Spring drip seven: Spring in Dependency injection (Dependency Injection:di)

There are two main types of dependency injection in the spring mechanism: constructor-based Dependency injection (based on construction method dependency Injection) and setter-based Dependency injection ( Based on setter method dependency Injection)

first, contructor-based Dependency Injection (based on the construction method Injection)

In the bean tab, use the <constructor-arg/> tag to implement the

Spring.xml

<?xml version= "1.0" encoding= "UTF-8"? ><beans xmlns= "http://www.springframework.org/schema/beans"Xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd "><bean id= "a"class= "com.test.spring.a" >
       <!--reference Other beans two different implementations --<constructor-arg><ref bean= "b"/></constructor-arg> <constructor-argref= "c"/> <constructor-arg name= "name" value= "zhang san"/> </bean> <bean id= "b"class= "com.test.spring.b" > </bean> <bean id= "c"class= "com.test.spring.c" > </bean></beans>

Java class:

 packagecom.test.spring; public classA {Privateb b; PrivateC c; PrivateString name;  publicA (b b, c c, String Name) { this. B =b;  this. C =c;  this. Name =name; }     publicB getb () {returnb; }     public voidSetb (b B) { this. B =b; }     publicC GetC () {returnc; }     public voidsetc (c C) { this. C =c; }     publicString getName () {returnname; }     public voidsetName (String Name) { this. Name =name; } @Override publicString toString () {return"A [b=" + B + ", c=" + C + ", name=" + name + "]"; }    }--------------------------------------------------------------------------------------------------------------- ---------------------------------- packagecom.test.spring; public classB {}--------------------------------------------------------------------------------------------------------------- ---------------------------------- packagecom.test.spring; public classC {}

Test:

 packagecom.test.spring;Importorg.junit.Before;Importorg.junit.Test;Importorg.springframework.context.support.AbstractApplicationContext;Importorg.springframework.context.support.ClassPathXmlApplicationContext; public classT {abstractapplicationcontext ApplicationContext=NULL; @Before public voidbefore () {System.out.println ("" Spring ApplicationContext container began to initialize ... "); ApplicationContext=NewClasspathxmlapplicationcontext (Newstring[]{"test1-service.xml"}); System.out.println ("" Spring ApplicationContext Container initialization is complete ... "); } @Test public voidTest () {a a=applicationcontext.getbean (A.class);    System.out.println (a); }}

Test Results:

"Spring ApplicationContext container begins to initialize ...
2017-03-19 14:02:53 info:classpathxmlapplicationcontext-refreshing org[email protected]18c92ff9:startup date [Sun Mar 14:02:53 CST 2017]; Root of context Hierarchy
2017-03-19 14:02:53 info:xmlbeandefinitionreader-loading XML Bean Definitions from class path resource [TEST1-SERVICE.XM L
"Spring ApplicationContext container initialization is complete ...
A [[email protected], [email protected], name= Zhang San]

The Spring website API provides enough to use the static factory approach to achieve these features:

Spring.xml

<?xml version= "1.0" encoding= "UTF-8"? ><beans xmlns= "http://www.springframework.org/schema/beans"Xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd "><bean id= "a"class= "com.test.spring.a"factory-method= "getinstence"> <constructor-arg> <ref bean= "b"/> </constructor-arg> <constructor-arg ref= "c"/> <constructor-arg name= "name" value= "zhang san"/> </bean> <bean id= "b"class= "com.test.spring.b" > </bean> <bean id= "c"class= "com.test.spring.c" > </bean></beans>

Java class:

 packagecom.test.spring; public classA {Privateb b; PrivateC c; PrivateString name; /*** Create a private construction method *@paramb *@paramc *@paramname*/    private A (b b, c c, String name) {this.b = b;        THIS.C = c;    THIS.name = name; }       public static a getinstence (B b,c c,string name) {System.out.println ("called static Factory method");        A = new A (b,c,name);    Return a; }     publicB getb () {returnb; }     public voidSetb (b B) { this. B =b; }     publicC GetC () {returnc; }     public voidsetc (c C) { this. C =c; }     publicString getName () {returnname; }     public voidsetName (String Name) { this. Name =name; } @Override publicString toString () {return"A [b=" + B + ", c=" + C + ", name=" + name + "]"; }    }--------------------------------------------------------------------------------
B.java C.java (slightly)

Test:

 packagecom.test.spring;Importorg.junit.Before;Importorg.junit.Test;Importorg.springframework.context.support.AbstractApplicationContext;Importorg.springframework.context.support.ClassPathXmlApplicationContext; public classT {abstractapplicationcontext ApplicationContext=NULL; @Before public voidbefore () {System.out.println ("" Spring ApplicationContext container began to initialize ... "); ApplicationContext=NewClasspathxmlapplicationcontext (Newstring[]{"test1-service.xml"}); System.out.println ("" Spring ApplicationContext Container initialization is complete ... "); } @Test public voidTest () {A A=applicationcontext.getbean (a.class); A A2=applicationcontext.getbean (A.class); System.out.println (a==A2)        ;//find The instance object of a as a singleton        System.out.println (a);    System.out.println (a2); }}

Test Results:

"Spring ApplicationContext container begins to initialize ...
2017-03-19 14:22:31 info:classpathxmlapplicationcontext-refreshing org[email protected]17ad352e:startup date [Sun Mar 14:22:31 CST 2017]; Root of context Hierarchy
2017-03-19 14:22:31 info:xmlbeandefinitionreader-loading XML Bean Definitions from class path resource [TEST1-SERVICE.XM L
A static factory method is called
"Spring ApplicationContext container initialization is complete ...
True
A [[email protected], [email protected], name= Zhang San]
A [[email protected], [email protected], name= Zhang San]

2.setter-based Dependency Injection (Setter-based Dependency injection): This injection method is often used

Spring.xml

<?xml version= "1.0" encoding= "UTF-8"? ><beans xmlns= "http://www.springframework.org/schema/beans"     xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"    xsi:schemalocation= "http// Www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/ Spring-beans.xsd ">   class=" com.test.spring.a ">       <property name=" b "ref=" B "/>       <property name= "c" ref= "c"/>       <property name= "name" value= "zhang san"/>    </bean>    class= "com.test.spring.b" >    </bean>    class= "com.test.spring.c" >    </bean></beans>

Java class:

 packagecom.test.spring; public classA {Privateb b; PrivateC c; PrivateString name;  publicB getb () {returnb; }     public voidSetb (b B) { this. B =b; }     publicC GetC () {returnc; }     public voidsetc (c C) { this. C =c; }     publicString getName () {returnname; }     public voidsetName (String Name) { this. Name =name; } @Override publicString toString () {return"A [b=" + B + ", c=" + C + ", name=" + name + "]"; }    }

Test:

 packagecom.test.spring;Importorg.junit.Before;Importorg.junit.Test;Importorg.springframework.context.support.AbstractApplicationContext;Importorg.springframework.context.support.ClassPathXmlApplicationContext; public classT {abstractapplicationcontext ApplicationContext=NULL; @Before public voidbefore () {System.out.println ("" Spring ApplicationContext container began to initialize ... "); ApplicationContext=NewClasspathxmlapplicationcontext (Newstring[]{"test1-service.xml"}); System.out.println ("" Spring ApplicationContext Container initialization is complete ... "); } @Test public voidTest () {//beanlifecycle beanlifecycle =applicationcontext.getbean ("beanlifecycle", beanlifecycle.class); //Applicationcontext.close (); //Applicationcontext.registershutdownhook (); A A=applicationcontext.getbean (a.class);    System.out.println (a); }}

Test Results:

"Spring ApplicationContext container begins to initialize ...
2017-03-19 14:34:20 info:classpathxmlapplicationcontext-refreshing org[email protected]17ad352e:startup date [Sun Mar 14:34:20 CST 2017]; Root of context Hierarchy
2017-03-19 14:34:20 info:xmlbeandefinitionreader-loading XML Bean Definitions from class path resource [TEST1-SERVICE.XM L
"Spring ApplicationContext container initialization is complete ...
A [[email protected], [email protected], name= Zhang San]

Both of these injections can be used together in a spring configuration file

Spring bit seven: Dependency Injection in spring (Dependency injection:di)