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使用jdbc连接sql数据库

2010-05-24 22:57 330 查看
基本上就是这些步骤：

下载你要连接的数据库的JDBC驱动程序（driver）。通常都是一个jar文件，复制到你的project里面，确保识别这个库就可以了。

加载驱动， 不同的数据库需要不同 JDBC driver。

连接数据库，不同的数据库同样需要不同的JDBC URL。

下面给出连接不同数据库的例子

连接 mini SQL

//  Establish a connection to a mSQL database using JDBC. 
import java.sql.*; 
class JdbcTest1 { 
  public static void main (String[] args) { 
    try
    {
      // Step 1: Load the JDBC driver. 
      Class.forName("com.imaginary.sql.msql.MsqlDriver"); 
      // Step 2: Establish the connection to the database. 
      String url = "jdbc:msql://www.myserver.com:1114/contact_mgr"; 
      Connection conn = DriverManager.getConnection(url,"user1","password");  
    }
    catch (Exception e)
    {
      System.err.println("Got an exception! "); 
      System.err.println(e.getMessage()); 
    } 
  } 
}




连接Interbase

//  Establish a connection to an Interbase database using JDBC and ODBC. 
import java.sql.*; 
class JdbcTest1
{
  public static void main (String[] args)
  { 
    try
    { 
      // Step 1: Load the JDBC ODBC driver. 
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); 
      // Step 2: Establish the connection to the database. 
      String url = "jdbc:odbc:contact_mgr"; 
      Connection conn = DriverManager.getConnection(url,"user1","password");  
    }
    catch (Exception e)
    { 
      System.err.println("Got an exception! "); 
      System.err.println(e.getMessage()); 
    } 
  } 
}




对于其他数据库，参考如下列表

数据库

JDBC URL (JDBC Connection String)

JDBC Driver

MySQLjdbc:mysql://HOST:PORT/DATABASE

com.mysql.jdbc.Driver
Postgresqljdbc:postgresql://HOST:PORT/DATABASE

org.postgresql.Driver
SQL Serverjdbc:microsoft:sqlserver://HOST:1433;DatabaseName=DATABASE

com.microsoft.jdbc.sqlserver.SQLServerDriver
DB2jdbc:as400://HOST:PORT/DATABASE;

com.ibm.as400.access.AS400JDBCDriver
sqlitejdbc:sqlite:DATABASE

org.sqlite.JDBC

Derbyjdbc:derby:DATABASE

org.apache.derby.jdbc.EmbeddedDriver

Oracle有三种类型的驱动，后面单独列出

其中sqlite是嵌入式数据库，所以连接相对简单。下面是一些例子：

MySQL

Class.forName("com.mysql.jdbc.Driver").newInstance();
 String url = "jdbc:mysql://HOST/DATABASE";
 conn = DriverManager.getConnection(url, "username", "password");


Postgresql

Class.forName("org.postgresql.Driver");
String url = "jdbc:postgresql://HOST/DATABASE";
Connection conn = DriverManager.getConnection(url,"username", "password");




sqlite

Class.forName("org.sqlite.JDBC");
    Connection conn = DriverManager.getConnection("jdbc:sqlite:test.db");


Oracle

JDBC Thin Driver (no local SQL*Net

installation required/ handy for applets)

JDBC OCI

for writing stand-alone Java applications

JDBC KPRB driver (default connection) for Java Stored Procedures and Database JSP's.

Thin Driver

import java.sql.*;
class Conn {
  public static void main (String args []) throws SQLException
  {
       try {
             Class.forName ("oracle.jdbc.driver.OracleDriver");
       } catch (ClassNotFoundException e) {
             e.printStackTrace();
       }
        Connection conn = DriverManager.getConnection
            ("jdbc:oracle:thin:@localhost:1521:orcl", "scott", "tiger");
                            // @machineName:port:SID,   userid,  password
        Statement stmt = conn.createStatement();
        ResultSet rset = stmt.executeQuery("select BANNER from SYS.V_$VERSION");
        while (rset.next())
              System.out.println (rset.getString(1));   // Print col 1
        stmt.close();
  }
}


我只用过第一个，个人觉得觉得简单的数据库操作基本上够用了，后面的两种没有用过。



OCI Driver

import java.sql.*;
class dbAccess {
  public static void main (String args []) throws SQLException
  {
        try {
              Class.forName ("oracle.jdbc.driver.OracleDriver");
        } catch (ClassNotFoundException e) {
              e.printStackTrace();
        }
        Connection conn = DriverManager.getConnection
             ("jdbc:oracle:oci8:@hostname_orcl", "scott", "tiger");
                     // or oci7 @TNSNames_Entry,    userid,  password
        Statement stmt = conn.createStatement();
        ResultSet rset = stmt.executeQuery("select BANNER from SYS.V_$VERSION");
        while (rset.next())
              System.out.println (rset.getString(1));   // Print col 1
        stmt.close();
  }
}




KPRB Driver

import java.sql.*;
class dbAccess {
  public static void main (String args []) throws SQLException
  {
        Connection conn = (new oracle.jdbc.driver.OracleDriver()).defaultConnection();
        Statement stmt = conn.createStatement();
        ResultSet rset = stmt.executeQuery("select BANNER from SYS.V_$VERSION");
        while (rset.next())
              System.out.println (rset.getString(1));   // Print col 1
        stmt.close();
  }
}




对于C/S架构的数据库，可以将连接的配置写到Java properties文件里面，以方便以后的使用。



不同的JDBC驱动，按照它们的实现方法，也分为四个不同的类别：


JDBC-ODBC bridge plus ODBC driver:

The Java Software
bridge product provides JDBC access via ODBC drivers.

Native-API partly-Java driver:

This kind of driver
converts JDBC calls into calls on the client API for Oracle, Sybase,
Informix, IBM DB2, or other DBMSs.

JDBC-Net pure Java driver:

This driver translates
JDBC calls into a DBMS-independent net protocol, which is then
translated to a DBMS protocol by a server.

Native-protocol pure Java driver:

This kind of driver
converts JDBC calls directly into the network protocol used by DBMSs.

下表给出了它们之间的异同点：


Direct -a connection that a JDBC client makes directly to the DBMS server, which may be remote


Indirect--a connection that a JDBC client makes to a middleware process that acts as a bridge to the DBMS server



DRIVER CATEGORY

ALL J***A

NETWORK CONNECTION

1 - JDBC-ODBC Bridge

No

Direct

2 - Native API as basis

No

Direct

3 - JDBC-Net

client Yes



server Maybe

Indirect

4 - Native protocol as basis

Yes

Direct

最后说一下异常和警告处理：

捕获异常并打印

try {
	// Code that could generate an exception goes here.
	// If an exception is generated, the catch block below
	// will print out information about it.
} catch(SQLException ex) {
	System.out.println("/n--- SQLException caught ---/n");
	while (ex != null) {
		System.out.println("Message:   "
                                   + ex.getMessage ());
		System.out.println("SQLState:  "
                                   + ex.getSQLState ());
		System.out.println("ErrorCode: "
                                   + ex.getErrorCode ());
		ex = ex.getNextException();
		System.out.println("");
	}
}


SQLWarning


对象是 
SQLException


子类，它不会中断程序的执行，但是却能够提供很多有价值的信息，尤其是debug的时候。
Connection


对象
，Statement


对象 (
包括PreparedStatement


和
CallableStatement


对象),或者
ResultSet


对象都有一个
getWarnings


方法。下面是一个列子：

Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select COF_NAME from COFFEES");
while (rs.next()) {
	String coffeeName = rs.getString("COF_NAME");
	System.out.println("Coffees available at the Coffee Break:  ");
	System.out.println("    " + coffeeName);
	SQLWarning warning = stmt.getWarnings();
	if (warning != null) {
		System.out.println("/n---Warning---/n");
		while (warning != null) {
			System.out.println("Message: "
                                           + warning.getMessage());
			System.out.println("SQLState: "
                                           + warning.getSQLState());
			System.out.print("Vendor error code: ");
			System.out.println(warning.getErrorCode());
			System.out.println("");
			warning = warning.getNextWarning();
		}
	}
	SQLWarning warn = rs.getWarnings();
	if (warn != null) {
		System.out.println("/n---Warning---/n");
		while (warn != null) {
			System.out.println("Message: "
                                           + warn.getMessage());
			System.out.println("SQLState: "
                                           + warn.getSQLState());
			System.out.print("Vendor error code: ");
			System.out.println(warn.getErrorCode());
			System.out.println("");
			warn = warn.getNextWarning();
		}
	}
}


参考：

［1］http://www.devdaily.com/java/edu/pj/pj010024/

［2］http://www.devdaily.com/java/jdbc-connection-string-mysql-postgresql-sqlserver

［3］http://www.orafaq.com/wiki/JDBC

［4］http://java.sun.com/j2se/1.4.2/docs/guide/jdbc/getstart/intro.html#1006158

［5］http://java.sun.com/docs/books/tutorial/jdbc/basics/index.html
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