Servlet init()怎么取不到值??

Question

大家看代码,请详细说明.深夜等.. 
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description>JDBC</description>
<display-name>JDBC</display-name>
<servlet-name>Conn</servlet-name>
<servlet-class>com.conn.Conn</servlet-class>
<init-param>
<param-name>DRIVER</param-name>
<param-value>com.mysql.jdbc.Driver</param-value>
</init-param>
<init-param>
<param-name>URL</param-name>
<param-value>
jdbc:mysql://localhost:3306/chinatravellinks
</param-value>
</init-param>
<init-param>
<param-name>USER</param-name>
<param-value>root</param-value>
</init-param>
<init-param>
<param-name>PASSWORD</param-name>
<param-value>null</param-value>
</init-param>
</servlet>
</web-app>
Conn.java
public class Conn extends HttpServlet {
String driver; // JDBC驱动程序,对应web.xml的driver属性
String url; // 数据库URL,对应web.xml的url属性
String user; // 用户名
String password; // 用户密码 Connection conn;
Statement stmt;
ResultSet rs; public Conn() {
super();
} public void init() throws ServletException {
driver = getInitParameter("DRIVER");
password = getInitParameter("PASSWORD");
url = getInitParameter("URL");
user = getInitParameter("USER");
} public Connection getConnection() throws Exception {
try {
Class.forName(driver);
conn = (Connection) DriverManager
.getConnection(url, user, password);
return conn;
} catch (SQLException e) {
System.err.println(e.getMessage());
throw e;
}
} /**
 * 功能:为执行SQL作准备,查询操作时专用 <br>
 * 
 * @return:Statement对象stmt
 */
public Statement getStmtread() {
try {
conn = getConnection();
stmt = (Statement) conn.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
return stmt;
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
return null;
} /**
 * 功能:为执行SQL作准备,非查询操作时用 <br>
 * 
 * @return:Statement对象stmt
 */
public Statement getStmt() {
try {
conn = getConnection();
stmt = (Statement) conn.createStatement();
return stmt;
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
return null;
} /**
 * 功能:关闭数据库连接
 */
public void close() {
try {
if (rs != null) {
rs.close(); // 关闭结果集
rs = null;
}
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
try {
if (stmt != null) {
stmt.close(); // 关闭SQL语句对象
stmt = null;
}
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
try {
if (conn != null) {
conn.close(); // 关闭数据库
conn = null;
}
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
}
}

Answer 1

你的设置错了吧，这样就可以了：
WEB.xml:
<context-param>
   <param-name>driver</param-name>
   <param-value>com.mysql.jdbc.Driver</param-value>  
  </context-param>
  <context-param>
   <param-name>url</param-name>
   <param-value>jdbc:mysql://127.0.0.1:3306/test?characterEncoding=gbk</param-value> 
  </context-param>
  <context-param>
   <param-name>username</param-name>
   <param-value>root</param-value>  
  </context-param>
  <context-param>
   <param-name>password</param-name>
   <param-value></param-value>  
  </context-param>Servlet类Init():
String driver=getServletContext().getInitParameter("driver");
String url=getServletContext().getInitParameter("url");
String username=getServletContext().getInitParameter("username");
String password=getServletContext().getInitParameter("password");

Answer 2

 driver = getInitParameter("DRIVER");
        password = getInitParameter("PASSWORD");
        url = getInitParameter("URL");你这样没有服错吗？我估计你是那里服错了