先创建一个数据库吧
package com.example.sqlitedatabase_transaction;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class Mysq extends SQLiteOpenHelper{
public Mysq(Context context) {
super(context, "wode.db", null, 1);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("create table mlove(_id integer primary key autoincrement,name varchar(20),count float(11,3))");
db.execSQL("insert into mlove values(null,'小明',1000)");
db.execSQL("insert into mlove values(null,'小刚',0)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
然后我又创建了内容提供者他实现了数据库
package com.example.sqlitedatabase_transaction;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.util.Log;
public class Mycontent extends ContentProvider{
public final static int code=1;
public final static int code2=2;
private String sqlname="mlove";
static UriMatcher uriMatcher;
private SQLiteDatabase db;
static{
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);//路径匹配
uriMatcher.addURI("com.wode", "A", code);//匹配的规则 参数1是在清单中定义的auth...写上 2,判断3的int值
uriMatcher.addURI("com.wode", "B", code2);//果2参都一如样下面会替代上面
}
@Override
public boolean onCreate() {//用于创建已有的数据库对象
Mysq mysq = new Mysq(getContext());
db = mysq.getReadableDatabase();
return false;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// TODO Auto-generated method stub
int match = uriMatcher.match(uri);//匹配路径返回code的int值//如果uri和addURI不匹配返回-1
Cursor query=null;
switch (match) {
case code:
Log.e("tag", match+"code");
query = db.query(sqlname, projection, selection, selectionArgs, null, null, sortOrder);
break;
case code2:
Log.e("tag", match+"code2");
break;
default:
break;
}
return query;
}
@Override
public String getType(Uri uri) {
// TODO Auto-generated method stub
return null;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
// TODO Auto-generated method stub
long l = db.insert(sqlname, null, values);//如果2参数是3没有值自动填写null
Uri uri2 =null;
if(l!=-1){
uri2 = Uri.parse(""+l);//我这里用uri2没有引用,new出来
Log.e("tag", uri2+"");
}else{
return null;
}
return uri2;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
int i = db.delete(sqlname, selection, selectionArgs);
return i;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
int update = db.update(sqlname, values, selection, selectionArgs);
return update;
}
}
在代码中写了四个点击方法
package com.example.sqlitedatabase_transaction;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
public class MainActivity extends Activity {
private ContentResolver resolver;
private Uri uri;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Mysq mysq = new Mysq(this);
SQLiteDatabase database = mysq.getReadableDatabase();
uri = Uri.parse("content://com.wode/A");//引用类(如果为空的话select不会崩溃因为他没有传入值!..毫无反应)
}
public void select(View v){
resolver = getContentResolver();
// 通过uri走清单com.wode然后跳转Mycontent类掉方法 A就是判断int值
Cursor query = resolver.query(uri, null, null, null, null, null);
if(query!=null){
query.moveToFirst();
query.moveToPrevious();
while(query.moveToNext()){
int _id = query.getInt(0);
String name = query.getString(1);
float count = query.getInt(2);
Log.e("tag", _id+name+count+"");
}
}
}
public void delete(View v){
int i = resolver.delete(uri, "name=?", new String[]{"小木棍"});
if(i>0){
Log.e("tag", "删除成功");
}else{
Log.e("tag", "删除失败");
}
}
public void update(View v){
ContentValues contentValues = new ContentValues();
contentValues.put("count", 11.55);
int i = resolver.update(uri, contentValues, "name=?", new String[]{"小木棍"});
if(i>0){
Log.e("tag", "修改成功");
}else{
Log.e("tag", "修改失败");
}
}
public void insert(View v){
ContentValues contentValues = new ContentValues();
contentValues.put("name", "小木棍");
contentValues.put("count", "823.5");
Uri insert = resolver.insert(uri, contentValues);
if(insert==null){
Log.e("tag", "添加失败");
}else{
String path = insert.getPath();
Log.e("tag", "添第"+path+"个数据");
}
}
}
主布局
清单中注册
android:exported属性设置成true：可被其他应用使用；
android:exported属性设置成false：只能被自己所在的应用使用；