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陈念焯注释

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cnz
cnz 3 months ago
parent 6c4c4e3359
commit 00b9185b28
1 changed files with 68 additions and 17 deletions
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85
src/net/micode/notes/data/NotesProvider.java
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@ -14,8 +14,9 @@
* limitations under the License.
*/
package net.micode.notes.data;
//这段代码是笔记应用的核心数据访问层，封装了所有数据库操作，并通过标准ContentProvider接口对外提供服务，同时实现了搜索功能集成。
package net.micode.notes.data;//导入包
import android.app.SearchManager;
import android.content.ContentProvider;
@ -34,24 +35,31 @@ import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.NoteColumns;
import net.micode.notes.data.NotesDatabaseHelper.TABLE;
/**
* 笔记应用的内容提供者，负责管理笔记数据的CRUD操作和搜索功能
*/
public class NotesProvider extends ContentProvider {
// URI匹配器，用于匹配不同的URI请求
private static final UriMatcher mMatcher;
// 数据库帮助类实例
private NotesDatabaseHelper mHelper;
// 日志标签
private static final String TAG = "NotesProvider";
private static final int URI_NOTE = 1;
private static final int URI_NOTE_ITEM = 2;
private static final int URI_DATA = 3;
private static final int URI_DATA_ITEM = 4;
private static final int URI_SEARCH = 5;
private static final int URI_SEARCH_SUGGEST = 6;
// URI匹配代码常量
private static final int URI_NOTE = 1; // 笔记集合操作
private static final int URI_NOTE_ITEM = 2; // 单条笔记操作
private static final int URI_DATA = 3; // 数据集合操作
private static final int URI_DATA_ITEM = 4; // 单条数据操作
private static final int URI_SEARCH = 5; // 搜索操作
private static final int URI_SEARCH_SUGGEST = 6; // 搜索建议操作
// 静态初始化块，配置URI匹配器
static {
mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// 添加URI匹配规则
mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
@ -62,8 +70,9 @@ public class NotesProvider extends ContentProvider {
}
/**
* x'0A' represents the '\n' character in sqlite. For title and content in the search result,
* we will trim '\n' and white space in order to show more information.
* 搜索结果的投影(列)定义
* x'0A'代表SQLite中的换行符'\n'。对于搜索结果中的标题和内容，
* 我们将修剪'\n'和空格以显示更多信息。
*/
private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
+ NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
@ -73,6 +82,7 @@ public class NotesProvider extends ContentProvider {
+ "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
+ "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
// 笔记片段搜索查询SQL
private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
+ " FROM " + TABLE.NOTE
+ " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
@ -81,6 +91,7 @@ public class NotesProvider extends ContentProvider {
@Override
public boolean onCreate() {
// 初始化数据库帮助类
mHelper = NotesDatabaseHelper.getInstance(getContext());
return true;
}
@ -91,27 +102,34 @@ public class NotesProvider extends ContentProvider {
Cursor c = null;
SQLiteDatabase db = mHelper.getReadableDatabase();
String id = null;
// 根据URI匹配不同类型的数据请求
switch (mMatcher.match(uri)) {
case URI_NOTE:
// 查询笔记表
c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
sortOrder);
break;
case URI_NOTE_ITEM:
// 查询单条笔记
id = uri.getPathSegments().get(1);
c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs, null, null, sortOrder);
break;
case URI_DATA:
// 查询数据表
c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
sortOrder);
break;
case URI_DATA_ITEM:
// 查询单条数据
id = uri.getPathSegments().get(1);
c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs, null, null, sortOrder);
break;
case URI_SEARCH:
case URI_SEARCH_SUGGEST:
// 处理搜索请求
if (sortOrder != null || projection != null) {
throw new IllegalArgumentException(
"do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
@ -131,6 +149,7 @@ public class NotesProvider extends ContentProvider {
}
try {
// 格式化搜索字符串并执行搜索查询
searchString = String.format("%%%s%%", searchString);
c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
new String[] { searchString });
@ -141,6 +160,8 @@ public class NotesProvider extends ContentProvider {
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
// 设置内容解析器通知URI
if (c != null) {
c.setNotificationUri(getContext().getContentResolver(), uri);
}
@ -151,11 +172,15 @@ public class NotesProvider extends ContentProvider {
public Uri insert(Uri uri, ContentValues values) {
SQLiteDatabase db = mHelper.getWritableDatabase();
long dataId = 0, noteId = 0, insertedId = 0;
// 根据URI匹配不同类型的数据插入
switch (mMatcher.match(uri)) {
case URI_NOTE:
// 插入笔记
insertedId = noteId = db.insert(TABLE.NOTE, null, values);
break;
case URI_DATA:
// 插入数据
if (values.containsKey(DataColumns.NOTE_ID)) {
noteId = values.getAsLong(DataColumns.NOTE_ID);
} else {
@ -166,18 +191,20 @@ public class NotesProvider extends ContentProvider {
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
// Notify the note uri
// 通知笔记URI变更
if (noteId > 0) {
getContext().getContentResolver().notifyChange(
ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
}
// Notify the data uri
// 通知数据URI变更
if (dataId > 0) {
getContext().getContentResolver().notifyChange(
ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
}
// 返回新插入数据的URI
return ContentUris.withAppendedId(uri, insertedId);
}
@ -187,16 +214,19 @@ public class NotesProvider extends ContentProvider {
String id = null;
SQLiteDatabase db = mHelper.getWritableDatabase();
boolean deleteData = false;
// 根据URI匹配不同类型的数据删除
switch (mMatcher.match(uri)) {
case URI_NOTE:
// 防止删除系统文件夹
selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
count = db.delete(TABLE.NOTE, selection, selectionArgs);
break;
case URI_NOTE_ITEM:
// 删除单条笔记
id = uri.getPathSegments().get(1);
/**
* ID that smaller than 0 is system folder which is not allowed to
* trash
* ID小于0的是系统文件夹，不允许删除
*/
long noteId = Long.valueOf(id);
if (noteId <= 0) {
@ -206,10 +236,12 @@ public class NotesProvider extends ContentProvider {
NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
break;
case URI_DATA:
// 删除数据
count = db.delete(TABLE.DATA, selection, selectionArgs);
deleteData = true;
break;
case URI_DATA_ITEM:
// 删除单条数据
id = uri.getPathSegments().get(1);
count = db.delete(TABLE.DATA,
DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
@ -218,6 +250,8 @@ public class NotesProvider extends ContentProvider {
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
// 通知数据变更
if (count > 0) {
if (deleteData) {
getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
@ -233,22 +267,28 @@ public class NotesProvider extends ContentProvider {
String id = null;
SQLiteDatabase db = mHelper.getWritableDatabase();
boolean updateData = false;
// 根据URI匹配不同类型的数据更新
switch (mMatcher.match(uri)) {
case URI_NOTE:
// 更新笔记时增加版本号
increaseNoteVersion(-1, selection, selectionArgs);
count = db.update(TABLE.NOTE, values, selection, selectionArgs);
break;
case URI_NOTE_ITEM:
// 更新单条笔记时增加版本号
id = uri.getPathSegments().get(1);
increaseNoteVersion(Long.valueOf(id), selection, selectionArgs);
count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs);
break;
case URI_DATA:
// 更新数据
count = db.update(TABLE.DATA, values, selection, selectionArgs);
updateData = true;
break;
case URI_DATA_ITEM:
// 更新单条数据
id = uri.getPathSegments().get(1);
count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs);
@ -258,6 +298,7 @@ public class NotesProvider extends ContentProvider {
throw new IllegalArgumentException("Unknown URI " + uri);
}
// 通知数据变更
if (count > 0) {
if (updateData) {
getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
@ -267,10 +308,21 @@ public class NotesProvider extends ContentProvider {
return count;
}
/**
* 解析选择条件，添加AND连接符
* @param selection 原始选择条件
* @return 格式化后的选择条件
*/
private String parseSelection(String selection) {
return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
}
/**
* 增加笔记版本号
* @param id 笔记ID，如果为-1则使用selection条件
* @param selection 选择条件
* @param selectionArgs 选择参数
*/
private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
StringBuilder sql = new StringBuilder(120);
sql.append("UPDATE ");
@ -298,8 +350,7 @@ public class NotesProvider extends ContentProvider {
@Override
public String getType(Uri uri) {
// TODO Auto-generated method stub
// TODO: 实现获取URI类型的方法
return null;
}
}

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