Struts 1.3.8 学习笔记（四）

第四个版本我们通过访问数据库来校验用户名和密码！

我们使用的数据库MySQL，所以我们要用到MySQL的驱动：mysql-connector-java-5.1.17-bin.jar

创建表的脚本

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS user;
CREATE TABLE user (
  username varchar(256) NOT NULL,
  password varchar(256) DEFAULT NULL,
  PRIMARY KEY (username)
) ENGINE=MyISAM DEFAULT CHARSET=UTF-8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO user VALUES ('admin', 'admin');
INSERT INTO user VALUES ('user', 'user');

同时需要JDBC来访问数据库

首先创建一个JDBC工具类，用来建立和关闭连接

JdbcUtil.java

package com.coderdream.ad.db;

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

public class JdbcUtil {
	public static void close(Statement st, Connection con) {
		try {
			st.close();
		} catch (Exception e) {
		}

		try {
			con.close();
		} catch (Exception e) {
		}
	}

	public static void close(ResultSet rs, Statement st, Connection con) {
		try {
			rs.close();
		} catch (Exception e) {
		}
		close(st, con);
	}

	public static Connection getConnection() throws Exception {
		Class.forName(SqlConstant.DB_NAME);
		return DriverManager.getConnection(SqlConstant.DB_URL, SqlConstant.DB_USER_NAME, SqlConstant.DB_PASSWORD);
	}
}

再创建一个常量类，用于保存数据库的连接属性

SqlConstan.java

package com.hp.gddc.ad.db;

public class SqlConstant {
	public static final String DB_NAME = "com.mysql.jdbc.Driver";
	public static final String DB_URL = "jdbc:mysql://localhost:3306/stu";
	public static final String DB_USER_NAME = "root";
	public static final String DB_PASSWORD = "1234";
}

 最后就可以通过UserDao来访问数据库了：

UserDao.java

package com.coderdream.db;

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

public class UserDao {

	public int queryUser(String username, String password) {
		Connection con = null;
		Statement st = null;
		ResultSet rs = null;
		int i = 0;
		try {
			con = JdbcUtil.getConnection();
			st = con.createStatement();
			String sql = "select * from user where username='" + username + "' and password='" + password + "'";
			System.out.println(sql);
			rs = st.executeQuery(sql);

			while (rs.next()) {
				i++;
				System.out.print("username=" + rs.getString("username"));
				System.out.print(",password=" + rs.getString("password"));
				System.out.println("");
			}
		} catch (Exception e) {
			e.printStackTrace();
			throw new RuntimeException(e);
		} finally {
			JdbcUtil.close(rs, st, con);
		}

		return i;
	}
}

 同时更新LoginAction中的相关代码，把硬编码比较改成访问数据库：

LoginAction.java

package com.coderdream.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

import com.hp.gddc.ad.db.UserDao;
import com.hp.gddc.ad.form.LoginForm;

public class LoginAction extends Action {
	/**
	 * 处理客户端请求
	 */
	@Override
	public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request,
			HttpServletResponse response) throws Exception {
		// 得到客户的的提交数据
		LoginForm lf = (LoginForm) form;
		UserDao studentDao = new UserDao();
		String username = lf.getUserName();

		String password = lf.getPassword();

		int result = studentDao.queryUser(username, password);
		// 业务调用
		if (1 <= result) {
			// 用户名密码验证成功，跳转到成功页面
			return mapping.findForward("success");
		} else {
			// 用户名密码错误，跳转到失败页面
			return mapping.findForward("failing");
		}
	}
}

运行结果和第三个版本一致！

源代码：