使用泛型类简化ibatis系统架构
jdk1.5的推出为我们带来了枚举、泛型、foreach循环、同步工具包等等好东西。其中，泛型的使用为我们的代码开发提供了很大的简便，简化了我们的代码。
1、设计思路
1）GenericDao泛型类提供所有的增删改查功能；
2）所有的dao在继承GenericDao泛型类拥有自身的增删改查功能，不需再写其他代码。
2、实现GenericDao，基类
public abstract class GenericDao<T, PK extends Serializable> {
protected final Logger logger = LoggerFactory.getLogger(getClass());
public static final String POSTFIX_SELECTBYID = ".selectById";
public static final String POSTFIX_SELECTBYIDS = ".selectByIds";
public static final String POSTFIX_SELECTBYMAP = ".selectByMap";
public static final String POSTFIX_SELECTIDSLIKEBYMAP = ".selectIdsLikeByMap";
public static final String POSTFIX_PKSELECTMAP = ".pkSelectByMap";
public static final String POSTFIX_COUNT = ".count";
public static final String POSTFIX_COUNTLIKEBYMAP = ".countLikeByMap";
public static final String POSTFIX_INSERT = ".insert";
public static final String POSTFIX_DELETEBYID = ".deleteById";
public static final String POSTFIX_DELETEBYIDS = ".deleteByIds";
public static final String POSTFIX_DELETEBYIDSMAP = ".deleteByIdsMap";
public static final String POSTFIX_DELETEBYMAP = ".deleteByMap";
public static final String POSTFIX_UPDATE = ".update";
public static final String POSTFIX_UPDATEBYMAP = ".updateByMap";
public static final String POSTFIX_UPDATEBYIDSMAP = ".updateByIdsMap";
protected Class<T> clazz;
protected String clazzName;
protected T t;
// 定义主从数据库服务器，主数据库负责（Write op），从数据库负责（read op）
@Autowired
protected SqlMapClientTemplate masterSqlMapClientTemplate;
@Autowired
protected SqlMapClientTemplate slaveSqlMapClientTemplate;
public GenericDao() {
// 通过范型反射，取得在子类中定义的class.
clazz = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
clazzName = clazz.getSimpleName();
}
public Integer count(String propertyName, Object propertyValue) {
return count(new String[]{propertyName},new Object[]{propertyValue});
}
public Integer count(String[] propertyNames, Object[] propertyValues) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < propertyNames.length; i++) {
map.put(propertyNames[i], propertyValues[i]);
}
return (Integer) slaveSqlMapClientTemplate.queryForObject(clazz.getName() + POSTFIX_COUNT, map);
}
@Override
public Integer countLikeByMap(String[] propertyNames, Object[] propertyValues) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < propertyNames.length; i++) {
map.put(propertyNames[i], propertyValues[i]);
}
return (Integer) slaveSqlMapClientTemplate.queryForObject(clazz.getName() + POSTFIX_COUNTLIKEBYMAP, map);
}
/** 根据自定义SqlMap中的条件语句查询出记录数量 */
public Integer countByStatementPostfix(String statementPostfix,String[] properties, Object[] propertyValues){
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
return (Integer) slaveSqlMapClientTemplate.queryForObject(clazz.getName() + statementPostfix, map);
}
/**
* 通过id得到实体对象
*/
public T findById(PK id) {
return (T) slaveSqlMapClientTemplate.queryForObject(clazz.getName() + POSTFIX_SELECTBYID, id);
}
/**
* 根据ids获取实体列表
*
* @param ids
* @return
*/
public List<T> findByIds(List<PK> ids) {
return (List<T>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + POSTFIX_SELECTBYIDS, ids);
}
/**
* 直接从数据库查询出ids列表（包括符合条件的所有id）
*
* @param properties
* 查询条件字段名
* @param propertyValues
* 字段取值
* @return
*/
public List<PK> findIdsBy(String[] properties, Object[] propertyValues, String orderBy, String order) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
if (orderBy != null) {
map.put("orderBy", orderBy);
map.put("order", order);
}
return (List<PK>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + POSTFIX_PKSELECTMAP, map);
}
/**
* 根据条件查询结果
*
* @param properties
* 查询条件名
* @param propertyValues
* 查询条件值
* @return
*/
public List<T> findByMap(String[] properties, Object[] propertyValues, String orderBy, String order) {
return (List<T>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + POSTFIX_SELECTBYMAP, map);
}
/**
* 根据条件查询结果的id列表
*
* @param properties
* 查询条件名
* @param propertyValues
* 查询条件值
* @return
*/
public List<PK> findIdsByMap(String[] properties, Object[] propertyValues, String orderBy, String order) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
if (orderBy != null) {
map.put("orderBy", orderBy);
map.put("order", order);
}
return (List<PK>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + POSTFIX_PKSELECTMAP, map);
}
/**
* 分页查询（未处理缓存）
*
* @param properties
* 查询条件字段名
* @param propertyValues
* 字段取值
* @return
*/
public List<T> pageQueryBy(String[] properties, Object[] propertyValues, String orderBy, String order, int pageSize, int pageNo) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
if (orderBy != null) {
map.put("orderBy", orderBy);
map.put("order", order);
}
map.put("limit", true);
map.put("start", (pageNo - 1) * pageSize );// limit 操作
map.put("end", pageSize);
return (List<T>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + POSTFIX_SELECTBYMAP, map);
}
/**
* 从数据库分页查询出ids列表的前200个id
*
* @param properties
* 查询条件字段名
* @param propertyValues
* 字段取值
* @return
*/
protected List<PK> pageQueryIdsBy(String[] properties, Object[] propertyValues, String orderBy, String order) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
if (orderBy != null) {
map.put("orderBy", orderBy);
map.put("order", order);
}
map.put("limit", true);
map.put("start", 0);// 操作
map.put("end", Config.getInstance().getPageCacheSize());
return (List<PK>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + POSTFIX_PKSELECTMAP, map);
}
/**
* 分页查询出id列表（处理缓存）
*
* @param properties
* 查询条件字段名
* @param propertyValues
* 字段取值
* @return
*/
public List<PK> pageQueryIdsByMap(String[] properties, Object[] propertyValues, String orderBy, String order, int pageSize, int pageNo) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
if (orderBy != null) {
map.put("orderBy", orderBy);
map.put("order", order);
}
map.put("limit", true);
map.put("start", (pageNo - 1) * pageSize );// limit 操作
map.put("end", pageSize);
return (List<PK>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + POSTFIX_PKSELECTMAP, map);
}
/** like分页查询(不走列表缓存) */
public List<T> pageLikeBy(String[] properties, Object[] propertyValues, String orderBy, String order, int pageSize, int pageNo){
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
if (orderBy != null) {
map.put("orderBy", orderBy);
map.put("order", order);
}
map.put("limit", true);
map.put("start", (pageNo - 1) * pageSize );// limit 操作
map.put("end", pageSize);
List<PK> ids = (List<PK>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + POSTFIX_SELECTIDSLIKEBYMAP, map);
return findByIds(ids);
}
/**
* 新增对象
*/
public Serializable insert(T o) throws Exception {
if (t instanceof QueryCachable) {
// 清除受影响的缓存
clearListCache(o);
}
return (Serializable) masterSqlMapClientTemplate.insert(clazz.getName() + POSTFIX_INSERT, o);
}
/**
* 更新对象
*/
public T update(T o) throws Exception {
masterSqlMapClientTemplate.update(clazz.getName() + POSTFIX_UPDATE, o);
return o;
}
/**
* 更新对象的部分属性
*/
public int update(PK id, String[] properties, Object[] propertyValues) throws Exception {
// 更新数据库
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
map.put("id", id);
return masterSqlMapClientTemplate.update(clazz.getName() + POSTFIX_UPDATEBYMAP, map);
}
/**
* 根据ID列表更新对象的部分属性
*/
public int updateByIdsMap(List<PK> ids,String[] properties, Object[] propertyValues) throws Exception{
// 更新数据库
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
map.put("ids", ids);
return masterSqlMapClientTemplate.update(clazz.getName() + POSTFIX_UPDATEBYIDSMAP, map);
}
/**
* 根据ID删除对象
*/
public void deleteById(PK id) throws Exception {
masterSqlMapClientTemplate.delete(clazz.getName() + POSTFIX_DELETEBYID, id);
}
/**
* 根据ID删除对象
*/
public void deleteByIds(List<PK> ids) throws Exception {
masterSqlMapClientTemplate.delete(clazz.getName() + POSTFIX_DELETEBYIDS, ids);
}
/** 根据ID及条件删除对象 */
public void deleteByIdsMap(List<PK> ids, String[] properties, Object[] propertyValues) throws Exception {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
map.put("ids", ids);
masterSqlMapClientTemplate.delete(clazz.getName() + POSTFIX_DELETEBYIDSMAP, map);
}
/**
* 根据条件删除对象
*/
public int deleteByMap(String[] properties, Object[] propertyValues) throws Exception {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
return masterSqlMapClientTemplate.delete(clazz.getName() + POSTFIX_DELETEBYMAP, map);
}
/**
* 根据自定义SqlMap中的条件语句查询出列表(注意：不处理缓存)
*/
public List<T> findByStatementPostfix(String statementPostfix, String[] properties, Object[] propertyValues, String orderBy, String order) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
if (orderBy != null) {
map.put("orderBy", orderBy);
map.put("order", order);
}
return slaveSqlMapClientTemplate.queryForList(clazz.getName() + statementPostfix, map);
}
/**
* 根据自定义SqlMap中的条件语句查询出列表(注意：不处理缓存)
*/
public List<T> pageQueryByStatementPostfix(String statementPostfix, String[] properties, Object[] propertyValues, String orderBy, String order,int pageSize,int pageNo) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
if (orderBy != null) {
map.put("orderBy", orderBy);
map.put("order", order);
}
map.put("limit", true);
map.put("start", (pageNo - 1) * pageSize );// limit 操作
map.put("end", pageSize);
List<PK> ids = (List<PK>) slaveSqlMapClientTemplate.queryForList(clazz.getName() + statementPostfix, map);
return findByIds(ids);
}
/**
* 根据自定义SqlMap中的条件语句更新数据（注意：不处理缓存）
*/
public void updateByStatementPostfix(String statementPostfix, String[] properties, Object[] propertyValues) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
masterSqlMapClientTemplate.update(clazz.getName() + statementPostfix, map);
}
/**
* 根据自定义SqlMap中的条件语句删除数据（注意：不处理缓存）
*/
public void deleteByStatementPostfix(String statementPostfix, String[] properties, Object[] propertyValues) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
masterSqlMapClientTemplate.delete(clazz.getName() + statementPostfix, map);
}
/**
* 根据自定义SqlMap中的条件语句插入数据（注意：不处理缓存）
*/
public void insertByStatementPostfix(String statementPostfix, String[] properties, Object[] propertyValues) {
Map<String, Object> map = new HashMap<String, Object>();
for (int i = 0; i < properties.length; i++) {
map.put(properties[i], propertyValues[i]);
}
masterSqlMapClientTemplate.insert(clazz.getName() + statementPostfix, map);
}
}
3、所有其他Dao只需继承GenericDao，传个具体的类型，不需再写增删改查的方法
package com.teacherclub.business.album.dao;
import org.springframework.stereotype.Repository;
import com.teacherclub.business.album.entity.Album;
import com.teacherclub.core.mem.MemcacheUtil;
import com.teacherclub.core.orm.EntityCachable;
import com.teacherclub.core.orm.dao.impl.GenericDao;
@Repository
public class AlbumDao extends GenericDao<Album,Integer> { //传参数Album类
}
此泛型的实现，关键在于：clazz = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
这在项目中经常使用。
