Detailed description of the principles of the Android Design Platform

The Free Software of the Android design platform can turn a mobile phone into a mobile bar code reader using a camera on a mobile phone. Through cooperation with mobile phone manufacturers and mobile operators around the world, develop useful and attractive mobile services and promote these products.

Currently, I know SQLite and db4o. SQLite is a simplified relational database built into the Android design platform. It can implement most of the functions of Standard relational databases. Db4o is an object database, which is easier to program. I personally prefer the use of object databases on mobile phones. Because the data to be processed on the mobile phone is a small amount after all.

Performance requirements are not as high as those of database servers. In this case, the advantages of the simple and flexible programming of the object database to adapt to future changes are shown. However, because db4o is not supported by Android, it cannot be seamlessly integrated with some Android-specific programming components. Android is embedded with the SQLite database, a lightweight relational database. Unlike J2SE, Android defines a new set of database operation APIs instead of using JDBC.

Db4objects announced that its flagship product db4o can run seamlessly on the Android platform. Db4o is an object-oriented native database. I personally do not like the built-in Android database API because it does not follow the JDBC specification. In my understanding, one of the highlights of Android is to embrace existing technologies and win the favor of java developers.

The new query API means that the original JDBC-based database-related programs cannot run directly on Android. From this perspective, db4o maintains a high degree of consistency in all APIs and does not need to be modified because db4o is a completely java-based native database.

Developers may be more accustomed to using relational databases, but db4o is very suitable for mobile device development in API design and is very concise. Using the built-in Contact data structure of the Android platform, you can store and read contacts. If you use db4o, you only need 10 lines of code. If you use SQLite, you need hundreds of lines of code.

Db4o directly faces objects and does not need to convert objects into table structure fields, because programming is less prone to errors. Different from the server, databases on mobile phones require adaptive management without database administrators. This is also one of the design goals of db4o. Db4o deployment on the Android design platform can run smoothly as a normal library without any configuration or changes. Because Android phones are not sold in the market, exact performance comparison cannot be provided.

However, the comparison on the simulator proves that the comprehensive capabilities of db4o are not inferior to that of SQLite. In some cases, db4o even has the advantages of an order of magnitude, such as the known data id for deletion, modification, and query, this is a very common use case for mobile apps.

There is no mature O/R Mapping Framework on the Android design platform. for developers who are used to Hibernate, JDO, iBatis, and other frameworks, object-oriented databases are more in line with their usage habits. In addition, the object-oriented database directly avoids the O/R Mapping problem, and the reconstruction code does not need to consider restructuring the database or configuration, or modify the SQL, so it is more agile.