Java language LINQ expression implementation method based on chained call

Abstract

The invention is suitable for the field of computer programming, and provides a chained-call-based Java language LINQ expression implementation method, which comprises the following steps: providing a LinqQuer interface, defining a chained operator, namely, a where operator and a select, and providing type security through a generic T; a user calls a chain operator of the LinqQuery interface to generate an operator tree, wherein the operator tree is used for recording query logic; analyzing the operator tree, executing query according to levels, and returning a result set; the method has the advantages that compared with traditional circulation and condition branch implementation, the number of code lines is reduced by about 40%, readability is remarkably improved, a developer can easily expand a query function through an open operator interface, query logic type check is completed in a compilation period through generic constraint, errors during operation are reduced, and the method is convenient to operate. Unified query of various scenes such as a memory set, database query and file reading is supported.

Description

Technical Field

[0001] The present invention belongs to the field of computer programming, and in particular relates to a Java language LINQ expression implementation method based on chain calling. Background Art

[0002] With the advent of the big data era and the increasing prevalence of complex data manipulation scenarios, the demand for efficient querying of collections, streams, and databases has exploded in the programming world. In this technological development trend, C#'s LINQ technology has emerged as a key feature of the C# ecosystem. It provides developers with powerful and convenient in-memory query capabilities, significantly improving the efficiency and convenience of data processing, making it a valuable tool for C# developers in data querying. In contrast, the Java language faces many difficulties in data query processing. Currently, when implementing similar query logic, Java developers often have to rely on cumbersome loops, conditional branch statements, or use external libraries to complete the process. This traditional query method has many drawbacks: on the one hand, the code is lengthy and cumbersome, and the large number of loops and conditional logic significantly reduces the readability of the code, increasing development and maintenance costs; on the other hand, although Java's built-in Stream API has certain query capabilities, it lacks good support for SQL-style queries, and its functions are scattered and limited. At the same time, its scalability is insufficient, making it difficult to meet the needs of complex and changing business scenarios. It also performs poorly in terms of type safety, with query conditions easily causing runtime errors and lacking effective type checking support at compile time. To solve the above technical problems, it is urgent to develop a Java language LINQ expression implementation method based on chain calls. Summary of the Invention

[0003] The purpose of the present invention is to provide a Java language LINQ expression implementation method based on chain call, aiming to solve the problems raised in the above background technology.

[0004] The present invention is implemented as follows: the present invention proposes a LINQ query expression parser and execution framework, the core modules of which include: Query context interface: Defines the basic structure of LINQ queries and supports chained calls. It provides type safety through generics. Specifically, it provides the LinqQuery interface and defines chained operators such as where and select. Operator Implementation Module: Implements common query operators, including Where, Select, GroupBy, and OrderBy. It uses functional interfaces to define query logic and supports lambda expressions, allowing developers to concisely write query conditions.

[0005] Query expression parsing module: Parses user-defined chain calls into operator trees, supports complex nested queries and multi-condition combinations, and can handle various complex query requirements. Execution Engine Module: Traverses the operator tree and executes the corresponding query operations. It supports diversified data sources and implements unified query operations in different scenarios. A Java language LINQ expression implementation method based on chain call, the steps are as follows: Define the query context: Provide the LinqQuery interface, define chain operators such as where and select, and use the generic T to ensure type checking at compile time to ensure type safety. Build an operator tree: Users generate an operator tree through chain calls. The operator tree records the complete query logic and provides a basis for subsequent parsing and execution. Parsing and executing queries: Parsing the operator tree, executing the query hierarchically, and finally returning the result set.

[0006] The present invention provides a Java language LINQ expression implementation method based on chain calls. Compared with traditional loop and conditional branch implementations, the number of lines of code is reduced by about 40%, and readability is significantly improved. Through the open operator interface, developers can easily expand query functions. Through generic constraints, type checking of query logic is completed at compile time, reducing runtime errors. It supports unified queries in various scenarios such as memory collections, database queries, and file reading. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is the main flow chart of the Java language LINQ expression implementation method based on chain calls. DETAILED DESCRIPTION

[0008] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0009] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0010] The present invention provides a Java language LINQ expression implementation method based on chain call, which solves the technical problems in the background technology.

[0011] like Figure 1 FIG. 1 is a main flow chart of a method for implementing a LINQ expression in Java based on chain calls according to an embodiment of the present invention. The method for implementing a LINQ expression in Java based on chain calls includes: Step S100: providing a LinqQuery interface, wherein the LinqQuery interface defines a chained operator where operator and select, and provides type safety through a generic type T; Step S200: The user generates an operator tree by calling the chain operator of the LinqQuery interface, and the operator tree is used to record the query logic; Step S300: parsing the operator tree, executing the query hierarchically, and returning a result set; When this embodiment is applied, first, the query context is defined, by providing the LinqQuery interface and defining chain operators such as where and select therein. With the help of generic T, the data type is strictly checked during the compilation phase, effectively avoiding type errors at runtime and providing solid type safety protection for the entire query process. This design not only improves the reliability of the code, but also makes developers feel more at ease when writing query logic. Then, an operator tree is constructed. When the user uses it, these operations will be converted into an operator tree by calling the chain operators of the LinqQuery interface. The operator tree is like a "blueprint" of the entire query logic, recording the query logic set by the user. Finally, the query is parsed and executed, the constructed operator tree is parsed, and the query operations are executed in sequence according to the hierarchy, and finally the result set that meets the conditions is returned to the user.

[0012] As a preferred embodiment of the present invention, it also includes a query expression parsing module, which parses user-defined chain calls into an operator tree and supports complex nested queries and multi-condition combinations. It also includes an execution engine module, which traverses the operator tree and executes corresponding query operations. The execution engine module supports diversified data sources, and the data sources include memory collections, databases, and file systems. The query logic is dynamically constructed through generic and functional interfaces, type safety is guaranteed at compile time, and query conditions are bound to operators to reduce the risk of runtime errors. The query logic is optimized using operator trees to avoid repeated calculations; delayed evaluation is performed in the execution phase, and queries are executed only when the results are required. By defining an open query context interface, user-defined operators and extended query functions are supported. The operator tree parsing and execution logic can be replaced with a parallel computing framework to improve performance, and the data source is extended to databases and files through the adapter mode.

[0013] When this embodiment is applied, the expression parsing module can accurately parse the query statements written by the user through chain calls into a structured operator tree. It supports complex nested queries and multi-condition combinations, and can easily cope with data query requirements in various complex business scenarios. As a visual "carrier" of query logic, the operator tree provides a solid foundation for subsequent query optimization and execution. At the optimization level, it can effectively identify and avoid repeated calculations, reducing unnecessary resource consumption. The execution engine module is responsible for traversing the operator tree and executing the corresponding query operations in sequence. It supports a variety of data sources, covering memory collections, databases, and file systems. During the execution phase, a delayed evaluation strategy is adopted, and the execution operation is triggered only when the query results need to be obtained, which further improves the query performance and resource utilization efficiency. In addition, the operator tree parsing and execution logic of the execution engine module are highly flexible and can be replaced with a parallel computing framework such as the Fork / Join framework or the parallel stream of Java Stream according to actual needs, thereby greatly improving the data processing speed. In terms of scalability, the present invention provides developers with space to customize operators and extend query functions by defining an open query context interface. Developers can flexibly add new query operators or expand existing functions according to specific business needs. At the same time, through the adapter mode, the data source can be seamlessly extended to databases, files, etc., which greatly enhances the applicability of this method in different application scenarios.

[0014] As a preferred embodiment of the present invention, a simple query of the memory collection is: Suppose there is a memory collection containing Person objects, which have name and age attributes. First, define the query context interface LinqQuery and implement the where and select operators. For example: public interface LinqQuery <t>{ LinqQuery <t>where(Predicate <t>predicate); <r>LinqQuery <r>select(Function<T, R> function); List <t>toList(); }; Then, users can construct queries through chained calls. For example, to query a list of names of people older than 18: List <person>personList = new ArrayList<>(); / / Initialize personList data; LinqQuery <person>query = new LinqQueryImpl<>(personList); List <string>names = query.where(person -> person.getAge() > 18) .select(Person::getName) .toList(); In the above code, a LinqQuery instance is first created and passed a list of Person objects. The query criteria are then set by chaining the where operator to filter out Person objects older than 18. The select operator is then used to convert these filtered Person objects into their names. Finally, the toList method is called to execute the query and obtain the result list. During actual execution, the query expression parsing module parses the user's chained calls into an operator tree. The execution engine traverses the operator tree, first performing the where operation for filtering, then performing the select operation for conversion, and finally returning the result set.

[0015] As a preferred embodiment of the present invention, data query in the order management system: In e-commerce order management systems, it is often necessary to perform complex queries on order data, such as filtering orders by conditions, calculating statistical information, grouping by users, etc. In this case, the data source is List <order>, the Order object contains key information such as the user ID, amount, and status of the order. By using the Java LINQ expression implementation method based on chain call of the present invention, specific query requirements can be achieved through the following core code: List <order>orders = getOrderList(); / / Query chain call List <userordersummary>result = LinqQuery.from(orders) .where(order->order.getAmount()>100&& "completed".equals(order.getStatus())) .groupBy(Order::getUserId, Collectors.summingDouble(Order::getAmount)) .select((userId, totalAmount) -> new UserOrderSummary(userId,totalAmount)) .toList(); The above code implements two core query operations: first, it filters out orders with a value greater than 100 and a "Completed" status; then, it groups these filtered orders by user ID and calculates each user's total order amount. Finally, it converts the result into a list of UserOrderSummary objects, which records the user ID and the corresponding total order amount.

[0016] The above embodiment of the present invention provides a Java language LINQ expression implementation method based on chain call, providing a LinqQuer interface, the LinqQuery interface defines chain operators where operator and select, and provides type safety through generic T; the user generates an operator tree by calling the chain operator of the LinqQuery interface, and the operator tree is used to record the query logic; the operator tree is parsed, the query is executed hierarchically, and a result set is returned; compared with traditional loop and conditional branch implementations, the number of lines of code is reduced by about 40%, and readability is significantly improved. Through the open operator interface, developers can easily expand query functions. Through generic constraints, type checking of query logic is completed at compile time, reducing runtime errors, and supporting unified queries in multiple scenarios such as memory collections, database queries, and file reading.

[0017] In order to enable the above-mentioned method and system to be loaded and run smoothly, in addition to the various modules mentioned above, the system may also include more or fewer components than described above, or a combination of certain components, or different components, for example, it may include input and output devices, network access devices, buses, processors and memories, etc.

[0018] The processor may be a central processing unit, other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor. The processor is the control center of the system, connecting various components using various interfaces and lines.

[0019] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0020] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0021] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.< / userordersummary> < / order> < / order> < / string> < / person> < / person> < / t> < / r> < / r> < / t> < / t> < / t>

Claims

1. A method for implementing a Java language LINQ expression based on chain calls, characterized in that: The method comprises: Provides a LinqQuery interface, which defines chained operators, a where operator, and a select operator, and provides type safety through a generic T. The user generates an operator tree by calling the chain operator of the LinqQuery interface, and the operator tree is used to record the query logic; The operator tree is parsed, the query is executed hierarchically, and a result set is returned.

2. The Java language LINQ expression implementation method based on chain call according to claim 1 is characterized in that: It also includes a query context interface, which defines the basic structure of a LINQ query and supports chain calls.

3. The Java language LINQ expression implementation method based on chain call according to claim 1 is characterized in that: It also includes an operator implementation module, which implements common query operators, including Where, Select, GroupBy, and OrderBy. The operator implementation module uses a functional interface to define query logic and supports lambda expressions.

4. The Java language LINQ expression implementation method based on chain call according to claim 1 is characterized in that: It also includes a query expression parsing module, which parses user-defined chain calls into operator trees and supports complex nested queries and multi-condition combinations.

5. The Java language LINQ expression implementation method based on chain call according to claim 1 is characterized in that: It also includes an execution engine module, which traverses the operator tree and executes corresponding query operations. The execution engine module supports diversified data sources, including memory collections, databases, and file systems.

6. The Java language LINQ expression implementation method based on chain call according to claim 1 is characterized in that: Dynamically build query logic through generics and functional interfaces to ensure type safety at compile time, and bind query conditions to operators to reduce the risk of runtime errors.

7. The Java language LINQ expression implementation method based on chain call according to claim 1 is characterized in that: Use operator trees to optimize query logic and avoid repeated calculations; perform lazy evaluation during the execution phase and execute queries only when the results are needed.

8. The Java language LINQ expression implementation method based on chain call according to claim 1 is characterized in that: By defining an open query context interface, it supports user-defined operators and extended query functions.

9. The Java language LINQ expression implementation method based on chain call according to claim 1 is characterized in that: The operator tree parsing and execution logic can be replaced with a parallel computing framework to improve performance.

10. The Java language LINQ expression implementation method based on chain call according to claim 1, characterized in that: Extend the data source to database and file through the adapter pattern.

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