JMock

English | 中文

Introduction

JMock is a high-performance data generation and simulation library implemented in Java. It generates data that more closely resembles real business data characteristics compared to random data generation.

Core Features

• High-performance data generation:
  Generates 2M+ user records per second (single thread). Each record contains 10+ attributes totaling 200+ bytes.
• Business-realistic data with i18n support:
  Produces data that accurately simulates real-world business scenarios with internationalization capabilities.
• Dual definition approaches:
  • Annotation-based: Applied to class fields
  • Function-based: Used in script files (txt, json, yml, etc.)
• Multiple storage options:
  Supports JDBC, in-memory, and local filesystem persistence for batch data.
• Extensible architecture:
  Plugin-based system for custom mock data functions.

Website

The website/ directory is a Next.js static site (function reference, getting started, playground).

• English: site root, e.g. /, /docs/functions
• 中文: /zh, e.g. /zh/docs/functions
• Function descriptions are loaded from docs/JMockFunction-en.json and docs/JMockFunction-zh_CN.json.

To build locally:

cd website && npm ci && npm run build

Output is written to website/out. For GitHub Pages project sites, set NEXT_PUBLIC_BASE_PATH=/YourRepoName when building (see website/next.config.js and .github/workflows/deploy-github-pages.yml).

Function Expressions

Expression Formats

Type	Parameterless Form	Parameterized Form
Annotation	@Annotation	@Annotation(param1=value1, param2=value2)
Function	@Function()	@Function(param1, param2) or @Function(param1,,param3)

Syntax Rules

1. Core Symbols

   • @ - Marks expression start
   • () - Encloses parameters
   • , - Separates parameters
   • | - Delimits array elements (array parameters only)
   • \ - Escapes special characters (@, ,, |)

2. Naming Conventions

   • Annotation/Function Names: UpperCamelCase
     Example: EmailValidator, RandomNumber
   • Parameter Names: lowerCamelCase
     Example: minValue, maxLength

3. Parameter Rules

   • Parameterless calls: Omit parentheses (annotations) or use empty () (functions)
   • Parameterized calls:
     • Annotation: param=value key-value pairs
     • Function: Positional values
   • Omitted parameters: Preserve commas
     Example: @Generate(1,,3) indicates empty second parameter

4. Special Character Handling
   Escape @, ,, | in parameter values:
   Example: @String("tom\@domain.com\|nick\@domain.com")

Usage Example

1. Add Maven dependencies (version 2.0.0 matches the parent POM)

<dependency>
  <groupId>cloud.xcan.jmock</groupId>
  <artifactId>xcan-jmock.core</artifactId>
  <version>2.0.0</version>
</dependency>

<!-- Optional: all built-in plugins -->
<dependency>
  <groupId>cloud.xcan.jmock</groupId>
  <artifactId>xcan-jmock.all-plugin</artifactId>
  <version>2.0.0</version>
  <scope>runtime</scope>
</dependency>

2. Render a template with MockEngine (recommended entry point)

import cloud.xcan.jmock.core.engine.MockEngine;

String content = """
    {
      "name": "@Name()",
      "email": "@Email()",
      "phone": "@Mobile()",
      "address": "@Address()",
      "hobbies": [ "reading", "hiking",  "cooking" ]
    }""";

MockEngine engine = MockEngine.defaultEngine();
String result = engine.render(content);
System.out.println(result);

For simple text replacement without the full engine pipeline, you can use DefaultMockTextReplacer from the core module.

Sample output:

{
  "name": "Durfee Jacob",
  "email": "9alJWYsUGJuJZtGuXT@yahoo.com.cn",
  "phone": "15292153757",
  "address": "ul. Akademika Pavlova, 12к3, Moskva",
  "hobbies": [
    "reading",
    "hiking",
    "cooking"
  ]
}

Repository

• GitHub: https://github.com/xcancloud/JMock