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：
完整的项目链接：
https://github.com/chenhaoxiang/Java/tree/master/myMvcWeb2
这里只写出一些核心的类的代码：
Book.java:
package cn.hncu.domain; /* alter table book add constraint fk_book foreign key (studid) references stud(id); 设置studid为book的外键(fk_book)为stud的主键id */ 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<Book > books = new ArrayList<Book>(); 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<Book> getBooks() { return books; } public void setBooks(List<Book> 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1 public static Object getProxy(Object srcObj){ Object proxiedObj = Proxy.newProxyInstance(TxProxy.class.getClassLoader(), srcObj.getClass().getInterfaces(), new TxProxy(srcObj)); return proxiedObj; } */ /* 版本2 public static<T> T getProxy(Object srcObj, Class<T> cls){ Object proxiedObj = Proxy.newProxyInstance(TxProxy.class.getClassLoader(), srcObj.getClass().getInterfaces(), new TxProxy(srcObj)); return (T)proxiedObj; } */ /* 版本3 public static<T> T getProxy(Class<T> cls){ Object srcObj = null; try { srcObj = cls.newInstance(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } Object proxiedObj = Proxy.newProxyInstance(TxProxy.class.getClassLoader(), srcObj.getClass().getInterfaces(), new TxProxy(srcObj)); return (T)proxiedObj; } */ //版本4 public static<T> 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); con.commit(); 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; /** * @author 陈浩翔 * * 2016-8-15 */ 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}, new InvocationHandler() { @Override public Object 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 return 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(); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } } public static synchronized Connection getConnection() throws InterruptedException{ //从本地线程管理对象t中拿 Connection con = t.get(); if(con==null){ if(pool.size()<=0){ Thread.sleep(50); return getConnection(); } con=pool.remove(0); //放入到t中 t.set(con); } return con; } }
StudServlet.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 = new 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 { price = Double.parseDouble(prices[i]); } catch (NumberFormatException e) { price=0.0; } 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); } } try { service.save(stud); } catch (SQLException e) { 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...."); } }
