servlet_day02.txt

详细讲述Servlet

1. public class MyServlet extends HttpServlet {
	public void doGet(
		HttpServletRequest request,
		HttpServletResponse response)
		throws ServletException,
		       IOException {

        }
	public void doPost(
		HttpServletRequest request,
		HttpServletResponse response)
		throws ServletException,
		       IOException {
        }	
   }
   
2. Web应用名称
       |
       -- WEB-INF
             |
	     -- register.html
             |
	     -- web.xml
	     |
	     -- lib
	     |
	     -- classes
	            |
		    -- ch01
		         |
			 --- DateServlet.class

3. request.getParameter(""); // String
   request.getParameterValues(""); //String[]
   request.getParameterNames("");  //Enumeration
   request.getQueryString();       //String

   http://localhost:8080/a/register?name=zs&age=10

web.xml

<servlet>
  <servlet-name></servlet-name>
  <servlet-class></servlet-class>
  <init-param>
     <param-name>age</param-name>
     <param-value>10</param-value>
  </init-param>
</servlet>
<servlet-mapping>
  <servlet-name></servlet-name>
  <url-pattern>/a</url-pattern>
</servlet-mapping>

url-pattern内容形式：

1. 固定路径:
   /a, /b, /a/b

   注意：一定要以 / 开头

2. 通配路径

   a. /a/*, /*     
   b. *.do  <-> ch02.MyServlet
      *.action <-> ch02.MyServlet2
      *.jd0801 <-> ch02.MyServlet3

<url-pattern>/c/*.do</url-pattern>

   http://localhost:8080/应用名称/c/b.do
   http://localhost:8080/应用名称/c.jd0801

   
   
   WebRoot
       |
       -- a
           |
	   --- register.html

   http://localhost:8080/应用名称/a/register.html



public abstract class HttpServlet 
       extends GenericServlet {
   ServletConfig config;

   public void init(ServletConfig conf) 
          throws ServletException {
	config=conf;
	init();
   }

   public String getInitParameter(String name) {
	return config.getInitParameter(name);
   }

   public void init() {}

   public void log(String msg) {
	getServletContext().log(msg);
   }
}


ch03

InitServlet.java

/init

网页计数器：

您是第 3 位访客!!!

ch03

CounterServlet.java

/counter


http://localhost:8080/servlet_jd0801/counter

使用JDBC和数据库交互的步骤：

1. 注册Driver

  *1) Class.forName("");  -> classes12.jar 
   2) Driver driver=new OracleDriver();
      DriverManager.registerDriver(driver);
   3) java -Djdbc.drivers=

2. 创建Connection

  *1) DriverManager.getConnection(
	String url,
	String user,
	String password);
   2) Driver driver=new OracleDriver();
      driver.connect(
	String url,
	Properties pro);

3. 实例化Statement

   1) 简单Statement
      Statement stmt=conn.createStatement();      
      ResultSet rs=stmt.executeQuery(sql);
      int i=stmt.executeUpdate(sql);
      boolean f=stmt.execute(sql);
   2) PreparedStatement
      PreparedStatement pstmt=
         conn.prepareStatement(sql); 
	 
      pstmt.setInt(1,1);
      pstmt.setString(2,"a");
      pstmt.setDate(3,new Date());

      ResultSet rs=pstmt.executeQuery();
      int i=pstmt.executeUpdate();
      boolean f=pstmt.execute();      

   3) CallableStatement

      String sql="{call procedure_name(?,?)}";
      String sql="{?=call function_name(?,?)}";
      CallableStatement cstmt=
	conn.prepareCall(sql);

      ResultSet rs=pcstmt.executeQuery();
      int i=cstmt.executeUpdate();
      boolean f=cstmt.execute(); 
      
4. 执行SQL

5. 处理结果集

   select id,name

   while(rs.next()) {
         rs.getString("name");
   }

6. 关闭对象，释放资源
   
   rs.close();
   stmt.close();
   conn.close();

当前工程
   |
   ---src
   |
   ---WebRoot
         |
	 -- WEB-INF
	      |
	      -- lib 
	          |
		  -- classes12.jar

$CATALINA_HOME/common/lib/classes12.jar


ch04

DBServlet.java

/db

http://localhost:8080/servlet_jd0801/db

ID	LAST_NAME	SALARY
1	zs		1000
2	ls		2000

JNDI使用

1. 获得上下文

   Context ctx=new InitialContext();

   Properties pro=new Properties();

   Context ctx=new InitialContext(pro);

2. 绑定

   ctx.bind("JNDI名字", new OracleDataSource());

3. 查找

   Context ctx=new InitialContext();
   DataSource ds=(DataSource)ctx.lookup("JNDI名字");
   Connection conn=ds.getConnection();

使用Tomcat配置数据源步骤：

1. 将数据库驱动程序置于目录：
   $CATALINA_HOME/common/lib
2. 使用Tomcat的Admin应用以图形化方式配置数据源

   $CATALINA_HOME/conf/Catalina/localhost/servlet_jd0801.xml

3. 修改web.xml文件，加入以下信息：   
   <resource-ref>
	<res-ref-name>jdbc/oracle</res-ref-name>
	<res-type>javax.sql.DataSource</res-type>
	<res-auth>Container</res-auth>
   </resource-ref>
4. 使用代码获得数据源：
   Context ctx=new InitialContext();
   DataSource ds=(DataSource)
        ctx.lookup("java:comp/env/jdbc/oracle");
   Connection conn=ds.getConnection();

ch04

DataSourceServlet

public class HttpServletRequestImpl implements
             HttpServletRequest {
  private Map<String, Object> 
     map=new HashMap<String,Object>();
  
  public void setAttribute(
	String key,
	Object value) {
     map.put(key,value);
  }

  public Object getAttribute(
	String key) {
     return map.get(key);
  }

}

getServletContext().getRequestDispatcher(“/students.jsp”).forward(req, res);

RequestDispatcher dispatcher=getServletContext().getRequestDispatcher(“/students.jsp”)

dispatcher.forward(req,res);


ch04		ch04	      ch04

ForwardServlet	ResultServlet IncludeServlet

/forward	/result       /include



public class RegisterServlet extends HttpServlet {
	public void doGet(...) {
	  String name=request.getParameter("name");
	  ...

	  Customer customer=new Customer();
	  customer.setName(name);
	  ...

	  CustomerDAO dao=
	     new CustomerDAOImpl();
          try {
		dao.save(customer);

	  RequestDispatcher dis=
	     getServletContext().
	     getRequestDispatcher("/login.html");
	  dis.forward(request,response);
	  
	  } catch(Exception e) {
	    RequestDispatcher dis=
	     getServletContext().
	     getRequestDispatcher("/register.html");
	     dis.forward(request,response);
	  }

	
	}


}

public class LoginServlet extends HttpServlet {
	public void doGet(...) {
	  String name=request.getParameter("name");
	  ...

	  Customer customer=new Customer();
	  customer.setName(name);
	  ...

	  CustomerDAO dao=
	     new CustomerDAOImpl();
          try {
		Customer c=dao.find(customer);
		if(c==null)
		  return new Exception("");

	  RequestDispatcher dis=
	     getServletContext().
	     getRequestDispatcher("/list.html");
	  dis.forward(request,response);
	  
	  } catch(Exception e) {
	    RequestDispatcher dis=
	     getServletContext().
	     getRequestDispatcher("/login.html");
	     dis.forward(request,response);
	  }

	
	}


}

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