废话不多说,直接上代码

一.写一个实体类

package generic;import java.io.Serializable;public class User implements Serializable{	/**	 * 	 */	private static final long serialVersionUID = 1L;		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;	}}

二.公共DAO:BaseDao(crud都写在这里)

package generic;public abstract class BaseDao
     
       {		public void save(T t){		System.out.println(".....");	}		public void delete(){		System.out.println("....");	}}
     

三.DAO的具体实现:UserDa继承BaseDao

package generic;import org.springframework.stereotype.Repository;@Repository("userDao")public class UserDao extends BaseDao
     
      {	}
     

四.公共Service:BaseService(这里写一些公共方法和一个抽象方法,抽象方法为了获取BaseService的具体实现)

package generic;public abstract class BaseService
     
       {	public abstract BaseDao
      
        getBaseDao();	public void save(T t){		getBaseDao().save(t);	}	}
      
     

五.写BaseService的具体实现:UserService并继承BaseService

package generic;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;@Service("userService")public class UserService extends BaseService
     
      {		@Autowired	private UserDao userDao;	@Override	public BaseDao
      
        getBaseDao() {			return userDao;	}}
      
     

　其中第四步和第五步是以前的写法,Spring4的新泻法如下:

 新四:

package generic;import org.springframework.beans.factory.annotation.Autowired;public abstract class BaseService
     
       {	@Autowired	private BaseDao
      
        baseDao;	public void save(T t){		baseDao.save(t);	}}
      
     

新五:

package generic;import org.springframework.stereotype.Service;@Service("userService")public class UserService extends BaseService
     
      {	}
     

大家可以看到现在的代码非常简洁,在步骤新四中,注入的时候spring会去自动去找BaseDao<User>的子类实现并注入