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pull/3/head
liuyitao 11 months ago
parent 69b8c477cc
commit 63094f152e
2 changed files with 132 additions and 150 deletions
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6
src/Notes-master/app/src/main/java/net/micode/notes/data/Notes.java
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@ -19,7 +19,7 @@ package net.micode.notes.data;
import android.net.Uri; import android.net.Uri;
/* /*
*功能描述：用于存储便签数据，包含了一条便签的各种属性，如标题、内容、创建时间、修改时间等 *功能描述：Notes 类中定义一些常量，用于构造便签内容及类型
*/ */
public class Notes { public class Notes {
public static final String AUTHORITY = "micode_notes"; // 定义内容提供器的权限 public static final String AUTHORITY = "micode_notes"; // 定义内容提供器的权限
@ -267,7 +267,7 @@ public class Notes {
} }
/* /*
* 定义了文本便签的数据结构 * 功能描述：定义了文本便签的数据结构
*/ */
public static final class TextNote implements DataColumns { public static final class TextNote implements DataColumns {
/** /**
@ -286,7 +286,7 @@ public class Notes {
} }
/* /*
* 定义电话便签的数据结构 * 功能描述：定义电话便签的数据结构
*/ */
public static final class CallNote implements DataColumns { public static final class CallNote implements DataColumns {
/** /**

276
src/Notes-master/app/src/main/java/net/micode/notes/data/NotesProvider.java
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@ -34,17 +34,23 @@ import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.NoteColumns; import net.micode.notes.data.Notes.NoteColumns;
import net.micode.notes.data.NotesDatabaseHelper.TABLE; import net.micode.notes.data.NotesDatabaseHelper.TABLE;
/*
* 功能描述：用于提供对便签数据的存储和获取功能，实现了创建、读取、更新、删除操作，以便其他组件可以通过 ContentResolver 访问和管理便签数据。 //为存储和获取数据提供接口。可以在不同的应用程序之间共享数据
* */ //ContentProvider提供的方法
//query：查询
//insert：插入
//update：更新
//delete：删除
//getType：得到数据类型
public class NotesProvider extends ContentProvider { public class NotesProvider extends ContentProvider {
private static final UriMatcher mMatcher;// UriMatcher用于匹配Uri // UriMatcher用于匹配Uri
private static final UriMatcher mMatcher;
private NotesDatabaseHelper mHelper;// 数据库帮助类 private NotesDatabaseHelper mHelper;
private static final String TAG = "NotesProvider";// 标签 private static final String TAG = "NotesProvider";
private static final int URI_NOTE = 1;// Uri匹配码 private static final int URI_NOTE = 1;
private static final int URI_NOTE_ITEM = 2; private static final int URI_NOTE_ITEM = 2;
private static final int URI_DATA = 3; private static final int URI_DATA = 3;
private static final int URI_DATA_ITEM = 4; private static final int URI_DATA_ITEM = 4;
@ -53,17 +59,16 @@ public class NotesProvider extends ContentProvider {
private static final int URI_SEARCH_SUGGEST = 6; private static final int URI_SEARCH_SUGGEST = 6;
static { static {
mMatcher = new UriMatcher(UriMatcher.NO_MATCH);// 创建UriMatcher时，调用UriMatcher(UriMatcher.NO_MATCH)表示不匹配任何路径的返回码 // 创建UriMatcher时，调用UriMatcher(UriMatcher.NO_MATCH)表示不匹配任何路径的返回码
/* mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
* 把需要匹配Uri路径全部给注册上 // 把需要匹配Uri路径全部给注册上
* */ mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);// 便签列表的路径 mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);// 便签详情的路径，其中 "#" 表示数字，表示具体的便签 ID mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);// 数据列表的路径 mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);
mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);// 数据详情的路径，其中 "#" 表示数字，表示具体的数据 ID mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);
mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);// 搜索的路径 mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);
mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);// 搜索建议的路径 mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);// 带搜索关键字的搜索建议的路径
} }
/** /**
@ -71,9 +76,7 @@ public class NotesProvider extends ContentProvider {
* we will trim '\n' and white space in order to show more information. * we will trim '\n' and white space in order to show more information.
*/ */
/* // 声明 NOTES_SEARCH_PROJECTION
* 查询搜索结果的投影。该投影包含了搜索结果需要的各个字段，如便签的 ID、搜索文本等
* */
private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + "," private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
+ NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + "," + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","
+ "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + "," + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + ","
@ -82,9 +85,7 @@ public class NotesProvider extends ContentProvider {
+ "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + "," + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","
+ "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA; + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;
/* // 声明NOTES_SNIPPET_SEARCH_QUERY
* 查询语句，用于查询搜索结果
* */
private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
+ " FROM " + TABLE.NOTE + " FROM " + TABLE.NOTE
+ " WHERE " + NoteColumns.SNIPPET + " LIKE ?" + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
@ -92,268 +93,249 @@ public class NotesProvider extends ContentProvider {
+ " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE; + " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;
@Override @Override
/* // Context只有在onCreate()中才被初始化
*在onCreate()中初始化Context，实例化mHelper // 对mHelper进行实例化
* */
public boolean onCreate() { public boolean onCreate() {
mHelper = NotesDatabaseHelper.getInstance(getContext()); mHelper = NotesDatabaseHelper.getInstance(getContext());
return true; return true;
} }
@Override @Override
/* // 查询uri在数据库中对应的位置
* 根据传入的Uri进行数据库查询操作
* */
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
String sortOrder) { String sortOrder) {
Cursor c = null;// 定义一个Cursor对象用于存放查询结果 Cursor c = null;
SQLiteDatabase db = mHelper.getReadableDatabase();// 获取可读数据库实例 // 获取可读数据库
String id = null;// 用于存放ID值 SQLiteDatabase db = mHelper.getReadableDatabase();
/* String id = null;
* 根据Uri使用Matcher匹配相应的操作，对于不同的匹配值，在数据库中查找相应的条目 // 匹配查找uri
* */
switch (mMatcher.match(uri)) { switch (mMatcher.match(uri)) {
// 对于不同的匹配值，在数据库中查找相应的条目
case URI_NOTE: case URI_NOTE:
c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null, c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null,
sortOrder);// 查询便签列表 sortOrder);
break; break;
case URI_NOTE_ITEM: case URI_NOTE_ITEM:
id = uri.getPathSegments().get(1);// 获取Uri中的ID值 id = uri.getPathSegments().get(1);
c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs, null, null, sortOrder);// 查询特定ID的便签详情 + parseSelection(selection), selectionArgs, null, null, sortOrder);
break; break;
case URI_DATA: case URI_DATA:
c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null, c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null,
sortOrder);// 查询数据列表 sortOrder);
break; break;
case URI_DATA_ITEM: case URI_DATA_ITEM:
id = uri.getPathSegments().get(1); // 获取Uri中的ID值 id = uri.getPathSegments().get(1);
c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs, null, null, sortOrder);// 查询特定ID的数据详情 + parseSelection(selection), selectionArgs, null, null, sortOrder);
break; break;
case URI_SEARCH: case URI_SEARCH:
case URI_SEARCH_SUGGEST: case URI_SEARCH_SUGGEST:
if (sortOrder != null || projection != null) { if (sortOrder != null || projection != null) {
// 不合法的参数异常
throw new IllegalArgumentException( throw new IllegalArgumentException(
"do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");// 如果存在不合法的参数则抛出异常 "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
} }
String searchString = null; String searchString = null;
if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) { if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
if (uri.getPathSegments().size() > 1) { if (uri.getPathSegments().size() > 1) {
searchString = uri.getPathSegments().get(1); // 获取搜索关键字 // getPathSegments()方法得到一个String的List，
// 在uri.getPathSegments().get(1)为第2个元素
searchString = uri.getPathSegments().get(1);
} }
} else { } else {
searchString = uri.getQueryParameter("pattern"); // 获取搜索关键字 searchString = uri.getQueryParameter("pattern");
} }
if (TextUtils.isEmpty(searchString)) { if (TextUtils.isEmpty(searchString)) {
return null;// 如果搜索关键字为空则直接返回null return null;
} }
try { try {
searchString = String.format("%%%s%%", searchString);// 格式化搜索关键字 searchString = String.format("%%%s%%", searchString);
c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY, c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY,
new String[] { searchString });// 执行搜索查询 new String[] { searchString });
} catch (IllegalStateException ex) { } catch (IllegalStateException ex) {
Log.e(TAG, "got exception: " + ex.toString());// 捕获异常 Log.e(TAG, "got exception: " + ex.toString());
} }
break; break;
default: default:
throw new IllegalArgumentException("Unknown URI " + uri);// 对于未知的Uri抛出异常 // 抛出异常
throw new IllegalArgumentException("Unknown URI " + uri);
} }
if (c != null) { if (c != null) {
c.setNotificationUri(getContext().getContentResolver(), uri);// 设置查询结果的变更通知URI c.setNotificationUri(getContext().getContentResolver(), uri);
} }
return c;// 返回查询结果的Cursor对象 return c;
} }
@Override @Override
/* // 插入一个uri
* 功能描述：实现对数据库表单的增加记录操作
* 输入参数：参数 uri 表示插入的 URI，values 表示插入的值
* */
public Uri insert(Uri uri, ContentValues values) { public Uri insert(Uri uri, ContentValues values) {
SQLiteDatabase db = mHelper.getWritableDatabase();// 获得可写的数据库 // 获得可写的数据库
long dataId = 0, noteId = 0, insertedId = 0;// 定义三个id值变量 SQLiteDatabase db = mHelper.getWritableDatabase();
/* long dataId = 0, noteId = 0, insertedId = 0;
* 根据Uri使用Matcher匹配相应的操作
* */
switch (mMatcher.match(uri)) { switch (mMatcher.match(uri)) {
// 新增一个条目
case URI_NOTE: case URI_NOTE:
insertedId = noteId = db.insert(TABLE.NOTE, null, values);// 在便签表中插入新记录 insertedId = noteId = db.insert(TABLE.NOTE, null, values);
break; break;
// 如果存在，查找NOTE_ID
case URI_DATA: case URI_DATA:
if (values.containsKey(DataColumns.NOTE_ID)) { if (values.containsKey(DataColumns.NOTE_ID)) {
noteId = values.getAsLong(DataColumns.NOTE_ID);// 如果数据内容包含NOTE_ID字段，获取NOTE_ID值 noteId = values.getAsLong(DataColumns.NOTE_ID);
} else { } else {
Log.d(TAG, "Wrong data format without note id:" + values.toString());// 如果不包含则输出日志信息 Log.d(TAG, "Wrong data format without note id:" + values.toString());
} }
insertedId = dataId = db.insert(TABLE.DATA, null, values);// 在数据表中插入新记录 insertedId = dataId = db.insert(TABLE.DATA, null, values);
break; break;
default: default:
throw new IllegalArgumentException("Unknown URI " + uri);// 对于未知的Uri抛出异常 throw new IllegalArgumentException("Unknown URI " + uri);
} }
// Notify the note uri // Notify the note uri
if (noteId > 0) {// 如果是便签新增操作 // notifyChange获得一个ContextResolver对象并且更新里面的内容
if (noteId > 0) {
getContext().getContentResolver().notifyChange( getContext().getContentResolver().notifyChange(
ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);// 通过ContentResolver对象发送通知，更新便签的变更通知URI ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
} }
// Notify the data uri // Notify the data uri
if (dataId > 0) {// 如果是数据新增操作 if (dataId > 0) {
getContext().getContentResolver().notifyChange( getContext().getContentResolver().notifyChange(
ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);// 通过ContentResolver对象发送通知，更新数据的变更通知URI ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
} }
return ContentUris.withAppendedId(uri, insertedId);// 返回插入的uri的路径 // 返回插入的uri的路径
return ContentUris.withAppendedId(uri, insertedId);
} }
@Override @Override
/* // 删除一个uri
* 功能描述：实现对数据库表单的删除记录操作
* 输入参数：参数 uri 表示删除的 URI，selection 表示删除条件，selectionArgs 表示删除条件值
* */
public int delete(Uri uri, String selection, String[] selectionArgs) { public int delete(Uri uri, String selection, String[] selectionArgs) {
//Uri代表要操作的数据，Android上可用的每种资源 -包括 图像、视频片段、音频资源等都可以用Uri来表示 //Uri代表要操作的数据，Android上可用的每种资源 -包括 图像、视频片段、音频资源等都可以用Uri来表示
int count = 0;// 定义计数变量 int count = 0;
String id = null;// 定义id字符串变量 String id = null;
SQLiteDatabase db = mHelper.getWritableDatabase();// 获取可写数据库实例 // 获得可写的数据库
boolean deleteData = false;// 是否删除数据标志位 SQLiteDatabase db = mHelper.getWritableDatabase();
/* boolean deleteData = false;
* 根据Uri使用Matcher匹配相应的操作
* */
switch (mMatcher.match(uri)) { switch (mMatcher.match(uri)) {
case URI_NOTE: case URI_NOTE:
selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";// 对于便签的删除操作，添加额外的条件限制 selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
count = db.delete(TABLE.NOTE, selection, selectionArgs);// 在便签表中删除符合条件的记录 count = db.delete(TABLE.NOTE, selection, selectionArgs);
break; break;
case URI_NOTE_ITEM: case URI_NOTE_ITEM:
id = uri.getPathSegments().get(1);// 获取Uri中的ID参数 id = uri.getPathSegments().get(1);
/** /**
* ID that smaller than 0 is system folder which is not allowed to * ID that smaller than 0 is system folder which is not allowed to
* trash * trash
*/ */
long noteId = Long.valueOf(id); long noteId = Long.valueOf(id);
if (noteId <= 0) {// 如果ID小于等于0，则不允许删除 if (noteId <= 0) {
break; break;
} }
count = db.delete(TABLE.NOTE, count = db.delete(TABLE.NOTE,
NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);// 在便签表中删除指定ID的记录 NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
break; break;
case URI_DATA: case URI_DATA:
count = db.delete(TABLE.DATA, selection, selectionArgs);// 在数据表中删除符合条件的记录 count = db.delete(TABLE.DATA, selection, selectionArgs);
deleteData = true;// 设置删除数据标志位为true deleteData = true;
break; break;
case URI_DATA_ITEM: case URI_DATA_ITEM:
id = uri.getPathSegments().get(1);// 获取Uri中的ID参数 id = uri.getPathSegments().get(1);
count = db.delete(TABLE.DATA, count = db.delete(TABLE.DATA,
DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);// 在数据表中删除指定ID的记录 DataColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
deleteData = true;// 设置删除数据标志位为true deleteData = true;
break; break;
default: default:
throw new IllegalArgumentException("Unknown URI " + uri);// 对于未知的Uri抛出异常 throw new IllegalArgumentException("Unknown URI " + uri);
} }
if (count > 0) {// 如果删除记录数大于0 if (count > 0) {
if (deleteData) { if (deleteData) {
getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);// 通过ContentResolver对象发送通知，更新便签变更通知URI getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
} }
getContext().getContentResolver().notifyChange(uri, null);// 通过ContentResolver对象发送通知，更新变更通知URI getContext().getContentResolver().notifyChange(uri, null);
} }
return count;// 返回删除的记录数 return count;
} }
@Override @Override
/* // 更新一个uri
* 功能描述：实现对数据库表单的更新操作
* 输入参数：参数 uri 表示更新的 URI，values 表示更新的值，selection 表示更新条件，selectionArgs 表示更新条件值
* */
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
int count = 0;// 定义计数变量 int count = 0;
String id = null;// 定义id字符串变量 String id = null;
SQLiteDatabase db = mHelper.getWritableDatabase();// 获取可写数据库实例 SQLiteDatabase db = mHelper.getWritableDatabase();
boolean updateData = false;// 是否更新数据标志位 boolean updateData = false;
/*
* 根据Uri使用Matcher匹配相应的操作
* */
switch (mMatcher.match(uri)) { switch (mMatcher.match(uri)) {
case URI_NOTE: case URI_NOTE:
increaseNoteVersion(-1, selection, selectionArgs);// 增加便签版本号，针对便签的更新操作，添加额外的条件限制 increaseNoteVersion(-1, selection, selectionArgs);
count = db.update(TABLE.NOTE, values, selection, selectionArgs);// 在便签表中更新符合条件的记录 count = db.update(TABLE.NOTE, values, selection, selectionArgs);
break; break;
case URI_NOTE_ITEM: case URI_NOTE_ITEM:
id = uri.getPathSegments().get(1);// 获取Uri中的ID参数 id = uri.getPathSegments().get(1);
increaseNoteVersion(Long.valueOf(id), selection, selectionArgs);// 增加便签版本号，针对便签的更新操作，添加额外的条件限制 increaseNoteVersion(Long.valueOf(id), selection, selectionArgs);
count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id count = db.update(TABLE.NOTE, values, NoteColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs);// 在便签表中更新指定ID的记录 + parseSelection(selection), selectionArgs);
break; break;
case URI_DATA: case URI_DATA:
count = db.update(TABLE.DATA, values, selection, selectionArgs);// 在数据表中更新符合条件的记录 count = db.update(TABLE.DATA, values, selection, selectionArgs);
updateData = true;// 设置更新数据标志位为tru updateData = true;
break; break;
case URI_DATA_ITEM: case URI_DATA_ITEM:
id = uri.getPathSegments().get(1);// 获取Uri中的ID参数 id = uri.getPathSegments().get(1);
count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id count = db.update(TABLE.DATA, values, DataColumns.ID + "=" + id
+ parseSelection(selection), selectionArgs);// 在数据表中更新指定ID的记录 + parseSelection(selection), selectionArgs);
updateData = true;// 设置更新数据标志位为true updateData = true;
break; break;
default: default:
throw new IllegalArgumentException("Unknown URI " + uri);// 对于未知的Uri抛出异常 throw new IllegalArgumentException("Unknown URI " + uri);
} }
if (count > 0) {// 如果更新记录数大于0 if (count > 0) {
if (updateData) { if (updateData) {
getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);// 通过ContentResolver对象发送通知，更新便签变更通知URI getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
} }
getContext().getContentResolver().notifyChange(uri, null);// 通过ContentResolver对象发送通知，更新变更通知URI getContext().getContentResolver().notifyChange(uri, null);
} }
return count;// 返回更新的记录数 return count;
} }
/* // 将字符串解析成规定格式
* 解析查询条件selection，如果selection不为空，则在其前面加上" AND "，用于拼接SQL语句
* */
private String parseSelection(String selection) { private String parseSelection(String selection) {
return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""); return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
} }
/* //增加一个noteVersion
* 根据传入的id和selection参数确定要更新的记录，并将版本号加1
* */
private void increaseNoteVersion(long id, String selection, String[] selectionArgs) { private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
StringBuilder sql = new StringBuilder(120);// 创建一个StringBuilder对象，用于构建SQL语句 StringBuilder sql = new StringBuilder(120);
sql.append("UPDATE ");// 构建UPDATE语句，指定要更新的表名 sql.append("UPDATE ");
sql.append(TABLE.NOTE);// 表名 sql.append(TABLE.NOTE);
sql.append(" SET ");// 指定要更新的字段和新的值 sql.append(" SET ");
sql.append(NoteColumns.VERSION);// 字段名 sql.append(NoteColumns.VERSION);
sql.append("=" + NoteColumns.VERSION + "+1 ");// 将版本号加1 sql.append("=" + NoteColumns.VERSION + "+1 ");
if (id > 0 || !TextUtils.isEmpty(selection)) { if (id > 0 || !TextUtils.isEmpty(selection)) {
sql.append(" WHERE ");// 根据传入的参数决定是否添加WHERE子句 sql.append(" WHERE ");
} }
if (id > 0) { if (id > 0) {
sql.append(NoteColumns.ID + "=" + String.valueOf(id)); // 如果传入的id大于0，则表示只更新指定id的记录 sql.append(NoteColumns.ID + "=" + String.valueOf(id));
} }
if (!TextUtils.isEmpty(selection)) {// 如果传入的selection不为空，则根据它来确定要更新的记录 if (!TextUtils.isEmpty(selection)) {
String selectString = id > 0 ? parseSelection(selection) : selection;// 调用parseSelection方法将selection转换为SQL语句中的WHERE子句 String selectString = id > 0 ? parseSelection(selection) : selection;
for (String args : selectionArgs) { for (String args : selectionArgs) {
selectString = selectString.replaceFirst("\\?", args);// 替换WHERE子句中的问号占位符为实际的参数值 selectString = selectString.replaceFirst("\\?", args);
} }
sql.append(selectString);// 添加WHERE子句到SQL语句中 sql.append(selectString);
} }
// execSQL()方法可以执行insert、delete、update和CREATE TABLE之类有更改行为的SQL语句 // execSQL()方法可以执行insert、delete、update和CREATE TABLE之类有更改行为的SQL语句
mHelper.getWritableDatabase().execSQL(sql.toString());// 添加WHERE子句到SQL语句中 mHelper.getWritableDatabase().execSQL(sql.toString());
} }
@Override @Override
/*
* 功能描述：用于根据 URI 返回相应的 MIME 类型
* 输入参数：参数 uri 表示查询或操作的 URI
* 函数中是环境自动生成的，也可自己改写
* */
public String getType(Uri uri) { public String getType(Uri uri) {
// TODO Auto-generated method stub // TODO Auto-generated method stub
return null; return null;
} }
} }

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