两种跳转方式:
方式1:(跳转后重新刷新页面,request丢失)
response.sendRedirect("地址");
方式2:(跳转后request不丢失)
ServletContext application = this.getServletContext();
RequestDispatcher rd =application.getRequestDispatcher("地址");
rd.forward(request,response);
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session使用方法:
String str1=request.getParameter("UserName");
session.setAttribute("UserName",str1);
String UserName=(String) session.getAttribute("UserName");
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servlet中使用:
1、out:
PrintWriter out = response.getWriter();//获得out
(获得request和response只需将out参数改为request和response)
2、session:
HttpSession session =request.getSession();//获得session
3、dopost中与doget功能合并:
this.doGet(request, response);//都在doget中做操作
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连接到数据库:
import java.sql.Statement;
try {
Class.forName("com.mysql.jdbc.Driver");//加载驱动
Connection conn=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/News?user=root&password=zhou");//建立数据库连接
//其中的写法:DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/数据库名?user=用户名&password=密码")
Statement stat =conn.createStatement();//运行sql语句
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查询并输出:String sql = "SELECT 学号,姓名 FROM 学籍";
ResultSet rs = stat.executeQuery(sql);//得到结果,ResultSet接口
while(rs.next())
{
String stuid = rs.getString("学号");
}
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添加: String a = "7666";
String b = "周磊";
String c = "男";
String d = "滨州";
String sql = "INSERT INTO 学籍(学号,姓名,性别,家庭住址) VALUES('"+a+"','"+b+"','"+c+"','"+d+"')";
int i = stat.executeUpdate(sql);
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删除:String sql = "DELETE FROM 学籍 WHERE 姓名='张三'";
int i = stat.executeUpdate(sql);
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修改:String sql = "UPDATE 学籍 SET 性别='女' WHERE 姓名='张三'";
int i = stat.executeUpdate(sql);
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} catch (ClassNotFoundException e) {e.printStackTrace();}
catch (SQLException e) {e.printStackTrace();}
catch(Exception ex){ex.printStackTrace();}
//关闭连接
public void closeConnection()
{
try{
if(conn!=null){
conn.close();
conn = null;}
}catch(Exception ex){ex.printStackTrace();}
}