All property types could be not only primitive, like String, Int.Therefore, we have to avoid BeanPropertyRowMapper or something like this, because they are reflection-based and too slow. For another performance boost, we shouldn't use reflection.This is highly important for high-performance applications, because string-based methods have to compare column names before, so it requires at least NxM unnecessary string equality calls, where N is row count and M is column count. we retrieve indexes for all columns before the first row arrived, remember them and then use these indexes for the each row). In case of huge query result, it is better to use index-based approach (e.g.What do we'd like to have: be able to mark some data object with attributes and some "SQL query result to DTO converter" is able to convert rows to the our class instances.įor instance, our client code can be like: I can advice Hibernate or Spring Data, which can do the same.
In the most cases there is already developed and supported solution. Article has simplified version, without logs, diagnostic, tests, etc.įirst of all: if you want to solve exact this task, please check the existing libraries. And of course we can use this approach to avoid copy-paste in case when the language expressive power isn't enough to extract the generalized block.Īll code is available on GitHub, however, you need to install Java 11 (or later) first. You can create programmable configuration (like TeamCity Build DSL), you can optimize the existing code (the generated code can be constructed after settings reading, so it will be branch-free). So developer is able to add annotations into the code and then our application will generate and execute the parser code in the runtime. We will use jsr233 standard for this.Īs task we use popular approach - we create AOP system to parse SQL query response, to parse the result table. Here we observe an approach to generate code and execute it after the application start. However, sometimes you have to create a separate library, so code isn't known during its compile time. Everybody knows tasks, which could be easily solved if you can generate and execute code instantly inside the JVM runtime.
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