book

Dependency Injection

Name: Dependency Injection
Author: Dhananjay Prasanna
ISBN: 9781933988559

by Dhananjay Prasanna

August 2009

Intermediate to advanced

352 pages

9h 21m

English

Manning Publications

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Praise from the Creator of Guice
Copyright
Preface
Acknowledgments
About This Book
About the cover illustration
1. Dependency injection: what's all the hype?
1.1. Every solution needs a problem1.1.1. Seeing objects as services1.2. Pre-DI solutions1.2.1. Construction by hand1.2.2. The Factory pattern1.2.3. The Service Locator pattern1.3. Embracing dependency injection1.3.1. The Hollywood Principle1.3.2. Inversion of Control vs. dependency injection1.4. Dependency injection in the real world1.4.1. Java1.4.2. DI in other languages and libraries1.5. Summary
2. Time for injection
2.1. Bootstrapping the injector2.2. Constructing objects with dependency injection2.3. Metadata and injector configuration2.3.1. XML injection in Spring2.3.2. From XML to in-code configuration2.3.3. Injection in PicoContainer2.3.4. Revisiting Spring and autowiring2.4. Identifying dependencies for injection2.4.1. Identifying by string keys2.4.2. Limitations of string keys2.4.3. Identifying by type2.4.4. Limitations of identifying by type2.4.5. Combinatorial keys: a comprehensive solution2.5. Separating infrastructure and application logic2.6. Summary
3. Investigating DI
3.1. Injection idioms3.1.1. Constructor injection3.1.2. Setter injection3.1.3. Interface injection3.1.4. Method decoration (or AOP injection)3.2. Choosing an injection idiom3.2.1. Constructor vs. setter injection3.2.2. The constructor pyramid problem3.2.3. The circular reference problem3.2.4. The in-construction problem3.2.5. Constructor injection and object validity3.3. Not all at once: partial injection3.3.1. The reinjection problem3.3.2. Reinjection with the Provider pattern3.3.3. The contextual injection problem3.3.4. Contextual injection with the Assisted Injection pattern3.3.5. Flexible partial injection with the Builder pattern3.4. Injecting objects in sealed code3.4.1. Injecting with externalized metadata3.4.2. Using the Adapter pattern3.5. Summary
4. Building modular applications
4.1. Understanding the role of an object4.2. Separation of concerns (my pants are too tight!)4.2.1. Perils of tight coupling4.2.2. Refactoring impacts of tight coupling4.2.3. Programming to contract4.2.4. Loose coupling with dependency injection4.3. Testing components4.3.1. Out-of-container (unit) testing4.3.2. I really need my dependencies!4.3.3. More on mocking dependencies4.3.4. Integration testing4.4. Different deployment profiles4.4.1. Rebinding dependencies4.4.2. Mutability with the Adapter pattern4.5. Summary

5. Scope: a fresh breath of state
5.1. What is scope?5.2. The no scope (or default scope)5.3. The singleton scope5.3.1. Singletons in practice5.3.2. The singleton anti-pattern5.4. Domain-specific scopes: the web5.4.1. HTTP request scope5.4.2. HTTP session scope5.5. Summary
6. More use cases in scoping
6.1. Defining a custom scope6.1.1. A quick primer on transactions6.1.2. Creating a custom transaction scope6.1.3. A custom scope in Guice6.1.4. A custom scope in Spring6.2. Pitfalls and corner cases in scoping6.2.1. Singletons must be thread-safe6.2.2. Perils of scope-widening injection6.3. Leveraging the power of scopes6.3.1. Cache scope6.3.2. Grid scope6.3.3. Transparent grid computing with DI6.4. Summary
7. From birth to death: object lifecycle
7.1. Significant events in the life of objects7.1.1. Object creation7.1.2. Object destruction (or finalization)7.2. One size doesn't fit all (domain-specific lifecycle)7.2.1. Contrasting lifecycle scenarios: servlets vs. database connections7.2.2. The Destructor anti-pattern7.2.3. Using Java's Closeable interface7.3. A real-world lifecycle scenario: stateful EJBs7.4. Lifecycle and lazy instantiation7.5. Customizing lifecycle with postprocessing7.6. Customizing lifecycle with multicasting7.7. Summary
8. Managing an object's behavior
8.1. Intercepting methods and AOP8.1.1. A tracing interceptor with Guice8.1.2. A tracing interceptor with Spring8.1.3. How proxying works8.1.4. Too much advice can be dangerous!8.2. Enterprise use cases for interception8.2.1. Transactional methods with warp-persist8.2.2. Securing methods with Spring Security8.3. Pitfalls and assumptions about interception and proxying8.3.1. Sameness tests are unreliable8.3.2. Static methods cannot be intercepted8.3.3. Neither can private methods8.3.4. And certainly not final methods!8.3.5. Fields are off limits8.3.6. Unit tests and interception8.4. Summary
9. Best practices in code design
9.1. Objects and visibility9.1.1. Safe publication9.1.2. Safe wiring9.2. Objects and design9.2.1. On data and services9.2.2. On better encapsulation9.3. Objects and concurrency9.3.1. More on mutability9.3.2. Synchronization vs. concurrency9.4. Summary
10. Integrating with third-party frameworks
10.1. Fragmentation of DI solutions10.2. Lessons for framework designers10.2.1. Rigid configuration anti-patterns10.2.2. Black box anti-patterns10.3. Programmatic configuration to the rescue10.3.1. Case study: JSR-30310.4. Summary
11. Dependency injection in action!
11.1. Crosstalk: a Twitter clone!11.1.1. Crosstalk's requirements11.2. Setting up the application11.3. Configuring Google Sitebricks11.4. Crosstalk's modularity and service coupling11.5. The presentation layer11.5.1. The HomePage template11.5.2. The Tweet domain object11.5.3. Users and sessions11.5.4. Logging in and out11.6. The persistence layer11.6.1. Configuring the persistence layer11.7. The security layer11.8. Tying up to the web lifecycle11.9. Finally: up and running!11.10. Summary
A. The Butterfly Container
A.1. A DSL for dependency injectionA.2. Application configurationA.2.1. The DSL basicsA.2.2. The Factory chainA.2.3. Contextual injection via input parametersA.2.4. Reinjection via factory injection
B. SmartyPants for Adobe Flex
B.1. The class+name keyB.1.1. Injection annotationsB.2. Injector rulesB.2.1. But how do I kickstart the whole thing?

Content preview from Dependency Injection

Chapter 2. Time for injection

"We shape our buildings, thereafter they shape us."

——Winston Churchill

In chapter 1, we saw that dependency injection offers a unique and concise solution to the problem of constructing object graphs, with a strong emphasis on unit testing. The crux of this solution is the fact that all your code is freed from constructing dependencies. Code written with DI in mind is behaviorally focused and without distracting clutter. Why is this important?

While the answer may seem self-evident (hard to argue with the less and more precise), it is well worth spelling out:

Behaviorally focused—Presumably, you set out to write code toward a specific purpose, and that purpose is not to construct more objects! Whether writing an email ...

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Dependency Injection

by Dhananjay Prasanna

Chapter 2. Time for injection

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