public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void onclick_bak(View view) throws IOException {
//content://sms查新系统所有短信的uri
Uri uri=Uri.parse("content://sms");
//获得 访问内容提供者
ContentResolver contentResolver=getContentResolver();
//通过contentResolver查询数据
Cursor cursor=contentResolver.query(uri,new String[]{"address","date","type","body"},null,null,null);
List<SmsInfo> smsInfoList=new ArrayList<SmsInfo>();
//cursor.moveToNext()移动到下一行
while (cursor.moveToNext()){
String address=cursor.getString(0);
long date=cursor.getLong(1);
int type=cursor.getType(2);
String body=cursor.getString(3);
SmsInfo smsInfo=new SmsInfo(date,type,body,address);
smsInfoList.add(smsInfo);
}
//读取数据结束
cursor.close();
//备份
SmsUtils.backUpSms(smsInfoList,this);
}

}

提供者--AppCompatActivity