite)-Android开发平台提供了操作SQLite数据库的相关API
内容提供器(ContentProvider)-当数据需要在应用程序之间共享时，可以在某程序中使用ContentProvider定义URI，以使其它应用程序可以通过此URI访问指定的数据
1、SQLite的Demo
DatabaseHelper.java
Java代码
代码
packagecom.webabcd.SQLite;
importandroid.content.Context;
importandroid.database.sqlite.SQLiteDatabase;
importandroid.database.sqlite.SQLiteOpenHelper;
importandroid.database.sqlite.SQLiteDatabase.CursorFactory;
//数据库操作的Helper类
publicclassDatabaseHelperextendsSQLiteOpenHelper{
DatabaseHelper(Contextcontext,Stringname,CursorFactorycursorFactory,intversion){
super(context,name,cursorFactory,version);
}
@Override
publicvoidonCreate(SQLiteDatabasedb){
//TODO创建数据库后，对数据库的操作
}
@Override
publicvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion){
//TODO更改数据库版本的操作
}
@Override
publicvoidonOpen(SQLiteDatabasedb){
super.onOpen(db);
//TODO每次成功打开数据库后首先被执行
}
}
Main.java
代码
packagecom.webabcd.SQLite;
importjava.util.Random;
importandroid.app.Activity;
importandroid.content.ContentValues;
importandroid.database.Cursor;
importandroid.database.SQLException;
importandroid.database.sqlite.SQLiteDatabase;
importandroid.os.Bundle;
importandroid.view.View;
importandroid.widget.Button;
importandroid.widget.TextView;
publicclassMainextendsActivity{
privateDatabaseHelperdbHelper;
privatestaticfinalStringDATABASE_NAME="db.db";
privatestaticfinalintDATABASE_VERSION=1;
privatestaticfinalStringTABLE_NAME="employee";
TextViewtxtMsg;
/**Calledwhentheactivityisfirstcreated.*/
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
dbHelper=newDatabaseHelper(this,DATABASE_NAME,null,
DATABASE_VERSION);
txtMsg=(TextView)this.findViewById(R.id.txtMsg);
Buttonbtn1=(Button)this.findViewById(R.id.btn1);
btn1.setText("创建表");
btn1.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
CreateTable();
}
});
Buttonbtn2=(Button)this.findViewById(R.id.btn2);
btn2.setText("插入3条记录");
btn2.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
insertItem();
}
});
Buttonbtn3=(Button)this.findViewById(R.id.btn3);
btn3.setText("删除全部记录");
btn3.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
deleteItem();
}
});
Buttonbtn4=(Button)this.findViewById(R.id.btn4);
btn4.setText("更新指定数据");
btn4.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
updateItem();
}
});
Buttonbtn5=(Button)this.findViewById(R.id.btn5);
btn5.setText("显示全部数据");
btn5.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
showItems();
}
});
Buttonbtn6=(Button)this.findViewById(R.id.btn6);
btn6.setText("删除表");
btn6.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
dropTable();
}
});
}
//创建数据表
privatevoidCreateTable(){
SQLiteDatabasedb=dbHelper.getWritableDatabase();
Stringsql="CREATETABLEIFNOTEXISTS"+TABLE_NAME
+"(IDINTEGERPRIMARYKEY,NameVARCHAR,AgeINTEGER);";
try{
db.execSQL(sql);
txtMsg.append("数据表成功创建/n");
}catch(SQLExceptionex){
txtMsg.append("数据表创建错误/n"+ex.toString()+"/n");
}
}
//插入数据
privatevoidinsertItem(){
SQLiteDatabasedb=dbHelper.getWritableDatabase();
try{
Randomrandom=newRandom();
for(inti=0;i<3;i++){
Stringsql="insertinto"+TABLE_NAME
+"(name,age)values('name"+String.valueOf(i)
+"',"+random.nextInt()+")";
//execSQL()-执行指定的sql
db.execSQL(sql);
}
txtMsg.append("成功插入3条数据/n");
}catch(SQLExceptionex){
txtMsg.append("插入数据失败/n"+ex.toString()+"/n");
}
}
//删除数据
privatevoiddeleteItem(){
try{
SQLiteDatabasedb=dbHelper.getWritableDatabase();
db.delete(TABLE_NAME,"id<999999",null);
txtMsg.append("成功删除数据/n");
}catch(SQLExceptione){
txtMsg.append("删除数据失败/n");
}
}
//更新数据
privatevoidupdateItem(){
SQLiteDatabasedb=dbHelper.getWritableDatabase();
try{
ContentValuesvalues=newContentValues();
values.put("name","批量更新后的名字");
db.update(TABLE_NAME,values,"id<?",newString[]{"3"});
txtMsg.append("成功更新数据/n");
}catch(SQLExceptione){
txtMsg.append("更新数据失败/n");
}
}
//查询数据
privatevoidshowItems(){
SQLiteDatabasedb=dbHelper.getReadableDatabase();
try{
String[]column={"id","name","age"};
Cursorcursor=db.query(TABLE_NAME,column,null,null,null,
null,null);
Integernum=cursor.getCount();
txtMsg.append("共"+Integer.toString(num)+"条记录/n");
cursor.moveToFirst();
while(cursor.getPosition()!=cursor.getCount()){
txtMsg.append(Integer.toString(cursor.getPosition())+","
+String.valueOf(cursor.getString(0))+","
+cursor.getString(1)+","
+String.valueOf(cursor.getString(2))+"/n");
cursor.moveToNext();
}
}catch(SQLExceptionex){
txtMsg.append("读取数据失败/n"+ex.toString()+"/n");
}
}
//删除数据表
privatevoiddropTable(){
SQLiteDatabasedb=dbHelper.getWritableDatabase();
Stringsql="DROPTABLEIFEXISTS"+TABLE_NAME;
try{
db.execSQL(sql);
txtMsg.append("数据表删除成功/n");
}catch(SQLExceptionex){
txtMsg.append("数据表删除错误/n"+ex.toString()+"/n");
}
}
}
2、ContentProvider的Demo
MyUser.java
代码
packagecom.webabcd.contentprovider;
importandroid.net.Uri;
importandroid.provider.BaseColumns;
//自定义ContentProvider所需的实体类
publicclassMyUser{
//必须要有_id字段。本例中BaseColumn类中已经包含了_id字段
publicstaticfinalclassUserimplementsBaseColumns{
//定义CONTENT_URI
publicstaticfinalUriCONTENT_URI=Uri.parse("content://com.webabcd.MyContentProvider");
//表数据列
publicstaticfinalStringUSER_NAME="USER_NAME";
}
}
MyContentProvider.java
代码
packagecom.webabcd.contentprovider;
importjava.io.File;
importjava.io.FileInputStream;
importjava.io.FileOutputStream;
importorg.apache.http.util.EncodingUtils;
importandroid.content.ContentProvider;
importandroid.content.ContentUris;
importandroid.content.ContentValues;
importandroid.database.Cursor;
importandroid.database.MatrixCursor;
importandroid.net.Uri;
//继承ContentProvider以实现自定义的ContentProvider（基于文件的信息存储）
publicclassMyContentProviderextendsContentProvider{
privateFilefile;
privateFileOutputStreamout;
privateFileInputStreamin;
//ContentProvider的删除数据接口
@Override
publicintdelete(Uriuri,Stringselection,String[]selectionArgs){
//TODOAuto-generatedmethodstub
return0;
}
@Override
publicStringgetType(Uriuri){
//TODOAuto-generatedmethodstub
returnnull;
}
//ContentProvider的插入数据接口
@Override
publicUriinsert(Uriuri,ContentValuesvalues){
try{
out=newFileOutputStream(file);
out.write(values.getAsString(MyUser.User.USER_NAME).getBytes());
out.close();
introwId=0;
UrirowUri=ContentUris.appendId(
MyUser.User.CONTENT_URI.buildUpon(),rowId).build();
getContext().getContentResolver().notifyChange(rowUri,null);
returnrowUri;
}catch(Exceptione){
returnnull;
}
}
//创建用于保存信息的文件
@Override
publicbooleanonCreate(){
try{
//每个包中应用程序的私有目录为：/data/data/包名/
//SD卡目录为：/sdcard
file=newFile("/data/data/com.webabcd.contentprovider/",
"demo.txt");
if(!file.exists())
file.createNewFile();
returntrue;
}catch(Exceptionex){
returnfalse;
}
}
//ContentProvider的查询数据接口
@Override
publicCursorquery(Uriuri,String[]projection,Stringselection,
String[]selectionArgs,StringsortOrder){
Stringcontent;
try{
in=newFileInputStream(file);
intlength=(int)file.length();
byte[]buffer=newbyte[length];
in.read(buffer,0,length);
content=EncodingUtils.getString(buffer,"UTF-8");
in.close();
String[]columns=newString[]{MyUser.User._ID,MyUser.User.USER_NAME};
MatrixCursorcur=newMatrixCursor(columns);
String[]values=newString[]{"0",content};
cur.moveToFirst();
cur.addRow(values);
returncur;
}catch(Exceptione){
returnnull;
}
}
//ContentProvider的更新数据接口
@Override
publicintupdate(Uriuri,ContentValuesvalues,Stringselection,
String[]selectionArgs){
//TODOAuto-generatedmethodstub
return0;
}
}
Main.java
代码
packagecom.webabcd.contentprovider;
importjava.util.Random;
importandroid.app.Activity;
importandroid.content.ContentUris;
importandroid.content.ContentValues;
importandroid.database.Cursor;
importandroid.net.Uri;
importandroid.os.Bundle;
importandroid.provider.Contacts;
importandroid.provider.Contacts.People;
importandroid.util.Log;
importandroid.view.View;
importandroid.widget.Button;
importandroid.widget.Toast;
/*
*几个常用的系统内置的ContentProvider如下：
*content://media/internal/images这个URI将返回设备上存储的所有图片
*content://contacts/people/这个URI将返回设备上的所有联系人信息
*content://contacts/people/45这个URI返回单个结果（联系人信息中ID为45的联系人记录）
*/
publicclassMainextendsActivity{
/**Calledwhentheactivityisfirstcreated.*/
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Buttonbtn1=(Button)this.findViewById(R.id.btn1);
btn1.setText("新增联系人记录");
btn1.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
Randomrandom=newRandom();
insertRecords("name"+String.valueOf(random.nextInt()),String
.valueOf(random.nextInt()));
}
});
Buttonbtn2=(Button)this.findViewById(R.id.btn2);
btn2.setText("查看联系人记录");
btn2.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
displayRecords();
}
});
Buttonbtn3=(Button)this.findViewById(R.id.btn3);
btn3.setText("清除联系人记录");
btn3.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
deleteRecords();
}
});
Buttonbtn4=(Button)this.findViewById(R.id.btn4);
btn4.setText("更新联系人记录");
btn4.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
//此处只是演示，id来自People._ID，可参见displayRecords()是如何获取id的
intid=0;
updateRecord(id,"修改后的name");
}
});
Buttonbtn5=(Button)this.findViewById(R.id.btn5);
btn5.setText("新增记录到MyContentProvider");
btn5.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
insertRecord2MyContentProvider("webabcd");
}
});
Buttonbtn6=(Button)this.findViewById(R.id.btn6);
btn6.setText("获取记录从MyContentProvider");
btn6.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
displayRecord2MyContentProvider();
}
});
}
//调用ContentProvider的插入接口
privatevoidinsertRecords(Stringname,StringphoneNum){
ContentValuesvalues=newContentValues();
values.put(People.NAME,name);
Uriuri=getContentResolver().insert(People.CONTENT_URI,values);
Log.d("MyDebug",uri.toString());
UrinumberUri=Uri.withAppendedPath(uri,
People.Phones.CONTENT_DIRECTORY);
Log.d("MyDebug",numberUri.toString());
values.clear();
values.put(Contacts.Phones.TYPE,People.Phones.TYPE_MOBILE);
values.put(People.NUMBER,phoneNum);
getContentResolver().insert(numberUri,values);
}
//调用ContentProvider的查询接口
privatevoiddisplayRecords(){
String[]columns=newString[]{People._ID,People.NAME,
People.NUMBER};
Uricontacts=People.CONTENT_URI;
Log.d("MyDebug",contacts.toString());
Cursorcur=managedQuery(contacts,columns,//要返回的数据字段
null,//WHERE子句
null,//WHERE子句的参数
null//Order-by子句
);
if(cur.moveToFirst()){
Stringid=null;
Stringname=null;
StringphoneNo=null;
while(cur.getPosition()!=cur.getCount()){
id=cur.getString(cur.getColumnIndex(People._ID));
name=cur.getString(cur.getColumnIndex(People.NAME));
phoneNo=cur.getString(cur.getColumnIndex(People.NUMBER));
Toast.makeText(this,id+"/"+name+"/"+phoneNo,
Toast.LENGTH_SHORT).show();
cur.moveToNext();
}
}
}
//调用ContentProvider的删除接口
privatevoiddeleteRecords(){
Uriuri=People.CONTENT_URI;
Log.d("MyDebug",uri.toString());
getContentResolver().delete(uri,null,null);
//getContentResolver().delete(uri,"NAME="+"'name'",null);
}
//调用ContentProvider的更新接口
privatevoidupdateRecord(intrecordNo,Stringname){
Uriuri=ContentUris.withAppendedId(People.CONTENT_URI,recordNo);
Log.d("MyDebug",uri.toString());
ContentValuesvalues=newContentValues();
values.put(People.NAME,name);
getContentResolver().update(uri,values,null,null);
}
//调用自定义ContentProvider的插入接口
privatevoidinsertRecord2MyContentProvider(Stringname){
ContentValuesvalues=newContentValues();
values.put(MyUser.User.USER_NAME,name);
getContentResolver().insert(MyUser.User.CONTENT_URI,values);
}
//调用自定义ContentProvider的查询接口
privatevoiddisplayRecord2MyContentProvider(){
String[]columns=newString[]{MyUser.User.USER_NAME};
Uriuri=MyUser.User.CONTENT_URI;
Cursorcur=managedQuery(uri,columns,null,null,null);
while(cur.getPosition()!=cur.getCount()){
Stringid=cur.getString(cur.getColumnIndex(People._ID));
Stringname=cur.getString(cur.getColumnIndex(MyUser.User.USER_NAME));
Toast.makeText(this,
id+"/"+name,
Toast.LENGTH_SHORT).show();
cur.moveToNext();
}
}
}
AndroidManifest.xml
代码
<?xmlversion="1.0"encoding="utf-8"?>
<manifestxmlns:android="http://schemas.android.com/apk/res/android"
package="com.webabcd.contentprovider"
android:versionCode="1"
android:versionName="1.0">
<applicationandroid:icon="@drawable/icon"android:label="@string/app_name">
<activityandroid:name=".Main"
android:label="@string/app_name">
<intent-filter>
<actionandroid:name="android.intent.action.MAIN"/>
<categoryandroid:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<!--
配置一个自定义的ContentProvider"
-->
<providerandroid:name="MyContentProvider"android:authorities="com.webabcd.MyContentProvider"/>
</application>
<uses-permissionandroid:name="android.permission.WRITE_CONTACTS"></uses-permission>
<uses-permissionandroid:name="android.permission.READ_CONTACTS"></uses-permission>
<uses-sdkandroid:minSdkVersion="3"/>
</manifest>

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