Spring依赖注入(dependency injection)
Spring的依赖注入包括两方面：
1、依赖：指bean对象创建依赖于容器；Bean对象的依赖资源。
2、注入：指bean对象依赖的资源由容器来设置和装配。
Spring的注入有两类：
1、构造器的注入：使用的是constructor-arg，如图：
2、setter注入：
要求被注入的属性，必须有set方法，set方法生成的方法名，由set+属性（首字母大写），如果属性是boolean类型，没有get方法，是is方法。
1）常量注入：
2）bean的注入：
给Address配置值之后如图：
Address类代码：
package com.myspring.vo;
public class Address {
private String address ;
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
Student类代码：
package com.myspring.vo;
public class Student {
private String name;
private Address addr ;
public void setAddr(Address addr) {
this.addr = addr;
}
public void setName(String name) {
this.name = name;
}
public void show() {
System.out.println("name=" + name +"---addr="+addr.getAddress());
}
}
3）数组注入：
在Student类中加入字符串数组，代码如：
package com.myspring.vo;
public class Student {
private String name;
private Address addr ;
private String[] books ;
public void setAddr(Address addr) {
this.addr = addr;
}
public void setName(String name) {
this.name = name;
}
public void setBooks(String[] books) {
this.books = books;
}
public void show() {
System.out.println("name=" + name +"---addr="+addr.getAddress());
System.out.print("books=");
for (int i = 0; i < books.length; i++) {
System.out.print(books[i]+" ");
}
System.out.println();
}
}
beans.xml代码增加了输入注入，如图：
傲慢与偏见
仲夏夜之梦
雾都孤儿
测试代码Test：
package com.myspring.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.myspring.vo.Student;
public class Test {
public static void main(String[] args) {
ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml") ;
Student student = (Student) ac.getBean("student") ;
student.show() ;
}
}
运行后控制台打印信息：
4）List注入：
在Student实体类中增加集合属性hobbies，代码如：
package com.myspring.vo;
import java.util.List;
public class Student {
private String name;
private Address addr ;
private String[] books ;
private List hobbies ;
public void setHobbies(List hobbies) {
this.hobbies = hobbies;
}
public void setAddr(Address addr) {
this.addr = addr;
}
public void setName(String name) {
this.name = name;
}
public void setBooks(String[] books) {
this.books = books;
}
public void show() {
System.out.println("name=" + name +"---addr="+addr.getAddress());
System.out.print("books=");
for (int i = 0; i < books.length; i++) {
System.out.print(books[i]+" ");
}
System.out.println();
System.out.println("hobbies = "+ hobbies);
}
}
在beans.xml中配置如下：
傲慢与偏见
仲夏夜之梦
雾都孤儿
羽毛球
乒乓球
足球
台球
运行test测试类代码：
package com.myspring.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.myspring.vo.Student;
public class Test {
public static void main(String[] args) {
ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml") ;
Student student = (Student) ac.getBean("student") ;
student.show() ;
}
}
控制台打印如下：
5）map注入：
实体类Student中增加map属性cards，代码如：
package com.myspring.vo;
import java.util.List;
import java.util.Map;
public class Student {
private String name;
private Address addr ;
private String[] books ;
private List hobbies ;
private Map cards ;
public void setCards(Map cards) {
this.cards = cards;
}
public void setHobbies(List hobbies) {
this.hobbies = hobbies;
}
public void setAddr(Address addr) {
this.addr = addr;
}
public void setName(String name) {
this.name = name;
}
public void setBooks(String[] books) {
this.books = books;
}
public void show() {
System.out.println("name=" + name +"---addr="+addr.getAddress());
System.out.print("books=");
for (int i = 0; i < books.length; i++) {
System.out.print(books[i]+" ");
}
System.out.println();
System.out.println("hobbies = "+ hobbies);
System.out.println("cards = "+ cards);
}
}
beans.xml中的配置文件如下：
傲慢与偏见
仲夏夜之梦
雾都孤儿
羽毛球
乒乓球
足球
台球
运行test类，代码同上面的test，控制台打印信息如下：
6）Set集合注入：
实体类Student代码如下：
package com.myspring.vo;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class Student {
private String name;
private Address addr ;
private String[] books ;
private List hobbies ;
private Map cards ;
private Set games ;
public void setGames(Set games) {
this.games = games;
}
public void setCards(Map cards) {
this.cards = cards;
}
public void setHobbies(List hobbies) {
this.hobbies = hobbies;
}
public void setAddr(Address addr) {
this.addr = addr;
}
public void setName(String name) {
this.name = name;
}
public void setBooks(String[] books) {
this.books = books;
}
public void show() {
System.out.println("name=" + name +"---addr="+addr.getAddress());
System.out.print("books=");
for (int i = 0; i < books.length; i++) {
System.out.print(books[i]+" ");
}
System.out.println();
System.out.println("hobbies = "+ hobbies);
System.out.println("cards = "+ cards);
System.out.println("games = " + games);
}
}
beans.xml代码如下：
傲慢与偏见
仲夏夜之梦
雾都孤儿
羽毛球
乒乓球
足球
台球
lol
dota
cs
cf
测试类代码test同上面，运行后控制台打印信息：
7）Null注入：
实体类Student代码：
package com.myspring.vo;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class Student {
private String name;
private Address addr ;
private String[] books ;
private List hobbies ;
private Map cards ;
private Set games ;
private String wife ;
public void setWife(String wife) {
this.wife = wife;
}
public void setGames(Set games) {
this.games = games;
}
public void setCards(Map cards) {
this.cards = cards;
}
public void setHobbies(List hobbies) {
this.hobbies = hobbies;
}
public void setAddr(Address addr) {
this.addr = addr;
}
public void setName(String name) {
this.name = name;
}
public void setBooks(String[] books) {
this.books = books;
}
public void show() {
System.out.println("name=" + name +"---addr="+addr.getAddress());
System.out.print("books=");
for (int i = 0; i < books.length; i++) {
System.out.print(books[i]+" ");
}
System.out.println();
System.out.println("hobbies = "+ hobbies);
System.out.println("cards = "+ cards);
System.out.println("games = " + games);
System.out.println("wife = "+ wife );
}
}
beans.xml代码：
傲慢与偏见
仲夏夜之梦
雾都孤儿
羽毛球
乒乓球
足球
台球
lol
dota
cs
cf
运行test测试类，控制台打印信息如下：
8）Properties注入
实体类Student代码：
package com.myspring.vo;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
public class Student {
private String name;
private Address addr;
private String[] books;
private List hobbies;
private Map cards;
private Set games;
private String wife;
private Properties info;
public void setInfo(Properties info) {
this.info = info;
}
public void setWife(String wife) {
this.wife = wife;
}
public void setGames(Set games) {
this.games = games;
}
public void setCards(Map cards) {
this.cards = cards;
}
public void setHobbies(List hobbies) {
this.hobbies = hobbies;
}
public void setAddr(Address addr) {
this.addr = addr;
}
public void setName(String name) {
this.name = name;
}
public void setBooks(String[] books) {
this.books = books;
}
public void show() {
System.out.println("name=" + name + "---addr=" + addr.getAddress());
System.out.print("books=");
for (int i = 0; i < books.length; i++) {
System.out.print(books[i] + " ");
}
System.out.println();
System.out.println("hobbies = " + hobbies);
System.out.println("cards = " + cards);
System.out.println("games = " + games);
System.out.println("wife = " + wife);
System.out.println("info = " + info);
}
}
beans.xml配置代码：
傲慢与偏见
仲夏夜之梦
雾都孤儿
羽毛球
乒乓球
足球
台球
lol
dota
cs
cf
11020039398
男
小明
运行测试类test结果如下：
9）、p命名空间注入：
我们从下面的文档截图中可以看到这是p命名空间的头文件，该文档所在路径可以从图中看到，
p命名空间的头文件部分和普通的头文件部分唯一的不同就是p命名空间的头文件多了xmlns:p="" 这部分，如图：
下面来看一下p命名怎么注入：
新建一个实体类User，代码如下：
package com.myspring.vo;
public class User {
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "User [name=" + name + ", age=" + age + "]";
}
}
beans.xml中的配置代码如下：
其中name和age是对应的实体类User中的name和age属性
测试类test代码如下：
package com.myspring.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.myspring.vo.Student;
import com.myspring.vo.User;
public class Test {
public static void main(String[] args) {
//p命名注入测试
ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml") ;
User user = (User) ac.getBean("user") ;
System.out.println(user);
}
}
控制台打印的运行结果如下：
3、c命名空间注入（其实就是构造方法注入）
c命名空间注入需要现在beans.xml头文件部分增加
xmlns:c="http://www.springframework.org/schema/c"
实体类User代码如下：
package com.myspring.vo;
public class User {
private String name;
private int age;
public User() {
// TODO Auto-generated constructor stub
}
public User(String name, int age) {
super();
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "User [name=" + name + ", age=" + age + "]";
}
}
beans.xml代码如下：
测试类Test代码：
package com.myspring.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.myspring.vo.Student;
import com.myspring.vo.User;
public class Test {
public static void main(String[] args) {
//p命名注入测试
ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml") ;
User user = (User) ac.getBean("c_user") ;
System.out.println(user);
}
}
控制台打印运行结果如下：
