struts中连接数据库

最新推荐文章于 2014-04-24 22:37:00 发布

最新推荐文章于 2014-04-24 22:37:00 发布 · 125 阅读

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#数据库 #java

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本文介绍如何在Struts框架中配置数据库连接，并演示了一个具体的登录验证Action示例，包括从数据库查询用户信息的过程。

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在struts中连接数据库，并且在action操作数据库，需要在struts.xml中进行配置，具体配置如下：

	<data-sources>
		<data-source type="org.apache.commons.dbcp.BasicDataSource">
			<set-property property="driverClassName"
				value="com.mysql.jdbc.Driver" />
			<set-property property="url"
				value="jdbc:mysql://localhost:3306/demo" />
			<set-property property="username" value="root" />
			<set-property property="password" value="" />
			<set-property property="maxActive" value="10" />
			<set-property property="maxWait" value="5000" />
			<set-property property="defaultAutoCommit" value="false" />
			<set-property property="defaultReadOnly" value="false" />
			<set-property property="validationQuery"
				value="SELECT COUNT(*) FROM user" />
		</data-source>
	</data-sources>

之后就可以在action中访问数据库了，具体方式如下：

package com.demo.struts.actions;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.sql.DataSource;

import org.apache.log4j.Logger;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.actions.DispatchAction;

import com.demo.struts.forms.LoginForm;
import com.demo.struts.util.Constants;

public class LoginAction extends DispatchAction {

	Logger log = Logger.getLogger(this.getClass());

	@SuppressWarnings("deprecation")
	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception {

		ActionErrors errors = new ActionErrors();
		ActionForward forward = new ActionForward();
		LoginForm loginForm = (LoginForm) form;

		try {
			// get parameters
			String username = loginForm.getUsername();

			// invalidate the original session if exists
			HttpSession session = request.getSession(false);
			if (session != null) {
				session.invalidate();
			}

			// create a new session for the user
			session = request.getSession(true);

			// login
			boolean isValid = valid(request, loginForm);
			if (isValid) {
				session.setAttribute(Constants.USERNAME_KEY, username);

				log.info("User " + username + " login.");
			} else {
				errors.add(ActionErrors.GLOBAL_MESSAGE, new ActionMessage(
						"login.message.failed"));
			}

		} catch (Exception e) {
			errors.add(ActionErrors.GLOBAL_MESSAGE, new ActionMessage(
					"login.message.failed"));

		}

		// If a message is required, save the specified key(s)
		// into the request for use by the <struts:errors> tag.

		if (!errors.isEmpty()) {
			saveErrors(request, errors);
			request.setAttribute("loginFormBean", loginForm);
			forward = mapping.findForward(Constants.FAILURE_KEY);
		} else {
			forward = mapping.findForward(Constants.SUCCESS_KEY);
		}

		// Finish with
		return (forward);
	}

	private boolean valid(HttpServletRequest request, LoginForm loginForm) {
		DataSource ds = null;
		Connection cn = null;
		boolean b = false;
		try {
			ds = getDataSource(request);
			cn = ds.getConnection();
			Statement st = cn.createStatement();
			ResultSet rs = st
					.executeQuery("select * from user where username='"
							+ loginForm.getUsername() + "' and password='"
							+ loginForm.getPassword() + "'");
			if (rs.next()) {
				b = true;
			}
			rs.close();
			st.close();
			cn.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return b;
	}
}