明顯是路徑?jīng)]找到，你調(diào)試下程序，在java代碼加下斷點(diǎn)，看看有沒(méi)有進(jìn)斷點(diǎn)。
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連接數(shù)據(jù)庫(kù)的典型步驟
第一步：加載正確的數(shù)據(jù)庫(kù)驅(qū)動(dòng)程序
第二步，定義所要連接數(shù)據(jù)庫(kù)的地址
String ODBCURL＝“jdbc:odbc:dbName”;
String oracleURL= "jdbc:oracle:thin:@host:port:dbName“;
String mysqlURL= "jdbc:mysql:// host:port/dbName“;
String sqlURL＝“jdbc:microsoft:sqlserver://host:1433;DatabaseName=dbName”;
第三步，建立與數(shù)據(jù)庫(kù)的連接
DriverManager.getConnection(oracleURL,
username,
password);
第四步，創(chuàng)建語(yǔ)句對(duì)象
Statement statement = connection.createStatement();
第五步，聲明SQL語(yǔ)句，并將該語(yǔ)句通過(guò)Statement對(duì)象提交給服務(wù)器進(jìn)行執(zhí)行。
Stringsql= “SELECT * FROM ONTACT_TABLE”;
ResultSet resultSet=statement.executeQuery(sql);
該語(yǔ)句將sql命令提交給數(shù)據(jù)庫(kù)服務(wù)器進(jìn)行執(zhí)行，并將執(zhí)行結(jié)果存儲(chǔ)在ResultSet對(duì)象中進(jìn)行執(zhí)行。
Statement接口主要有如下三個(gè)方法：
1. ResultSet executeQuery(String sql)
用于執(zhí)行查詢語(yǔ)句，返回 ResultSet結(jié)果集（一個(gè)二維表）
2. int executeUpdate(String sql)
用于執(zhí)行添加、刪除或修改操作，返回被更新記錄的條數(shù)
3. boolean execute(String sql)
執(zhí)行參數(shù)部分的SQL語(yǔ)句；
當(dāng)SQL語(yǔ)句的執(zhí)行結(jié)果是一個(gè)ResultSet結(jié)果集時(shí)，本方法返回true；并可以通過(guò)Statement?getResultSet()方法得到返回的結(jié)果集
當(dāng)SQL語(yǔ)句執(zhí)行后沒(méi)有返回的結(jié)果集時(shí)，該方法返回false
第六步：對(duì)查詢結(jié)果進(jìn)行分析
while(resultSet.next()){
name =resultSet.getString(1);
phone =resultSet.getString(2);
System.out.println(name+","+phone);
}
第七步，關(guān)閉打開(kāi)的資源
resultSet.close();
statement.close();
connection.close();
將打開(kāi)的資源關(guān)閉。
注意：資源關(guān)閉的順序和打開(kāi)的順序恰恰相反。
簡(jiǎn)單的增刪改查功能
package?EBookDao;
import?java.sql.Connection;
import?java.sql.PreparedStatement;
import?java.sql.ResultSet;
import?java.sql.SQLException;
import?java.util.ArrayList;
import?java.util.List;
import?DBUtil.DBUtil;
import?DBUtil.EBook;
/*
*查詢書(shū)集信息
*?
*?*/
public?class?EBookCZ?{
public?ListEBook?find()?{
Connection?conn?=?null;
PreparedStatement?ps?=?null;
ResultSet?rs?=?null;
ListEBook?list?=?new?ArrayListEBook();
try?{
conn?=?DBUtil.getConnection();
String?sql?=?"SELECT?*?FROM?ebook";
ps?=?conn.prepareStatement(sql);
rs?=?ps.executeQuery();
while?(rs.next())?{
EBook?eBook?=?new?EBook();
eBook.setId(rs.getInt("ID"));
eBook.setBname(rs.getString("bname"));
eBook.setPrice(rs.getString("price"));
list.add(eBook);
System.out.println(rs.getInt("ID")+rs.getString("bname")+rs.getString("price"));
}
}?catch?(SQLException?sqle)?{
sqle.printStackTrace();
}?finally?{
DBUtil.close(conn,?ps,?rs);
}
return?list;
}
/*
?*通過(guò)id刪除書(shū)集信息
?*?
?*?*/
public?static?EBook?DelById(int?id)?{
Connection?conn?=?null;
PreparedStatement?ps?=?null;
ResultSet?rs?=?null;
EBook?book?=?null;
try?{
conn?=?DBUtil.getConnection();
String?sql?=?"delete?ebook?";
sql?+=?"WHERE?ID=??";
ps?=?conn.prepareStatement(sql);
ps.setInt(1,?id);
rs?=?ps.executeQuery();
if?(rs.next())?{
book?=?new?EBook();
book.setId(rs.getInt("ID"));
book.setBname(rs.getString("bname"));
book.setPrice(rs.getString("price"));
}
}?catch?(SQLException?sqle)?{
sqle.printStackTrace();
}?finally?{
DBUtil.close(conn,?ps,?rs);
}
return?book;
}
}
package?EBookServlet;
import?java.io.IOException;
import?java.io.PrintWriter;
import?java.util.List;
import?javax.servlet.ServletException;
import?javax.servlet.http.HttpServlet;
import?javax.servlet.http.HttpServletRequest;
import?javax.servlet.http.HttpServletResponse;
import?DBUtil.EBook;
import?EBookDao.EBookCZ;
public?class?EBookServlet?extends?HttpServlet?{
/**
?*?
?*/
private?static?final?long?serialVersionUID?=?1L;
/**
?*?Constructor?of?the?object.
?*/
public?EBookServlet()?{
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);
}
/**
?*?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?{
response.setContentType("text/html;charset=utf-8");
PrintWriter?out?=?response.getWriter();
String?method?=?request.getParameter("method");
String?url?=?"";
EBookCZ?bookCZ=new?EBookCZ();
?if?(method?!=?null??method.equals("find"))?{
?System.out.println("find做完了");
??url?=?"EBookMNG.jsp";
??ListEBook?list?=?bookCZ.find();
??request.setAttribute("list",?list);
}?else?if?(method?!=?null??method.equals("findById"))?{
?System.out.println("findbyid做完了");
??url?=?"OK.jsp";
??int?id?=?Integer.parseInt(request.getParameter("id"));
??EBook?book?=?EBookCZ.DelById(id);
??request.setAttribute("book",?book);
}
request.getRequestDispatcher(url).forward(request,?response);
out.flush();
out.close();
}
/**
?*?Initialization?of?the?servlet.?br
?*?
?*?@throws?ServletException
?*?????????????if?an?error?occurs
?*/
public?void?init()?throws?ServletException?{
//?Put?your?code?here
}
}
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