Java使用PrepareStatement实现数据的插入与查询操作

public class PreparedStatementUpdateTest {
    @Test
    public void testInsert() {
        Connection connection = null;
        PreparedStatement ps = null;
 
        try {
            //1.获取链接
            connection = JDBCUtils.getConnection();
            //2.预编译sql语句，返回PreparedStatement实例
            String sql = "insert into customers(name,email,birth)
            value(?,?,?)";
            ps = connection.prepareStatement(sql);
            //3.填充占位符
            ps.setString(1,"哪吒");
            ps.setString(2,"nezha@gmail.com");
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            java.util.Date parse = sdf.parse("2001-03-21");
            long time = parse.getTime();
            //这个Date是sql中的Date
            ps.setDate(3,new Date(time));
            //4.执行操作
            ps.execute();
        } catch (Exception e) {
            e.printStackTrace();
        }
        //5.资源释放
        JDBCUtils.closeConnection(connection,ps);
    }
}

public class CustomerForQuery {
    public Customer commonQueryForCustomer(String sql,Object ...obj){
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet resultSet = null;
        try {
            //1.获取连接
            conn = JDBCUtils.getConnection();
            //2.预编译sql语句，返回PreparedStatement实例
            ps = conn.prepareStatement(sql);
            //3.填充占位符
            for (int i = 0; i < obj.length; i++) {
                ps.setObject(i+1,obj[i]);
            }
            //4.执行查询操作
            resultSet = ps.executeQuery();
            //5.获取描述结果集的对象
            ResultSetMetaData metaData = resultSet.getMetaData();
            int columnCount = metaData.getColumnCount();
            //6.处理结果集
            if(resultSet.next()){
                Customer customer = new Customer();
                for (int i = 0; i < columnCount; i++) {
                    Object object = resultSet.getObject(i + 1);
                    String columnName = metaData.getColumnName(i + 1);
                    Field declaredField =
                            Customer.class.getDeclaredField(columnName);
                    declaredField.setAccessible(true);
                    declaredField.set(customer,object);
                }
                return customer;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            //7.关闭资源
            JDBCUtils.closeConnection(conn,ps,resultSet);
        }
        return null;
    }
    @Test
    public void test(){
        String sql = "select name,email from customers where id=?";
        Customer customer = commonQueryForCustomer(sql, 2);
        System.out.println(customer);
    }
}

public class Customer {
    private int id;
    private String name;
    private String email;
    private Date birth;
 
    public Customer() {
    }
 
    public Customer(int id, String name, String email, Date birth) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.birth = birth;
    }
 
    public int getId() {
        return id;
    }
 
    public void setId(int id) {
        this.id = id;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getEmail() {
        return email;
    }
 
    public void setEmail(String email) {
        this.email = email;
    }
 
    public Date getBirth() {
        return birth;
    }
 
    public void setBirth(Date birth) {
        this.birth = birth;
    }
 
    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", birth=" + birth +
                '}';
    }
}