mybatis帮助程序猿省去了很多工作了，需要结合好BaseDao与BaseService，这里就提供下我所使用的BaseXXX。

前提，mybatis的映射文件是采用mybatis-generator自动生成的（）

1、BaseDao，我们知道在mybatis与SpringMVC结合的时候，Dao层只需要写interface即可，剩下的实现工作将由mybatis自动为我们实现，这个BaseDao省去interface这层，采用SpringMvc的@Repository标签进行注入管理，上代码：

import java.io.Serializable;  import java.lang.reflect.InvocationTargetException;  import java.util.HashMap;  import java.util.List;  import java.util.Map;    import org.apache.commons.beanutils.PropertyUtils;  import org.apache.ibatis.session.RowBounds;  import org.apache.ibatis.session.SqlSessionFactory;  import org.mybatis.spring.support.SqlSessionDaoSupport;  import org.springframework.beans.factory.annotation.Autowired;  import org.springframework.stereotype.Repository;    import com.alibaba.dubbo.common.utils.CollectionUtils;  import com.github.pagehelper.PageHelper;  import com.github.pagehelper.PageInfo;  //工具类  import com.ivan.core.util.GenericsUtils;  //分页Form  import com.ivan.core.util.page.PageForm;    @Repository("baseDao")  public class BaseDao
    
      extends SqlSessionDaoSupport implements Serializable {            private static final long serialVersionUID = 7623507504198633838L;        private final String POSTFIX = "Dao";        private final String _INSERT = ".insert";        private final String _INSERTSELECTIVE = ".insertSelective";        private final String _SELECTBYPRIMARYKEY = ".selectByPrimaryKey";        private final String _UPDATEBYPRIMARYKEY = ".updateByPrimaryKey";        private final String _UPDATEBYPRIMARYKEYSELECTIVE = ".updateByPrimaryKeySelective";        private final String _DELETEBYPRIMARYKEY = ".deleteByPrimaryKey";            @Autowired      public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {          super.setSqlSessionFactory(sqlSessionFactory);      }      /*GenericsUtils为工具类，请见下方代码           泛型获得XXXEntity，将其转换为XXXEntityDao，具体操作替换掉Entity变成XXXDao，对应Mapper.xml中的namespace命名         */      @SuppressWarnings({ "unchecked", "rawtypes" })      public String getNampSpace() {          Class
     
       clazz = (Class)GenericsUtils.getSuperClassGenricType(this.getClass());          String simpleName = clazz.getSimpleName() + POSTFIX;          return simpleName;      }            public int insert(T entity) {          return getSqlSession().insert(                  (this.getNampSpace().contains("Entity") ? this.getNampSpace().replace("Entity", "")                          : this.getNampSpace()) + _INSERT, entity);      }                  public int insertSelective(T record) {          return getSqlSession().insert(                  (this.getNampSpace().contains("Entity") ? this.getNampSpace().replace("Entity", "")                          : this.getNampSpace()) + _INSERTSELECTIVE, record);      }        public T selectByPrimaryKey(PK id) {          return getSqlSession().selectOne(                  (this.getNampSpace().contains("Entity") ? this.getNampSpace().replace("Entity", "")                          : this.getNampSpace()) + _SELECTBYPRIMARYKEY, id);      }              public int updateByPrimaryKey(T record) {          return getSqlSession().update(                  (this.getNampSpace().contains("Entity") ? this.getNampSpace().replace("Entity", "")                          : this.getNampSpace()) + _UPDATEBYPRIMARYKEY, record);      }        public int updateByPrimaryKeySelective(T record) {          return getSqlSession().update(                  (this.getNampSpace().contains("Entity") ? this.getNampSpace().replace("Entity", "")                          : this.getNampSpace()) + _UPDATEBYPRIMARYKEYSELECTIVE, record);      }        public int deleteByPrimaryKey(PK id) {          return getSqlSession().delete(                  (this.getNampSpace().contains("Entity") ? this.getNampSpace().replace("Entity", "")                          : this.getNampSpace()) + _DELETEBYPRIMARYKEY, id);      }        @SuppressWarnings({ "rawtypes", "unchecked" })      public PageInfo
      
        pageFind(String statementKey, PageForm pageForm, Object parameter,              Boolean isSimplePage) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {          Map params = new HashMap();          if (parameter != null) {              if (parameter instanceof Map) {                  params.putAll((Map) parameter);              } else {                  Map parameterObject = PropertyUtils.describe(parameter);                  params.putAll(parameterObject);              }          }          PageHelper.startPage(pageForm.getPage(), pageForm.getRows());          List
       
         list = getSqlSession().selectList(statementKey, params);          PageInfo
        
          pageInfo = new PageInfo(list);            return pageInfo;      }        @SuppressWarnings({ "rawtypes", "unchecked" })      public List
         
           findTop(int top, String statementKey, Object parameter) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { Map params = new HashMap(); if (parameter != null) { if (parameter instanceof Map) { params.putAll((Map) parameter); } else { Map parameterObject = PropertyUtils.describe(parameter); params.putAll(parameterObject); } } List
          
            list = getSqlSession().selectList(statementKey, params, new RowBounds(0, top)); return list; } public T findTopOne(String statementKey, Object parameter) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { List
           
             list = findTop(1, statementKey, parameter); return CollectionUtils.isEmpty(list) ? null : list.get(0); } @SuppressWarnings({ "rawtypes", "unchecked" }) public 
            
              PageInfo
             
               pageFindModel(String statementKey, PageForm pageForm, Object parameter) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { Map params = new HashMap(); if (parameter != null) { if (parameter instanceof Map) { params.putAll((Map) parameter); } else { Map parameterObject = PropertyUtils.describe(parameter); params.putAll(parameterObject); } } PageHelper.startPage(pageForm.getPage(), pageForm.getRows()); List
              
                list = getSqlSession().selectList(statementKey, params); PageInfo
               
                 pageInfo = new PageInfo(list); return pageInfo; } }
               
              
             
            
           
          
         
        
       
      
     
    

2、泛型工具类，GenericsUtils：

import java.lang.reflect.Field;  import java.lang.reflect.Method;  import java.lang.reflect.ParameterizedType;  import java.lang.reflect.Type;  import java.util.ArrayList;  import java.util.List;  import java.util.Random;    import javax.servlet.http.HttpSession;    import org.springframework.web.context.request.RequestContextHolder;  import org.springframework.web.context.request.ServletRequestAttributes;    /**  * 泛型工具类  *   * @author ShunLi  * @notes Created on 2010-1-21
  *        Revision of last commit:$Revision: 1.1 $
  *        Author of last commit:$Author: ghp $
  *        Date of last commit:$Date: 2010-01-25 16:48:17 +0800 (周一, 25 一月 2010)  *        $
  *        
  */  public class GenericsUtils {      /**      * 通过反射,获得指定类的父类的泛型参数的实际类型. 如BuyerServiceBean extends DaoSupport
     
            *       * @param clazz      *            clazz 需要反射的类,该类必须继承范型父类      * @param index      *            泛型参数所在索引,从0开始.      * @return 范型参数的实际类型, 如果没有实现ParameterizedType接口，即不支持泛型，所以直接返回      *         
      Object.class      */      public static Class getSuperClassGenricType(Class clazz, int index) {          Type genType = clazz.getGenericSuperclass();// 得到泛型父类          // 如果没有实现ParameterizedType接口，即不支持泛型，直接返回Object.class          if (!(genType instanceof ParameterizedType)) {              return Object.class;          }          // 返回表示此类型实际类型参数的Type对象的数组,数组里放的都是对应类型的Class, 如BuyerServiceBean extends          // DaoSupport
      
       就返回Buyer和Contact类型          Type[] params = ((ParameterizedType) genType).getActualTypeArguments();          if (index >= params.length || index < 0) {              throw new RuntimeException("你输入的索引" + (index < 0 ? "不能小于0" : "超出了参数的总数"));          }          if (!(params[index] instanceof Class)) {              return Object.class;          }          return (Class) params[index];      }        /**      * 通过反射,获得指定类的父类的第一个泛型参数的实际类型. 如BuyerServiceBean extends DaoSupport
       
              *       * @param clazz      *            clazz 需要反射的类,该类必须继承泛型父类      * @return 泛型参数的实际类型, 如果没有实现ParameterizedType接口，即不支持泛型，所以直接返回      *         
        Object.class      */      @SuppressWarnings("unchecked")      public static Class getSuperClassGenricType(Class clazz) {          return getSuperClassGenricType(clazz, 0);      }        /**      * 通过反射,获得方法返回值泛型参数的实际类型. 如: public Map
        
          getNames(){}      *       * @param Method      *            method 方法      * @param int index 泛型参数所在索引,从0开始.      * @return 泛型参数的实际类型, 如果没有实现ParameterizedType接口，即不支持泛型，所以直接返回      *         
         Object.class      */      @SuppressWarnings("unchecked")      public static Class getMethodGenericReturnType(Method method, int index) {          Type returnType = method.getGenericReturnType();          if (returnType instanceof ParameterizedType) {              ParameterizedType type = (ParameterizedType) returnType;              Type[] typeArguments = type.getActualTypeArguments();              if (index >= typeArguments.length || index < 0) {                  throw new RuntimeException("你输入的索引" + (index < 0 ? "不能小于0" : "超出了参数的总数"));              }              return (Class) typeArguments[index];          }          return Object.class;      }        /**      * 通过反射,获得方法返回值第一个泛型参数的实际类型. 如: public Map
         
           getNames(){} * * @param Method * method 方法 * @return 泛型参数的实际类型, 如果没有实现ParameterizedType接口，即不支持泛型，所以直接返回 * 
          Object.class */ @SuppressWarnings("unchecked") public static Class getMethodGenericReturnType(Method method) { return getMethodGenericReturnType(method, 0); } /** * 通过反射,获得方法输入参数第index个输入参数的所有泛型参数的实际类型. 如: public void add(Map
          
            maps, List
           
             names){} * * @param Method * method 方法 * @param int index 第几个输入参数 * @return 输入参数的泛型参数的实际类型集合, 如果没有实现ParameterizedType接口，即不支持泛型，所以直接返回空集合 */ @SuppressWarnings("unchecked") public static List
            
              getMethodGenericParameterTypes(Method method, int index) { List
             
               results = new ArrayList
              
               (); Type[] genericParameterTypes = method.getGenericParameterTypes(); if (index >= genericParameterTypes.length || index < 0) { throw new RuntimeException("你输入的索引" + (index < 0 ? "不能小于0" : "超出了参数的总数")); } Type genericParameterType = genericParameterTypes[index]; if (genericParameterType instanceof ParameterizedType) { ParameterizedType aType = (ParameterizedType) genericParameterType; Type[] parameterArgTypes = aType.getActualTypeArguments(); for (Type parameterArgType : parameterArgTypes) { Class parameterArgClass = (Class) parameterArgType; results.add(parameterArgClass); } return results; } return results; } /** * 通过反射,获得方法输入参数第一个输入参数的所有泛型参数的实际类型. 如: public void add(Map
               
                 * maps, List
                
                  names){} * * @param Method * method 方法 * @return 输入参数的泛型参数的实际类型集合, 如果没有实现ParameterizedType接口，即不支持泛型，所以直接返回空集合 */ @SuppressWarnings("unchecked") public static List
                 
                   getMethodGenericParameterTypes(Method method) { return getMethodGenericParameterTypes(method, 0); } /** * 通过反射,获得Field泛型参数的实际类型. 如: public Map
                  
                    names; * * @param Field * field 字段 * @param int index 泛型参数所在索引,从0开始. * @return 泛型参数的实际类型, 如果没有实现ParameterizedType接口，即不支持泛型，所以直接返回 * 
                   Object.class */ @SuppressWarnings("unchecked") public static Class getFieldGenericType(Field field, int index) { Type genericFieldType = field.getGenericType(); if (genericFieldType instanceof ParameterizedType) { ParameterizedType aType = (ParameterizedType) genericFieldType; Type[] fieldArgTypes = aType.getActualTypeArguments(); if (index >= fieldArgTypes.length || index < 0) { throw new RuntimeException("你输入的索引" + (index < 0 ? "不能小于0" : "超出了参数的总数")); } return (Class) fieldArgTypes[index]; } return Object.class; } /** * 通过反射,获得Field泛型参数的实际类型. 如: public Map
                   
                     names; * * @param Field * field 字段 * @param int index 泛型参数所在索引,从0开始. * @return 泛型参数的实际类型, 如果没有实现ParameterizedType接口，即不支持泛型，所以直接返回 * 
                    Object.class */ @SuppressWarnings("unchecked") public static Class getFieldGenericType(Field field) { return getFieldGenericType(field, 0); } /** * 根据实体得到实体的所有属性 * @param objClass * @return * @throws ClassNotFoundException */ public static String[] getColumnNames(String objClass) throws ClassNotFoundException { String[] wageStrArray = null; if (objClass != null) { Class class1 = Class.forName(objClass); Field[] field = class1.getDeclaredFields();// 这里便是获得实体Bean中所有属性的方法 StringBuffer sb = new StringBuffer(); for (int i = 0; i < field.length; i++) {// 这里不多说了 sb.append(field[i].getName()); // 这是分割符 是为了去掉最后那个逗号 // 比如 如果不去最后那个逗号 最后打印出来的结果是 "id,name," // 去了以后打印出来的是 "id,name" if (i < field.length - 1) { sb.append(","); } } // split(",");这是根据逗号来切割字符串使字符串变成一个数组 wageStrArray = sb.toString().split(","); return wageStrArray; } else { return wageStrArray; } } public static Object[] field2Value(Field[] f, Object o) throws Exception { Object[] value = new Object[f.length]; for (int i = 0; i < f.length; i++) { value[i] = f[i].get(o); } return value; } /** * returns the current http session object * * @return session */ public HttpSession getSession() { HttpSession session=null; ServletRequestAttributes attr = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes(); HttpSession contextSess = attr == null ? session : attr.getRequest().getSession(true); return contextSess; } /** * 得到实体类 * @param objClass 实体类包含包名 * @return */ public static Class getEntityClass(String objClass){ Class entityClass = null; try { entityClass = Class.forName(objClass); } catch (ClassNotFoundException e) { e.printStackTrace(); } return entityClass; } /** * 定义字符集 * @param * @return */ private static char[] chars = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B','C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'}; //72个字符集 /** * * @param passLength * 随机密码长度 * @param count * 随机密码个数 * @return 随机密码数组 */ public static String getPasswords(int passLength) { String passwords = "";// 新建一个长度为指定需要密码个数的字符串数组 Random random = new Random(); StringBuilder password = new StringBuilder("");// 保存生成密码的变量 for (int m = 1; m <= passLength; m++) {// 内循环 从1开始到密码长度 正式开始生成密码 password.append(chars[random.nextInt(62)]);// 为密码变量随机增加上面字符中的一个 } passwords = password.toString();// 将生成出来的密码赋值给密码数组 return passwords; } }
                   
                  
                 
                
               
              
             
            
           
          
         
        
       
      
     

3、BaseService接口，为什么这层要选择接口来实现呢？有很多需要前后分离的应用，暴露的服务就是接口暴露Service层，所以采用接口。

import java.io.Serializable;  import java.lang.reflect.InvocationTargetException;  import java.util.List;    @SuppressWarnings("hiding")  public interface BaseService
    
      {            public int insert(T record);      public int insertSelective(T record);      public T selectByPrimaryKey(String id);      public int updateByPrimaryKey(T record);      public int updateByPrimaryKeySelective(T record);      public int deleteByPrimaryKey(String id);      public List
     
       findTop(int top, String statementKey, Object parameter) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException;      public T findTopOne(String statementKey, Object parameter) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException;  }
     
    

4、BaseService接口的实现类BaseServiceImpl，需要注入BaseDao（其中必须对BaseDao进行set，否则无法获取具体泛型）

import java.io.Serializable;  import java.lang.reflect.InvocationTargetException;  import java.util.List;    import org.springframework.beans.factory.annotation.Autowired;    import com.alibaba.dubbo.config.annotation.Service;  import com.ivan.api.base.BaseService;  import com.ivan.base.BaseDao;    @Service  public abstract class BaseServiceImpl
    
      implements BaseService
     
      {            @Autowired      private BaseDao
      
        baseDao;            public BaseDao
       
         getBaseDao() {          return baseDao;      }      public void setBaseDao(BaseDao
        
          baseDao) {          this.baseDao = baseDao;      }        public int insert(T entity) {          return baseDao.insert(entity);      }        public int insertSelective(T record) {          return baseDao.insertSelective(record);      }        public T selectByPrimaryKey(String id) {          return baseDao.selectByPrimaryKey(id);      }        public int updateByPrimaryKey(T record) {          return baseDao.updateByPrimaryKey(record);      }        public int updateByPrimaryKeySelective(T record) {          return baseDao.updateByPrimaryKeySelective(record);      }        public int deleteByPrimaryKey(String id) {          return baseDao.deleteByPrimaryKey(id);      }        public List
         
           findTop(int top, String statementKey, Object parameter) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { return baseDao.findTop(top, statementKey, parameter); } public T findTopOne(String statementKey, Object parameter) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { return baseDao.findTopOne(statementKey, parameter); } }
         
        
       
      
     
    

5、Mapper.xml文件的定义，需要注意的是namespace的命名，会通过这个命名找到具体的mapper文件，进行数据的操作。

        
        
           
            
            
          
         
     
            id, name, age    
             
           select            from user            
           select             from user      where id = #{id,jdbcType=INTEGER}        
     
            delete from user      where id = #{id,jdbcType=INTEGER}    
         
     
            insert into user (id, name, age        )      values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER}        )    
         
     
            insert into user      
              
       
                  id,        
               
       
                  name,        
               
       
                  age,        
             
            
              
       
                  #{id,jdbcType=VARCHAR},        
               
       
                  #{name,jdbcType=VARCHAR},        
               
       
                  #{age,jdbcType=INTEGER},        
             
          
         
     
            update user      
              
       
                  name = #{name,jdbcType=VARCHAR},        
               
       
                  age = #{age,jdbcType=INTEGER},        
             
            where id = #{id,jdbcType=VARCHAR}    
         
     
            update user      set name = #{name,jdbcType=VARCHAR},        age = #{age,jdbcType=INTEGER}      where id = #{id,jdbcType=VARCHAR}    
       
    

6、具体的使用方法：

a、定义UserDao：

@Repository("userDao")  public class UserDao extends BaseDao
    
     {        /**      *       */      private static final long serialVersionUID = 9152785684346322571L;    }
    

b、定义UserService接口

public interface UserService extends BaseService
    
     {            }
    

c、实现UserService接口

@Service  public class UserServiceImpl extends BaseServiceImpl
    
      implements UserService{        }
    

d、调用UserService接口

@Controller  @RequestMapping("/user")  public class UserController {            @SuppressWarnings("unused")      private static final Logger logger = LoggerFactory.getLogger(UserController.class);            @Reference      private UserService userService;  }