JavaWeb学习服务端开发流程

package com.product.dbutil.register.action;控制层

package com.product.dbutil.register.service;服务层

package com.product.dbutil.register.dao;数据访问层。

控制层的定义代码：

package com.product.dbutil.register.action;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

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

import com.product.dbutil.register.dao.RegisterDao;
import com.product.dbutil.register.service.RegisterService;
import com.sun.org.apache.bcel.internal.generic.ARRAYLENGTH;

public class RegisterAction extends HttpServlet {

	private RegisterService service;//服务层接口

	/**
	 * Constructor of the object.
	 */
	public RegisterAction() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 *
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doPost(request, response);//复写doPost方法
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to
	 * post.
	 *
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		String path = request.getContextPath();//用来重定向
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();

		String username = request.getParameter("username");
		String pswd = request.getParameter("pswd");
		String realname = request.getParameter("realname");
		List<Object> params = new ArrayList<Object>();
		params.add(username);
		params.add(pswd);
		params.add(realname);
		boolean flag = service.registerUser(params);
		if (flag) {
			response.sendRedirect(path + "/index.jsp");//重定向的实现
		}
		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException
	 *             if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
		service = new RegisterDao();
	}

}

服务层，定义业务逻辑处理规范。代码如下：

package com.product.dbutil.register.service;

import java.util.List;

public interface RegisterService {

	//完成用户的注册功能
	public boolean registerUser(List<Object> params);
}

数据访问层访问数据库：

package com.product.dbutil.register.dao;

import java.util.List;

import com.product.dbutil.jdbc.JdbcUtils;
import com.product.dbutil.register.service.RegisterService;

public class RegisterDao implements RegisterService {

	private JdbcUtils utils = null;

	public RegisterDao() {
		//操作数据库
		utils = new JdbcUtils();
	}

	/*
	 * 完成了对用户注册的dao的编写
	 *
	 * @see
	 * com.product.dbutil.register.service.RegisterService#registerUser(java
	 * .util.List)
	 */
	public boolean registerUser(List<Object> params) {
		// TODO Auto-generated method stub
		boolean flag = false;

		String sql = "insert into userinfo(username,pswd,realname) values(?,?,?)";
		try {
			// 先获得链接
			utils.getConnection();
			flag = utils.updateByPreparedStatement(sql, params);
			System.out.println("-flag-->>" + flag);
		} catch (Exception e) {
			e.printStackTrace();
			// TODO: handle exception
		} finally {
			// 关闭数据库的链接
			utils.releaseConn();
		}
		return flag;
	}

}

数据库工具类：

package com.product.dbutil.jdbc;

import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class JdbcUtils {

	// 表示定义数据库的用户名
	private final String USERNAME = "root";
	// 定义数据库的密码
	private final String PASSWORD = "admin";
	// 定义数据库的驱动信息
	private final String DRIVER = "com.mysql.jdbc.Driver";
	// 定义访问数据库的地址
	private final String URL = "jdbc:mysql://localhost:3306/mydb";
	// 定义数据库的链接
	private Connection connection;
	// 定义sql语句的执行对象
	private PreparedStatement pstmt;
	// 定义查询返回的结果集合
	private ResultSet resultSet;
	// 实现批处理操作的功能
	private Statement stmt;

	public JdbcUtils() {
		try {
			Class.forName(DRIVER);
			System.out.println("注册驱动成功!!");
		} catch (Exception e) {
			// TODO: handle exception
		}
	}

	// 定义获得数据库的链接
	public Connection getConnection() {
		try {
			connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
		} catch (Exception e) {
			// TODO: handle exception
		}
		return connection;
	}

	public boolean deleteByBatch(String[] sql) throws SQLException{
		boolean flag = false;
		stmt = connection.createStatement();
		if(sql!=null){
			for(int i=0;i<sql.length;i++){
				stmt.addBatch(sql[i]);
			}
		}
		int[] count = stmt.executeBatch();
		if(count!=null){
			flag = true;
		}
		return flag;
	}
	/**
	 * 完成对数据库的表的添加删除和修改的操作
	 *
	 * @param sql
	 * @param params
	 * @return
	 * @throws SQLException
	 */
	public boolean updateByPreparedStatement(String sql, List<Object> params)
			throws SQLException {
		boolean flag = false;
		int result = -1;// 表示当用户执行添加删除和修改的时候所影响数据库的行数
		pstmt = connection.prepareStatement(sql);
		int index = 1;
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		result = pstmt.executeUpdate();
		flag = result > 0 ? true : false;
		return flag;
	}

	/**
	 * 查询返回单条记录
	 *
	 * @param sql
	 * @param params
	 * @return
	 * @throws SQLException
	 */
	public Map<String, Object> findSimpleResult(String sql, List<Object> params)
			throws SQLException {
		Map<String, Object> map = new HashMap<String, Object>();
		int index = 1;
		pstmt = connection.prepareStatement(sql);
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		resultSet = pstmt.executeQuery();// 返回查询结果
		ResultSetMetaData metaData = resultSet.getMetaData();
		int col_len = metaData.getColumnCount();// 获得列的名称
		while (resultSet.next()) {
			for (int i = 0; i < col_len; i++) {
				String cols_name = metaData.getColumnName(i + 1);
				Object cols_value = resultSet.getObject(cols_name);
				if (cols_value == null) {
					cols_value = "";
				}
				map.put(cols_name, cols_value);
			}
		}
		return map;
	}

	/**
	 * 查询返回多行记录
	 *
	 * @param sql
	 * @param params
	 * @return
	 * @throws SQLException
	 */
	public List<Map<String, Object>> findMoreResult(String sql,
			List<Object> params) throws SQLException {
		List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
		int index = 1;
		pstmt = connection.prepareStatement(sql);
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		resultSet = pstmt.executeQuery();
		ResultSetMetaData metaData = resultSet.getMetaData();
		int cols_len = metaData.getColumnCount();
		while (resultSet.next()) {
			Map<String, Object> map = new HashMap<String, Object>();
			for (int i = 0; i < cols_len; i++) {
				String cols_name = metaData.getColumnName(i + 1);
				Object cols_value = resultSet.getObject(cols_name);
				if (cols_value == null) {
					cols_value = "";
				}
				map.put(cols_name, cols_value);
			}
			list.add(map);
		}
		return list;
	}

	// jdbc的封装可以用反射机制来封装：
	public <T> T findSimpleRefResult(String sql, List<Object> params,
			Class<T> cls) throws Exception {
		T resultObject = null;
		int index = 1;
		pstmt = connection.prepareStatement(sql);
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		resultSet = pstmt.executeQuery();
		ResultSetMetaData metaData = resultSet.getMetaData();
		int cols_len = metaData.getColumnCount();
		while (resultSet.next()) {
			// 通过反射机制创建实例
			resultObject = cls.newInstance();
			for (int i = 0; i < cols_len; i++) {
				String cols_name = metaData.getColumnName(i + 1);
				Object cols_value = resultSet.getObject(cols_name);
				if (cols_value == null) {
					cols_value = "";
				}
				Field field = cls.getDeclaredField(cols_name);
				field.setAccessible(true);// 打开javabean的访问private权限
				field.set(resultObject, cols_value);
			}
		}
		return resultObject;
	}

	/**
	 * 通过反射机制访问数据库
	 *
	 * @param <T>
	 * @param sql
	 * @param params
	 * @param cls
	 * @return
	 * @throws Exception
	 */
	public <T> List<T> findMoreRefResult(String sql, List<Object> params,
			Class<T> cls) throws Exception {
		List<T> list = new ArrayList<T>();
		int index = 1;
		pstmt = connection.prepareStatement(sql);
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		resultSet = pstmt.executeQuery();
		ResultSetMetaData metaData = resultSet.getMetaData();
		int cols_len = metaData.getColumnCount();
		while (resultSet.next()) {
			T resultObject = cls.newInstance();
			for (int i = 0; i < cols_len; i++) {
				String cols_name = metaData.getColumnName(i + 1);
				Object cols_value = resultSet.getObject(cols_name);
				if (cols_value == null) {
					cols_value = "";
				}
				Field field = cls.getDeclaredField(cols_name);
				field.setAccessible(true);
				field.set(resultObject, cols_value);
			}
			list.add(resultObject);
		}
		return list;
	}

	public void releaseConn() {
		if (resultSet != null) {
			try {
				resultSet.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (stmt != null) {
			try {
				stmt.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (pstmt != null) {
			try {
				pstmt.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (connection != null) {
			try {
				connection.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}

控制层调用服务层服务层调用dao层。