使用SpringMVC框架实现的小型Web系统——myLibrary图书借阅系统
作者：互联网
最近在学习SpringMVC框架，为了练习，写了一个小型的web项目，使用的是典型的三层结构，控制层Controller，数据库Dao，数据库用的是Mysql，前端用的是jsp。
项目的结构和功能分解如下
其中*1处需要用户输入用户名和密码，
username<input type="text" name="username"><br/> password<input type="password" name="password"><br/>
然后跳转到Controller中的CheckLogin中检验
查询
CheckLogin.java中的关键代码为
@Controller
@SessionAttributes("student")
public class CheckLogin{
@RequestMapping(method=RequestMethod.POST,value="check")//必须将@RequestMapping("")写在方法前，类前可写可不写
public ModelAndView check(@RequestParam("username") String username,@RequestParam("password") String password) {
Student student = new Student();
student.setName(username);
student.setPassword(password);
int count=Login.isLogin(student);
if(count>0) {
ModelAndView modelAndView = new ModelAndView("success");
modelAndView.addObject("student", student);
return modelAndView;
}else {
ModelAndView modelAndView = new ModelAndView("login");
return modelAndView;
}
}
}
login.java数据库代码为
public class Login {
private static final String url="jdbc:mysql://localhost:3306/test";
private static final String user="root";
private static final String password="1234";
public static int isLogin(Student student) {
Connection connection = null;
PreparedStatement preparedStatement = null;
int count=-1;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
String sql = "select count(*) from student where name=? and password=?;";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, student.getName());
preparedStatement.setString(2, student.getPassword());
ResultSet resultSet = preparedStatement.executeQuery();
if(resultSet.next()) {
count=resultSet.getInt(1);
}
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
if(connection!=null) {
try {
connection.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(preparedStatement!=null) {
try {
preparedStatement.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return count;
}
*2，登录之后借阅图书，需要先根据书名查询图书，
QueryBook.java代码为，前端传来bookname
@Controller
public class QueryBook {
@RequestMapping(method=RequestMethod.POST,value="queryBook")
public ModelAndView queryBook(@RequestParam("bookname") String bookname) {
Book book=null;
book=QBook.getBookByName(bookname);
ModelAndView modelAndView = new ModelAndView("queryBook");
if(book!=null) {
modelAndView.addObject("book", book);
return modelAndView;
}else {
return modelAndView;
}
//return "a";
}
}
连接数据库查询
public class QBook {
private static final String url="jdbc:mysql://localhost:3306/test";
private static final String user="root";
private static final String password="1234";
public static Book getBookByName(String bookname1) {
Book book=new Book();
Connection connection = null;
PreparedStatement prepareStatement = null;
ResultSet resultSet = null;
String sql = null;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
sql="select id,bookname,count from book where bookname=?";
prepareStatement = connection.prepareStatement(sql);
prepareStatement.setString(1, bookname1);
//prepareStatement.setString(2, bookname2);
resultSet = prepareStatement.executeQuery();
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
try {
while(resultSet.next()) {
book.setId(resultSet.getInt("id"));
book.setName(resultSet.getString("bookname"));
book.setCount(resultSet.getInt("count"));
}
} 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();
}
}
if(prepareStatement!=null) {
try {
prepareStatement.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return book;
}
查询结果
*3:点击借阅后，数据库中名字为Java的书数目减一，借阅列表中增加一条记录，通调用Dao层UpdateBook.java和UpdateList.java中的方法修改。
BorrowBook.java
@Controller
public class BorrowBook {
@RequestMapping(method=RequestMethod.POST,value="borrowBook")
public ModelAndView borrowBook(@RequestParam("bookname") String bookname,HttpServletRequest request) {
HttpSession session = request.getSession();
Student student=(Student) session.getAttribute("student");
String name = student.getName();
UpdateList.addBook(name,bookname);
int count=UpdateBook.reduceBookByName(bookname);
if(count>0) {
ModelAndView modelAndView = new ModelAndView("borrowDone");
return modelAndView;
}else {
ModelAndView modelAndView = new ModelAndView("borrowFail");
return modelAndView;
}
}
}
Dao层UpdateBook.java和UpdateList.java中的方法
public static int reduceBookByName(String bookname) {
Book book=new Book();
Connection connection = null;
PreparedStatement prepareStatement = null;
ResultSet resultSet = null;
String sql = null;
int count=0;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
sql="select count from book where bookname=?";
prepareStatement = connection.prepareStatement(sql);
prepareStatement.setString(1, bookname);
resultSet = prepareStatement.executeQuery();
if(resultSet.next()) {
int has=resultSet.getInt(1);
if(has>0) {
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
sql="update book set count=count-1 where bookname=?";
prepareStatement = connection.prepareStatement(sql);
prepareStatement.setString(1, bookname);
count= prepareStatement.executeUpdate();
//System.out.print(count);
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}else {
//System.out.print(count);
return count;
}
}
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
if(connection!=null) {
try {
connection.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(prepareStatement!=null) {
try {
prepareStatement.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//System.out.print(count);
return count;
}
public static int reduceBook(int returnBookId) {
String sql=null;
Connection connection = null;
PreparedStatement preparedStatement = null;
int i = 0;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
sql="delete from borrowlist where id=?";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, returnBookId);
i = preparedStatement.executeUpdate();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
*4:
归还图书功能需要先查询已经借阅的图书列表,因为登录时已经将username放在session中，所以从Session中取出，根据用户名查询
QureyBookList.java的代码为
@Controller
public class QueryBookList {
@RequestMapping("queryBookList")
public static ModelAndView queryBookList(HttpSession httpSession) {
Student student = (Student) httpSession.getAttribute("student");
String name = student.getName();
ArrayList<Book> arrayList = new ArrayList<Book>();
arrayList=QBookList.getBookByStudent(name);
ModelAndView modelAndView = new ModelAndView("borrowList");
if(arrayList!=null) {
modelAndView.addObject("arrayList", arrayList);//放到request域中
return modelAndView;
}else {
return modelAndView;
}
}
}
数据库连接QBookList.java
public class QBookList {
private static final String url="jdbc:mysql://localhost:3306/test";
private static final String user="root";
private static final String password="1234";
public static ArrayList<Book> getBookByStudent(String name) {
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
ArrayList<Book> arrayList = new ArrayList<Book>();
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
String sql = null;
sql="select id,bookname from borrowlist where name=?;";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, name);
resultSet = preparedStatement.executeQuery();
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
try {
while(resultSet.next()) {
Book book=new Book();
book.setId(resultSet.getInt(1));
book.setName(resultSet.getString(2));
arrayList.add(book);
}
} catch (SQLException e) {
e.printStackTrace();
}
if(connection!=null) {
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(preparedStatement!=null) {
try {
preparedStatement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return arrayList;
}
前端展示：
<h2 style="text-align: center"><font color="blue"><%Book book=(Book)request.getAttribute("book");%>
图书编号:<%=book.getId()%><br>
图书名字:<%=book.getName()%><br>
可借阅:<%=book.getCount()%>本<br></font></h2><br/>
<h2 style="text-align: center"><font color="blue">
<form action="borrowBook" method="post">
<input type="text" name="bookname" value=<%=book.getName()%>>
<input type="submit" value="borrow">
</form>
</font></h2><br/>
*5输入上图中的归还图书名字和编号，跳转到Controller中的ReturnBook.java，然后调用Dao层的UpdateBook.Java和UpdateList.java来更新数据库中的余书库存以及借阅列表
代码如下ReturnBook.java
@Controller
public class ReturnBook {
@RequestMapping(method=RequestMethod.POST,value="returnBook")
public ModelAndView returnBook(@RequestParam("returnBookName") String returnBookName,@RequestParam("returnBookId") int returnBookId) {
UpdateBook.addBookByName(returnBookName);
int i = UpdateList.reduceBook(returnBookId);
if(i>0){
ModelAndView modelAndView = new ModelAndView("returnDone");
return modelAndView;
}else {
ModelAndView modelAndView = new ModelAndView("returnFail");
return modelAndView;
}
}
}
UpdateBook.Java和UpdateList.java
public static int addBookByName(String bookname) {
Book book=new Book();
Connection connection = null;
PreparedStatement prepareStatement = null;
ResultSet resultSet = null;
String sql = null;
int count=0;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
sql="select count from book where bookname=?";
prepareStatement = connection.prepareStatement(sql);
prepareStatement.setString(1, bookname);
resultSet = prepareStatement.executeQuery();
if(resultSet.next()) {
int has=resultSet.getInt(1);
if(has>0) {
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
sql="update book set count=count+1 where bookname=?";
prepareStatement = connection.prepareStatement(sql);
prepareStatement.setString(1, bookname);
count= prepareStatement.executeUpdate();
//System.out.print(count);
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}else {
//System.out.print(count);
return count;
}
}
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
public static int addBook(String name,String bookname) {
String sql=null;
Connection connection = null;
PreparedStatement preparedStatement = null;
int i = 0;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url, user, password);
sql="insert into borrowlist (name,bookname) values (?,?)";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, name);
preparedStatement.setString(2, bookname);
i = preparedStatement.executeUpdate();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
标签：count,Web,String,SpringMVC,prepareStatement,connection,myLibrary,catch,null 来源： https://www.cnblogs.com/licheng1995/p/11552982.html