实现这个的方法很简单，我们使用ContentProvider创建一个内容提供者，类似与传统的服务（或网站），ContentResolver是用来控制服务或网站的一个类。下面代码就是ContentResolver用来控制ContentProvider类的增删改查的方法，由于代码太多，所以没有贴出全部代码，代码将会打包上传到网盘。
链接：http://pan.baidu.com/s/1kVbD9x9 密码：vt41
//ContentResolver类中读取,按钮事件代码class OnClick implements View.OnClickListener{ private static final String TAG = "OnClickLog"; private Context mContext; private Activity mActivity; private View v; private EditText book_name,book_money,book_remark; private ListView listView; private int type; private int _id; private int position; private int res; private ContentValues values; private int[] toids = {R.id.book_item_id,R.id.book_item_name,R.id.book_item_remark,R.id.book_item_money}; private String[] strs = {"id","name","remark","money"}; private ContentResolver resolver; private static ArrayList<Map<String,String>> list; private static SimpleAdapter adapter; public OnClick(Context ctx,int t,int id,int pos){ mContext = ctx; mActivity = (Activity)ctx; type = t; _id = id; position = pos; resolver = ctx.getContentResolver(); book_name = (EditText)mActivity.findViewById(R.id.book_name); book_money = (EditText)mActivity.findViewById(R.id.book_money); book_remark = (EditText)mActivity.findViewById(R.id.book_remark); listView = (ListView)mActivity.findViewById(R.id.book_list); } @Override public void onClick(View v) { switch (type){ case 0://读 Cursor cursor = resolver.query(Book.Books.ALL_URI,Book.Books.clos,null,null,Book.Books._ID+" desc"); list = new ArrayList<Map<String,String>>(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.CHINA); while (cursor.moveToNext()){ Map<String,String> item = new HashMap<String,String>(); item.put("id",cursor.getString(0)); item.put("name",cursor.getString(1)); item.put("money","￥"+cursor.getString(2)); item.put("remark",cursor.getString(3)); item.put("add_time",cursor.getString(4)); Log.i(TAG, "add_time:"+sdf.format(new Date(Long.valueOf(cursor.getString(4))))); list.add(item); } Log.i(TAG,"READ"); adapter = new SimpleAdapter(mContext,list,R.layout.book_items, strs,toids); listView.setAdapter(adapter); break; case 1://增 values = new ContentValues(); values.put("name",book_name.getText().toString()); values.put("money",book_money.getText().toString()); values.put("remark",book_remark.getText().toString()); values.put("add_time", new Date().getTime()); Uri uri = resolver.insert(Book.Books.ALL_URI,values); res = (int)ContentUris.parseId(uri); if(res > 0){ Toast.makeText(mContext,"保存成功!",Toast.LENGTH_LONG).show(); Map<String,String> item = new HashMap<String,String>(); item.put("id", String.valueOf(res)); item.put("name",book_name.getText().toString()); item.put("money","￥"+book_money.getText().toString()); item.put("remark",book_remark.getText().toString()); item.put("add_time", String.valueOf(new Date().getTime())); list.add(item); adapter.notifyDataSetChanged(); book_name.setText(""); book_money.setText(""); book_remark.setText(""); } Log.i(TAG,uri.toString()); break; case 2://改 values = new ContentValues(); values.put("name",book_name.getText().toString()); values.put("money",book_money.getText().toString()); values.put("remark", book_remark.getText().toString()); res = resolver.update(ContentUris.withAppendedId(Book.Books.ONE_URI, _id),values,null,null); if(res > 0){ Toast.makeText(mContext,"保存成功!",Toast.LENGTH_LONG).show(); book_name.setText(""); book_money.setText(""); book_remark.setText(""); } break; case 3://删 res = resolver.delete(ContentUris.withAppendedId(Book.Books.ONE_URI, _id), null, null); if(res > 0){ Toast.makeText(mContext,"删除成功!",Toast.LENGTH_LONG).show(); book_name.setText(""); book_money.setText(""); book_remark.setText(""); } list.remove(position); adapter.notifyDataSetChanged(); break; default: Log.i(TAG,"Nothing"); break; } } }
//ContentProvider类的核心代码
import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.support.annotation.Nullable;
public class ProviderTest extends ContentProvider {
private DBHelper dbHelper;
private static UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
private static final int MODE1 = 1;
private static final int MODE2 = 2;
private static final String[] clos = {"id","name","money","remark","add_time"};
static {
uriMatcher.addURI(Book.AUTHORITY,"/book",MODE1);
uriMatcher.addURI(Book.AUTHORITY,"/book/#",MODE2);
}
@Override
public boolean onCreate() {
dbHelper = new DBHelper(this.getContext());
return false;
}
@Nullable
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
SQLiteDatabase db = dbHelper.getReadableDatabase();
switch (uriMatcher.match(uri)){
case MODE1:
return db.query("book",projection,selection,selectionArgs,null,null,sortOrder);
case MODE2:
long id = ContentUris.parseId(uri);
String where = Book.Books._ID+"="+id;
if(selection!=null && !"".equals(selection)){
where = where+" and "+selection;
}
return db.query("book",projection,where,selectionArgs,null,null,sortOrder);
default:
throw new IllegalArgumentException("Unknown Uri:"+uri);
}
}
@Nullable
@Override
public String getType(Uri uri) {
switch (uriMatcher.match(uri)){
case MODE1:
return "vnd.android.cursor.dir/com.test.contentprovider";
case MODE2:
return "vnd.android.cursor.item/com.test.contentprovider";
default:
throw new IllegalArgumentException("Unknown Uri:"+uri.toString());
}
}
@Nullable
@Override
public Uri insert(Uri uri, ContentValues values) {
SQLiteDatabase db = dbHelper.getReadableDatabase();
if(uriMatcher.match(uri) == MODE1){
long id = db.insert("book",Book.Books._ID,values);
Uri resUri = ContentUris.withAppendedId(uri,id);
//通知Resolver 数据已经改变
getContext().getContentResolver().notifyChange(resUri,null);
return resUri;
}else{
throw new IllegalArgumentException("Unknown Uri:"+uri);
}
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
SQLiteDatabase db = dbHelper.getReadableDatabase();
int num;
switch (uriMatcher.match(uri)){
case MODE1:
//删除全部
num = db.delete("book",selection,selectionArgs);
break;
case MODE2:
//取出后缀ID
long _id = ContentUris.parseId(uri);
//组装where条件
String where = Book.Books._ID + " = "+_id;
if(selection != null && !"".equals(selection)){
where = where +" and "+selection;
}
//执行删除
num = db.delete("book",where,selectionArgs);
break;
default:
throw new IllegalArgumentException("Unknown Uri:"+uri);
}
getContext().getContentResolver().notifyChange(uri,null);
return num;
}
@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
SQLiteDatabase db = dbHelper.getReadableDatabase();
int num;
switch (uriMatcher.match(uri)){
case MODE1:
num = db.update("book",values,selection,selectionArgs);
break;
case MODE2:
long _id = ContentUris.parseId(uri);
String where = Book.Books._ID+"="+_id;
if(selection!=null && !"".equals(selection)){
where = where + " and "+selection;
}
num = db.update("book",values,where,selectionArgs);
break;
default:
throw new IllegalArgumentException("Unknown Uri:"+uri);
}
getContext().getContentResolver().notifyChange(uri,null);
return num;
}
}
//Books类的公共代码
import android.net.Uri;
import android.provider.BaseColumns;
/**
* Created by Alan on 2016/05/18 0018.
*/
public class Book {
public static final String AUTHORITY = "com.test.contentprovider.ProviderTest";
public static final class Books implements BaseColumns{
public static final String _ID = "id";
public static final String NAME = "name";
public static final String MONEY = "money";
public static final String REMARK = "remark";
public static final String ADD_TIME = "add_time";
public static final String[] clos = {"id","name","money","remark","add_time"};
public static final Uri ALL_URI = Uri.parse("content://"+AUTHORITY+"/book");
public static final Uri ONE_URI = Uri.parse("content://"+AUTHORITY+"/book/#");
}
}
