package com.lcx.test;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Savepoint;import java.util.Properties;public class Test {    public static void main(String[] args) {        String url1="jdbc:mysql://localhost:3306/JAVA?user=root&password=root&useUnicode=true&charactorEncoding=UTF8";        String url2="jdbc:mysql://localhost:3306/JAVA?useUnicode=true&charactorEncoding=UTF8";        String url3="jdbc:mysql://localhost:3306/JAVA";        String user="root";        String password="root";        Connection conn3 = null;        Savepoint point1 = null;        try {            //1、加載數(shù)據(jù)庫驅(qū)動，包名一般為域名反寫            Class.forName("com.mysql.jdbc.Driver");            Properties info = new Properties();            info.put("user", "root");            info.put("password", "root");            info.put("useUnicode","true");            info.put("charactorEncoding","utf8");            /*             * 2、獲取數(shù)據(jù)連接對象，DriverManager.getConnection方法有3個重載方法             *///          Connection conn1 = DriverManager.getConnection(url3, user, password);//將連接的用戶名、密碼放到方法參數(shù)中//          Connection conn2 = DriverManager.getConnection(url2,info);//將連接的屬性鍵值對放在Properties對象中            conn3 = DriverManager.getConnection(url1);//將所有連接信息都放在URL中            /*             * 3、根據(jù)SQL獲取sql會話對象，有2種方式 Statement、PreparedStatement             *      1、 PreparedStatement接口繼承Statement， PreparedStatement 實例包含已編譯的 SQL 語句，所以其執(zhí)行速度要快于 Statement 對象。             *      2、作為 Statement 的子類，PreparedStatement 繼承了 Statement 的所有功能。三種方法  execute、 executeQuery 和 executeUpdate 已被更改以使之不再需要參數(shù)             *      3、在JDBC應(yīng)用中,如果你已經(jīng)是稍有水平開發(fā)者,你就應(yīng)該始終以PreparedStatement代替 Statement.也就是說,在任何時候都不要使用Statement.             *          一.代碼的可讀性和可維護性.Statement需要不斷地拼接，而PreparedStatement不會。             *          二.PreparedStatement盡最大可能提高性能.DB有緩存機制，相同的預(yù)編譯語句再次被調(diào)用不會再次需要編譯。             *          三.最重要的一點是極大地提高了安全性.Statement容易被SQL注入，而PreparedStatementc傳入的內(nèi)容不會和sql語句發(fā)生任何匹配關(guān)系。             * 最常用的api             * addBatch()/addBatch(String sql) 預(yù)編譯SQL語句,只編譯一回哦,效率高啊。剝瓜子，一個一個剝，最后一口吃。             * setXXX(parameterIndex,value) 設(shè)置指定參數(shù)的值。             * execute()  執(zhí)行 SQL 語句，該語句可以是任何種類的 SQL 語句。             * executeQuery() 執(zhí)行查詢語句返回ResultSet             * executeUpdate() 執(zhí)行增刪改，返回影響的行數(shù)。             *              */            String sql_other = "TRUNCATE TABLE t_user_info";            String sql_insert = "insert into t_user_info(id,user,sex,age) value(null,?,?,?)";            String sql_query = "select * from t_user_info where id < ?";            conn3.setAutoCommit(false);//關(guān)閉自動提交            PreparedStatement preparedStatement_other = conn3.prepareStatement(sql_other);            PreparedStatement preparedStatement_insert = conn3.prepareStatement(sql_insert);            PreparedStatement preparedStatement_query = conn3.prepareStatement(sql_query);            preparedStatement_other.execute();            for(int i=0;i<100;i++){                preparedStatement_insert.setString(1, "user_"+i);                preparedStatement_insert.setString(2, "n");                preparedStatement_insert.setInt(3, i);                if(i>50){//                  preparedStatement_insert.setString(3, "我是錯誤的嘗試");                }                preparedStatement_insert.addBatch();            }            //一次性插入100條記錄，如果中間有出錯，那么這一次性的插入都不會成功            int[] updateInt = preparedStatement_insert.executeBatch();            conn3.commit();            point1 = conn3.setSavepoint("point1");            System.out.println(updateInt.length);            preparedStatement_query.setInt(1, 50);            //4、執(zhí)行SQL語句，查詢語句就獲取結(jié)果集            ResultSet result = preparedStatement_query.executeQuery();            while(result.next()){                int a = result.getInt("id");                int b = result.getInt(1);                System.out.println("第一列值，通過列名:"+a+",通過下標："+b);            }            /*             * 5、關(guān)閉結(jié)果集、關(guān)閉會話、關(guān)閉連接             */            result.close();            preparedStatement_other.close();            preparedStatement_insert.close();            preparedStatement_query.close();            conn3.close();        } catch (ClassNotFoundException e) {            System.out.println("驅(qū)動沒有加載到。。。");            e.printStackTrace();        } catch (SQLException e) {            System.out.println("出現(xiàn)sql異常。。。");            try {                conn3.rollback(point1);;            } catch (SQLException e1) {                e1.printStackTrace();            }            e.printStackTrace();        }    }}JDBC 進一步封裝
我們將獲取連接和釋放連接封裝到工具類中，執(zhí)行SQL的感覺沒有必要封裝，這樣更靈活。
[java] view plain copy print?package com.lcx.test;    import java.sql.Connection;  import java.sql.DriverManager;  import java.sql.ResultSet;  import java.sql.SQLException;  import java.sql.Statement;    public class JDBCUtil {      /**      * jdbc:mysql://主機名稱：連接端口/數(shù)據(jù)庫的名稱?參數(shù)=值      * String url = “jdbc:mysql://localhost:3306/JAVA?user=root&password=root&useUnicode=true&characterEncoding=UTF8”;      * 也可在獲取連接的時候使用用戶名和密碼      * 避免中文亂碼要指定useUnicode和characterEncoding, 執(zhí)行數(shù)據(jù)庫操作之前要在數(shù)據(jù)庫管理系統(tǒng)上創(chuàng)建一個數(shù)據(jù)庫，名字自己定，      */      private static final String url=“jdbc:mysql://localhost:3306/JAVA”;      private static final String user=“root”;      private static final String password=“root”;      private static Connection conn;      //靜態(tài)代碼塊，類加載時就加載驅(qū)動      static {          //1、加載驅(qū)動          try {              Class.forName(”com.mysql.jdbc.Driver”);          } catch (ClassNotFoundException e) {              System.out.println(”Exception: com.mysql.jdbc.driver not found Exception”);              e.printStackTrace();          }      }      private JDBCUtil(){                }      //2獲取連接的方法，只產(chǎn)生一個連接      public static Connection getConnection(){          try {              if(conn==null){                  synchronized (JDBCUtil.class) {                      if(conn==null){                          conn = DriverManager.getConnection(url, user, password);                      }                  }              }          } catch (SQLException e) {              System.out.println(”Exception: get mysql connection Exception”);              e.printStackTrace();          }          return conn;      }      //最后釋放資源，中間操作由preparedStatement 去操作更靈活      public static void free(ResultSet result,Statement statement,Connection connection){          try {              if(result!=null){//關(guān)閉結(jié)果集                  result.close();              }          } catch (SQLException e) {              e.printStackTrace();          }finally{              try {                  if(statement!=null){//關(guān)閉statement會話                      statement.close();                  }              } catch (SQLException e) {                  e.printStackTrace();              }finally{                  try {                      if(connection!=null){                          connection.close();//關(guān)閉連接                      }                  } catch (SQLException e) {                      e.printStackTrace();                  }              }                        }                }  }  
package com.lcx.test;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class JDBCUtil {    /**     * jdbc:mysql://主機名稱：連接端口/數(shù)據(jù)庫的名稱?參數(shù)=值     * String url = "jdbc:mysql://localhost:3306/JAVA?user=root&password=root&useUnicode=true&characterEncoding=UTF8";     * 也可在獲取連接的時候使用用戶名和密碼     * 避免中文亂碼要指定useUnicode和characterEncoding, 執(zhí)行數(shù)據(jù)庫操作之前要在數(shù)據(jù)庫管理系統(tǒng)上創(chuàng)建一個數(shù)據(jù)庫，名字自己定，     */    private static final String url="jdbc:mysql://localhost:3306/JAVA";    private static final String user="root";    private static final String password="root";    private static Connection conn;    //靜態(tài)代碼塊，類加載時就加載驅(qū)動    static {        //1、加載驅(qū)動        try {            Class.forName("com.mysql.jdbc.Driver");        } catch (ClassNotFoundException e) {            System.out.println("Exception: com.mysql.jdbc.driver not found Exception");            e.printStackTrace();        }    }    private JDBCUtil(){    }    //2獲取連接的方法，只產(chǎn)生一個連接    public static Connection getConnection(){        try {            if(conn==null){                synchronized (JDBCUtil.class) {                    if(conn==null){                        conn = DriverManager.getConnection(url, user, password);                    }                }            }        } catch (SQLException e) {            System.out.println("Exception: get mysql connection Exception");            e.printStackTrace();        }        return conn;    }    //最后釋放資源，中間操作由preparedStatement 去操作更靈活    public static void free(ResultSet result,Statement statement,Connection connection){        try {            if(result!=null){//關(guān)閉結(jié)果集                result.close();            }        } catch (SQLException e) {            e.printStackTrace();        }finally{            try {                if(statement!=null){//關(guān)閉statement會話                    statement.close();                }            } catch (SQLException e) {                e.printStackTrace();            }finally{                try {                    if(connection!=null){                        connection.close();//關(guān)閉連接                    }                } catch (SQLException e) {                    e.printStackTrace();                }            }        }    }}使用工具類操作數(shù)據(jù)處理
[java] view plain copy print?package com.lcx.test;    import java.sql.Connection;  import java.sql.PreparedStatement;  import java.sql.ResultSet;  import java.sql.SQLException;    public class JDBCTest {        public static void main(String[] args) {          //1、加載驅(qū)動、獲取連接          Connection connection = JDBCUtil.getConnection();          String sql_init =”TRUNCATE TABLE t_user_info”;          String sql_insert = ”insert into t_user_info(id,user,sex,age) value(null,?,?,?)”;          String sql_query = ”select * from t_user_info where id < ?”;          PreparedStatement ps_init;          PreparedStatement ps_insert;          PreparedStatement ps_query;          try {              connection.setAutoCommit(false);              //2、根據(jù)sql語句獲取 獲取預(yù)編譯語句對象              ps_init = connection.prepareStatement(sql_init);              ps_insert = connection.prepareStatement(sql_insert);              ps_query = connection.prepareStatement(sql_query);                            ps_init.execute();//可以執(zhí)行任何種類的SQL語句              //3、有參數(shù)值，就設(shè)置參數(shù)值，然后執(zhí)行預(yù)編譯語句，獲取結(jié)果集              for(int i=0;i<100;i++){                  ps_insert.setString(1, “user_”+i);                  ps_insert.setString(2, “n”);                  ps_insert.setInt(3, i);                  ps_insert.addBatch();//增加的批處理隊列中              }              ps_insert.executeBatch();//一次性執(zhí)行                            ps_query.setInt(1, 50);              //查詢記錄，獲取結(jié)果集              ResultSet result = ps_query.executeQuery();              while(result.next()){                  int a = result.getInt(“id”);                  int b = result.getInt(1);                  System.out.println(”第一列通過列明:”+a+“,第一列通過index:”+b);              }              connection.commit();              //5、釋放資源              JDBCUtil.free(result, ps_query, connection);              JDBCUtil.free(result, ps_init, connection);              JDBCUtil.free(result, ps_insert, connection);          } catch (SQLException e) {              try {                  connection.rollback();              } catch (SQLException e1) {                  e1.printStackTrace();              }              e.printStackTrace();          }                }    }  
package com.lcx.test;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;public class JDBCTest {    public static void main(String[] args) {        //1、加載驅(qū)動、獲取連接        Connection connection = JDBCUtil.getConnection();        String sql_init ="TRUNCATE TABLE t_user_info";        String sql_insert = "insert into t_user_info(id,user,sex,age) value(null,?,?,?)";        String sql_query = "select * from t_user_info where id < ?";        PreparedStatement ps_init;        PreparedStatement ps_insert;        PreparedStatement ps_query;        try {            connection.setAutoCommit(false);            //2、根據(jù)sql語句獲取 獲取預(yù)編譯語句對象            ps_init = connection.prepareStatement(sql_init);            ps_insert = connection.prepareStatement(sql_insert);            ps_query = connection.prepareStatement(sql_query);            ps_init.execute();//可以執(zhí)行任何種類的SQL語句            //3、有參數(shù)值，就設(shè)置參數(shù)值，然后執(zhí)行預(yù)編譯語句，獲取結(jié)果集            for(int i=0;i<100;i++){                ps_insert.setString(1, "user_"+i);                ps_insert.setString(2, "n");                ps_insert.setInt(3, i);                ps_insert.addBatch();//增加的批處理隊列中            }            ps_insert.executeBatch();//一次性執(zhí)行            ps_query.setInt(1, 50);            //查詢記錄，獲取結(jié)果集            ResultSet result = ps_query.executeQuery();            while(result.next()){                int a = result.getInt("id");                int b = result.getInt(1);                System.out.println("第一列通過列明:"+a+",第一列通過index:"+b);            }            connection.commit();            //5、釋放資源            JDBCUtil.free(result, ps_query, connection);            JDBCUtil.free(result, ps_init, connection);            JDBCUtil.free(result, ps_insert, connection);        } catch (SQLException e) {            try {                connection.rollback();            } catch (SQLException e1) {                e1.printStackTrace();            }            e.printStackTrace();        }    }}