这里有新鲜出炉的Java函数式编程,程序狗速度看过来!
java 是一种可以撰写跨平台应用软件的面向对象的程序设计语言,是由Sun Microsystems公司于1995年5月推出的Java程序设计语言和Java平台(即JavaEE(j2ee), JavaME(j2me), JavaSE(j2se))的总称。
这篇文章主要为大家详细介绍了java学生信息管理系统设计,学生信息添加进入数据库的事务,具有一定的参考价值,感兴趣的小伙伴们可以参考一下
本例的学生信息添加进入数据库的事务(可以提交事务,事务回滚,用本地线程完善)
主页面index.jsp
- <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
- <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
- <html>
- <head>
- <title>学生信息管理</title>
- </head>
- <body>
- <a href='<c:url value="/query"/>?cmd=query'>查看学生信息</a>
- <br><br>
- <!--
- <a href="<c:url value='/StudServlet?cmd=save' />">学生信息添加</a>
- -->
- <h2>学生信息添加</h2>
- <form action='<c:url value="/query"/>?cmd=add' method="post">
- 姓名:<input type="text" name="name"/><br><br>
- <fieldset style="border: solid;border-color: red;width: 250px;">
- <legend>图书1</legend>
- 书名:<input type="text" name="book"/><br><br>
- 价格:<input type="text" name="price"/>
- </fieldset>
- <br>
- <fieldset style="border: solid;border-color:green;width: 250px;">
- <legend>图书2</legend>
- 书名:<input type="text" name="book"/><br><br>
- 价格:<input type="text" name="price"/>
- </fieldset>
- <br><br>
- <input type="submit" value="提交"/><br><br>
- </form>
- </body>
- </html>
工具包
获取数据库连接的工具ConnUtils5.java
- package cn.hncu.utils;
- 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.util.ArrayList;
- import java.util.List;
- import java.util.Properties;
- public class ConnUtils5 {
- //本地线程管理对象,用于实现: 同一个线程获取的连接是同一个
- private static ThreadLocal < Connection > t = new ThreadLocal < Connection > ();
- private final static List < Connection > pool = new ArrayList < Connection > ();
- private static int SIZE; //由资源文件读取
- private ConnUtils5() {
- }
- static {
- Properties p = new Properties();
- try {
- //下面这种方式在纯Java项目中可以读取到classpath下的资源文件,但无法读取JavaEE项目的。因为Tomcat把系统的默认类加载器改了
- //p.load( ClassLoader.getSystemClassLoader().getSystemResourceAsStream("jdbc.properties"));
- // p.load(ClassLoader.getSystemResourceAsStream("jdbc.properties"));
- //读取Web项目的classpath下的资源文件,用这个可以
- p.load(ConnUtils3.class.getClassLoader().getResourceAsStream("jdbc.properties"));
- String driver = p.getProperty("driver");
- String url = p.getProperty("url");
- String name = p.getProperty("username");
- String pwd = p.getProperty("password");
- String ssize = p.getProperty("size");
- SIZE = Integer.parseInt(ssize);
- Class.forName(driver);
- for (int i = 0; i < SIZE; i++) {
- final Connection con = DriverManager.getConnection(url, name, pwd);
- System.out.println("con==" + con);
- //更改conn.close()方法
- //用代理模式生成一个增强版的conn对象,把它的close()方法拦截更改掉
- Object nCon = Proxy.newProxyInstance(ConnUtils3.class.getClassLoader(),
- // conn.getClass().getInterfaces(),
- //后面这种方式不行,应该是驱动中的实现类和我们当前程序不在同一空间(类加载器不同)
- new Class[] {
- Connection.class
- },
- new InvocationHandler() {@Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
- if (method.getName().equals("close")) {
- System.out.println("还回一个链接:" + (Connection) proxy);
- pool.add((Connection) proxy);
- return null;
- }
- return method.invoke(con, args);
- }
- });
- pool.add((Connection) nCon);
- }
- } catch(Exception e) {
- e.printStackTrace();
- }
- }
- public static synchronized Connection getConnection() {
- //先从t中拿,如果有就拿出去,如果没有再到池中拿且把该对象放到t中
- Connection con = t.get();
- if (con == null) {
- if (pool.size() <= 0) {
- System.out.println("池中连接没有了...");
- try {
- Thread.sleep(1000);
- } catch(InterruptedException e) {
- e.printStackTrace();
- }
- return getConnection();
- }
- con = pool.remove(0);
- t.set(con); //放到t中
- }
- return con; //拿一个移一个
- }
- }
代理
- package cn.hncu.utils;
- import java.lang.reflect.InvocationHandler;
- import java.lang.reflect.Method;
- import java.lang.reflect.Proxy;
- import java.sql.Connection;
- import java.sql.SQLException;
- public class TxProxy implements InvocationHandler {
- private Object srcObj=null;
- private TxProxy(Object srcObj) {
- this.srcObj = srcObj;
- }
- public static Object getProxy(Object srcObj){
- System.out.println("srcObj:"+srcObj);
- Object newObj=Proxy.newProxyInstance(
- TxProxy.class.getClassLoader(),
- srcObj.getClass().getInterfaces(),
- new TxProxy(srcObj));
- System.out.println("newObj:"+newObj);
- return newObj;
- }
- @Override
- public Object invoke(Object proxy, Method method, Object[] args)
- throws Throwable {
- Connection con=null;
- Object returnObj=null;
- try {
- con=ConnUtils5.getConnection();
- System.out.println("invoke拿到一个链接:"+con);
- con.setAutoCommit(false);
- returnObj=method.invoke(srcObj, args);
- System.out.println("提交一个事务...");
- con.commit();
- } catch (Exception e) {
- try {
- System.out.println("回滚一个事务...");
- con.rollback();
- } catch (SQLException e1) {
- e1.printStackTrace();
- }
- }finally{
- try {
- con.setAutoCommit(true);
- con.close();
- } catch (SQLException e) {
- e.printStackTrace();
- }
- }
- return returnObj;
- }
- }
代理2:不需要强转,但是代理了所有
- package cn.hncu.utils;
- import java.lang.reflect.InvocationHandler;
- import java.lang.reflect.Method;
- import java.lang.reflect.Proxy;
- import java.sql.Connection;
- import java.sql.SQLException;
- public class TxProxy2 implements InvocationHandler {
- private Object srcObj=null;
- private TxProxy2(Object srcObj) {
- this.srcObj = srcObj;
- }
- public static<T> T getProxy(Class<T> c){
- Object obj=null;
- try {
- obj = c.newInstance();
- } catch (Exception e) {
- e.printStackTrace();
- }
- Object newObj=Proxy.newProxyInstance(
- TxProxy2.class.getClassLoader(),
- c.getInterfaces(),
- new TxProxy2(obj));
- return (T) newObj;
- }
- @Override
- public Object invoke(Object proxy, Method method, Object[] args)
- throws Throwable {
- Connection con=null;
- Object returnObj=null;
- try {
- con=ConnUtils5.getConnection();
- System.out.println("invoke拿到一个链接:"+con);
- con.setAutoCommit(false);
- returnObj=method.invoke(srcObj, args);
- System.out.println("提交一个事务...");
- con.commit();
- } catch (Exception e) {
- try {
- System.out.println("回滚一个事务...");
- con.rollback();
- } catch (SQLException e1) {
- e1.printStackTrace();
- }
- }finally{
- try {
- con.setAutoCommit(true);
- con.close();
- } catch (SQLException e) {
- e.printStackTrace();
- }
- }
- return returnObj;
- }
- }
注解
- package cn.hncu.utils;
- import java.lang.annotation.ElementType;
- import java.lang.annotation.Retention;
- import java.lang.annotation.RetentionPolicy;
- import java.lang.annotation.Target;
- @Target(value=ElementType.METHOD)
- @Retention(RetentionPolicy.RUNTIME)
- public @interface Transaction {
- }
代理3:用注解实现需要事务则用事务
- package cn.hncu.utils;
- import java.lang.reflect.InvocationHandler;
- import java.lang.reflect.Method;
- import java.lang.reflect.Proxy;
- import java.sql.Connection;
- import java.sql.SQLException;
- public class TxProxy3 implements InvocationHandler {
- private Object srcObj = null;
- private TxProxy3(Object srcObj) {
- this.srcObj = srcObj;
- }
- public static < T > T getProxy(T srcObj) {
- Object newObj = Proxy.newProxyInstance(TxProxy3.class.getClassLoader(), srcObj.getClass().getInterfaces(), new TxProxy3(srcObj));
- return (T) newObj;
- }
- @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
- /* 这种方式来实现只拦截指定的方法
- if(method.getName().equals("close")){
- ...拦截
- }else{
- return method.invoke(srcObj, args);
- }
- */
- if (method.isAnnotationPresent(Transaction.class)) {
- Connection con = null;
- Object returnObj = null;
- try {
- con = ConnUtils5.getConnection();
- System.out.println("invoke拿到一个链接:" + con);
- con.setAutoCommit(false);
- //真正的业务代码,放行
- returnObj = method.invoke(srcObj, args);
- System.out.println("提交一个事务...");
- con.commit();
- } catch(Exception e) {
- try {
- System.out.println("回滚一个事务...");
- con.rollback();
- } catch(SQLException e1) {
- e1.printStackTrace();
- }
- } finally {
- try {
- con.setAutoCommit(true);
- con.close();
- } catch(SQLException e) {
- e.printStackTrace();
- }
- }
- return returnObj;
- } else {
- System.out.println("不存在事务注解,直接放行!");
- return method.invoke(srcObj, args);
- }
- }
- }
资源文件jdbc.properties
- ##MySQL
- driver=com.mysql.jdbc.Driver
- url=jdbc:mysql://127.0.0.1:3306/hncu?useUnicode=true&characterEncoding=utf-8
- username=root
- password=1234
- size=3
- ##Oracle
- #driver=oracle.jdbc.driver.OracleDriver
- #url=jdbc:oracle:thin:@127.0.0.1:1521:orcl
- #username=scott
- #password=tiger
stud层的servlet层–QueryServlet.java
- package cn.hncu.stud.servlet;
- import java.io.IOException;
- 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.stud.service.IStudService;
- import cn.hncu.stud.service.StudServiceImpl;
- import cn.hncu.utils.TxProxy3;
- public class QueryServlet extends HttpServlet {
- //注入
- //1.
- // IStudService service=(IStudService) TxProxy.getProxy(new StudServiceImpl());
- //2.
- // IStudService service=TxProxy2.getProxy(StudServiceImpl.class);
- //3.
- IStudService service = TxProxy3.getProxy(new StudServiceImpl());
- public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
- IOException {
- doPost(request, response);
- }
- public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,
- IOException {
- String cmd = request.getParameter("cmd");
- System.out.println("cmd:" + cmd);
- if ("query".equals(cmd)) {
- query(request, response);
- } else if ("add".equals(cmd)) {
- add(request, response);
- }
- }
- public void query(HttpServletRequest request, HttpServletResponse response) throws ServletException,
- IOException {
- System.out.println("service:" + service);
- List < Map < String,
- String >> studs = service.query();
- request.setAttribute("studs", studs);
- request.getRequestDispatcher("/jsps/show.jsp").forward(request, response);
- }
- public void add(HttpServletRequest request, HttpServletResponse response) throws ServletException,
- IOException {
- //1收集参数 2组织参数(id字段留到dao中去补)
- String name[] = request.getParameterValues("name");
- Stud s = new Stud();
- s.setName(name[0]);
- //图书信息
- String books[] = request.getParameterValues("book");
- //防护一下 ---价格的防护应该也要写,这里我们偷懒了
- if (books == null || books.length <= 0) {
- return;
- }
- String prices[] = request.getParameterValues("price");
- for (int i = 0; i < books.length; i++) {
- Book b = new Book();
- b.setName(books[i]);
- b.setPrice(Double.parseDouble(prices[i]));
- //※完成两个值对象的“一对多”关系的数据封装
- s.getBooks().add(b); //一方
- b.setS(s); //多方
- }
- //3调用service层
- try {
- service.save(s);
- } catch(Exception e) {
- //导向失败页面
- }
- }
- }
stud层的service层–
接口:
- package cn.hncu.stud.service;
- import java.util.List;
- import java.util.Map;
- import cn.hncu.domain.Stud;
- import cn.hncu.utils.Transaction;
- public interface IStudService {
- public List<Map<String, String>> query();
- //注意,注解只有放在接口才有用,,,,写在实现类中的方法无效(不会决定开启事务)
- @Transaction
- public void save(Stud stud) throws Exception ;
- }
实现类
- package cn.hncu.stud.service;
- import java.sql.Connection;
- import java.sql.SQLException;
- import java.util.List;
- import java.util.Map;
- import cn.hncu.domain.Stud;
- import cn.hncu.stud.dao.BookDAO;
- import cn.hncu.stud.dao.BookJdbcDao;
- import cn.hncu.stud.dao.StudDAO;
- import cn.hncu.stud.dao.StudJdbcDAO;
- import cn.hncu.utils.ConnUtils5;
- /*我们以后开发时通常都要采用一个dao独立操作一个表,系统中有几个实体表就写几个dao,
- * 以后框架都是这么干的,我们也要这样做,因为架构好!
- *
- * 采用事务的场合:
- * 1、如果只有一个dao,但要执行多条sql语句且涉及增删改,则要开启事务
- * 2、如果一个service调用多个dao,通常也要开启事务。
- */
- public class StudServiceImpl implements IStudService {
- //注入
- StudDAO dao_stud=new StudJdbcDAO();
- BookDAO dao_book=new BookJdbcDao();
- @Override
- public List<Map<String, String>> query() {
- return dao_stud.query();
- }
- @Override
- public void save(Stud stud) throws Exception {
- dao_stud.save(stud);
- dao_book.save(stud.getBooks());
- }
- }
stud层的dao层–
Stud接口–分离式做法,一个表对应一个dao,为框架做准备
- package cn.hncu.stud.dao;
- import java.util.List;
- import java.util.Map;
- import cn.hncu.domain.Stud;
- public interface StudDAO {
- public List < Map < String,
- String >> query();
- public void save(Stud stud) throws Exception;
- }
Stud实现类
- 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.Book;
- import cn.hncu.domain.Stud;
- import cn.hncu.utils.ConnUtils3;
- public class StudJdbcDAO implements StudDAO {
- @Override public List < Map < String,
- String >> query() {
- List < Map < String,
- String >> list = new ArrayList < Map < String,
- String >> ();
- //一个map就是一行数据, List<Map>就是整个数据表
- Connection con = null;
- try {
- con = ConnUtils3.getConnection();
- Statement st = con.createStatement();
- String sql = "select * from stud";
- ResultSet rs = st.executeQuery(sql);
- while (rs.next()) {
- Map < String,
- String > m = new HashMap < String,
- String > ();
- m.put("id", (String) rs.getObject(1));
- m.put("name", (String) rs.getObject(2));
- list.add(m);
- }
- rs.close();
- st.close();
- } catch(SQLException e) {
- e.printStackTrace();
- } finally {
- try {
- con.close();
- } catch(SQLException e) {
- e.printStackTrace();
- }
- }
- return list;
- }
- @Override public void save(Stud stud) throws Exception {
- Connection con = ConnUtils3.getConnection();
- System.out.println("拿到一个链接:" + con);
- String sql = "insert into stud values(?,?)";
- String uuid = UUID.randomUUID().toString().replace("-", "");
- PreparedStatement pst = con.prepareStatement(sql);
- stud.setId(uuid); //为了"多方"即book能够拿到"一方"的id,专门补的
- pst.setString(1, uuid);
- pst.setString(2, stud.getName());
- System.out.println("1:" + uuid + ",2:" + stud.getName());
- pst.executeUpdate();
- // con.close();//拿到同一个con,这里就不需要关了
- }
- }
Book接口
- package cn.hncu.stud.dao;
- import java.util.List;
- import cn.hncu.domain.Book;
- public interface BookDAO {
- public void save(List < Book > books) throws Exception;
- }
Book实现类
- package cn.hncu.stud.dao;
- import java.sql.Connection;
- import java.sql.PreparedStatement;
- import java.util.List;
- import cn.hncu.domain.Book;
- import cn.hncu.utils.ConnUtils3;
- public class BookJdbcDao implements BookDAO {
- @Override
- public void save(List<Book> books) throws Exception {
- Connection con=ConnUtils3.getConnection();
- System.out.println("拿到一个链接:"+con);
- String sql="insert into book(name,price,studid) values(?,?,?)";
- PreparedStatement pst=con.prepareStatement(sql);
- for(Book b:books){
- pst.setString(1, b.getName());
- pst.setDouble(2, b.getPrice());
- pst.setObject(3, "12132312");//异常(故意给一个不存在的外键字段,以测试事务回滚)--测事务回滚
- // pst.setObject(3, b.getS().getId());
- System.out.println("1:"+b.getName()+",2:"+b.getPrice()+",3:"+b.getS().getId());
- pst.addBatch();//添加到批处理
- }
- pst.executeBatch();//执行批处理
- // con.close();//这里拿到同一个con,这里不需要关
- }
- }
值对象
Stud对象
- package cn.hncu.domain;
- import java.util.ArrayList;
- import java.util.List;
- /*
- * 一对多中的 “一”方 值对象的建法
- */
- public class Stud {
- private String id;
- private String name;
- //※专为“多”方添加一个集合---体现多表中的“一对多关系”
- private List<Book> books=new ArrayList<Book>();//注意,该集合要在构造时或之前就new出来。
- 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 String toString() {
- return "id=" + id + "," + name + "," + books;
- }
- }
Book对象
- package cn.hncu.domain;
- /*
- * 一对多中的 “多”方 值对象的建法
- */
- public class Book {
- private Integer id;
- //基本数据类型全部用包装类的声明,为以后使用框架做技术准备---包装类能够兼容框架(因为一般框架都会使用类反射)
- private String name;
- private Double price;
- //※专为“一”方添加一个对象类型的变量(注意,不用studid)---体现多表中的“一对多关系”
- private Stud s; //设置主人
- //private String studid;//★★不要这样设
- public Integer getId() {
- return id;
- }
- public void setId(Integer id) {
- this.id = id;
- }
- public String getName() {
- return name;
- }
- public void setName(String name) {
- this.name = name;
- }
- public Double getPrice() {
- return price;
- }
- public void setPrice(Double price) {
- this.price = price;
- }
- public Stud getS() {
- return s;
- }
- public void setS(Stud s) {
- this.s = s;
- }
- /*
- * 多表关联时的toString()方法要注意一个陷阱,就是一方输出另一方,同时另一方又反过来输出前一方,形成无穷递归!
- */
- @Override public String toString() {
- return "id=" + id + "," + name + "," + price; //这里不能输出Stud对象,否则无穷递归
- }
- }
显示学生信息页面jsps/show.jsp
- <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
- <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
- <html>
- <head>
- <title>学生信息管理</title>
- </head>
- <body>
- <h2>学生信息</h2>
- <c:forEach items="${studs}" var="x">
- ${x.id},${x.name}<br/>
- </c:forEach>
- </body>
- </html>
效果图:
来源: http://www.phperz.com/article/17/1125/359393.html