因为项目迭代 所以项目复用是必须的 idea 拷贝项目

项目梗概

1. 在crm/customer/list 下面显示
2. list.jsp跳转add.html 进行save操作
3. crm/customer/save

添加Artifacts

对于新创建项目如果未出现 可以在这里进行删除 添加

如果全部删掉

可以进行添加

修改Application context：

资源文件

jar->WEB-INF->lib中

创建lib文件夹 复制jar进去

resources

将阿里巴巴的druid资源文件复制到resources下面

编译一波

Dbs工具类

• 读取配置 注册mysql驱动 DriverManager 或 获取 Datasource（druid）
• 不涉及bean层，dao层

设计一个update功能

要求

• 传入一个sql语句和多个obj用于完善 PreparedStatement
• 返回值int（利用executexx返回值即可）

Dao层呢？

public static boolean save(Customer customer) {
    //String sql = "INSERT INTO customer (name,phone) VALUES ('王盼盼','13505613657');";
    String sql = "INSERT INTO customer (name,phone) VALUES (?,?);";
    return Dbs.update(sql,customer.getName(),customer.getPhone()) > 0 ? true : false;
}

Dbs层

public static int update(String sql,Object... args) {
    try {
        Connection connection = dataSource.getConnection();
        PreparedStatement statement = connection.prepareStatement(sql);
        int index = 1;
        for (Object arg : args) {
            statement.setObject(index,args[index -1]);
            index++;
        }
        System.out.println(statement.toString());
        return statement.executeUpdate();
    } catch (Exception e) {
        return 0;
    }
}

测试

Customer customer = new Customer();
customer.setName("赵小米1");
customer.setPhone("16666666666");
System.out.println(CustomerDao.save(customer) ? "插入成功" : "插入失败");

设计一个query功能

• 返回范型 总不能把bean层传入吧
• 其余类似update功能 Dao层

public static List<Customer> list() {
    //SELECT name,phone FROM customer WHERE `name` LIKE '王%';
    String sql = "SELECT id,name,phone,company_id FROM customer WHERE `name` LIKE ?;";
    List<Customer> list = Dbs.query(sql,(rs, row) -> {
        Customer customer = new Customer();
        customer.setId(Integer.valueOf(rs.getInt("id")));
        customer.setName(rs.getString("name"));
        customer.setPhone(rs.getString("phone"));
        customer.setCompany_id(Integer.valueOf(rs.getInt("company_id")));
        return customer;
    },"王%");
    /**
     * Dbs.query(sql, new Dbs.RowMapper<Customer>() {
     *             @Override
     *             public Customer map(ResultSet rs, int row) throws Exception {
     *                 return null;
     *             }
     *         },"王%");
     */
    return list;
}

Dds层

public static <T> List<T> query(String sql, RowMapper<T> mapper,Object... args) {
    try {
        Connection connection = dataSource.getConnection();
        try (PreparedStatement statement = connection.prepareStatement(sql);){
            int index = 1;
            for (Object arg : args) {
                statement.setObject(index,args[index -1]);
                index++;
            }
            System.out.println(statement.toString());
            List<T> list = new ArrayList<>();
            try (ResultSet resultSet = statement.executeQuery();){
                for (int row = 0; resultSet.next(); row++) {
                    list.add(mapper.map(resultSet,row));
                }
            }
            return list;
        }
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }

}

public interface RowMapper<T> {
    T map(ResultSet rs, int row) throws Exception;
}

测试

List<Customer> list = CustomerDao.list();
for (Customer customer : list) {
    System.out.println(customer);
}

创建servlet 实现多路径

@WebServlet("/customer/*")

做映射