Java连接MySql数据库，并且实现增删改查功能！
这是我最近写的一个连接MySql数据库的一个例子，主要实现了插入，删除，更新，选择操作，用的环境是 j2sdk1.4.2_08，Eclipse3.1。下面我把在Eclipse3.1下怎样配置数据库连接信息简单说一下。
1.启动Eclipse3.1。
2.建立一个Java project就叫DbConnect 吧，再在该Project下建立一个新类也叫DbConnect 吧。
3.右击DbConnect.java文件点import，选择Archive file然后选择你的
mysql-connector-java-3.1.8-bin.jar文件，点Finish。你会看到有好些文件被加载进来，OK这就是连接MySql所需的驱动信息。如果到了这里你都成功的话那么恭喜你，你已经成功一半了！：）
4.接下来把我下面的代码copy到你的Java文件中，修改相关的数据库连接信息运行一下。OK？
我说一下那个mysql-connector-java-3.1.8-bin.jar文件，其实这就是一个MySql的驱动，各数据库厂商提供了不同的适用于JDBC的驱动使得在Java中连接数据库非常简单。这里我就不多说了，以后我会写篇专门介绍数据库驱动的文章。关于MySql的驱动还有更新版本的，你需要到MySql的网站上去下载，这个网上到处都是，我就不多说
了。下面看程序，有些地方我写了详细的注释应该能看懂。这个类是非常有特色的，在每个方法的传人参数和返回值不变的情况下，希望高手能提出改进意见。多指教，谢谢！
/**
* 数据库连接、选择、更新、删除演示
*/
//import java.sql.*;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.DriverManager;
import java.util.*;
public class DbConnect
{
/////////////////////////////////////////———–>>>数据成员 and 构造函数
private Connection dbconn;
private Statement dbstate;
private ResultSet dbresult;
DbConnect(
{
dbconn = null;
dbstate = null;
dbresult = null;
}
/////////////////////////////////////////———–>>>类方法
public void print(String str//简化输出
{
System.out.println(str;
}//end print(…
/**
* 连接MySql数据库
* @param host
* @param port
* @param dbaName
* @param usName
* @param psw
* @return bool值，连接成功返回真，失败返回假
*/
public boolean dbConnection(String host, String port, String dbaName, String usName, String psw
{
String driverName = \"com.mysql.jdbc.Driver\";//\"org.gjt.mm.mysql.Driver\"两个驱动都可以用
String dbHost = host;//数据库的一些信息
String dbPort = port;
String dbName = dbaName;
String enCoding = \"?useUnicode=true&characterEncoding=gb2312\"; //解决MySql中文问题,要连续写不能空格
String userName = usName;
String Psw = psw;
String url = \"jdbc:mysql://\" + dbHost + \":\" + dbPort + \"/\" + dbName + enCoding;
try
{
Class.forName(driverName.newInstance(;
dbconn = DriverManager.getConnection(url, userName, Psw;
//getConnection(url, userName, Psw从给的driver中选择合适的去连接数据库
//return a connection to the URL
}catch(Exception e{
print(\"url = \" + url; //发生错误时，将连接数据库信息打印出来
print(\"userName = \" + userName;
print(\"Psw\" + Psw;
print(\"Exception: \" + e.getMessage(;//得到出错信息
}
if (dbconn != null//dbconn != null 表示连接数据库成功，由异常保证！？
return true;
else
return false;
}// end boolean dbConnection(…
/**
* 对数据库表进行选择操作！
* @param tableName 数据库表名
* @param fieles 字段名
* @param selCondition 选择条件
* @return 一个含有map的List（列表）
*/
public ArrayList dbSelect(String tableName, ArrayList fields, String selCondition
{
ArrayList mapInList = new ArrayList(;
String selFields = \"\";
for (int i = 0; i
selFields += fields.get(i + \
String selFieldsTem = selFields.substring(0, selFields.length( – 2;//根据String的索引提取子串
try{
dbstate = dbconn.createStatement(;
String sql = \"select \" + selFieldsTem + \" from \" + tableName + selCondition;
print(\"sql = \" + sql;
try{
dbresult = dbstate.executeQuery(sql;
}catch(Exception err{
print(\"Sql = \" + sql;
print(\"Exception: \" + err.getMessage(;
}
pspan while(dbresult.next({ pspan Map selResult = new HashMap(;
selResult.put(\"message_type\
selResult.put(\"message_content\
mapInList.add(selResult;
}
}catch(Exception e{
print(\"Exception: \" + e.getMessage(;
}
return mapInList;
}//end String dbSelect(…
/**
* 对数据库表中的记录进行删除操作
* @param tableName
* @param condition
* @return bool值，表示删除成功或者失败。
*/
public boolean dbDelete(String tableName, String condition
{//——–>>>删除操作
boolean delResult = false;
String sql = \"delete from \" + tableName + \" \" + condition;
try{
dbstate.executeUpdate(sql; //return int // int delRe = ??
delResult = true;
}catch(Exception e{
print (\"sql = \" + sql;
print (\"Exception: \" + e.getMessage(;
}
if (delResult
return true;
else
return false;
}//end dbDelete(…
/**
* 对数据库表中记录进行更新操作
* @param tabName
* @param reCount
* @return bool值，成功返回true，失败返回false
*/
public boolean dbUpdate(String tabName, HashMap reCount, String upCondition
{
boolean updateResult = false;
String Values = \"\";
Iterator keyValues = reCount.entrySet(.iterator(;
for(int i = 0; i
{
Map.Entry entry = (Map.Entry keyValues.next(;
Object key = entry.getKey(;
Object value = entry.getValue(;
Values += key + \"=\" + \"’\" + value + \"’\" + \
}
String updateValues = Values.substring(0, Values.length( – 2;
String sql = \"update \" + tabName + \" set \" + updateValues + \" \" + upCondition;
try
{
dbstate.executeUpdate(sql;
updateResult = true;
}catch(Exception err{
print(\"sql = \" + sql;
print(\"Exception: \" + err.getMessage(;
}
if (updateResult
return true;
else
return false;
}//end dbUpdate(…
/**
* 对数据库表进行插入操作
* @param tabName
* @param hm
* @return bool值，成功返回true，失败返回false
*/
public boolean dbInsert(String tabName, HashMap values
{
String sql = \"\";
String insertFields = \"\
String insertValues = \"\
boolean insertResult = false;
Iterator keyValues = values.entrySet(.iterator(;
for(int i = 0; i
{
Map.Entry entry = (Map.Entry keyValues.next(;
Object key = entry.getKey(;
Object value = entry.getValue(;
temFields += key + \
temValues += \"’\" + value + \"’\" + \
}
insertFields = temFields.substring(0, temFields.length( – 2;
insertValues = temValues.substring(0, temValues.length( – 2;
sql += \"insert into \" + tabName + \" (\" + insertFields + \" values\" + \"(\" + insertValues + \"\";
try
{
dbstate.executeUpdate(sql;
insertResult = true;
}catch(Exception e{
print(\"Sql = \" + sql;
print(\"Exception: \" + e.getMessage(;
}
if (insertResult
return true;
else
return false;
}//end dbInsert(…
/**
* 断开数据库
* @return bool值，成功返回true，失败返回false
*/
public boolean dbClose(
{
boolean closeResult = false;
try
{
dbconn.close(;
closeResult = true;
}catch(Exception e{
print(\"Exception: \" + e.getMessage(;
}
if (closeResult
return true;
else
return false;
}//end dbClose(
/*/////////////////////////////////////////———–>>>入口主函数 */
public static void main(String[] args
{
DbConnect dc = new DbConnect(;
//连接数据库用到的一些参数.
String dbHost = \"localhost\";
String dbPort = \"3306\";
String dbName = \"feast\";
String dbuserName = \"root\";
String dbpsw = \"\";
boolean con = dc.dbConnection(dbHost, dbPort, dbName, dbuserName, dbpsw; //连接数据库
if (con
{
ArrayList fields = new ArrayList(;
fields.add(\"message_content\";
fields.add(\"message_type\";
Map lmap = new HashMap(;
String selCondition = \" where message_type = 1 limit 2\";
ArrayList str = dc.dbSelect(\"feast\—>>>选择记录
if (str.size( != 0{
dc.print(\"select OK!\";
dc.print(\"str’s size = \" + str.size(;
for(int i = 0; i
lmap = (HashMapstr.get(i;
dc.print(\"lmap = \" + lmap;
}
}
}
else
dc.print(\"fail\";
String tableName = \"feast\";
String condition = \"where message_type = 5\";
boolean del = dc.dbDelete(tableName, condition;//—>>>删除数据
if ( del
dc.print(\"delete ok\";
else
dc.print(\"delete error!\";
HashMap m = new HashMap(;
m.put(\"message_content\
m.put(\"message_number\
String upCondition = \"where message_type = 4\";
boolean ur = dc.dbUpdate(\"feast\—>>>更新数据
if ( ur
dc.print(\"update OK\";
else
dc.print(\"update error!\";
HashMap mm = new HashMap(;
mm.put(\"message_number\
mm.put(\"message_content\
mm.put(\"message_type\
boolean in = dc.dbInsert(\"feast\—>>>插入
if (in
dc.print(\"insert OK\";
else
dc.print(\"insert error!\";
boolean close = dc.dbClose(;//—–>断开数据库
if (close
dc.print(\"close OK\";
else
dc.print(\"close fail\";
}//end main(
}//end class DbConnect
