web层：

 public String query(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /* * 1. 封装表单数据到Customer对象中，它只有四个属性（cname、gender、cellphone、email） * 它就是一个条件 * 2. 使用Customer调用service方法，得到List<Customer> * 3. 保存到request域中 * 4. 转发到list.jsp */ Customer criteria = CommonUtils.toBean(request.getParameterMap(), Customer.class); List<Customer> cstmList = customerService.query(criteria); request.setAttribute("cstmList", cstmList); return "/list.jsp"; }

service层：

 /** * 多条件组合查询 * @param criteria * @return */ public List<Customer> query(Customer criteria) { return customerDao.query(criteria); }

domain层：

/** * 领域对象 与表单和数据库表对应 * * @author cxf * */public class Customer { /* * 对应数据库表 */ private String cid;// 主键 private String cname;// 客户名称 private String gender;// 客户性别 private String birthday;// 客户生日 private String cellphone;// 客户手机 private String email;// 客户邮箱 private String description;// 客户的描述 public String getCid() { return cid; } public void setCid(String cid) { this.cid = cid; } public String getCname() { return cname; } public void setCname(String cname) { this.cname = cname; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public String getBirthday() { return birthday; } public void setBirthday(String birthday) { this.birthday = birthday; } public String getCellphone() { return cellphone; } public void setCellphone(String cellphone) { this.cellphone = cellphone; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } @Override public String toString() { return "Customer [cid=" + cid + ", cname=" + cname + ", gender=" + gender + ", birthday=" + birthday + ", cellphone=" + cellphone + ", email=" + email + ", description=" + description + "]"; }}

dao层：

 /** * 多条件组合查询 * @param criteria * @return */ public List<Customer> query(Customer criteria) { try { /* * 1. 给出sql模板 * 2. 给出参数 * 3. 调用query方法，使用结果集处理器：BeanListHandler */ /* * 一、　给出sql模板 * 二、　给出参数！ */ /* * 1. 给出一个sql语句前半部 */ StringBuilder sql = new StringBuilder("select * from t_customer where 1=1"); /* * 2. 判断条件，完成向sql中追加where子句 */ /* * 3. 创建一个ArrayList，用来装载参数值 */ List<Object> params = new ArrayList<Object>(); String cname = criteria.getCname(); if(cname != null && !cname.trim().isEmpty()) { sql.append(" and cname like ?"); params.add("%" + cname + "%"); } String gender = criteria.getGender(); if(gender != null && !gender.trim().isEmpty()) { sql.append(" and gender=?"); params.add(gender); } String cellphone = criteria.getCellphone(); if(cellphone != null && !cellphone.trim().isEmpty()) { sql.append(" and cellphone like ?"); params.add("%" + cellphone + "%"); } String email = criteria.getEmail(); if(email != null && !email.trim().isEmpty()) { sql.append(" and email like ?"); params.add("%" + email + "%"); } /* * 三、执行query */ return qr.query(sql.toString(), new BeanListHandler<Customer>(Customer.class), params.toArray()); } catch(SQLException e) { throw new RuntimeException(e); } }