SOLID原则在Java中的实践解析

class User {
    private String name;
<pre class="brush:java;toolbar:false;">public void setName(String name) {
    this.name = name;
}

public void saveToFile() {
    // 保存用户到文件
}

}

interface Shape {
    double area();
}
<p>class Rectangle implements Shape {
double width, height;
public double area() { return width * height; }
}</p><p>class Circle implements Shape {
double radius;
public double area() { return Math.PI <em> radius </em> radius; }
}</p><p>class AreaCalculator {
public double totalArea(List<shape> shapes) {
return shapes.stream().mapToDouble(Shape::area).sum();
}
}</shape></p>

interface Flyable {
    void fly();
}
<p>class Sparrow implements Flyable {
public void fly() { System.out.println("麻雀飞行"); }
}</p><p>class Penguin { // 不实现Flyable
public void swim() { System.out.println("企鹅游泳"); }
}</p>

interface Workable {
    void work();
}
<p>interface Eatable {
void eat();
}</p><p>class HumanWorker implements Workable, Eatable {
public void work() { /<em> 工作 </em>/ }
public void eat() { /<em> 吃饭 </em>/ }
}</p><p>class RobotWorker implements Workable {
public void work() { /<em> 工作 </em>/ }
// 不实现eat，避免无效方法
}</p>

interface Database {
    void connect();
    void save(String data);
}
<p>class MySQLDatabase implements Database {
public void connect() { /<em> 连接MySQL </em>/ }
public void save(String data) { /<em> 保存到MySQL </em>/ }
}</p><p>class UserService {
private Database db;</p><pre class="brush:java;toolbar:false;">public UserService(Database db) {
    this.db = db;
}

public void saveUser(String user) {
    db.save(user);
}

}