注入参数基本分7类：
1.基本类型值
2.注入bean
3.内部bean
4.注入null值
5.级联属性
6.List，Set，Map集合的注入
7.properties文件的注入（和集合注入基本是一样的）
下面就是实体类People2，beans.xml的源码
package com.maya.model; import java.util.ArrayList; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Properties; import java.util.Set; public class People2 { private int id; private String name; private int age; private Dog dog;//注入bean private List<String> myList=new ArrayList<String>();//List集合注入 private Set<String> mySet=new HashSet<String>();//Set集合注入 private Map<String,String> myMap=new HashMap<String,String>();//Map集合注入 private Properties jdbc=new Properties();//properties文件注入，和map差不多都是以key、value的形式 public Map<String, String> getMyMap() { return myMap; } public void setMyMap(Map<String, String> myMap) { this.myMap = myMap; } public Set<String> getMySet() { return mySet; } public void setMySet(Set<String> mySet) { this.mySet = mySet; } public List<String> getMyList() { return myList; } public void setMyList(List<String> myList) { this.myList = myList; } public Dog getDog() { return dog; } public void setDog(Dog dog) { this.dog = dog; } public int getId() { return id; } public void setId(int id) { this.id = id; } 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; } public People2() { super(); } public People2(int id, String name, int age, Dog dog) { super(); this.id = id; this.name = name; this.age = age; this.dog = dog; } public Properties getJdbc() { return jdbc; } public void setJdbc(Properties jdbc) { this.jdbc = jdbc; } @Override public String toString() { return "People2 [id=" + id + ", name=" + name + ", age=" + age + ", dog=" + dog + ", myList=" + myList + ", mySet=" + mySet + ", myMap=" + myMap + ", jdbc=" + jdbc + "]"; } //当要使用dog.name是就要注意beans.xml文件的配置 }
<?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"> <!-- 注入参数 --> <!-- 基本类型注入 --> <bean id="people21" class="com.maya.model.People2"> <constructor-arg name="id" value="0"></constructor-arg> <constructor-arg name="name" value="张三"></constructor-arg> <constructor-arg name="age" value="10"></constructor-arg> <constructor-arg name="dog" ref="dog1"></constructor-arg> </bean> <!-- 注入bean --> <bean id="dog1" class="com.maya.model.Dog"> <property name="name" value="阿黄"></property> </bean> <bean id="people22" class="com.maya.model.People2"> <property name="id" value="1"></property> <property name="name" value="小明2"></property> <property name="age" value="22"></property> <property name="dog" ref="dog1"></property><!-- 注入bean时ref是要注入的bean的id --> </bean> <!-- 注入内部bean --> <bean id="people23" class="com.maya.model.People2"> <property name="id" value="3"></property> <property name="name" value="小明3"></property> <property name="age" value="33"></property> <property name="dog"> <bean class="com.maya.model.Dog"> <property name="name" value="UZI"></property><!-- 分开写而已 --> </bean> </property> </bean> <!-- 注入null --> <bean id="people24" class="com.maya.model.People2"> <property name="id" value="3"></property> <property name="name" value="小明3"></property> <property name="age" value="33"></property> <property name="dog"> <null></null><!-- 给dog属性注入一个null --> </property> </bean> <!-- 级联方式注入 --> <!-- <bean id="people25" class="com.maya.model.People2"> <property name="id" value="3"></property> <property name="name" value="小明3"></property> <property name="age" value="33"></property> <property name="dog.name" value="小明的狗"></property> 注意：以这种方式进行赋值时，因为我们没用注入Dog的实例对象，所以我们要在People2的dog属性后new一个Dog实例！这样才能成功赋值 </bean> --> <!-- 注入List集合,Set集合,Map集合 --> <bean id="people26" class="com.maya.model.People2"> <property name="id" value="3"></property> <property name="name" value="小明3"></property> <property name="age" value="33"></property> <property name="dog" ref="dog1"></property> <!-- List集合 --> <property name="myList"> <list> <value>a</value> <value>b</value> <value>c</value> <value>d</value> </list> </property> <!-- Set集合，Set集合是自动去掉重复值得！所以输出的结果还是a,b,c --> <property name="mySet"> <set> <value>a</value> <value>b</value> <value>c</value> <value>c</value> <value>b</value> <value>a</value> </set> </property> <!-- Map集合 --> <property name="myMap"> <map> <entry> <key><value>上午</value></key> <value>写代码</value> </entry> <entry> <key><value>下午</value></key> <value>测试代码</value> </entry> </map> </property> <!-- 配置properties文件 --> <property name="jdbc"> <props> <prop key="qd">com.mysql.jdbc.Driver</prop> <prop key="url">jdbc:mysql://localhost:3306/spring4?characterEncoding=GBK</prop> <prop key="user">root</prop> </props> </property> </bean> <!-- 配置properties文件 --> <bean id="people27" class="com.maya.model.People2"> <!-- 在这之前没有为其他属性赋值，这是可以得。但是当使用其引用bean的某些方法时就必须给其赋值而且不能是null --> <property name="jdbc"> <props> <prop key="qd">com.mysql.jdbc.Driver</prop> <prop key="url">jdbc:mysql://localhost:3306/spring4?characterEncoding=GBK</prop> <prop key="user">root</prop> </props> </property> </bean> </beans>
常见错误：
Could not resolve matching constructor（构造函数问题）
Loading XML bean definitions from class path resource（实体类中 引用的其他bean类正在使用它的某些方法！去掉使用的方法就好了）