Cache persistence mechanism in Java caching technology

With the continuous development of Internet applications, data caching technology is particularly important in large-scale applications. As a widely used programming language, Java also has many tools and technologies to deal with caching technology. The cache persistence mechanism has important application value in Java. This article will elaborate on this technology.

1. Application of caching technology

In Java applications, the role of data caching is very important. As the scale of applications continues to expand, higher requirements are placed on data processing capabilities and data storage capabilities. Caching technology is a solution that can optimize application performance and increase data processing speed. Common cache types include memory cache, Redis cache, etc.

Caching technology mainly consists of two operations, namely reading data and writing data. Reading data is to store the read data in the cache for subsequent quick access. Writing data means storing the data in a database or other data storage device to prevent data loss or misoperation. Caching technology can reduce the number of reads to the database by storing the most frequently used data.

2. Principle of cache persistence mechanism

The cache persistence mechanism is to persist cache data to disks and other media to prevent data loss. In practical applications, data in memory is usually only temporarily stored in memory, while data in disk can be stored for a long time.

The cache persistence mechanism in Java mainly consists of the following two aspects:

1. Cache data writing operation to disk

When the amount of data in memory reaches a certain amount When writing data, data needs to be written to disk to prevent insufficient memory when writing data. At this point, you can store the data in a file or use a database for persistent storage. During this process, it is necessary to select the most appropriate storage media for different usage scenarios and performance requirements.

2. Data reading operation from the disk

When the application is restarted or a failure occurs, the data stored in the disk needs to be read into the memory for recovery. At this time, you can choose to use file read and write operations or database read and write operations according to the specific situation. It should be noted that reading data from disk is more time-consuming than data from memory and needs to be optimized for specific situations.

3. Implementation of cache persistence mechanism

The cache persistence mechanism in Java is mainly implemented in two ways, namely using files for persistent storage and using databases for persistent storage.

When using files for persistent storage, you need to use the built-in API, which can be implemented using Java IO or NIO. Among them, the process implemented using Java IO is as follows:

1. Create a File (file) or FileOutputStream (output stream) object

2. Use the output stream to write the cached data into the file. Data can be written to files using FileWriter, OutputStreamWriter, etc.

3. When you need to read data, create a BufferedReader or FileInputStream object, and use the object's readLine to read the data.

When using a database for persistent storage, you need to use an ORM framework for Java applications, such as Hibernate, MyBatis, etc. Among them, the process of using Hibernate is as follows:

1. Create POJO classes and entity classes and map the database

2. Create Hibernate configuration file and establish a connection

3. Open Transaction, perform insert or update operation

4. Complete the operation, commit the transaction and close the session.

4. Cache persistence application scenarios

The cache persistence mechanism is mainly aimed at caching scenarios for write operations, such as shopping carts, article comments, etc. In scenarios where the amount of data is small, the memory cache can be used to store the data directly. However, in scenarios where the data scale is large enough, you can choose to use the cache persistence mechanism to save the data to disk to improve access to large-scale data. Performance and data recovery.

The cache persistence mechanism can also play a buffering role in high concurrency scenarios. For example, when multiple users modify the same data, subsequent users can be allowed to read the data from the disk instead of reading directly from the database to reduce database pressure.

In short, the Java cache persistence mechanism is necessary, especially in scenarios with large amounts of data. Different storage media and implementation methods have their own application scenarios, and the most appropriate technical solution needs to be selected based on the actual situation to improve system performance and reliability.

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