使用ContentResolver查询 ContentResolver 共享出来的数据。 使用ContentObserver内容观察者实时监听ContentResolver 共享的数据的变化
代码用例
一、创建一个demo程序 com.example.kangxg.first
1.activity 布局文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/bg"
android:paddingBottom="16sp"
android:paddingLeft="16sp"
android:paddingTop="16dp"
android:paddingRight="16dp"
tools:context=".MailListActivity">
<LinearLayout
android:id="@+id/ll_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_above="@+id/ll_phone"
android:layout_alignLeft="@+id/ll_btn"
android:layout_alignStart="@+id/ll_btn"
android:orientation="horizontal">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="18sp"
android:text="姓 名：" />
<EditText
android:id="@+id/et_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="16sp"
android:maxLines="1"
android:hint="请输入姓名" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/ll_phone"
android:layout_marginBottom="10dp"
android:layout_above="@+id/ll_btn"
android:layout_alignLeft="@+id/ll_name"
android:layout_alignStart="@+id/ll_name"
android:orientation="horizontal">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="18dp"
android:text="电 话：" />
<EditText
android:id="@+id/et_phone"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="16sp"
android:maxLines="1"
android:hint="请输入手机号" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/ll_btn"
android:orientation="horizontal"
android:layout_centerVertical="true">
<Button
android:id="@+id/btn_add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:textSize="18dp"
android:background="#B9B9FF"
android:layout_marginRight="2dp"
android:text="添加" />
<Button
android:id="@+id/btn_query"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:textSize="18dp"
android:background="#DCB5FF"
android:layout_marginRight="2dp"
android:layout_weight="1"
android:text="查询" />
<Button
android:id="@+id/btn_update"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:textSize="18dp"
android:background="#E6CAFF"
android:layout_marginRight="2dp"
android:layout_weight="1"
android:text="修改" />
<Button
android:id="@+id/btn_delete"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:textSize="18dp"
android:background="#ACD6FF"
android:layout_weight="1"
android:text="删除" />
</LinearLayout>
<TextView
android:id="@+id/tv_show"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="25dp"
android:layout_below="@+id/ll_btn"
android:textSize="20sp"
android:text="" />
</RelativeLayout>
2.activity实体类
public class MailListActivity extends AppCompatActivity implements View.OnClickListener{
private EditText mEtName;
private EditText mEtPhone;
private TextView mTvShow;
private Button mBtnAdd;
private Button mBtnUpdate;
private Button mBtnQuery;
private Button mBtnDelete;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mail_list);
initView();
}
private void initView()
{
mEtName = (EditText)findViewById(R.id.et_name);
mEtPhone = (EditText)findViewById(R.id.et_phone);
mTvShow = (TextView)findViewById(R.id.tv_show);
mBtnAdd = (Button)findViewById(R.id.btn_add);
mBtnQuery = (Button)findViewById(R.id.btn_query);
mBtnUpdate = (Button)findViewById(R.id.btn_update);
mBtnDelete = (Button)findViewById(R.id.btn_delete);
mBtnAdd.setOnClickListener(this);
mBtnQuery.setOnClickListener(this);
mBtnUpdate.setOnClickListener(this);
mBtnDelete.setOnClickListener(this);
}
private ContentResolver contentResolver;
private ContentValues values;
private Uri uri;
@Override
public void onClick(View v)
{
contentResolver = getContentResolver();
uri = Uri.parse("content://com.example.kangxg.first/userInformation");
values = new ContentValues();
switch (v.getId())
{
case R.id.btn_add:
values = new ContentValues();
values.put("name",mEtName.getText().toString().trim());
values.put("phone",mEtPhone.getText().toString().trim());
Uri newuri = contentResolver.insert(uri,values);
Toast.makeText(this,"信息已经添加",Toast.LENGTH_SHORT).show();
Log.i("数据库应用：","添加");
break;
case R.id.btn_query:
List<Map<String,String>> data = new ArrayList<Map<String, String>>();
Cursor cursor = contentResolver.query(uri,new String[]{"_id","name","phone"},null,null,null);
mTvShow.setText("");
while (cursor.moveToNext())
{
Map<String,String> map = new HashMap<String,String>();
map.put("_id",cursor.getString(0));
map.put("name",cursor.getString(1));
map.put("phone",cursor.getString(2));
data.add(map);
mTvShow.append("Name: "+ cursor.getString(1)+" :Tel: " + cursor.getString(2)+"\n");
}
cursor.close();
Log.i("数据库应用：","查询结果"+data.toString());
break;
case R.id.btn_update:
String phone ;
values.put("phone", phone = mEtPhone.getText().toString().trim());
int updatecount = contentResolver.update(uri,values,"name=?",new String[]{mEtName.getText().toString().trim()});
Toast.makeText(this,"数据更新了"+updatecount+"行",Toast.LENGTH_SHORT).show();
Log.i("数据库应用：","数据更新了"+updatecount+"行");
break;
case R.id.btn_delete:
int count = contentResolver.delete(uri,"name=?",new String[]{mEtName.getText().toString().trim()});
Toast.makeText(this,"数据成功删除了"+count+"行",Toast.LENGTH_SHORT).show();
Log.i("数据库应用：","数据成功删除了"+count+"行");
break;
default:
break;
}
}
}
3.创建数据库帮助类
public class UserDBHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "user.db";
private static final int DB_VERSION = 2;
private static UserDBHelper mHelper = null;
private SQLiteDatabase mDB = null;
private UserDBHelper(Context context)
{
super(context,DB_NAME,null,DB_VERSION);
}
private UserDBHelper(Context context,int version)
{
super(context,DB_NAME,null,version);
}
public static UserDBHelper getInstance(Context context,int version)
{
if (version>0 && mHelper == null)
{
mHelper = new UserDBHelper(context,version);
}
else {
mHelper = new UserDBHelper(context);
}
return mHelper;
}
public SQLiteDatabase openReadLink() {
if(mDB == null|| mDB.isOpen() != true)
{
mDB = mHelper.getReadableDatabase();
}
return mDB;
}
public SQLiteDatabase openWriteLink() {
if(mDB == null|| mDB.isOpen() != true)
{
mDB = mHelper.getWritableDatabase();
}
return mDB;
}
public void closeLink()
{
if (mDB != null || mDB.isOpen() == true)
{
mDB.close();
}
mDB = null;
}
public String getDbName() {
if (mHelper != null)
{
return mHelper.getDatabaseName();
}
return DB_NAME;
}
private void createTable(String tablename,SQLiteDatabase
db) {
if (db != null)
{
String sql = "create table if not exists userInformation(_id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(20),phone VARCHAR(20))";
db.execSQL(sql);
}
}
@Override
public void onCreate(SQLiteDatabase db)
{
createTable("usertable",db);
}
@Override
public void onUpgrade(SQLiteDatabase var1, int var2, int var3){
}
}
4.创建一个内容提供者ContentProvider
public class UserProvider extends ContentProvider {
private static UriMatcher matcher = new UriMatcher((-1));
private static String tablename = "userInformation";
private static final int SUCCESS = 1;
private UserDBHelper dbHelper ;
static {
matcher.addURI("com.example.kangxg.first",tablename,SUCCESS);
}
@Override
public boolean onCreate() {
// TODO: Implement this to initialize your content provider on startup.
dbHelper = com.example.kangxg.first.tool.UserDBHelper.getInstance(getContext(),2);
return false;
}
public UserProvider() {
}
@Override
public String getType(Uri uri) {
// TODO: Implement this to handle requests for the MIME type of the data
// at the given URI.
return null;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// TODO: Implement this to handle query requests from clients.
int code = matcher.match(uri);
if (code == SUCCESS)
{
SQLiteDatabase db = dbHelper.getWritableDatabase();
return db.query(tablename,projection,selection,selectionArgs,null,null,sortOrder);
}else {
throw new IllegalArgumentException("路径不正确，停止使用提供数据");
}
}
@Override
public Uri insert(Uri uri, ContentValues values) {
// TODO: Implement this to handle requests to insert a new row.
int code = matcher.match(uri);
if (code == SUCCESS)
{
SQLiteDatabase db = dbHelper.getReadableDatabase();
long rowid = db.insert(tablename,null,values);
if (rowid>0)
{
Uri insertedUri = ContentUris.withAppendedId(uri,rowid);
getContext().getContentResolver().notifyChange(insertedUri,null);
return insertedUri;
}
dbHelper.closeLink();
return uri;
}
else
{
throw new IllegalArgumentException("路径不正确，停止插入数据");
}
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
// Implement this to handle requests to delete one or more rows.
int code = matcher.match(uri);
if (code == SUCCESS)
{
SQLiteDatabase db = dbHelper.getWritableDatabase();
int count = db.delete(tablename,selection,selectionArgs);
if (count>0)
{
getContext().getContentResolver().notifyChange(uri,null);
}
db.close();
return count;
}
else {
throw new IllegalArgumentException("路径不正确，停止删除数据");
}
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// TODO: Implement this to handle requests to update one or more rows.
int code = matcher.match(uri);
if (code == SUCCESS)
{
SQLiteDatabase db = dbHelper.getReadableDatabase();
int count = db.update(tablename,values,selection,selectionArgs);
if (count>0){
getContext().getContentResolver().notifyChange(uri,null);
}
db.close();
return count;
}
else {
throw new IllegalArgumentException("路径不正确，停止更新数据");
}
}
}
5创建一个名为MonitorData的程序
public class MainActivity extends AppCompatActivity {
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView)findViewById(R.id.tv_change);
Uri uri = Uri.parse("content://com.example.kangxg.first/userInformation");
getContentResolver().registerContentObserver(uri,true,new MyObserver(new Handler()));
}
private class MyObserver extends ContentObserver{
public MyObserver(Handler handler)
{
super(handler);
}
@Override
public void onChange(boolean selfChange)
{
//Log.i("监测数据变化","有人动了你的程序");
textView.setText("有人动了你的程序");
super.onChange(selfChange);
Uri uri = Uri.parse("content://com.example.kangxg.first/userInformation");
ContentResolver resolver = getContentResolver();
Cursor cursor = resolver.query(uri,new String[]{"_id","name","phone"},null,null,null);
cursor.moveToFirst();
textView.setText("name:"+cursor.getString(1)+"phone:"+cursor.getString(2));
Log.i("监测数据变化","有人动了你的程序"+"name:"+cursor.getString(1)+"phone:"+cursor.getString(2));
cursor.close();
}
}
}
二 运行程序
1.首先运行MonitorData程序 再运行first程序
2.在first程序上进行操作
3.在logcat看到日志输出