咱們先看看 query() 是怎麽實現的。
public Cursor query(String table, String[] columns, String selection,
String[] selectionArgs, String groupBy, String having, String orderBy) {
return query(false, table, columns, selection, selectionArgs, groupBy,
having, orderBy, null /* limit */);
}
public Cursor query(boolean distinct, String table, String[] columns,
String selection, String[] selectionArgs, String groupBy,
String having, String orderBy, String limit) {
return queryWithFactory(null, distinct, table, columns, selection, selectionArgs,
groupBy, having, orderBy, limit, null);
}
這幾個方法都沒有具體實現。
public Cursor queryWithFactory(CursorFactory cursorFactory,
boolean distinct, String table, String[] columns,
String selection, String[] selectionArgs, String groupBy,
String having, String orderBy, String limit, CancellationSignal cancellationSignal) {
acquireReference();
try {
String sql = SQLiteQueryBuilder.buildQueryString(
distinct, table, columns, selection, groupBy, having, orderBy, limit);
return rawQueryWithFactory(cursorFactory, sql, selectionArgs,
findEditTable(table), cancellationSignal);
} finally {
releaseReference();
}
}
最終調用的就是這個方法。
public Cursor rawQueryWithFactory(
CursorFactory cursorFactory, String sql, String[] selectionArgs,
String editTable, CancellationSignal cancellationSignal) {
acquireReference();
try {
SQLiteCursorDriver driver = new SQLiteDirectCursorDriver(this, sql, editTable,
cancellationSignal);
return driver.query(cursorFactory != null ? cursorFactory : mCursorFactory,
selectionArgs);
} finally {
releaseReference();
}
}
咱們再看看 rawQuery() 是怎麽實現的。
public Cursor rawQuery(String sql, String[] selectionArgs) {
return rawQueryWithFactory(null, sql, selectionArgs, null, null);
}
還是這個方法。
public Cursor rawQueryWithFactory(
CursorFactory cursorFactory, String sql, String[] selectionArgs,
String editTable, CancellationSignal cancellationSignal) {
acquireReference();
try {
SQLiteCursorDriver driver = new SQLiteDirectCursorDriver(this, sql, editTable,
cancellationSignal);
return driver.query(cursorFactory != null ? cursorFactory : mCursorFactory,
selectionArgs);
} finally {
releaseReference();
}
}
可以看到，最後，調用的都是rawQueryWithFactory(CursorFactory,String,String[],String,CancellationSignal) 這個方法，妳完全可以代碼都不用看懂都可以找到答案。
回到問題上，這兩個方法的區別在於，最終的 SQL 語句，誰來拼？query() 做的壹件事就是幫妳拼寫 SQL 語句，而調用 rawQuery() 是妳自己拼寫好語句。我認為的差別僅次而已。