MVC案例——模糊查詢

模糊查詢：

——根據傳入的name,password屬性列進行查詢

——需要在CustomerDAO接口中定義一個getForListWithCriteriaCustomer(CriteriaCustomer cc).

其中CriteriaCustomer用於封裝查詢條件：name，address，phone。

因為查詢條件很多時候和domain類並不相同，所以要做成一個單獨的類

——拼SQL：

• SQL："SELECT ID,NAME,PASSWORD FROM CUSTOMER WHERE"+"NAME LIKE ? AND PASSWORD LIKE ? ";
• 為了正確的填充占位符時，重寫了CriteriaCustomer的getter： 

——修改Servlet：獲取請求參數；把請求參數封裝為CriteriaCustomer對象，再調用getForListWithCriteriaCustomer(CriteriaCustomer cc)方法

 

步驟：

1.首先在CustomerDAO接口中添加該方法。

public List<Customer> getListWithCirteriaCustomer(CriteriaCustomer cc);

　　

2.創建一個CriteriaCustomer類，對成員變量進行封裝

package com.mvcapp.entity;

public class CriteriaCustomer {
    private String name;
    private String password;

    public CriteriaCustomer(String name, String password) {
        this.name = name;
        this.password = password;
    }

    public CriteriaCustomer() {
    }

    public String getName() {
        if (name == null){
            name="%%";
        }else{
            name="%"+ name +"%";
        }
        return name;
    }

    @Override
    public String toString() {
        return "CriteriaCustomer{" +
                "name='" + name + '\'' +
                ", password='" + password + '\'' +
                '}';
    }


    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        if (password == null){
            password="%%";
        }else{
            password="%"+ password +"%";
        }
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

　　

3.在CustomerDAOimpl實現類實現該方法

 public List<Customer> getListWithCirteriaCustomer(CriteriaCustomer cc) {
        String sql = "SELECT ID,NAME,PASSWORD FROM CUSTOMER WHERE" + " NAME LIKE ? AND PASSWORD LIKE ?";
        return getForList(sql,cc.getName(),cc.getPassword());//調用DAO層中方法
    }

　　

4.可以對這個實現方法進行一個測試

 @Test
    public void testGetListWithCriteriaCustomer(){
        CriteriaCustomer criteriaCustomer = new CriteriaCustomer("Y",null);
        List<Customer> customers = customerDAO.getListWithCirteriaCustomer(criteriaCustomer);
        System.out.println(customers);
    }

　　

5.修改Servlet，修改query方法

 private void query(HttpServletRequest req,HttpServletResponse resp){
        String name = req.getParameter("name");
        String password = req.getParameter("password");
        CriteriaCustomer criteriaCustomer = new CriteriaCustomer(name,password);

        List<Customer> list =  customerDAO.getListWithCirteriaCustomer(criteriaCustomer);
        req.setAttribute("list",list);
        try {
            req.getRequestDispatcher("/query.jsp").forward(req,resp);
        } catch (ServletException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

　　

效果：