在struts中以无参数的javabeans的方式调用struts-confi.doc

在struts中以无参数的javabeans的方式调用struts-config.xml中我是从JSP转来学STRUTS的，一开始的时候有很多地方不习惯。比如对数据库的操作，在JSP中，一般是写一个javabeans来封装对数据库的连接与操作，如：Conn.javapublic class Conn private Connection conn = null;private Statement stmt = null;private ResultSet rs = null;private String dataSource = java:comp/env/jdbc/CpDB;public Conn() try Context ctx = new InitialContext();DataSource ds = (DataSource) ctx.lookup(dataSource);conn = ds.getConnection(); catch (Exception e) System.err.println(e.getMessage();public Statement createStatement() throws Exception stmt = conn.createStatement();return stmt;public ResultSet executeQuery(String sql) throws Exception createStatement();return stmt.executeQuery(sql);public int executeUpdate(String sql) throws Exception createStatement();return stmt.executeUpdate(sql);public void close() 然后在JSP页面中用这样的代码：Conn myConn = new Conn();String sqlStr = “.”;ResultSet rs = myConn.exeuteQuery(sqlStr);.但是在STRUTS中，假设我们在struts-config.xml中配置了数据源，如： 我们要访问这个数据源，必须要有request对象才行。假设我们在action中访问数据库，则：public ActionForward execute(.) try DataSource = getDataSource(request,org.apache.struts.action.DATA_SOURCE);Connection myConnection = dataSource.getConnection();Statement myStmt= myConnection.createStatement();String sqlStr = .;ResultSet rs = myStmt.executeQuery(sqlStr);.我觉得这样，一是要写多写很多代码，二是在没有request的地方就不好操作数据库了(当然可以把request当作参数传过去，但是还是有一点麻烦)。所以我写了一个struts的plugin类Conn.java可以在系统启动的时候，找到数据源，实现与以前在JSP下调用JavaBeans相同的结果。package com.strutsLogin2.util;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.Enumeration;import javax.sql.DataSource;import org.apache.struts.action.ActionServlet;import org.apache.struts.action.PlugIn;import org.apache.struts.config.ModuleConfig;public class Conn implements PlugIn private static DataSource dataSource = null;private Connection conn = null;private PreparedStatement preStmt = null;private Statement stmt = null;/ 得到数据源public void init(ActionServlet servlet, ModuleConfig config) dataSource = (DataSource) servlet.getServletContext().getAttribute(org.apache.struts.action.DATA_SOURCE);public Conn() throws SQLException if (dataSource != null) conn = dataSource.getConnection();public ResultSet executeQuery(String sql) ResultSet rs = null;try if (stmt = null) stmt = conn.createStatement();rs = stmt.executeQuery(sql); catch (SQLException e) e.printStackTrace();return rs;public void executeUpdate(String sql) throws SQLException if (stmt = null) stmt = conn.createStatement();stmt.executeUpdate(sql);public Connection getConn() return conn;public void prepareStatement(String sqlStr) throws SQLException preStmt = conn.prepareStatement(sqlStr);public void setString(int index, String value) throws SQLException preStmt.setString(index, value);public void setInt(int index, int value) throws SQLException preStmt.setInt(index, value);public void setBoolean(int index, boolean value) throws SQLException preStmt.setBoolean(index, value);public void setLong(int index, long value) throws SQLException preStmt.setLong(index, value);public void setFloat(int index, float value) throws SQLException preStmt.setFloat(index, value);public void setBytes(int index, byte value) throws SQLException preStmt.setBytes(index, value);public void clearPreStmt() throws SQLException preStmt.clearParameters();preStmt = null;public ResultSet executeQuery() throws SQLException if (preStmt != null) return preStmt.executeQuery(); elsereturn null;public void executeUpdate() throws SQLException if (preStmt != null)preStmt.executeUpdate();public void close() try if (stmt != null) stmt.close();stmt = null;if (preStmt != null) preStmt.close();preStmt = null;if (conn != null) conn.close();conn = null;System.out.println(* a connection is closed); catch (Exception e) System.err.println(e.getMessage();public void destroy() 其实很简单，关键就在于dataSource = (DataSource) servlet.getServletContext().getAttribute(org.apache.struts.action.DATA_SOURCE);我们原来也可以从servlet中得到这个数据源，并不只是可以从requ