通过Java反射做实体查询

我们在使用hibernate的时候，查询的时候都会和实体中的一些字段相结合去查询，当然字段少了，还算是比较简单，当字段多了，就不那么容易了，所以就自己写了个方法，根据实体中的字段信息去查询，废话不多说上代码：

/**
     * 根据实体查询，将所有的参数封装到实体中查询即可，不可查询为null的信息
     * @param t
     * @return
     * @throws SecurityException
     * @throws NoSuchMethodException
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     */
    public List<T> queryAll(T t) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException{
        //存放参数
        List<Object> paraList = new ArrayList<Object>();
        List<T> list = new ArrayList<T>();
        StringBuffer sb = new StringBuffer("from ");
        sb.append(entityClass.getSimpleName()).append(" where 1=1 ");
        if( t == null){
            list = find(sb.toString());
            return list;
        }
        //拼接hql语句
        //获取类中所有的属性
        Field[] fields = t.getClass().getDeclaredFields();
        for(Field field : fields){
            //字段名称
            String fieldName = field.getName();
            //方法名称
            String methodName = getMethodName(fieldName, "get");
            //方法
            Method method = UserInfo.class.getDeclaredMethod(methodName);
            //方法的返回值类型
            String methodReturnType = method.getReturnType().getSimpleName();
            Object obj = null;
            obj = method.invoke(t);
            //返回值为空则跳过
            if( obj == null ){
                continue;
            }
            if ("String".equals(methodReturnType)) {
                String str = String.valueOf(obj.toString());
                sb.append(" and ").append(fieldName).append("= ? ");
                paraList.add(str);
            } else if ("Date".equals(methodReturnType)) {
                Date date = (Date)obj;
                sb.append(" and ").append(fieldName).append("= ? ");
                paraList.add(date);
            } else if ("Integer".equals(methodReturnType)
                    || "int".equals(methodReturnType)) {
                Integer i = Integer.valueOf(obj.toString());
                sb.append(" and ").append(fieldName).append("= ? ");
                paraList.add(i);
            } else if ("Long".equalsIgnoreCase(methodReturnType)) {
                Long L = Long.valueOf(obj.toString());
                sb.append(" and ").append(fieldName).append("= ? ");
                paraList.add(L);
            } else if ("Double".equalsIgnoreCase(methodReturnType)) {
                Double d = Double.valueOf(obj.toString());
                sb.append(" and ").append(fieldName).append("= ? ");
                paraList.add(d);
            } else if ("Boolean".equalsIgnoreCase(methodReturnType)) {
                Boolean b = Boolean.valueOf(obj.toString());
                sb.append(" and ").append(fieldName).append("= ? ");
                paraList.add(b);
            }
        }
        Query query = createQuery(sb.toString(), paraList.toArray());
        list = query.list();
        return list;
    }

    /**
     * 或实体中属性的get或set方法
     * @param methodName  字段名
     * @param methodType  方法类型：get或set
     * @return
     */
    private String getMethodName(String methodName, String methodType){
        if( methodName == null || "".equals(methodName.trim()) ){
            return null;
        }
        StringBuffer sb = new StringBuffer();
        sb.append(methodType);
        sb.append(methodName.substring(0, 1).toUpperCase());
        sb.append(methodName.substring(1));
        return sb.toString();
    }

本人反射学得比较浅显，希望高手能够多多指点。

通过Java反射做实体查询