关于Servlet一点，做个简单的emp页面（1）
servlet是个web服务器的标准组件规范，
删除
一般都和tomcat一起使用，tomact应用（java）容器，用来处理动态页面
现在写一个小程序，关于员工列表。会用到jdbc。用的是oracal数据库
具体的流程是1，进入html页面，点提交按钮
2，会直接跳转至list页面进行数据插入，将数据插入至oracal数据库
3，跳转页面至listAll，此页面会显示员工的所有信息，包括delete，modifi，和add
4,按个人所需进行曾，查，改，删操作
这个程序使用myecplise
首先写个html文件
<!DOCTYPE html>
<html>
<head>
<title>MyHtml.html</title>
<meta name="keywords" content="keyword1,keyword2,keyword3">
<meta name="description" content="this is my page">
<meta name="content-type" content="text/html; charset=UTF-8">
<!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
</head>
<body >
<form action="list" method="post">
<div >
姓名<input type="text" name="name"><br>
年龄<input type="text" name="age"><br>
工资<input type="text" name="sal"><br>
<input type="submit" value="提交">
</div>
</form>
</body>
</html>在这个html中。只有表单，有submit这个提交type，action是用来连接，值就是xml中servlet的url-patten，看下面的xml文件
在这里还需定义一个xml文件。用来作为文件之间的关联。查找的联系是这样的
先在<servlet-mapping>中查找url-mapping，就会有对应的，servler-name，
根据servlet-name,在<servlet>中查找同样的servlet-name，就会获取servlet-class
servlet-class中的内容是这样定义的： 包名.class文件名，
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">
<servlet>
<servlet-name>addemp</servlet-name>
<servlet-class>web03.AddEmp</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>addemp</servlet-name>
<url-pattern>/list</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>listall</servlet-name>
<servlet-class>web03.ListAll</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>listall</servlet-name>
<url-pattern>/alllist</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>delall</servlet-name>
<servlet-class>web03.DelEmp</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>delall</servlet-name>
<url-pattern>/alldel</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>loademp</servlet-name>
<servlet-class>web03.LoadEmp</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>loademp</servlet-name>
<url-pattern>/load</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>modifyemp</servlet-name>
<servlet-class>web03.ModifyEmp</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>modifyemp</servlet-name>
<url-pattern>/modify</url-pattern>
</servlet-mapping>
</web-app>在这个xml文件中。定义了几个操作员工表的操作
1，list 用来插入单条数据
2，load和modify一起使用，用load获取员工的单条记录，然后进行modify操作
3，alldel用来删除员工的单条记录
4，alllist用来获取员工表数据。
接下来，根据前面的html页面会跳转至此下页面。用来插入单条emp数据
public class AllEmp extends HttpServlet {
public void service(HttpServletRequest req,HttpServletResponse res) throws ServletException, IOException {
res.setContentType("text/html;charset=utf-8");
PrintWriter out = res.getWriter();
String name=req.getParameter("name");
String age=req.getParameter("age");
String sal=req.getParameter("sal");
out.println(name);
Connection conn=null;
PreparedStatement ps=null;
try{
Class.forName("oracle.jdbc.driver.OracleDriver");
conn=DriverManager.getConnection("jdbc:oracle:thin:@192.168.0.202:1521:tarena", "jsd1505", "jsd1505");
ps = conn.prepareStatement("insert into emp_dongruisu(id,name,age,sal) values (id.nextval,?,?,?)" );
ps.setString(1,name);
ps.setInt(2,Integer.parseInt(age));
ps.setInt(3,Integer.parseInt(sal));
ps.executeUpdate();
res.sendRedirect("alllist");
}catch(Exception e){
e.printStackTrace();
out.print("错了");
}finally{
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
此 上面页面的res.sendRedirect(url-pattern),，重定向，会清空之前获取的数据，跳转至url-pattern制定的页面。
接着就是跳转至制定页面，在这里是员工列表页面
public class ListAll extends HttpServlet {
public void service(HttpServletRequest req,HttpServletResponse res) throws ServletException, IOException {
req.setCharacterEncoding("UTF-8");
res.setContentType("text/html;charset=utf-8");
PrintWriter out=res.getWriter();
Connection conn=null;
PreparedStatement ps=null;
ResultSet rs=null;
try{
Class.forName("oracle.jdbc.driver.OracleDriver");
conn=DriverManager.getConnection("jdbc:oracle:thin:@192.168.0.202:1521:tarena", "jsd1505", "jsd1505");
ps=conn.prepareStatement("select * from emp_dongruisu");
rs=ps.executeQuery();
out.println("<table width='60%' border='1' cellpadding='0' cellspacing='0'>");
out.println("<tr><td>id</td><td>姓名</td><td>年龄</td><td>工资</td><td>操作</td></tr>");
while(rs.next()){
int id=rs.getInt("id");
String name=rs.getString("name");
int age=rs.getInt("age");
int sal=rs.getInt("sal");
out.println("<tr><td>"+id+"</td><td>"+name+"</td><td>"+age+"</td><td>+"+sal+"</td>"
+"<td><a href='alldel?id="+id+"'>删除</a>$nbsp;<a href='load?id="+id+"'>修改</a></td></tr>"
);
}
out.println("</table>");
out.print("<a href='MyHtml.html'>添加员工</a>");
}catch(Exception e){
e.printStackTrace();
}finally{
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}在这个页面就可进行增，查，改，删这4个操作，根据所选不同，进行不同的操作
接下来是，修改和删除
修改：先要跳转到需要修改单条员工数据的页面，在进行操作修改
public class LoadEmp extends HttpServlet{
public void service(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException{
res.setContentType("text/html;charset=utf-8");
PrintWriter out=res.getWriter();
int id=Integer.parseInt(req.getParameter("id"));
Connection conn=null;
PreparedStatement ps=null;
ResultSet rs=null;
try{
Class.forName("oracle.jdbc.driver.OracleDriver");
conn=DriverManager.getConnection("jdbc:oracle:thin:@192.168.0.202:1521:tarena", "jsd1505", "jsd1505");
ps= conn.prepareStatement( "select * from emp_dongruisu where id=?" );
ps.setInt(1, id);
rs=ps.executeQuery();
if(rs.next()){
String name=rs.getString("name");
int age=rs.getInt("age");
int sal=rs.getInt("sal");
out.println("<form action='modify' method='post'>");
out.println("id:"+id+"<br>");
out.println("姓名：<input name='name' value='"+name+"'><br>");
out.println("年龄：<input name='age' value='"+age+"'><br>");
out.println("工资：<input name='sal' value="+sal+"><br>");
out.println("<input type='hidden' name='id' value='" + id + "'/>");
out.println("<input type='submit' value='提交'>");
out.println("</form>");
}
}catch(Exception e){
}finally{
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
public class ModifyEmp extends HttpServlet {
public void service(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException{
res.setContentType("text/html;charset=utf-8");
PrintWriter out=res.getWriter();
Connection conn=null;
PreparedStatement ps=null;
try{
Class.forName("oracle.jdbc.driver.OracleDriver");
conn=DriverManager.getConnection("jdbc:oracle:thin:@192.168.0.202:1521:tarena", "jsd1505", "jsd1505");
ps=conn.prepareStatement("update emp_dongruisu set name=?,age=?,sal=? where id=?");
ps.setString(1, req.getParameter("name"));
ps.setInt(2,Integer.parseInt(req.getParameter("age")));
ps.setInt(3,Integer.parseInt(req.getParameter("sal")));
ps.setInt(4, Integer.parseInt(req.getParameter("id")));
ps.executeUpdate();
res.sendRedirect("alllist");
}catch(Exception e){
e.printStackTrace();
}finally{
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
删除
public class DelEmp extends HttpServlet {
public void service(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException{
res.setContentType("text/html;charset=utf-8");
PrintWriter out=res.getWriter();
int id=Integer.parseInt(req.getParameter("id"));
Connection conn=null;
PreparedStatement ps=null;
try{
Class.forName("oracle.jdbc.driver.OracleDriver");
conn=DriverManager.getConnection("jdbc:oracle:thin:@192.168.0.202:1521:tarena", "jsd1505", "jsd1505");
ps = conn.prepareStatement("delete from emp_dongruisu where id=?" );
ps.setInt(1, id);
ps.executeUpdate();
res.sendRedirect("alllist");
}catch(Exception e){
e.printStackTrace();
out.print("wrong");
}finally{
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}