20165235 第八周课下补做
本周考试内容在课堂中已经完成，但是我对代码分析以及编程题代码写了相关的博客，基本内容如下：
教材11.1-11.10的代码发分析
- 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 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
教材第十一章的编程题目
- 编程题1
import java.sql.*;public class BianCheng1 { public static void main(String args[]) { Connection con; Statement sql; ResultSet rs; con = GetDBConnection.connectDB("students","root",""); if(con == null ) return; String sqlStr = "select * from mess "+"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); } }}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; }} - 编程题2
import javax.management.Query;import javax.swing.*;public class BianCheng2 { 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); }} class Query { String databaseName=""; String SQL; String [] columnName; String [][] record; public Query() { try{ Class.forName("com.mysql.jdbc.Driver"); } 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(); 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); } i++; } con.close(); } catch(SQLException e) { System.out.println("请输入正确的表名"+e); } } }