MySQL---数据库从入门走向大神系列(十二)-构建MVC项目。这个是对前面技术的一个小总结吧，用到的大概技术有：
MVC框架，加注解，Struts框架的思想，动态代理，线程管理对象ThreadLocal，Connection对象池，Properties文件读取，EL表达式，JSTL，JavaBean，Java访问MySQL数据库，增删改查…
其实做出来界面挺简单：
这里只写出一些核心的类的代码：
Book.java:
package cn.hncu.domain;public class Book { private Integer id; private String namem; private Double price; // ※一对多关系中的多方(外键字段): 在写JavaBean时，要包含对方(一方)的整个值对象类型的变量 private Stud stud;//设置书的主人 public Book() { super(); } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getNamem() { return namem; } public void setNamem(String namem) { this.namem = namem; } public Double getPrice() { return price; } public void setPrice(Double price) { this.price = price; } public Stud getStud() { return stud; } public void setStud(Stud stud) { this.stud = stud; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((id == null) ? 0 : id.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; Book other = (Book) obj; if (id == null) { if (other.id != null) return false; } else if (!id.equals(other.id)) return false; return true; }}Stud.java
package cn.hncu.domain;import java.util.ArrayList;import java.util.List;public class Stud { private String id; private String name; //※一对多中的一方: 添加一个集合(用set也行)以表示该关系 private List books = new ArrayList(); public Stud() { super(); } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public List getBooks() { return books; } public void setBooks(List books) { this.books = books; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((id == null) ? 0 : id.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; Stud other = (Stud) obj; if (id == null) { if (other.id != null) return false; } else if (!id.equals(other.id)) return false; return true; } //注意,如果要添加toString()方法，注意一对多关系中的信息输出嵌套} TxProxy.java:
package cn.hncu.pubs.tx;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import java.sql.Connection;import cn.hncu.pubs.ConnsUtil;public class TxProxy implements InvocationHandler{ private Object srcObj; public TxProxy(Object srcObj) { this.srcObj = srcObj; } //版本4 public static T getProxy(T srcObj){ Object proxiedObj = Proxy.newProxyInstance(TxProxy.class.getClassLoader(), srcObj.getClass().getInterfaces(), new TxProxy(srcObj)); return (T)proxiedObj; } @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { //判断method方法是不是添加了注解 if(method.isAnnotationPresent(Transaction.class)){ Connection con=null; Object returnValue =null; try { con = ConnsUtil.getConnection(); con.setAutoCommit(false); System.out.println("在动态代理中开启一个事务...."); returnValue = method.invoke(srcObj, args); conmit(); System.out.println("在动态代理中提交一个事务...."); } catch (Exception e) { con.rollback(); System.out.println("在动态代理中回滚一个事务...."); }finally{ if(con!=null){ try { con.setAutoCommit(true); con.close(); } catch (Exception e) { throw new RuntimeException("数据库连接关闭失败", e); } } } return returnValue; }else{//没有添加注解,直接放行 return method.invoke(srcObj, args); } }} Transaction.java:注解
package cn.hncu.pubs.tx;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Retention(RetentionPolicy.RUNTIME)@Target(value=ElementType.METHOD)public @interface Transaction {}baseServlet.java:
package cn.hncu.pubs;import java.io.IOException;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public abstract class baseServlet extends HttpServlet{ @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); resp.setCharacterEncoding("utf-8"); String cmd = req.getParameter("cmd"); if(cmd==null){ cmd="execute"; } try { System.out.println("this:"+this); //下面这句不能访问私有方法 //Method m = this.getClass().getMethod(cmd, HttpServletRequest.class,HttpServletResponse.class ); //如果要用类反射实现访问类的私有方法，则需要这2步,这样子类的方法就不用设置成public了。 //1获得私有方法 Method m = this.getClass().getDeclaredMethod(cmd, HttpServletRequest.class,HttpServletResponse.class ); //2设置私有方法可以被访问 m.setAccessible(true); m.invoke(this, req,resp);//这里的this是子类对象，谁调用这里的，这个this就是谁 //下面这几句是给大家启发Struts框架的思想// String str =(String) m.invoke(this, request,response);// String resPage = "";//从配置struts.xml文件中读取str所对应的结果页面的地址// request.getRequestDispatcher(resPage).forward(request,response); } catch (NoSuchMethodException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); } } //如果没有参数cmd为null，转向的界面，由子类自己实现 public abstract void execute(HttpServletRequest request, HttpServletResponse response);}ConnsUtil.java
package cn.hncu.pubs; import java.io.IOException;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;import java.util.Properties; public class ConnsUtil { private static List<connection> pool = new ArrayList<connection>(); private static final int NUM = 3; private static ThreadLocal<connection> t = new ThreadLocal<connection>(); static{ try { //读取配置文件 Properties p = new Properties(); p.load(ConnsUtil.class.getClassLoader().getResourceAsStream("jdbc.properties")); String driver = p.getProperty("driver"); String url = p.getProperty("url"); String user = p.getProperty("username"); String password = p.getProperty("password"); Class.forName(driver); for(int i=0;i<num;i++){ final="" connection="" conn="DriverManager.getConnection(url," user,="" password);="" system.out.println(conn.getclass().getclassloader());="" appclassloader="" 使用动态代理,代理conn对象，实现对close方法的拦截="" object="" obj="Proxy.newProxyInstance(ConnsUtil.class.getClassLoader()," new="" class[]{connection.class},="" invocationhandler()="" {="" @override="" public="" invoke(object="" proxy,="" method="" method,="" object[]="" args)="" throws="" throwable="" 拦截close方法="" if(method.getname().equalsignorecase("close")="" &&(args="=null||args.length==0)" ){="" pool.add((connection)proxy);="" proxy为代理后的对象="" t.set(null);="" 把存储在本地线程管理类中的当前线程对应的对象设为空="" return="" null;="" }="" conn为被代理的对象="" method.invoke(conn,="" args);="" });="" pool.add(="" (connection)obj);="" 把代理后的conn对象即obj加入池中="" catch="" (ioexception="" e)="" e.printstacktrace();="" (classnotfoundexception="" (sqlexception="" static="" synchronized="" getconnection()="" interruptedexception{="" 从本地线程管理对象t中拿="" con="t.get();" if(con="=null){" if(pool.size()<="0){" thread.sleep(50);="" getconnection();="" 放入到t中="" t.set(con);="" con;="" <="" pre=""> <h2 id="studservletjava">StudServlet.java:</h2> <pre class="brush:java;">package cn.hncu.stud; import java.io.IOException;import java.sql.SQLException;import java.util.List;import java.util.Map; import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse; import cn.hncu.domain.Book;import cn.hncu.domain.Stud;import cn.hncu.pubs.baseServlet;import cn.hncu.pubs.tx.TxProxy;import cn.hncu.stud.service.IStudService;import cn.hncu.stud.service.StudService; public class StudServlet extends baseServlet { //版本1 //private IStudService service = (IStudService) TxProxy.getProxy(new StudService()); //版本2 //private IStudService service = TxProxy.getProxy(new StudService(),IStudService.class); //版本3 //private IStudService service = TxProxy.getProxy(StudService.class);//用实现类的class //版本4 private IStudService service = TxProxy.getProxy(new StudService());//用实现类的class private void save(HttpServletRequest request, HttpServletResponse response) throws InterruptedException, ServletException, IOException { //收集并封装stud String name = request.getParameter("name"); if(name==null||name.trim().length()<=0){ response.sendRedirect("index.jsp");//重定向 return ; } Stud stud = new Stud(); stud.setName(name); //收集并封装所有book String bookNames[] = request.getParameterValues("bookname");//获取多个值 String prices[] = request.getParameterValues("price"); if(bookNames!=null){ for(int i=0;i<booknames.length;i++){ book="" book();="" if(booknames[i]="=null" ||="" booknames[i].trim().length()<="0){" continue;="" }="" book.setnamem(booknames[i]);="" if(prices[i]!="null" &&="" prices[i].trim().length()!="0" ){="" double="" price="0.0;" try="" {="" catch="" (numberformatexception="" e)="" book.setprice(price);="" book.setstud(stud);="" 继续封装stud----为stud中的books属性赋值--一方中的集合="" stud.getbooks().add(book);="" service.save(stud);="" (sqlexception="" e.printstacktrace();="" private="" void="" query(httpservletrequest="" request,="" httpservletresponse="" response)="" throws="" servletexception,="" ioexception="" list<map<string,="" string="">> studs = service.query(); request.setAttribute("studs", studs); request.getRequestDispatcher("/jsps/show.jsp").forward(request, response); } @Override public void execute(HttpServletRequest request, HttpServletResponse response) { System.out.println("调用默认业务处理方法...."); }}</booknames.length;i++){></pre> <h2 id="bookdaojdbcjava">BookDAOJdbc.java:</h2> <pre class="brush:java;">package cn.hncu.stud.dao; import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.SQLException;import java.util.List; import cn.hncu.domain.Book;import cn.hncu.pubs.ConnsUtil; public class BookDAOJdbc implements IBookDAO { @Override public void save(List<book> books) throws InterruptedException, SQLException { Connection con = ConnsUtil.getConnection(); String sql = "insert into book(name,price,studid) values(?,?,?)"; PreparedStatement pst = con.prepareStatement(sql); for(Book book:books){ pst.setString(1, book.getNamem()); pst.setDouble(2, book.getPrice()); //stud中设置了uuid这里才能设置成功 pst.setString(3, book.getStud().getId()); pst.addBatch(); } pst.executeBatch(); }}</book></pre> <h2 id="studdaojdbcjava">StudDAOJdbc.java</h2> <pre class="brush:java;">package cn.hncu.stud.dao; import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.UUID; import cn.hncu.domain.Stud;import cn.hncu.pubs.ConnsUtil; public class StudDAOJdbc implements StudDAO { @Override public List<map<string, string="">> query() { List<map<string, string="">> list = new ArrayList<map<string,string>>(); Connection con = null; try { con = ConnsUtil.getConnection(); String sql="select * from stud"; Statement st = con.createStatement(); ResultSet rs = st.executeQuery(sql); while(rs.next()){ Map<string, string=""> map = new HashMap<string, string="">(); map.put("id", rs.getString("id")); map.put("name", rs.getString("name")); //一个map就是一条记录(数据行) list.add(map); } } catch (InterruptedException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); }finally{ if(con!=null){ try { con.close(); } catch (SQLException e) { throw new RuntimeException("数据库连接关闭失败", e); } } } return list; } @Override public void save(Stud stud) throws InterruptedException, SQLException { Connection con = ConnsUtil.getConnection(); String sql = "insert into stud values(?,?)"; PreparedStatement pst = con.prepareStatement(sql); String uuid = UUID.randomUUID().toString().replaceAll("-",""); pst.setString(1, uuid); pst.setString(2, stud.getName()); pst.executeUpdate(); //在这里为book补外键字段的值 stud.setId(uuid); //这一句执行在前，这样在BookDAOJdbc中会调用book.getStud().getId()就可以拿到该id值了 } }</string,></string,></map<string,string></map<string,></map<string,></pre> <h2 id="istudservicejava">IStudService.java:</h2> <pre class="brush:java;">package cn.hncu.stud.service; import java.sql.SQLException;import java.util.List;import java.util.Map; import cn.hncu.domain.Stud;import cn.hncu.pubs.tx.Transaction; public interface IStudService { public abstract List< Map<string, string=""> > query(); @Transaction//注意，注解必须加在接口上，加在实现类上是无效的!,因为我们的动态代理是面向接口的 public abstract void save(Stud stud) throws InterruptedException, SQLException;}</string,></pre> <h2 id="studservicejava">StudService.java:</h2> <pre class="brush:java;">package cn.hncu.stud.service; import java.sql.SQLException;import java.util.List;import java.util.Map; import cn.hncu.domain.Stud;import cn.hncu.stud.dao.BookDAOJdbc;import cn.hncu.stud.dao.IBookDAO;import cn.hncu.stud.dao.StudDAO;import cn.hncu.stud.dao.StudDAOJdbc; public class StudService implements IStudService { //注入 private StudDAO studDao = new StudDAOJdbc(); private IBookDAO bookDao = new BookDAOJdbc(); @Override public List<map<string, string="">> query() { return studDao.query(); } //※利用动态代理在背后帮忙实现事务功能，注意：该方法内部的异常必须抛出来给动态代理捕捉处理 @Override public void save(Stud stud) throws InterruptedException, SQLException { studDao.save(stud);//在这个内部为stud对象补id--先执行 bookDao.save(stud.getBooks());//通过book拿到stud对象，进而拿到studid,完成外键字段的赋值 } }</map<string,></pre> <h2 id="jdbcproperties">jdbc.properties:</h2> <pre class="brush:java;">##MySQLdriver=com.mysql.jdbc.Driverurl=jdbc:mysql://127.0.0.1:3306/hncu?useUnicode=true&characterEncoding=utf-8username=rootpassword=1234 ##Oracle#driver=oracle.jdbc.driver.OracleDriver#url=jdbc:oracle:thin:@localhost:1521:orcl#username=scott#password=tiger</pre> <h2 id="indexjsp">index.jsp:</h2> <pre class="brush:java;"><%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib uri="java.sun/jsp/jstl/core" prefix="c"%> <title>mvc示例演示</title> <br> 学生信息查询 <hr> <form action="<c:url value='/StudServlet?cmd=save'/>" method="post"> 姓名:<input type="text" name="name"><br> <fieldset> <legend>图书1</legend> 书名:<input type="text" name="bookname"><br><br> 价格:<input type="text" name="price"> </fieldset> <fieldset> <legend>图书2</legend> 书名:<input type="text" name="bookname"><br><br> 价格:<input type="text" name="price"> </fieldset><br> <input type="submit" value="保存"> </form> <br> 默认请求 </pre> <h2 id="showjsp">show.jsp</h2> <pre class="brush:java;"><%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@taglib uri="java.sun/jsp/jstl/core" prefix="c"%> <title>学生信息查询</title> <style type="text/css"> table,tr,td,th{ border: 1px; border-style: solid; margin: auto; } </style> <h2>学生信息</h2> <c:foreach items="${studs}" var="stud"> </c:foreach><table> <tbody><tr> <th>ID</th> <th>姓名</th></tr> <tr> <td>${stud.id }</td> <td>${stud.name }</td> </tr> </tbody></table> </pre> <h2 id="webxml">web.xml</h2> <pre class="brush:java;"><servlet> <servlet-name>StudServlet</servlet-name> <servlet-class>cn.hncu.stud.StudServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>StudServlet</servlet-name> <url-pattern>/StudServlet</url-pattern> </servlet-mapping> </pre> <p>嗯，我就不做过多的解释啦，这个只是自己对以前知识点的一个小总结吧。</p> <p>转载请附上原文博客链接： <br>blog.csdn.net/qq_26525215</p> </num;i++){></connection></connection></connection></connection>