JavaWeb代码复用

servlet部分，可能用得到的复用的代码：

1、dopost设置字符

request.setCharacterEncoding("utf-8");

response.setCharacterEncoding("utf-8");

response.setContentType("application/json;charset=utf-8");

2、SQL语句：

增加：

String SQL_ADD="INSERT INTO book(bookid,bookname,bookauthor,pressname,availablenum) VALUE(?,?,?,?,?);";

preparedStatement=connection.prepareStatement(SQL_ADD);

connection.setAutoCommit(false);

preparedStatement.setString(1,bookid);

preparedStatement.setString(2,bookname);

preparedStatement.setString(3,bookauthor);

preparedStatement.setString(4,pressname);

preparedStatement.setString(5,availablenum);

int flag=preparedStatement.executeUpdate();

connection.commit();

删除：

String SQL_DELETE="DELETE FROM book where bookid=?";

preparedStatement=connection.prepareStatement(SQL_DELETE);

preparedStatement.setString(1, bookid);

int flag=preparedStatement.executeUpdate();

if(flag>0)

{

System.out.println("成功删除"+flag+"条图书信息！");

}else {

System.out.println("遇到问题，删除图书信息失败！");

}

修改：

SQL="UPDATE book SET availablenum=? WHERE bookid=?;";

preparedStatement = connection.prepareStatement(SQL);

preparedStatement.setString(1,strnum);

preparedStatement.setString(2, bookid);

查询：

1、查询全部：

String SQL_SELECTALL = "SELECT *FROM book";

preparedStatement = connection.prepareStatement(SQL_SELECTALL);

resultSet = preparedStatement.executeQuery();

while(resultSet.next()) {

String bookid=resultSet.getString("bookid");

String bookname=resultSet.getString("bookname");

String bookauthor=resultSet.getString("bookauthor");

String pressname=resultSet.getString("pressname");

String availablenum=resultSet.getString("availablenum");

newbook=new NewBook(bookid,bookname,bookauthor,pressname,availablenum);

list.add(newbook);

}

2、条件查询（模糊查询）

String SQL="SELECT * FROM book where bookname LIKE ?";

preparedStatement = connection.prepareStatement(SQL);

preparedStatement.setString(1, "%"+bookname+"%");

connection.commit();

resultSet = preparedStatement.executeQuery();

前台jsp页面

1、使用jstl标签

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

2、默认界面

<c:forEach items="${list}" var="book"></c:forEach>

前台调用servlet：

删除

${pageContext.request.contextPath}/

3、验证（servlet传一个message）

<%

　　　　String message = (String)request.getAttribute("message");

　　　　if(message!=null){

%>

<%} %>