2019独角兽企业重金招聘Python工程师标准>>> 
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（mybatis-generator使用方法）
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<T, PK extends Serializable> 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<T> 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<T> 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<T> list = getSqlSession().selectList(statementKey, params); PageInfo<T> pageInfo = new PageInfo(list); return pageInfo; } @SuppressWarnings({ "rawtypes", "unchecked" }) public List<T> 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<T> list = getSqlSession().selectList(statementKey, params, new RowBounds(0, top)); return list; } public T findTopOne(String statementKey, Object parameter) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { List<T> list = findTop(1, statementKey, parameter); return CollectionUtils.isEmpty(list) ? null : list.get(0); } @SuppressWarnings({ "rawtypes", "unchecked" }) public <M> PageInfo<M> 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<M> list = getSqlSession().selectList(statementKey, params); PageInfo<M> 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 <a href="http://www.blogjava.net/lishunli/" * target="_jeecg">ShunLi</a> * @notes Created on 2010-1-21<br> * Revision of last commit:$Revision: 1.1 $<br> * Author of last commit:$Author: ghp $<br> * Date of last commit:$Date: 2010-01-25 16:48:17 +0800 (周一, 25 一月 2010) * $<br> * <p> */
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<Buyer> * * @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 * <code>Object.class</code> */ 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<Buyer,Contact>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<Buyer> * * @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 * <code>Object.class</code> */ @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<String, Buyer> 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 * <code>Object.class</code> */ @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<String, Buyer> 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 * <code>Object.class</code> */ @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<String, * Buyer> maps, List<String> 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<Class> getMethodGenericParameterTypes(Method method, int index) { List<Class> results = new ArrayList<Class>(); 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<String, Buyer> * maps, List<String> 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<Class> 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<String, Buyer> 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 * <code>Object.class</code> */ @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<String, Buyer> 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 * <code>Object.class</code> */ @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<T, Serializable> { 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<T> 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<T> implements BaseService<T, Serializable>{ @Autowired private BaseDao<T, Serializable> baseDao; public BaseDao<T, Serializable> getBaseDao() { return baseDao; } public void setBaseDao(BaseDao<T, Serializable> 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<T> 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。
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="UserDao" > <resultMap id="BaseResultMap" type="com.ivan.entity.UserEntity" > <id column="id" property="id" jdbcType="VARCHAR" /> <result column="name" property="name" jdbcType="VARCHAR" /> <result column="age" property="age" jdbcType="INTEGER" /> </resultMap> <sql id="Base_Column_List" > id, name, age </sql> <select id="selectAll" resultMap="BaseResultMap"> select <include refid="Base_Column_List" /> from user </select> <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="String" > select <include refid="Base_Column_List" /> from user where id = #{id,jdbcType=INTEGER} </select> <delete id="deleteByPrimaryKey" parameterType="String" > delete from user where id = #{id,jdbcType=INTEGER} </delete> <insert id="insert" parameterType="com.ivan.entity.UserEntity" > insert into user (id, name, age ) values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER} ) </insert> <insert id="insertSelective" parameterType="com.ivan.entity.UserEntity" > insert into user <trim prefix="(" suffix=")" suffixOverrides="," > <if test="id != null" > id, </if> <if test="name != null" > name, </if> <if test="age != null" > age, </if> </trim> <trim prefix="values (" suffix=")" suffixOverrides="," > <if test="id != null" > #{id,jdbcType=VARCHAR}, </if> <if test="name != null" > #{name,jdbcType=VARCHAR}, </if> <if test="age != null" > #{age,jdbcType=INTEGER}, </if> </trim> </insert> <update id="updateByPrimaryKeySelective" parameterType="com.ivan.entity.UserEntity" > update user <set > <if test="name != null" > name = #{name,jdbcType=VARCHAR}, </if> <if test="age != null" > age = #{age,jdbcType=INTEGER}, </if> </set> where id = #{id,jdbcType=VARCHAR} </update> <update id="updateByPrimaryKey" parameterType="com.ivan.entity.UserEntity" > update user set name = #{name,jdbcType=VARCHAR}, age = #{age,jdbcType=INTEGER} where id = #{id,jdbcType=VARCHAR} </update>
</mapper> 6、具体的使用方法：
a、定义UserDao：
@Repository("userDao")
public class UserDao extends BaseDao<UserEntity, Serializable>{ /** * */ private static final long serialVersionUID = 9152785684346322571L; } b、定义UserService接口
public interface UserService extends BaseService<UserEntity, Serializable>{ } c、实现UserService接口
@Service
public class UserServiceImpl extends BaseServiceImpl<UserEntity> 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;
}