Android dependence on database practice sharing: simplify the development process and improve code maintenance
Android dependence on database practice sharing: simplify the development process and improve code maintenance
introduction:
In Android development, we often encounter complex class dependencies, such as a class that depends on multiple other classes, third -party libraries or system services.In order to solve the dependence between these classes, we often need to create and manage objects manually, and at the same time, we need to pass these instances in different modules, resulting in long and difficult to maintain the code.Dependency inject is a design mode that can help us manage the dependency relationship between categories and improve the maintenance, reuse, and scalability of code.
1. What is dependent injection
Dependent injection is a way to pass the dependent relationship to the object through external sources (usually a framework or container).Its core idea is to separate the object's creation and dependence relationship, so that the object focuses on its core function, and the dependencies of the object are managed by the outside.This can reduce the coupling between objects and improve the modularity and testability of code.
2. Why use dependency injection
1. Simplify the development process: The process of using dependencies can avoid the process of manual management object instances, reduce the amount of manual creation objects and the number of code transmitted, thereby simplifying the development process.
2. Improve code maintenance: dependency injection to pull the dependencies of the object from the code, make the code clearer and concise, reduce the emergence of duplicate code, and improve the readability and maintenance of the code.
3. Increase the testability of the code: The dependency injection can easily replace the dependent object of the class, making the test code easier, flexible, and easy to write and maintain.
3. Common ways to rely on injection
1. Constructor inject: The dependency relationship is passed to the object through the constructor of the class as a parameter.For example:
public class MyClass {
private MyDependency myDependency;
public MyClass(MyDependency myDependency) {
this.myDependency = myDependency;
}
}
2. Setter method injection (Setter Injection): The dependent relationship is passed to the object through the open Setter method.For example:
public class MyClass {
private MyDependency myDependency;
public void setMyDependency(MyDependency myDependency) {
this.myDependency = myDependency;
}
}
3. Interface Injection: Exposure to the object through the interface to enable it to obtain a dependent instance.For example:
public interface Injectable {
void inject(MyDependency myDependency);
}
public class MyClass implements Injectable {
private MyDependency myDependency;
@Override
public void inject(MyDependency myDependency) {
this.myDependency = myDependency;
}
}
4. Annotation Injection: The relying injection through reflection and other methods is achieved by reflecting through the attributes or methods required by the annotation mark.For example:
public class MyClass {
@Inject
private MyDependency myDependency;
}
4. Commonly used dependent injection libraries
1. Dagger: Dagger is a dependent injection library developed by Google. It adopts the method of relying in injection during compilation, and generates a high -performance, reliable dependency injection solution through the annotation processor to generate a dependent injection code.
2. Butterknife: Butterknife is a view -injecting framework, which also provides the function of dependent injection, and realizes dependency injection through annotations.
3. Androidannotations: Androidannotations is a very powerful Android development framework that provides functions such as dependency injection, view injection, event binding and other functions.
4. Koin: Koin is a lightweight dependency injection framework. It uses a unique DSL (special language) method to achieve dependency injection, which can simplify the dependency injection of Android applications.
Fifth, the best practice to rely on injection
1. Do not abuse dependencies injection: Moderate use of dependencies injection, do not abuse, otherwise it will cause the code to be too complicated and increase the difficulty of understanding and maintenance.
2. Try to use the constructor injection: The constructor injection is the most commonly used dependent injection method. It will pass the dependency relationship when the object is created to ensure the integrity and consistency of the object.
3. Use interface injection to achieve replaceability: The replaceability of the class can be achieved through the method of injecting the interface, making the dependency more flexible, so as to facilitate unit testing and modular development.
4. Avoid the use of global dependencies: try to avoid using global dependencies, but to pass the dependent relationship to the required objects to avoid coupling between objects by dependent injection.
in conclusion:
Dependent injection is an excellent design model that can help us simplify the development process and improve the maintenance of code.In the development of Android, selecting suitable dependencies injection libraries and following the best practice of dependent injection can make the code clearer, simple, and improve the testability and scalability of the code.
