带条件查询及分页
1.思路分析
2.代码编写
JSP 动作元素:
| jsp:forward |
把请求转到一个新的页面 |
Index.jsp进入servlet
| <body> <jsp:forward page="bookServlet.do" /> body> |
在每个页面跳转到Servlet添加一个变量(choose),根据操作的不同传递不同的值,来区分用户的操作
Index.jsp
add.jsp
Servlet
- 编写查询
需求：
- 在booklist.jsp页面需要显示所有图书类型
1.需要查询全部图书类型
Booklist.jsp
| <style type="text/css"> div{ width: 800px; height: 600px; margin: 0px auto; border: 1px solid red;}
style> head> <body> <div> <h1 style="text-align: center;">图书借阅系统h1> <form action="bookServlet.do" method="post" style="text-align: center;" > 图书分类<select name="booktypeid"> <option value="0">全部option> select> 图书名称<input type="text" name="bookname"> 是否借阅<select name="borrow"> <option value="-1">请选择option> <option value="0">未借阅option> <option value="1">已借阅option> select> <input type="hidden" name="choose" value="1"> <input type="submit" value="查询">
form> div> body> |
Servlet中查询的代码编写
查询图书类型
| /** * 查询图书类型 * @param request * @param response * @throws ServletException * @throws IOException */ protected void queryBookType(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //调用service层的方法 List //存 HttpSession session=request.getSession(); session.setAttribute("bookTypes",bookTypes );
} |
三层编写
| public class BookTypeDaoImpl implements BookTypeDao {
private QueryRunner queryRunner=C3P0Util.getQueryRunner();
@Override public List String sql="SELECT * from book_type"; List try { bookTypes= queryRunner.query(sql,new BeanListHandler } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return bookTypes; }
} |
- 页面是带3个条件的分页的动态查询
在servlet中需要获取到3个参数及当前页码数
参数:
图书分类
图书名称
是否借阅
当前页码数
分析：
页面 需要显示当前页码数 和总页数
最终页面要显示的数据:
图书的集合
当前页码数
总页数
选择图书类型及按图书名称和状态查询后 在对应的位置参数要回显
#7行数数据 如果每页显示3行--》3页
#总页数=总记录数/每页显示的行数 (总记录数%每页显示的行数==0)
#总页数=总记录数/每页显示的行数+1 (总记录数%每页显示的行数!=0)
#第一页
SELECT * from book_info LIMIT 0,3
#第二页
SELECT * from book_info LIMIT 3,3
#第三页
SELECT * from book_info LIMIT 6,3
#第一个参数与当前页码数的关系 （当前页码数-1）*每页显示的行数
--》将分页需要的参数 封装成javaBean
| /** * 属性设置的顺序:1.pageSize(每页显示的行数) 2.rows(总行数) 3. pageNo(当前页码数) * @author Administrator * * @param */ public class PageBean
private List private Integer pageNo = 1;// 当前页码数 private Integer pageSize = 4; // 每页显示的行数 private Integer totalPage;// 总页数 private Integer rows;// 总行数
public List return lists; }
public void setLists(List this.lists = lists; }
public Integer getPageNo() { return pageNo; }
public void setPageNo(Integer pageNo) { if (null == pageNo) { this.pageNo = 1; // 当前页码数 一直点击下一页 变成了 5了 但是数据库查询出来的总页数 只有3页 // 这种情况 当前页码数=总页数(3) //如果在进行上述计算的时候 查询总页数的代码有问题 导致总页数=0 //这个时候当前页码数=0 } else if (pageNo > this.totalPage&&this.totalPage>0) { // --》totalPage有值--》pageSize(rows) 要预防多条件查询 总记录数为0 导致当前页码数为0 limit第一个参数为负数 this.pageNo = this.totalPage; } else if(pageNo<=0){ this.pageNo = 1; }else{ this.pageNo=pageNo; } }
public Integer getPageSize() { return pageSize; }
public void setPageSize(Integer pageSize) { this.pageSize = pageSize; }
public Integer getTotalPage() { return totalPage; }
public Integer getRows() { return rows; }
public void setRows(Integer rows) { this.rows = rows; //自动计算出总页数 this.totalPage=rows%this.pageSize==0?rows/this.pageSize:rows/this.pageSize+1; }
}
|
动态条件查询分页代码编写:
分页动态查询Servlet
| protected void queryBook(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 取调存转 String booktypeid = request.getParameter("booktypeid"); String bookname = request.getParameter("bookname"); String borrow = request.getParameter("borrow"); String pageno = request.getParameter("pageno");
// 查询总行数 int count = bookService.bookCount(Integer.parseInt(booktypeid), bookname, Integer.parseInt(borrow)); // 创建分页工具类的对象 PageBean pageBean.setPageSize(3);// 每页显示的行数 pageBean.setRows(count); // null 注意 pageno要检测是否为null 为null 报 NumberFromatException pageBean.setPageNo(Integer.parseInt(pageno)); // 获取分页的第一个参数 int first = (pageBean.getPageNo() - 1) * pageBean.getPageSize(); // 调用service层 将 查询的条件及 limit的2个参数传递过去 List pageBean.getPageSize());
} |
Service
| public class BookServiceImpl implements BookService {
private BookDao bookdao = new BookDaoImpl();
@Override public int addBook(Book book) {
return bookdao.addBook(book); }
@Override public List // TODO Auto-generated method stub return bookdao.queryBook(booktype, bookname, borrow, frist, end); }
@Override public int bookCount(int booktype, String bookname, int borrow) { // TODO Auto-generated method stub return 0; }
}
|
Dao
| public interface BookDao {
int addBook(Book book);
int bookCount(int booktype,String bookname, int borrow); /** * 动态条件分页查询 * @param booktype 图书类型id 0代码查询全部 * @param bookname 图书名称 * @param borrow 是否借阅 -1代码不按状态查询 * @param frist 分页参数1 * @param end 分页参数2 * @return */ List } |
| public class BookDaoImpl implements BookDao {
private QueryRunner queryRunner = C3P0Util.getQueryRunner();
@Override public int addBook(Book book) { String sql = "insert into book_info(book_code,book_name,book_type,book_author,publish_press,publish_date,is_borrow) VALUES(?,?,?,?,?,?,?) "; int num = 0; try { num = queryRunner.update(sql, book.getBook_code(), book.getBook_name(), book.getBook_type(), book.getBook_author(), book.getPublish_press(), book.getPublish_date(), book.getIs_borrow()); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }
return num; }
@SuppressWarnings({ "unchecked", "rawtypes", "null" }) @Override public List StringBuffer sb = new StringBuffer(); List par = new ArrayList(); List sb.append( "SELECT book_info.book_id,book_info.book_code,book_info.book_name,book_info.book_type,book_info.book_author,book_info.publish_press,book_info.publish_date,book_info.is_borrow,book_info.path, book_type.type_name FROM book_info INNER JOIN book_type ON book_info.book_type = book_type.id where 1=1"); if (booktype != 0) { sb.append(" and book_type=? "); par.add(booktype); } if (bookname != null && !"".equals(bookname)) {
sb.append(" and book_name like ?"); par.add("%" + bookname + "%"); } if (borrow != -1) { sb.append(" and is_borrow=?"); par.add(borrow); } sb.append(" limit ?,?"); par.add(frist); par.add(end); try { books = queryRunner.query(sb.toString(), new BeanListHandler } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return books; }
@SuppressWarnings({ "rawtypes", "unchecked" }) @Override public int bookCount(int booktype, String bookname, int borrow) { StringBuffer sb = new StringBuffer(); sb.append("select COUNT(*) from book_info where 1=1 "); List par = new ArrayList(); Long count = 0l; if (booktype != 0) { sb.append(" and book_type=? "); par.add(booktype); } if (bookname != null && !"".equals(bookname)) {
sb.append(" and book_name like ?"); par.add("%" + bookname + "%"); } if (borrow != -1) { sb.append(" and is_borrow=?"); par.add(borrow); }
try { count = (Long) queryRunner.query(sb.toString(), new ScalarHandler(1), par.toArray()); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }
return count.intValue(); }
}
|
测试
| public class TestServlet { public static void main(String[] args) {
BookService bookService = new BookServiceImpl(); // 取调存转 String booktypeid = "1"; String bookname = "我"; String borrow = "0"; String pageno = "1";
// 查询总行数 int count = bookService.bookCount(Integer.parseInt(booktypeid), bookname, Integer.parseInt(borrow)); // 创建分页工具类的对象 PageBean pageBean.setPageSize(3);// 每页显示的行数 pageBean.setRows(count); // null 注意 pageno要检测是否为null 为null 报 NumberFromatException pageBean.setPageNo(Integer.parseInt(pageno)); // 获取分页的第一个参数 int first = (pageBean.getPageNo() - 1) * pageBean.getPageSize(); // 调用service层 将 查询的条件及 limit的2个参数传递过去 List first, pageBean.getPageSize());
for (Book book : books) { System.out.println(book); } } }
|