spring set注入

上篇文章说到了构造器注入。可是有时候构造器注入并非非常好用，如今来看下set注入。

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看下样例：

public class Roles {
  private int id;
  private String roleName;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getRoleName() {
    return roleName;
  }
  public void setRoleName(String roleName) {
    this.roleName = roleName;
  }
  //重写toString方法。方便測试
  @Override
  public String toString() {
    return "Roles [id=" + id + ", roleName=" + roleName + "]";
  }
}

spring配置：

<bean id="roles" class="cn.com.ztz.spring.model.Roles">
    <property name="id" value="2"/>
    <property name="roleName" value="管理员"/>
  </bean>

測试main方法:

public static void main(String[] args) {
    ApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
    Roles r=(Roles)context.getBean("roles");
    System.out.println(r.toString());
  }

输出结果:

Roles [id=2, roleName=管理员]

看spring配置。我们能发现构造器<constructor-arg/> set注入是<property/> 

一个bean引用其它的bean也是几乎相同的。看下样例

public class Roles {
  private int id;
  private String roleName;
  private Users users;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getRoleName() {
    return roleName;
  }
  public void setRoleName(String roleName) {
    this.roleName = roleName;
  }
  public void setUsers(Users users) {
    this.users = users;
  }
  public Users getUsers() {
    return users;
  }
  //重写toString方法，方便測试
  @Override
  public String toString() {
    return "Roles [id=" + id + ", roleName=" + roleName + ", users="
        + users + "]";
  }
}

public class Users {
  private int id;
  private String name;
  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;
  }

  @Override
  public String toString() {
    return "Users [id=" + id + ", name=" + name + "]";
  }
}

spring配置：

<bean id="roles" class="cn.com.ztz.spring.model.Roles">
    <property name="id" value="2"/>
    <property name="roleName" value="管理员"/>
    <property name="users" ref="users"/>
  </bean>

  <bean id="users" class="cn.com.ztz.spring.model.Users">
    <property name="id" value="2"/>
    <property name="name" value="张三"/>
  </bean>

执行以上測试方法输出结果：

Roles [id=2, roleName=管理员, users=Users [id=2, name=张三]]