技術標籤：java

問題：

package DependenceInversionPrinciple.one;

public class Json {
	public void studyjava() {
		System.out.println("Json study java");
	}
	
	public void studyjavascript() {
		System.out.println("Json study javascript");
	}

	public static void main(String[] args) {
 

	
		Json json=new Json();
		json.studyjava();
		json.studyjavascript();
		
	}

}
//以上開發方式問題：業務擴充套件，程式碼要從底層到高層進行修改，這樣會造成系統開發不穩定，帶來風險

優化1：

package DependenceInversionPrinciple.two;

public interface ICource {

	public void study();
}

package DependenceInversionPrinciple.two;

public class JavaCource
 
 implements ICource {

	@Override
	public void study() {
		System.out.println("Json study java");
		
	}

}

package DependenceInversionPrinciple.two;

public class JavaScriptCource implements ICource {

	@Override
	public void study() {
		System.out.println("Json study javascript"
 
);
		
	}
}

package DependenceInversionPrinciple.two;

public class Json {
	public void study(ICource icource) {
		icource.study();
	}
}

package DependenceInversionPrinciple.two;

public class Test {
public static void main(String[] args) {
	Json json=new Json();
	json.study(new JavaCource());
	json.study(new JavaScriptCource());
	
}
}
//這種方式也就是依賴注入

優化2：

package DependenceInversionPrinciple.three;

public interface ICource {

	public void study();
}

package DependenceInversionPrinciple.three;

public class Json {
	private ICource cource;
	public Json(ICource cource) {
	this.cource=cource;	
	}
	public void study() {
		cource.study();
	}
}
//依賴注入構成器方式

package DependenceInversionPrinciple.three;

public class JavaCource implements ICource {

	@Override
	public void study() {
		System.out.println("Json study java");
		
	}

}

package DependenceInversionPrinciple.three;

public class JavaScriptCource implements ICource {

	@Override
	public void study() {
		System.out.println("Json study javascript");
		
	}
}

package DependenceInversionPrinciple.three;

public class Test {
public static void main(String[] args) {
	Json json=new Json(new JavaCource());
	json.study();
}
}
//依賴注入構成器方式

優化3：

package DependenceInversionPrinciple.four;

public interface ICource {

	public void study();
}

package DependenceInversionPrinciple.four;

public class Json {
	private ICource cource;
	public void setCource(ICource cource) {
	this.cource=cource;	
	}
	public void study() {
		cource.study();
	}
}
//依賴注入setter方式

package DependenceInversionPrinciple.four;

public class JavaCource implements ICource {

	@Override
	public void study() {
		System.out.println("Json study java");
		
	}

}

package DependenceInversionPrinciple.four;

public class JavaScriptCource implements ICource {

	@Override
	public void study() {
		System.out.println("Json study javascript");
		
	}
}

package DependenceInversionPrinciple.four;

public class Test {
public static void main(String[] args) {
	Json json=new Json();
	json.setCource(new JavaScriptCource());
	json.study();
	json.setCource(new JavaCource());
	json.study();
}
} 
//依賴注入setter方式