ContentProvider数据共享方法的使用
ContentProvider 完全屏蔽的了数据提供者的数据存取方式，只要通过调用ContentProvider提供的借口就可以去所有的数据进行操作
ContentProvider数据模式类似于数据库的表，每一行都是一条数据，每一列都具有相同的数据类型，其通过URI来获取数据源，其使用的URI语法结构如下：
content://
(content://)表示前缀，表示该URI用于ContentProvider定位资源，无须修改
例如：content://com.lonuery.mycontentprovider/abc 表示的就是在com.lonuery.mycontentprovider 包下的数据集abc
一：创建数据提供者
一般分为三步：1：继承ContentProvider，实现基本数据操作的六个函数 2：声明contenturi 实现UriMatcher 3:注册ContentProvider
下面是一个创建数据提供者的小例子：
public class MyProvider extends ContentProvider {
Context context;
SQLiteDatabase sdb;
private static UriMatcher uriMatche;//用来分析客户端那发来的额URI到底数个什么样的URI
static {
uriMatche = new UriMatcher(UriMatcher.NO_MATCH);
uriMatche.addURI("com.lonuery.mycontextprovider","abc", 1);
//authority 一般用包名指定(保证全球唯一)
//path:取数据的路径，取数据的方式
//code 匹配的结果
//content://com.lonuery.DatabaseServer/abc/1 取单条数据，abc后数字为几就表示取几条数据，如果没有那就是多条
//content://com.lonuery.DatabaseServer/abc 取多条数据
uriMatche.addURI("com.lonuery.mycontextprovider", "abc/#", 2);
};//初始化UriMatcher (添加的匹配的规则)
//做白日梦的人，上不了最前线，敢爱敢做的人超级精彩！
@Override
public int delete(Uri arg0, String arg1, String[] arg2) {
String argId = arg0.getPathSegments().get(1);
int delcount = sdb.delete("student", "_id=?", new String[]{argId});
return delcount;
}
@Override
public String getType(Uri arg0) {
String retString = null;
switch (uriMatche.match(arg0)) {
case 2:
retString = "vnd.android:cursor.item/vnd.com.lonuery.mycontextprovider.abc";
break;
case 1:
retString="vnd.android:cursor.dir/vnd.com.lonuery.mycontextprovider.abc";
break;
default:
break;
}
return retString;
}
@Override
public Uri insert(Uri arg0, ContentValues arg1) {
long retId = sdb.insert("Student", null,arg1);
if(retId>0){
Uri tempUri = Uri.parse("com.lonuery.mycontextprovider/abc");
Uri newUri = ContentUris.withAppendedId(tempUri,retId);
return newUri;
}
throw new SQLException("数据插入失败"+arg0);
}
/*
* 创建数据库*/
@Override
public boolean onCreate() {
Context context = getContext();
DatabaseHepler databaseHepler = new DatabaseHepler(context, "Student.db", null, 1);
sdb = databaseHepler.getWritableDatabase();
if(sdb!=null){
return true;//创建成功则返回true
}
return false;
}
@Override
public Cursor query(Uri arg0, String[] arg1, String arg2, String[] arg3,
String arg4){
Cursor cursor=null;
switch (uriMatche.match(arg0)) {
case 2://单条数据
String argId = arg0.getPathSegments().get(1);通过content使用数据提供者的数据，进行，插入，单行查询，多行查询，删除行，更新行
public class ClientActivity extends Activity implements OnClickListener{
Button btnInsert,btnQuerySingle,btnQueryMore,btnDelete,btnUpDate;
TextView tv;
EditText et;
ContentResolver cr;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_client);
cr = getContentResolver();//得到数据共享的客户端
btnInsert = (Button)findViewById(R.id.button1);
btnQuerySingle =(Button)findViewById(R.id.button2);
btnQueryMore =(Button)findViewById(R.id.button3);
btnUpDate =(Button)findViewById(R.id.button4);
btnDelete =(Button)findViewById(R.id.button5);
tv =(TextView)findViewById(R.id.textView1);
et =(EditText)findViewById(R.id.editText1);
btnInsert.setOnClickListener(this);
btnQueryMore.setOnClickListener(this);
btnQuerySingle.setOnClickListener(this);
btnUpDate.setOnClickListener(this);
btnDelete.setOnClickListener(this);
}
@Override
public void onClick(View arg0) {
switch (arg0.getId()) {
case R.id.button1:
String baseuri = "content://com.lonuery.mycontextprovider/abc";
Uri uri = Uri.parse(baseuri);
ContentValues cv = new ContentValues();
cv.put("name", "你妹");
cv.put("age", "23");
cv.put("sex", "男");
cr.insert(uri, cv);
break;
case R.id.button2:
String queryBaseUri = "content://com.lonuery.mycontextprovider/abc";
String id = et.getText().toString();
String queryOneUri = queryBaseUri + "/" + id;
// content://com.newer.DataBaseServer/abc/7
Cursor cursorOne
= cr.query(Uri.parse(queryOneUri), null, null, null, null);
if (cursorOne.moveToFirst()) {
String idStr =cursorOne.getString(cursorOne.getColumnIndex("_id"));
String name =cursorOne.getString(cursorOne.getColumnIndex("name"));
String sex =cursorOne.getString(cursorOne.getColumnIndex("sex"));
String age =cursorOne.getString(cursorOne.getColumnIndex("age"));
tv.setText(" "+idStr + " " + name + " " + sex + " " + age + " \n");
}
break;
case R.id.button3:
String queryAllUri = "content://com.lonuery.mycontextprovider/abc";
Cursor cursor = cr.query(Uri.parse(queryAllUri), null, null, null, null);
tv.setText("");
if (cursor.moveToFirst()) {
do {
String idMany =cursor.getString(cursor.getColumnIndex("_id"));
String name =cursor.getString(cursor.getColumnIndex("name"));
String sex =cursor.getString(cursor.getColumnIndex("sex"));
String age =cursor.getString(cursor.getColumnIndex("age"));
tv.append(" "+idMany + " " + name + " " + sex + " " + age + " \n");
} while(cursor.moveToNext());
}
break;
case R.id.button5:
String queryBaseUri2 = "content://com.lonuery.mycontextprovider/abc";
String delId = et.getText().toString();
String delOneUri = queryBaseUri2 + "/" + delId;
cr.delete(Uri.parse(delOneUri), null, null);
break;
case R.id.button4:
String updataBaseUri="content://com.lonuery.mycontextprovider/abc";
String updataColumn = et.getText().toString();
ContentValues updata = new ContentValues();
updata.put("sex",updataColumn);
cr.update(Uri.parse(updataBaseUri), updata,null,null);
break;
default:
break;
}
}
}