java连接数据库增删改查公共方法

package dao;

import java.io.IOException;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Timestamp;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class DBCon {
     private static String DBDRIVER="com.microsoft.sqlserver.jdbc.SQLServerDriver";
     private static String DBURL="jdbc:sqlserver://localhost:1433;databasename=改为数据库名称";
     private static String DBUID="登录账户";
     private static String DBPWD="登录密码";
     private static Connection conn = null;
     private static Statement stmt = null;

   //打开连接
     public static void open() {
         //加载驱动
         try {
             Class.forName(DBDRIVER);
             conn=DriverManager.getConnection(DBURL,DBUID,DBPWD);

         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         } catch (SQLException e) {
                 e.printStackTrace();
         }
     }
     //关闭连接
     public static void close() {
         try {
             if(stmt!=null)
                     stmt.close();
             if(conn!=null && !conn.isClosed())
                 conn.close();
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }
     //得到一个连接对象，当用户使用DBUtil无法解决个性问题时
     //可以通过本方法获得连接对象
     public static Connection getConnection() {
         try {
             if(conn==null ||conn.isClosed())
                 open();
         } catch (SQLException e) {
             e.printStackTrace();
         }
         return conn;
     }

     //executeQuery
     //executeUpdate
     //execute
     //获得查询的数据集
     //select * from student where name='' and sex=''
     public static ResultSet executeQuery(String sql) {
         try {
             open();//保证连接是成功的
             stmt = conn.createStatement();
             return stmt.executeQuery(sql);
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         return null;
     }

     //修改表格内容
     public static int executeUpdate(String sql) {
         int result = 0;
         try {
             open();//保证连接是成功的
             stmt = conn.createStatement();
             result = stmt.executeUpdate(sql);
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } finally {
             close();
         }
         return result;
     }
     //如果执行的查询或存储过程，会返回多个数据集，或多个执行成功记录数
     //可以调用本方法，返回的结果，
     //是一个List<ResultSet>或List<Integer>集合
     public static Object execute(String sql) {
         boolean b=false;
         try {
             open();//保证连接是成功的
             stmt = conn.createStatement();
             b = stmt.execute(sql);
             //true,执行的是一个查询语句，我们可以得到一个数据集
             //false,执行的是一个修改语句，我们可以得到一个执行成功的记录数
             if(b){
                 return stmt.getResultSet();
             }
             else {
                 return stmt.getUpdateCount();
             }
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } finally {
             if(!b) {
                 close();
             }
         }
         return null;
     }

     //
     //select * from student where name=? and sex=?
     public static ResultSet executeQuery(String sql,Object[] in) {
         try {
             open();//保证连接是成功的
             PreparedStatement pst = conn.prepareStatement(sql);
             for(int i=0;i<in.length;i++)
                 pst.setObject(i+1, in[i]);
             stmt = pst;//只是为了关闭命令对象pst
             return pst.executeQuery();
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         return null;
     }

     public static int executeUpdate(String sql,Object[] in) {
         try {
             open();//保证连接是成功的
             PreparedStatement pst = conn.prepareStatement(sql);
             for(int i=0;i<in.length;i++)
                 pst.setObject(i+1, in[i]);
             stmt = pst;//只是为了关闭命令对象pst
             return pst.executeUpdate();
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }finally {
             close();
         }
         return 0;
     }
     public static Object execute(String sql,Object[] in) {
         boolean b=false;
         try {
             open();//保证连接是成功的
             PreparedStatement pst = conn.prepareStatement(sql);
             for(int i=0;i<in.length;i++)
                 pst.setObject(i+1, in[i]);
             b = pst.execute();
             //true,执行的是一个查询语句，我们可以得到一个数据集
             //false,执行的是一个修改语句，我们可以得到一个执行成功的记录数
             if(b){
                 System.out.println("----");
                 /*List<ResultSet> list = new ArrayList<ResultSet>();
                 list.add(pst.getResultSet());
                 while(pst.getMoreResults()) {
                     list.add(pst.getResultSet());
                 }*/
                 return pst.getResultSet();
             }
             else {
                 System.out.println("****");
                 List<Integer> list = new ArrayList<Integer>();
                 list.add(pst.getUpdateCount());
                 while(pst.getMoreResults()) {
                     list.add(pst.getUpdateCount());
                 }
                 return list;
             }
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } finally {
             if(!b) {
                 System.out.println("====");
                 close();
             }
         }
         return null;
     }
     //调用存储过程  proc_Insert(?,?,?)
     public static Object executeProcedure(String procName,Object[] in) {
         open();
         try {
             procName = "{call "+procName+"(";
             String link="";
             for(int i=0;i<in.length;i++) {
                 procName+=link+"?";
                 link=",";
             }
             procName+=")}";
             CallableStatement cstmt = conn.prepareCall(procName);
             for(int i=0;i<in.length;i++) {
                 cstmt.setObject(i+1, in[i]);
             }
             if(cstmt.execute())
             {
                 return cstmt.getResultSet();
             }
             else {
                 return cstmt.getUpdateCount();
             }
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }

         return null;
     }

     /*
      * 调用存储过程，并有输出参数
      * @procName ，存储过程名称：proc_Insert(?,?)
      * @in ,输入参数集合
      * @output,输出参数集合
      * @type,输出参数类型集合
      * */
     public static Object executeOutputProcedure(String procName,
             Object[] in,Object[] output,int[] type){
         Object result = null;
         try {
             CallableStatement cstmt = conn.prepareCall("{call "+procName+"}");
             //设置存储过程的参数值
             int i=0;
             for(;i<in.length;i++){//设置输入参数
                 cstmt.setObject(i+1, in[i]);
                 //print(i+1);
             }
             int len = output.length+i;
             for(;i<len;i++){//设置输出参数
                 cstmt.registerOutParameter(i+1,type[i-in.length]);
                 //print(i+1);
             }
             boolean b = cstmt.execute();
             //获取输出参数的值
             for(i=in.length;i<output.length+in.length;i++)
                 output[i-in.length] = cstmt.getObject(i+1);
             if(b) {
                 result = cstmt.getResultSet();
             }
             else {
                 result = cstmt.getUpdateCount();
             }
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         return result;
     }
     public static String toJson(Object obj){
         String reuqest=null;
         //对象映射
         ObjectMapper mapper=new ObjectMapper();
         //设置时间格式
         SimpleDateFormat dateFormat=new SimpleDateFormat("yyyy年MM月dd日");
         mapper.setDateFormat(dateFormat);
             try {
                 reuqest=mapper.writeValueAsString(obj);
             } catch (JsonProcessingException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         return reuqest;
     }
     public static <T> T toObject(String src,Class<T> valueType){
         T request=null;
             //对象反射
           ObjectMapper mapper=new ObjectMapper();
           try {
             request=mapper.readValue(src, valueType);
         } catch (JsonParseException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (JsonMappingException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         return request;
     }
     public static Date date(String date_str) {
         try {
             Calendar zcal = Calendar.getInstance();//日期类
             Timestamp timestampnow = new Timestamp(zcal.getTimeInMillis());//转换成正常的日期格式
             SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");//改为需要的东西
             ParsePosition pos = new ParsePosition(0);
             java.util.Date current = formatter.parse(date_str, pos);
             timestampnow = new Timestamp(current.getTime());
             return timestampnow;
         }
         catch (NullPointerException e) {
             return null;
         }
     }
     /**
      * 获取当前时间 yyyy-MM-dd HH:mm:ss
      * @param date
      * @return
      */
     public static String newDate(String date){
         Date day=new Date();
         SimpleDateFormat df = new SimpleDateFormat(date);
         return df.format(day);
     }

}