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);
}
}