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){
%>

<%} %>