Question

java连接数据库的例子

谁能帮忙写个java连接数据库的例子，JDBC我已经弄好了，数据库用的是SQL SEVRER 2005,登陆名xz，密码test,新建了数据库student,其中有表Users，内有UserName和UserPas字段。要求读取这个表并输出其中的数据。小弟初学，麻烦大家了！

Answer 1

ConnectionManager.java
import java.sql.*;
public class ConnectionManager {
private static final String DRIVER_CLASS="com.microsoft.sqlserver.jdbc.SQLServerDriver";
private static final String DATABASE_URL="jdbc:sqlserver://localhost:1433;DatabaseName=student";
private static final String DATABASE_USER="xz";
private static final String DATABASE_PASSWORD="test";
private ConnectionManager()
{}
/**
* 返回连接
* @return Connection
* @throws DBAccessException
*/
public static Connection getConnection()
{
Connection dbConnection=null;
try {
Class.forName(DRIVER_CLASS);
dbConnection=DriverManager.getConnection(DATABASE_URL,DATABASE_USER,DATABASE_PASSWORD);
} catch (ClassNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return dbConnection;
}
/**
* 关闭连接
* @param conn
* Connection
*/
public static void closeConnection(Connection conn)
{
try{
if(conn!=null && !conn.isClosed())
{
conn.close();
conn=null;
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
/**
* 关闭结果集
* @param rs
* ResultSet
*/
public static void closeResultSet(ResultSet rs)
{
try{
if(rs!=null)
{
rs.close();
rs=null;
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
/**
* 关闭SQL预处理语句
* @param pstmt
* PreparedStatement
*/
public static void closePreparedStatement(PreparedStatement pstmt)
{
try{
if(pstmt!=null)
{
pstmt.close();
pstmt=null;
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
/**
* 关闭SQL语句
* @param stmt
* Statement
*/
public static void closeStatement(Statement stmt)
{
try{
if(stmt!=null)
{
stmt.close();
stmt=null;
}
}catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
public static void main(String[]args)
{

try {
Connection con=ConnectionManager.getConnection();
if(!con.isClosed())
System.out.println("数据库连接成功。。。。。");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
User.javapublic class User {
private String username;
private String userpass;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getUserpass() {
return userpass;
}
public void setUserpass(String userpass) {
this.userpass = userpass;
}
}
UserDAO.javaimport java.util.*;
import java.sql.*;
public class UserDAO {
public List<User> getAllUser()
{
Connection conn=null;
PreparedStatement pstmt=null;
ResultSet rs=null;
List<User> userList=new ArrayList<User>();
String sql="select UserName,UserPas from Users";

try {
conn=ConnectionManager.getConnection();
pstmt=conn.prepareStatement(sql);
rs=pstmt.executeQuery();
while(rs.next())
{
User u=new User();
u.setUsername(rs.getString("UserName"));
u.setUserpass(rs.getString("UserPas"));
userList.add(u);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally
{
ConnectionManager.closeConnection(conn);
ConnectionManager.closePreparedStatement(pstmt);
ConnectionManager.closeResultSet(rs);
}
return userList;
}
}

Answer 2

public List getObject(String sql, Object[] object) { //sql执行语句，object是你sql语句里面的参数
List list = new ArrayList();
Connection con = null;
PreparedStatement pre = null;
ResultSet rs = null;
try{
con = C3P0Util.getInstance().getConnection(); //这是你获得数据库连接，你把这里改成调用你自己写的jdbc方法
pre = con.prepareStatement(sql); //执行sql语句
if(object!=null){
for(int i=0;i<object.length;i++){
pre.setObject(i+1, object[i]); //给sql里面的参数进行赋值
}
}
rs = pre.executeQuery();
while(rs.next()){
Users u = new User();
u.setUserName(rs.getString("UserName"));
u.setUserPas(rs.getString("UserPas")); list.add(u);
}
}catch(Exception e){
e.printStackTrace();
return null;
}finally{
C3P0Util.close(con, pre, rs); //关闭数据库资源
}
return list; //返回list集合
}
注意：list里面保存的是User对象的信息
你要获得User对象的信息，那么就要遍历list
for(int i=0;i<list.size;i++){
User u = (User)list.get(i); System.out.println("UserName:"+u.getUserName());
System.out.println("UserPas:"+u.getUserPas());
} 上面是针对list里面有很多个User对象，当然list里面只有一个User对象，也是可以的。
如果你的list里面只有一个User,那么可以直接：User u = (User)list.get(0);
System.out.println("UserName:"+u.getUserName());
System.out.println("UserPas:"+u.getUserPas());

希望对你有帮助！

Answer 3

Java连接数据库实例 此文中的代码主要列出连接数据库的关键代码，其他访问数据库代码省略

1、Oracle8/8i/9i数据库（thin模式）
Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
String url="jdbc:oracle:thin:@localhost:1521:orcl";
//orcl为数据库的SID
String user="test";
String passWord="test";
Connection conn= DriverManager.getConnection(url,user,password);

2、DB2数据库
Class.forName("com.ibm.db2.jdbc.app.DB2Driver ").newInstance();
String url="jdbc:db2://localhost:5000/sample";
//sample为你的数据库名
String user="admin";
String password="";
Connection conn= DriverManager.getConnection(url,user,password);

3、Sql Server7.0/2000数据库
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=mydb";
//mydb为数据库
String user="sa";
String password="";
Connection conn= DriverManager.getConnection(url,user,password);

4、Sybase数据库
Class.forName("com.sybase.jdbc.SybDriver").newInstance();
String url =" jdbc:sybase:Tds:localhost:5007/myDB";
//myDB为你的数据库名
Properties sysProps = System.getProperties();
SysProps.put("user","userid");
SysProps.put("password","user_password");
Connection conn= DriverManager.getConnection(url, SysProps);

5、Informix数据库
Class.forName("com.informix.jdbc.IfxDriver").newInstance();
String url =
"jdbc:informix-sqli://123.45.67.89:1533/myDB:INFORMIXSERVER=myserver;
user=testuser;password=testpassword";
//myDB为数据库名
Connection conn= DriverManager.getConnection(url);

6、MySQL数据库
Class.forName("org.gjt.mm.mysql.Driver").newInstance();
String url ="jdbc:mysql://localhost/myDB?user=soft&password=soft1234&useUnicode=true&characterEncoding=8859_1"
//myDB为数据库名
Connection conn= DriverManager.getConnection(url);

7、PostgreSQL数据库
Class.forName("org.postgresql.Driver").newInstance();
String url ="jdbc:postgresql://localhost/myDB"
//myDB为数据库名
String user="myuser";
String password="mypassword";
Connection conn= DriverManager.getConnection(url,user,password);

Answer 4

public 返回对象 方法名(){//创建数据库连接Connection con = JDBC.getConnection();string sql="select * from 表名";//创建预处理器
PreparedStatement pre = con.prepareStatement(sql); //执行sql语句
ResultSet rs = pre.executeQuery();if(rs.read()){ 对象 u= new 对象(); //设置值 u.属性=rs.get类型("字段名");}//关闭结果集rs.close();//关闭连接conn.close();
}