数据库操作
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？
/**
*
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
+= 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());
}
while(dbresult.next()){
Map selResult = new HashMap();
selResult.put("message_type", dbresult.getString("message_type"));
selResult.put("message_content", dbresult.getString("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 = "", temFields = "";
String insertValues = "", temValues = "";
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.s
ubstring(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", fields, selCondition); //—>>>选择记录
if (str.size() != 0){
dc.print("select OK!");
dc.print("str’s size = " + str.size());
for(int i = 0; i
dc.print("lmap = " + lmap);
}
}
}
else
dc.print("fail");
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!");
String tableName = "feast";
HashMap m = new HashMap();
m.put("message_content", "ookkk");
m.put("message_number", "9");
String upCondition = "where message_type = 4";
boolean ur = dc.dbUpdate("feast", m, upCondition); //—>>>更新数据
if ( ur)
dc.print("update OK");
else
dc.print("update error!");
HashMap mm = new HashMap();
mm.put("message_number", "6");
mm.put("message_content", "insertefasdfas");
mm.put("message_type", "4");
boolean in = dc.dbInsert("feast", mm); //—>>>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