码迷，mamicode.com
首页 > 其他好文 > 详细

20165301第八周课下作业

时间：2018-04-22 21:48:14      阅读：187      评论：0      收藏：0      [点我收藏+]

标签：nec   jta   直接   type   frame   创建   comm   trim   before   

第八周课下作业

相关知识点总结

  • MYSQL数据库的安装与使用
  • JDBC语句连接数据库，关闭连接
  • 循序查询、条件与排序查询
  • 添加与删除操作
  • 通用查询和事务管理

课下补做

技术分享图片

技术分享图片

技术分享图片

代码分析

Example11_1
import java.sql.*; 
public class Example11_1 {
   public static void main(String args[]) {
      Connection con=null;
      Statement sql; 
      ResultSet rs;
      try{  Class.forName("com.mysql.jdbc.Driver"); //加载JDBC_MySQL驱动
      }
      catch(Exception e){}
      String uri = "jdbc:mysql://localhost:3306/students?useSSL=true";
      String user ="root";
      String password ="";
      try{  
         con = DriverManager.getConnection(uri,user,password); //连接代码
      }
      catch(SQLException e){ }
      try { 
          sql=con.createStatement();
          rs=sql.executeQuery("SELECT * FROM mess"); //查询mess表
          while(rs.next()) {//当存在下一个数据是返回true
             String number=rs.getString(1);//将表第一列的数据传给number
             String name=rs.getString(2);
             Date date=rs.getDate(3);
             float height=rs.getFloat(4);
             System.out.printf("%s\t",number);
             System.out.printf("%s\t",name);
             System.out.printf("%s\t",date); 
             System.out.printf("%.2f\n",height);
          }
          con.close();//关闭连接
      }
      catch(SQLException e) { 
         System.out.println(e);
      }
  }
}
  • 这个代码是用来查询student数据库中的mess表的全部记录。
Example11_2
import java.sql.*; 
public class Example11_2 {
   public static void main(String args[]) {
      Connection con;
      Statement sql; 
      ResultSet rs;
      con = GetDBConnection.connectDB("students","root","");
      if(con == null ) return;
      try { 
          sql=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
                                    ResultSet.CONCUR_READ_ONLY);
          rs = sql.executeQuery("SELECT * FROM mess ");
          rs.last();
          int max = rs.getRow();
          System.out.println("表共有"+max+"条记录,随机抽取2条记录：");
          int [] a =GetRandomNumber.getRandomNumber(max,2);//得到1-max之间2个不同随机数
          for(int i:a){
             rs.absolute(i);//油标移动到第i行
             String number = rs.getString(1);
             String name = rs.getString(2);
             Date date = rs.getDate(3);
             float h = rs.getFloat(4);
             System.out.printf("%s\t",number);
             System.out.printf("%s\t",name);
             System.out.printf("%s\t",date); 
             System.out.printf("%.2f\n",h);
          }
          con.close();
      }
      catch(SQLException e) { 
         System.out.println(e);
      }
  }
}
import java.sql.*; 
public class GetDBConnection {
   public static Connection connectDB(String DBName,String id,String p) {
      Connection con = null;
      String 
      uri = "jdbc:mysql://localhost:3306/"+DBName+"?useSSL=true&characterEncoding=utf-8";
      try{  Class.forName("com.mysql.jdbc.Driver");//加载JDBC-MySQL驱动
      }
      catch(Exception e){}
      try{  
         con = DriverManager.getConnection(uri,id,p); //连接代码
      }
      catch(SQLException e){}
      return con;
   }
}
import java.util.*;
public class GetRandomNumber {
   public static int [] getRandomNumber(int max,int amount) {
      //1-max之间的amount个不同随机整数
     int [] randomNumber = new int[amount];
     int index =0;
     randomNumber[0]= -1;
     Random random = new Random();
     while(index<amount){
       int number = random.nextInt(max)+1;
       boolean isInArrays=false;
       for(int m:randomNumber){//m依次取数组randomNumber元素的值（见3.7）
          if(m == number)
            isInArrays=true;  //number在数组里了
       }
       if(isInArrays==false){
           //如果number不在数组randomNumber中:
           randomNumber[index] = number;
           index++;   
       }
     }
     return  randomNumber;
   }
}
  • 将数据库单独分装在一个GetDatabaseConnection类中。随机查询student数据库中的mess表的两条记录。
Example11_3
import java.sql.*; 
public class Example11_3 {
   public static void main(String args[]) {
      Connection con;
      Statement sql; 
      ResultSet rs;
      con = GetDBConnection.connectDB("students","root","");
      if(con == null ) return;
      String c1=" year(birthday)<=2000 and month(birthday)>7";//条件1
      String c2=" name Like ‘张_%‘";
      String c3=" height >1.65";
      String sqlStr =
      "select * from mess where "+c1+" and "+c2+" and "+c3+"order by birthday";
      try { 
          sql=con.createStatement();
          rs = sql.executeQuery(sqlStr);
          while(rs.next()) { 
             String number=rs.getString(1);
             String name=rs.getString(2);
             Date date=rs.getDate(3);
             float height=rs.getFloat(4);
             System.out.printf("%s\t",number);
             System.out.printf("%s\t",name);
             System.out.printf("%s\t",date); 
             System.out.printf("%.2f\n",height);
          }
          con.close();
      }
      catch(SQLException e) { 
         System.out.println(e);
      }
  }
}
import java.sql.*; 
public class GetDBConnection {
   public static Connection connectDB(String DBName,String id,String p) {
      Connection con = null;
      String uri = 
     "jdbc:mysql://localhost:3306/"+DBName+"?useSSL=true&characterEncoding=utf-8";
      try{  Class.forName("com.mysql.jdbc.Driver");//加载JDBC-MySQL驱动
      }
      catch(Exception e){}
      try{  
         con = DriverManager.getConnection(uri,id,p); //连接代码
      }
      catch(SQLException e){}
      return con;
   }
}
  • 这个代码是查询mess表中姓张，身高大于16.5，出生年份为2000或2000年之前，月份在七月份之后的学生，并按出生日期排序。
Example11_4
import java.sql.*; 
public class Example11_4 {
   public static void main(String args[]) {
      Connection con;
      Statement sql; 
      ResultSet rs;
      con = GetDBConnection.connectDB("students","root","");
      if(con == null ) return;
      String jiLu="(‘R11q‘,‘王三‘,‘2000-10-23‘,1.66),"+
                  "(‘R10q‘,‘李武‘,‘1989-10-23‘,1.76)";    //2条记录
      String sqlStr ="insert into mess values"+jiLu;
      try { 
          sql=con.createStatement(); 
          int ok = sql.executeUpdate(sqlStr);
          rs = sql.executeQuery("select * from mess");
          while(rs.next()) { 
             String number=rs.getString(1);
             String name=rs.getString(2);
             Date date=rs.getDate(3);
             float height=rs.getFloat(4);
             System.out.printf("%s\t",number);
             System.out.printf("%s\t",name);
             System.out.printf("%s\t",date); 
             System.out.printf("%.2f\n",height);
          }
          con.close();
      }
      catch(SQLException e) { 
         System.out.println("记录中number值不能重复"+e);
      }
  }
}
  • 这个代码是在mess表中插入两条记录。
Example11_5
import java.sql.*; 
public class Example11_5 {
   public static void main(String args[]) {
      Connection con;
      PreparedStatement preSql;  //预处理语句对象preSql
      ResultSet rs;
      con = GetDBConnection.connectDB("students","root","");
      if(con == null ) return;
      String sqlStr ="insert into mess values(?,?,?,?)";
      try { 
          preSql = con.prepareStatement(sqlStr);//得到预处理语句对象preSql
          preSql.setString(1,"A001");       //设置第1个?代表的值
          preSql.setString(2,"刘伟");       //设置第2个?代表的值
          preSql.setString(3,"1999-9-10"); //设置第3个?代表的值
          preSql.setFloat(4,1.77f);        //设置第4个?代表的值   
          int ok = preSql.executeUpdate();
          sqlStr="select * from mess where name like ? ";
          preSql = con.prepareStatement(sqlStr);//得到预处理语句对象preSql
          preSql.setString(1,"张%");       //设置第1个?代表的值
          rs = preSql.executeQuery();
          while(rs.next()) { 
             String number=rs.getString(1);
             String name=rs.getString(2);
             Date date=rs.getDate(3);
             float height=rs.getFloat(4);
             System.out.printf("%s\t",number);
             System.out.printf("%s\t",name);
             System.out.printf("%s\t",date); 
             System.out.printf("%.2f\n",height);
          }
          con.close();
      }
      catch(SQLException e) { 
         System.out.println("记录中number值不能重复"+e);
      }
  }
}
import java.sql.*; 
public class GetDBConnection {
   public static Connection connectDB(String DBName,String id,String p) {
      Connection con = null;
      String uri = 
     "jdbc:mysql://localhost:3306/"+DBName+"?useSSL=true&characterEncoding=utf-8";
      try{  Class.forName("com.mysql.jdbc.Driver");//加载JDBC-MySQL驱动
      }
      catch(Exception e){}
      try{  
         con = DriverManager.getConnection(uri,id,p); //连接代码
      }
      catch(SQLException e){}
      return con;
   }
}
  • 此代码是使用预处理语句向mess表添加并查询了姓张的记录
Example11_6
import javax.swing.*;
public class Example11_6 {
   public static void main(String args[]) {
  String [] tableHead;
  String [][] content; 
  JTable table ;
  JFrame win= new JFrame();
  Query findRecord = new  Query();
  findRecord.setDatabaseName("students");
  findRecord.setSQL("select * from mess");
  content = findRecord.getRecord();
  tableHead=findRecord.getColumnName();
  table = new JTable(content,tableHead); 
  win.add(new JScrollPane(table));
  win.setBounds(12,100,400,200);
  win.setVisible(true); 
  win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   }
}
import java.sql.*;
public class Query {
   String databaseName="";      //数据库名
   String SQL;              //SQL语句
   String [] columnName;        //全部字段（列）名
   String [][] record;          //查询到的记录
   public Query() {
  try{  Class.forName("com.mysql.jdbc.Driver");//加载JDBC-MySQL驱动
  }
  catch(Exception e){}
   }
   public void setDatabaseName(String s) {
  databaseName=s.trim();
   }
   public void setSQL(String SQL) {
  this.SQL=SQL.trim();
   }
   public String[] getColumnName() {
   if(columnName ==null ){
       System.out.println("先查询记录");
       return null;
   }
   return columnName;
   }
   public String[][] getRecord() {
   startQuery();
   return record;
   }
   private void startQuery() { 
  Connection con;
  Statement sql;  
  ResultSet rs;
  String uri = 
 "jdbc:mysql://localhost:3306/"+
  databaseName+"?useSSL=true&characterEncoding=utf-8";
  try { 
    con=DriverManager.getConnection(uri,"root","");
    sql=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
                            ResultSet.CONCUR_READ_ONLY);
    rs=sql.executeQuery(SQL);
    ResultSetMetaData metaData = rs.getMetaData();
    int columnCount = metaData.getColumnCount();//字段数目 
    columnName=new String[columnCount]; 
    for(int i=1;i<=columnCount;i++){
        columnName[i-1]=metaData.getColumnName(i);
    } 
    rs.last(); 
    int recordAmount =rs.getRow();  //结果集中的记录数目
    record = new String[recordAmount][columnCount];
    int i=0;
    rs.beforeFirst();
    while(rs.next()) { 
      for(int j=1;j<=columnCount;j++){
         record[i][j-1]=rs.getString(j); //第i条记录，放入二维数组的第i行
      }
      i++;
    }
    con.close();
  }
  catch(SQLException e) {
    System.out.println("请输入正确的表名"+e);
  }
   }    
}
  • 这段代码的功能是将数据库名以及SQL语句传递给Query类的对象。
Example11_7
import java.sql.*; 
public class Example11_7{
    public static void main(String args[]){
       Connection con = null;
       Statement sql;
       ResultSet rs; 
       String sqlStr;
       con = GetDBConnection.connectDB("students","root","");
       if(con == null ) return;
       try{ float n = 0.02f;
            con.setAutoCommit(false);       //关闭自动提交模式
            sql = con.createStatement();
            sqlStr = "select name,height from mess where number=‘R1001‘";
            rs = sql.executeQuery(sqlStr);
            rs.next();
            float h1 = rs.getFloat(2);
            System.out.println("事务之前"+rs.getString(1)+"身高:"+h1);
            sqlStr = "select name,height from mess where number=‘R1002‘"; 
            rs = sql.executeQuery(sqlStr);
            rs.next();
            float h2 = rs.getFloat(2);
            System.out.println("事务之前"+rs.getString(1)+"身高:"+h2);  
            h1 = h1-n;
            h2 = h2+n;
            sqlStr = "update mess set height ="+h1+" where number=‘R1001‘";
            sql.executeUpdate(sqlStr);
            sqlStr = "update mess set height ="+h2+" where number=‘R1002‘";
            sql.executeUpdate(sqlStr);
            con.commit(); //开始事务处理,如果发生异常直接执行catch块
            con.setAutoCommit(true); //恢复自动提交模式
            String s = "select name,height from mess"+
                      " where number=‘R1001‘or number=‘R1002‘";
            rs = 
            sql.executeQuery(s);
            while(rs.next()){
               System.out.println("事务后"+rs.getString(1)+
                                  "身高:"+rs.getFloat(2));  
            }
            con.close();
         }
         catch(SQLException e){
            try{ con.rollback();          //撤销事务所做的操作
            }
            catch(SQLException exp){}
         }
    }
}
import java.sql.*; 
public class GetDBConnection {
   public static Connection connectDB(String DBName,String id,String p) {
      Connection con = null;
      String uri = 
     "jdbc:mysql://localhost:3306/"+DBName+"?useSSL=true&characterEncoding=utf-8";
      try{  Class.forName("com.mysql.jdbc.Driver");//加载JDBC-MySQL驱动
      }
      catch(Exception e){}
      try{  
         con = DriverManager.getConnection(uri,id,p); //连接代码
      }
      catch(SQLException e){}
      return con;
   }
}
  • 这段代码的功能是将mess表中的number字段R1001的height值减少n，并将减少的n增加到字段是R1002的height上。
Example11_8
import java.sql.*;
public class Example11_8 {
   public static void main(String[] args) {
      Connection con =null;
      Statement sta = null;
      ResultSet rs;
      String SQL;
      try { 
        Class.forName("org.apache.derby.jdbc.EmbeddedDriver");//加载驱动
      }
      catch(Exception e) {
        System.out.println(e);  
        return;
      }
      try { 
         String uri ="jdbc:derby:students;create=true";
         con=DriverManager.getConnection(uri);  //连接数据库
         sta = con.createStatement();
      }
      catch(Exception e) {
        System.out.println(e);  
        return;
      }
      try { SQL = "create table chengji(name varchar(40),score float)";
            sta.execute(SQL);//创建表
      }
      catch(SQLException e) { 
         //System.out.println("该表已经存在"); 
      }
      SQL ="insert into chengji values"+
            "(‘张三‘, 90),(‘李斯‘, 88),(‘刘二‘, 67)";
      try {
         sta.execute(SQL);
         rs = sta.executeQuery("select * from chengji "); // 查询表中的记录
         while(rs.next()) {
            String name=rs.getString(1);
            System.out.print(name+"\t");
            float score=rs.getFloat(2);
            System.out.println(score);
         }
         con.close();
      } 
      catch(SQLException e) {
          System.out.println(e);  
      }
  }
}
  • 这段代码的功能是使用了Derby数据库系统创建了名字是student的数据库，并在数据库中建立了chengji表

补做教材第十一章的编程题目

习题11编程题

  • 第一题

    import java.sql.*;
public class test1 {
public static void main(String args[]) {
    Connection con;
    Statement sql;
    ResultSet rs;
    con = GetDBConnection.connectDB("students","root","");//连接数据库
    if(con == null ) return;
    String sqlStr =
            "select * from mess "+"order by birthday";
    //通过order by排序
    try {
        sql=con.createStatement();
        rs = sql.executeQuery(sqlStr);
        while(rs.next()) {
            String number=rs.getString(1);
            String name=rs.getString(2);
            Date date=rs.getDate(3);
            float height=rs.getFloat(4);
            System.out.printf("%s\t",number);
            System.out.printf("%s\t",name);
            System.out.printf("%s\t",date);
            System.out.printf("%.2f\n",height);
        }
        con.close();
    }
    catch(SQLException e) {
        System.out.println(e);
    }
}
}
import java.sql.*; 
public class GetDBConnection {
   public static Connection connectDB(String DBName,String id,String p) {
      Connection con = null;
      String 
      uri = "jdbc:mysql://localhost:3306/"+DBName+"?useSSL=true&characterEncoding=utf-8";
      try{  Class.forName("com.mysql.jdbc.Driver");//加载JDBC-MySQL驱动
      }
      catch(Exception e){}
      try{  
         con = DriverManager.getConnection(uri,id,p); //连接代码
      }
      catch(SQLException e){}
      return con;
   }
}

技术分享图片

  • 第二题

    import java.sql.*;
public class Query {
   String databaseName="";      //数据库名
   String SQL;              //SQL语句
   String [] columnName;        //全部字段（列）名
   String [][] record;          //查询到的记录
   public Query() {
  try{  Class.forName("com.mysql.jdbc.Driver");//加载JDBC-MySQL驱动
  }
  catch(Exception e){}
   }
   public void setDatabaseName(String s) {
  databaseName=s.trim();
   }
   public void setSQL(String SQL) {
  this.SQL=SQL.trim();
   }
   public String[] getColumnName() {
   if(columnName ==null ){
       System.out.println("先查询记录");
       return null;
   }
   return columnName;
   }
   public String[][] getRecord() {
   startQuery();
   return record;
   }
   private void startQuery() { 
  Connection con;
  Statement sql;  
  ResultSet rs;
  String uri = 
 "jdbc:mysql://localhost:3306/"+
  databaseName+"?useSSL=true&characterEncoding=utf-8";
  try { 
    con=DriverManager.getConnection(uri,"root","");
    sql=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
                            ResultSet.CONCUR_READ_ONLY);
    rs=sql.executeQuery(SQL);
    ResultSetMetaData metaData = rs.getMetaData();
    int columnCount = metaData.getColumnCount();//字段数目 
    columnName=new String[columnCount]; 
    for(int i=1;i<=columnCount;i++){
        columnName[i-1]=metaData.getColumnName(i);
    } 
    rs.last(); 
    int recordAmount =rs.getRow();  //结果集中的记录数目
    record = new String[recordAmount][columnCount];
    int i=0;
    rs.beforeFirst();
    while(rs.next()) { 
      for(int j=1;j<=columnCount;j++){
         record[i][j-1]=rs.getString(j); //第i条记录，放入二维数组的第i行
      }
      i++;
    }
    con.close();
  }
  catch(SQLException e) {
    System.out.println("请输入正确的表名"+e);
  }
   }    
}
import javax.management.Query;
import javax.swing.*;
public class test2 {
    public static void main (String args[]) {
        String [] tableHead;
        String [] content;
        JTable table;
        JFrame win= new JFrame();
        Query findRecord = new Query();
        findRecord.setDatabaseName(args[0]);
        findRecord.setSQL("select * from "+args[1]);
        content = findRecord.getRecord();
        tableHead=findRecord.getColumnName();
        table = new JTable(content,tableHead);
        win.add(new JScrollPane(table));
        win.setBounds(12,100,400,200);
        win.setVisible(true);
        win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

20165301第八周课下作业

标签：nec   jta   直接   type   frame   创建   comm   trim   before   

原文地址：https://www.cnblogs.com/CTF5301/p/8908907.html
踩
(0)
赞
(0)
   
举报
评论 一句话评论（0）
登录后才能评论！
分享档案
更多>
2021年07月29日 (22)
2021年07月28日 (40)
2021年07月27日 (32)
2021年07月26日 (79)
2021年07月23日 (29)
2021年07月22日 (30)
2021年07月21日 (42)
2021年07月20日 (16)
2021年07月19日 (90)
2021年07月16日 (35)
周排行
mamicode.com排行更多图片
更多
友情链接
兰亭集智   国之画   百度统计   站长统计   阿里云   chrome插件   新版天听网
关于我们 - 联系我们 - 留言反馈
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码！