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NotesProvider注释

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ice
karlsilver 2 months ago
parent 1fa43e79b1
commit e81957f3e4
1 changed files with 140 additions and 30 deletions
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134
java/net/micode/notes/data/NotesProvider.java
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@ -16,7 +16,6 @@
package net.micode.notes.data;
import android.app.SearchManager;
import android.content.ContentProvider;
import android.content.ContentUris;
@ -34,14 +33,19 @@ import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.NoteColumns;
import net.micode.notes.data.NotesDatabaseHelper.TABLE;
/**
* 该类是一个内容提供者，用于处理对便签数据库的增删改查操作，并支持搜索功能。
* 它继承自ContentProvider，提供了对便签表和数据记录表的访问接口。
*/
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，方便调试和日志记录
private static final String TAG = "NotesProvider";
// 定义不同URI的匹配码
private static final int URI_NOTE = 1;
private static final int URI_NOTE_ITEM = 2;
private static final int URI_DATA = 3;
@ -51,7 +55,9 @@ public class NotesProvider extends ContentProvider {
private static final int URI_SEARCH_SUGGEST = 6;
static {
// 初始化URI匹配器
mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// 添加不同URI的匹配规则
mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
@ -62,8 +68,8 @@ 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.
* 便签搜索的投影，定义了搜索结果的列
* x'0A'表示sqlite中的'\n'字符，用于去除搜索结果中的换行符和空格，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 + ","
@ -73,46 +79,71 @@ public class NotesProvider extends ContentProvider {
+ "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
+ "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
// 便签片段搜索的SQL查询语句
private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
+ " FROM " + TABLE.NOTE
+ " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
+ " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER
+ " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;
/**
* 内容提供者创建时调用，初始化数据库帮助类
*
* @return 创建成功返回true，否则返回false
*/
@Override
public boolean onCreate() {
// 获取数据库帮助类实例
mHelper = NotesDatabaseHelper.getInstance(getContext());
return true;
}
/**
* 处理查询请求，根据不同的URI匹配码执行相应的查询操作
*
* @param uri 请求的URI
* @param projection 查询的列
* @param selection 查询条件
* @param selectionArgs 查询条件的参数
* @param sortOrder 排序规则
* @return 查询结果的游标
*/
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
String sortOrder) {
Cursor c = null;
// 获取可读数据库
SQLiteDatabase db = mHelper.getReadableDatabase();
String id = null;
switch (mMatcher.match(uri)) {
case URI_NOTE:
// 查询便签表
c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
sortOrder);
break;
case URI_NOTE_ITEM:
// 获取便签ID
id = uri.getPathSegments().get(1);
// 查询指定ID的便签
c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs, null, null, sortOrder);
break;
case URI_DATA:
// 查询数据记录表
c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
sortOrder);
break;
case URI_DATA_ITEM:
// 获取数据记录ID
id = uri.getPathSegments().get(1);
// 查询指定ID的数据记录
c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs, null, null, sortOrder);
break;
case URI_SEARCH:
case URI_SEARCH_SUGGEST:
if (sortOrder != null || projection != null) {
// 搜索查询不允许指定排序规则和投影列
throw new IllegalArgumentException(
"do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
}
@ -120,59 +151,80 @@ public class NotesProvider extends ContentProvider {
String searchString = null;
if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
if (uri.getPathSegments().size() > 1) {
// 从URI路径中获取搜索字符串
searchString = uri.getPathSegments().get(1);
}
} else {
// 从URI查询参数中获取搜索字符串
searchString = uri.getQueryParameter("pattern");
}
if (TextUtils.isEmpty(searchString)) {
// 搜索字符串为空，返回null
return null;
}
try {
// 处理搜索字符串，添加通配符
searchString = String.format("%%%s%%", searchString);
// 执行搜索查询
c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
new String[] { searchString });
new String[]{searchString});
} catch (IllegalStateException ex) {
// 处理查询异常
Log.e(TAG, "got exception: " + ex.toString());
}
break;
default:
// 未知URI，抛出异常
throw new IllegalArgumentException("Unknown URI " + uri);
}
if (c != null) {
// 设置游标通知URI，当数据变化时通知观察者
c.setNotificationUri(getContext().getContentResolver(), uri);
}
return c;
}
/**
* 处理插入请求，根据不同的URI匹配码将数据插入到相应的表中
*
* @param uri 请求的URI
* @param values 要插入的数据
* @return 插入数据的URI
*/
@Override
public Uri insert(Uri uri, ContentValues values) {
// 获取可写数据库
SQLiteDatabase db = mHelper.getWritableDatabase();
long dataId = 0, noteId = 0, insertedId = 0;
switch (mMatcher.match(uri)) {
case URI_NOTE:
// 插入便签数据
insertedId = noteId = db.insert(TABLE.NOTE, null, values);
break;
case URI_DATA:
if (values.containsKey(DataColumns.NOTE_ID)) {
// 获取便签ID
noteId = values.getAsLong(DataColumns.NOTE_ID);
} else {
// 数据格式错误，记录日志
Log.d(TAG, "Wrong data format without note id:" + values.toString());
}
// 插入数据记录
insertedId = dataId = db.insert(TABLE.DATA, null, values);
break;
default:
// 未知URI，抛出异常
throw new IllegalArgumentException("Unknown URI " + uri);
}
// Notify the note uri
// 通知便签URI数据变化
if (noteId > 0) {
getContext().getContentResolver().notifyChange(
ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
}
// Notify the data uri
// 通知数据记录URI数据变化
if (dataId > 0) {
getContext().getContentResolver().notifyChange(
ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
@ -181,96 +233,148 @@ public class NotesProvider extends ContentProvider {
return ContentUris.withAppendedId(uri, insertedId);
}
/**
* 处理删除请求，根据不同的URI匹配码从相应的表中删除数据
*
* @param uri 请求的URI
* @param selection 删除条件
* @param selectionArgs 删除条件的参数
* @return 删除的数据行数
*/
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
int count = 0;
String id = null;
// 获取可写数据库
SQLiteDatabase db = mHelper.getWritableDatabase();
boolean deleteData = false;
switch (mMatcher.match(uri)) {
case URI_NOTE:
// 处理删除便签的条件
selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
// 删除便签数据
count = db.delete(TABLE.NOTE, selection, selectionArgs);
break;
case URI_NOTE_ITEM:
// 获取便签ID
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) {
break;
}
// 删除指定ID的便签
count = db.delete(TABLE.NOTE,
NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
break;
case URI_DATA:
// 删除数据记录
count = db.delete(TABLE.DATA, selection, selectionArgs);
deleteData = true;
break;
case URI_DATA_ITEM:
// 获取数据记录ID
id = uri.getPathSegments().get(1);
// 删除指定ID的数据记录
count = db.delete(TABLE.DATA,
DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
deleteData = true;
break;
default:
// 未知URI，抛出异常
throw new IllegalArgumentException("Unknown URI " + uri);
}
if (count > 0) {
if (deleteData) {
// 通知便签URI数据变化
getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
}
// 通知当前URI数据变化
getContext().getContentResolver().notifyChange(uri, null);
}
return count;
}
/**
* 处理更新请求，根据不同的URI匹配码更新相应表中的数据，并增加便签版本号
*
* @param uri 请求的URI
* @param values 要更新的数据
* @param selection 更新条件
* @param selectionArgs 更新条件的参数
* @return 更新的数据行数
*/
@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
int count = 0;
String id = null;
// 获取可写数据库
SQLiteDatabase db = mHelper.getWritableDatabase();
boolean updateData = false;
switch (mMatcher.match(uri)) {
case URI_NOTE:
// 增加便签版本号
increaseNoteVersion(-1, selection, selectionArgs);
// 更新便签数据
count = db.update(TABLE.NOTE, values, selection, selectionArgs);
break;
case URI_NOTE_ITEM:
// 获取便签ID
id = uri.getPathSegments().get(1);
// 增加指定ID便签的版本号
increaseNoteVersion(Long.valueOf(id), selection, selectionArgs);
// 更新指定ID的便签
count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs);
break;
case URI_DATA:
// 更新数据记录
count = db.update(TABLE.DATA, values, selection, selectionArgs);
updateData = true;
break;
case URI_DATA_ITEM:
// 获取数据记录ID
id = uri.getPathSegments().get(1);
// 更新指定ID的数据记录
count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs);
updateData = true;
break;
default:
// 未知URI，抛出异常
throw new IllegalArgumentException("Unknown URI " + uri);
}
if (count > 0) {
if (updateData) {
// 通知便签URI数据变化
getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
}
// 通知当前URI数据变化
getContext().getContentResolver().notifyChange(uri, null);
}
return count;
}
/**
* 解析查询条件，添加额外的条件
*
* @param selection 查询条件
* @return 解析后的查询条件
*/
private String parseSelection(String selection) {
return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
}
/**
* 增加便签的版本号，根据ID和查询条件更新便签的版本号
*
* @param id 便签ID
* @param selection 查询条件
* @param selectionArgs 查询条件的参数
*/
private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
StringBuilder sql = new StringBuilder(120);
sql.append("UPDATE ");
@ -293,13 +397,19 @@ public class NotesProvider extends ContentProvider {
sql.append(selectString);
}
// 执行更新版本号的SQL语句
mHelper.getWritableDatabase().execSQL(sql.toString());
}
/**
* 获取URI对应的MIME类型，目前未实现
*
* @param uri 请求的URI
* @return MIME类型
*/
@Override
public String getType(Uri uri) {
// TODO Auto-generated method stub
return null;
}
}
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