Hql拼接助手代码,Java代码库,德仔网

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【Java】 Hql拼接助手
作者:osc村长 / 发布于2015/4/8/ 572

	import java.util.ArrayList;
	import java.util.List;
	
	/**
	* HQL语句生成助手类
	*/
	public class HqlHelper {
	 private String selectClause; // Select子句
	 private String fromClause; // From子句
	 private String whereClause; // Where子句
	 private String orderClause; // Order子句
	
	 private List<Object> paramList = new ArrayList<Object>();
	
	
	 /**
	 * 生成From子句
	 *
	 * @param clazz
	 */
	 public HqlHelper(Class clazz) {
	 fromClause = "FROM " + clazz.getName();
	 }
	
	 /**
	 * 生成From子句，使用指定的别名
	 *
	 * @param clazz
	 * @param alias
	 */
	 public HqlHelper(Class clazz, String alias) {
	 fromClause = " FROM " + clazz.getName() + " " + alias;
	 }
	
	 /**
	 * 拼接Select子句
	 *
	 * @param propertyName
	 */
	 public HqlHelper addSelectProperty(String propertyName) {
	 if (selectClause == null) {
	 selectClause = "SELECT DISTINCT " + propertyName;
	 } else {
	 selectClause += ", " + propertyName;
	 }
	
	 return this;
	 }
	
	 /**
	 * 拼接Where子句
	 *
	 * @param condition where条件,如："name>?" "age=?"
	 * @param paramValues 对应于where条件中?传递的参数
	 * @return HqlHelper本身，支持方法链调用
	 */
	 public HqlHelper addWhereCondition(String condition, Object...paramValues) {
	 if (whereClause == null) {
	 whereClause = " WHERE " + condition;
	 } else {
	 whereClause += " AND " + condition;
	 }
	
	 // 保存参数??
	 if (paramValues != null && paramValues.length > 0) {
	 for (Object obj : paramValues) {
	 paramList.add(obj);
	 }
	 }
	
	 return this;
	 }
	
	 /**
	 * 添加 IN 条件
	 * @param propertyName
	 * @param paramValues
	 * @return
	 */
	 public HqlHelper addInCondition(String propertyName,Object...paramValues){
	 if(paramValues==null||paramValues.length==0){
	 return this;
	 }
	 if(whereClause==null){
	 whereClause=" WHERE "+propertyName+" IN (?";
	 }else{
	 whereClause+=" AND "+propertyName+"IN (?";
	 }
	 for(int i=1;i<paramValues.length;i++){
	 whereClause+=",?";
	 }
	 whereClause+=") ";
	 // 保存参数??
	 for (Object obj : paramValues) {
	 paramList.add(obj);
	 }
	 return this;
	 }
	 /**
	 * 拼接Order子句
	 *
	 * @param propertyName 排序的字段名称
	 * @param isAsc 是否是升序
	 */
	 public HqlHelper addOrderProperty(String propertyName, boolean isAsc) {
	 if (orderClause == null) {
	 orderClause = " ORDER BY " + propertyName + (isAsc ? " ASC" : " DESC");
	 } else {
	 orderClause += ", " + propertyName + (isAsc ? " ASC" : " DESC");
	 }
	 return this;
	 }
	
	 /**
	 * 获取查询数据列表的HQL语句
	 *
	 * @return
	 */
	 public String getQueryListHql() {
	 StringBuffer hql = new StringBuffer();
	
	 // 1，Select子句
	 if (selectClause != null) {
	 hql.append(selectClause);
	 }
	
	 // 2，Form子句
	 hql.append(fromClause);
	
	 // 3，Where子句
	 if (whereClause != null) {
	 hql.append(whereClause);
	 }
	
	 // 4，Order子句
	 if (orderClause != null) {
	 hql.append(orderClause);
	 }
	
	 return hql.toString();
	 }
	
	 /**
	 * 获取查询总记录数的HQL语句（没有Order子句?)
	 *
	 * @return
	 */
	 public String getQueryCountHql() {
	 StringBuffer hql = new StringBuffer();
	
	 // 1，Select子句
	 if (selectClause == null) {
	 hql.append("SELECT COUNT(*) ");
	 } else {
	 // SELECT DISTINCT id,name --> SELECT COUNT(DISTINCT id,name)
	 hql.append("SELECT COUNT(" + selectClause.substring("SELECT ".length()) + ") ");
	 }
	
	 // 2，Form子句
	 hql.append(fromClause);
	
	 // 3，Where子句
	 if (whereClause != null) {
	 hql.append(whereClause);
	 }
	
	 // 不需要Order子句
	
	 return hql.toString();
	 }
	
	 /**
	 * 获取参数列表
	 *
	 * @return
	 */
	 public List<Object> getParamList() {
	 return paramList;
	 }
	
	}
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