20165329 第八週補作
20165329 第八週補作
相關知識點
JDBC
- 加載JDBC橋鏈接
- Class.forName（"sun.jdbc.odbc.JdbcOdbcDriver");
- 創建和dataSource數據源的連接
- Connection con=DriverManager.getConnection("jdbc:odbc:dataSource","loginName","password");
- 獲得statement語句
- Statement sql=con.creatStatement();
- 向數據源發送SQL語句，必要時返回resultset對象
ResultSet rs=sql.executeQueryjava
補作內容截圖
代碼分析
Example11_1mysql
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"); //加載JDBC_MySQL驅動
}
catch(Exception e){}
String uri = "jdbc:mysql://localhost:3306/students?useSSL=true";
String user ="root";
String password ="";
try{
con = DriverManager.getConnection(uri,user,password); //鏈接代碼
}
catch(SQLException e){ }
try {
sql=con.createStatement();
rs=sql.executeQuery("SELECT * FROM mess"); //查詢mess表
while(rs.next()) {//當存在下一個數據是返回true
String number=rs.getString(1);//將表第一列的數據傳給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();//關閉鏈接
}
catch(SQLException e) {
System.out.println(e);
}
}
}
這個代碼是用來查詢student數據庫中的mess表的所有記錄sql
Example11_2數據庫
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+"條記錄,隨機抽取2條記錄：");
int [] a =GetRandomNumber.getRandomNumber(max,2);//獲得1-max之間2個不一樣隨機數
for(int i:a){
rs.absolute(i);//油標移動到第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");//加載JDBC-MySQL驅動
}
catch(Exception e){}
try{
con = DriverManager.getConnection(uri,id,p); //鏈接代碼
}
catch(SQLException e){}
return con;
}
}
import java.util.*;
public class GetRandomNumber {
public static int [] getRandomNumber(int max,int amount) {
//1-max之間的amount個不一樣隨機整數
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依次取數組randomNumber元素的值（見3.7）
if(m == number)
isInArrays=true; //number在數組裏了
}
if(isInArrays==false){
//若是number不在數組randomNumber中:
randomNumber[index] = number;
index++;
}
}
return randomNumber;
}
}
將數據庫單獨分裝在一個GetDatabaseConnection類中。隨機查詢student數據庫中的mess表的兩條記錄。apache
Example11_3編程
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";//條件1
String c2=" name Like '張_%'";
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");//加載JDBC-MySQL驅動
}
catch(Exception e){}
try{
con = DriverManager.getConnection(uri,id,p); //鏈接代碼
}
catch(SQLException e){}
return con;
}
}
這個代碼是查詢mess表中姓張，身高大於16.5，出生年份爲2000或2000年以前，月份在七月份以後的學生，並按出生日期排序。數組
Example11_4dom
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條記錄
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("記錄中number值不能重複"+e);
}
}
}
這個代碼是在mess表中插入兩條記錄。this
Example11_53d
import java.sql.*;
public class Example11_5 {
public static void main(String args[]) {
Connection con;
PreparedStatement preSql; //預處理語句對象preSql
ResultSet rs;
con = GetDBConnection.connectDB("students","root","");
if(con == null ) return;
String sqlStr ="insert into mess values(?,?,?,?)";
try {
preSql = con.prepareStatement(sqlStr);//獲得預處理語句對象preSql
preSql.setString(1,"A001"); //設置第1個?表明的值
preSql.setString(2,"劉偉"); //設置第2個?表明的值
preSql.setString(3,"1999-9-10"); //設置第3個?表明的值
preSql.setFloat(4,1.77f); //設置第4個?表明的值
int ok = preSql.executeUpdate();
sqlStr="select * from mess where name like ? ";
preSql = con.prepareStatement(sqlStr);//獲得預處理語句對象preSql
preSql.setString(1,"張%"); //設置第1個?表明的值
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("記錄中number值不能重複"+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");//加載JDBC-MySQL驅動
}
catch(Exception e){}
try{
con = DriverManager.getConnection(uri,id,p); //鏈接代碼
}
catch(SQLException e){}
return con;
}
}
此代碼是使用預處理語句向mess表添加並查詢了姓張的記錄
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=""; //數據庫名
String SQL; //SQL語句
String [] columnName; //所有字段（列）名
String [][] record; //查詢到的記錄
public Query() {
try{ Class.forName("com.mysql.jdbc.Driver");//加載JDBC-MySQL驅動
}
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("先查詢記錄");
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();//字段數目
columnName=new String[columnCount];
for(int i=1;i<=columnCount;i++){
columnName[i-1]=metaData.getColumnName(i);
}
rs.last();
int recordAmount =rs.getRow(); //結果集中的記錄數目
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條記錄，放入二維數組的第i行
}
i++;
}
con.close();
}
catch(SQLException e) {
System.out.println("請輸入正確的表名"+e);
}
}
}
這段代碼的功能是將數據庫名以及SQL語句傳遞給Query類的對象。
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); //關閉自動提交模式
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("事務以前"+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("事務以前"+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(); //開始事務處理,若是發生異常直接執行catch塊
con.setAutoCommit(true); //恢復自動提交模式
String s = "select name,height from mess"+
" where number='R1001'or number='R1002'";
rs =
sql.executeQuery(s);
while(rs.next()){
System.out.println("事務後"+rs.getString(1)+
"身高:"+rs.getFloat(2));
}
con.close();
}
catch(SQLException e){
try{ con.rollback(); //撤銷事務所作的操做
}
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");//加載JDBC-MySQL驅動
}
catch(Exception e){}
try{
con = DriverManager.getConnection(uri,id,p); //鏈接代碼
}
catch(SQLException e){}
return con;
}
}
這段代碼的功能是將mess表中的number字段R1001的height值減小n，並將減小的n增長到字段是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");//加載驅動
}
catch(Exception e) {
System.out.println(e);
return;
}
try {
String uri ="jdbc:derby:students;create=true";
con=DriverManager.getConnection(uri); //鏈接數據庫
sta = con.createStatement();
}
catch(Exception e) {
System.out.println(e);
return;
}
try { SQL = "create table chengji(name varchar(40),score float)";
sta.execute(SQL);//建立表
}
catch(SQLException e) {
//System.out.println("該表已經存在");
}
SQL ="insert into chengji values"+
"('張三', 90),('李斯', 88),('劉二', 67)";
try {
sta.execute(SQL);
rs = sta.executeQuery("select * from chengji "); // 查詢表中的記錄
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);
}
}
}
這段代碼的功能是使用了Derby數據庫系統建立了名字是student的數據庫，並在數據庫中創建了chengji表
補作教材第十一章的編程題目
習題11編程題
第一題
import java.sql.*;
public class test1 {
public static void main(String args[]) {
Connection con;
Statement sql;
ResultSet rs;
con = GetDBConnection.connectDB("students","root","");//鏈接數據庫
if(con == null ) return;
String sqlStr =
"select * from mess "+"order by birthday";
//經過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);
}
}
}
GetDBConnection 類
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");//加載JDBC-MySQL驅動
}
catch(Exception e){}
try{
con = DriverManager.getConnection(uri,id,p); //鏈接代碼
}
catch(SQLException e){}
return con;
}
}
第二題
import java.sql.*;
public class Query {
String databaseName=""; //數據庫名
String SQL; //SQL語句
String [] columnName; //所有字段（列）名
String [][] record; //查詢到的記錄
public Query() {
try{ Class.forName("com.mysql.jdbc.Driver");//加載JDBC-MySQL驅動
}
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("先查詢記錄");
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();//字段數目
columnName=new String[columnCount];
for(int i=1;i<=columnCount;i++){
columnName[i-1]=metaData.getColumnName(i);
}
rs.last();
int recordAmount =rs.getRow(); //結果集中的記錄數目
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條記錄，放入二維數組的第i行
}
i++;
}
con.close();
}
catch(SQLException e) {
System.out.println("請輸入正確的表名"+e);
}
}
}
Query類
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);
}
}
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