jdbc连接数据库演示(Statement、PrepareStatement，CallableStatement的演示)

import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;

public class ConnFactory {
private static Connection con = null;

private ConnFactory(){
}
static{
try {
Properties p = new Properties();        p.load(ConnFactory.class.getClassLoader().getResourceAsStream("jdbc.properties"));
String driver = p.getProperty("driver");
String url = p.getProperty("url");
String user = p.getProperty("username");
String password = p.getProperty("password");
Class.forName(driver);
con = DriverManager.getConnection(url, user, password);
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection getConnection(){
return con;
}
public static void main(String[] args) {
System.out.println(getConnection());
}
}

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import org.junit.Test;

import cn.hncu.util.ConnFactory;

public class JdbcDemo {
@Test   //测试executeQuery()  只能用于查询
public void testExecuteQuery(){
Connection con = ConnFactory.getConnection();
try {
Statement st = con.createStatement();
String sql = "select * from stud";
ResultSet rs = st.executeQuery(sql);
while(rs.next()){
String no = rs.getString(1);
String name = rs.getString(2);
Integer age = rs.getInt(3);
String address = rs.getString(4);
System.out.println(no+","+name+","+age+","+address);
}
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}

@Test   //测试executeUpdate()     可用于增删改
public void testExecuteUpdate(){
Connection con = ConnFactory.getConnection();
try {
Statement st = con.createStatement();
//String sql = "insert into stud values('1009','小王',24,'杭州')";
//String sql = "delete from stud where sno='1009'";
String sql = "update stud set sname='王大拿' where sno='1007'";
st.executeUpdate(sql);
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}

@Test   //测试    execute()   //可用于增删改查
public void testExecute(){
Connection con = ConnFactory.getConnection();
try {
Statement st = con.createStatement();
//String sql = "insert into stud values('1010','四毛',24,'武汉')";
//String sql = "update stud set saddress='广州' where sno='1003'";
//String sql = "delete from stud where sno='1007'";
String sql = "select * from stud";
boolean boo = st.execute(sql);
if(boo){
ResultSet rs = st.getResultSet();
while(rs.next()){
String no = rs.getString(1);
String name = rs.getString(2);
Integer age = rs.getInt(3);
String address = rs.getString(4);
System.out.println(no+"-"+name+"-"+age+"-"+address);
}
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}

String datetime = st.getDate(m)+st.gettime(m);//其中m为数据所在字段的序号

@Test //容易产生bug：如输入name值为: aa,b'c
public void reg() throws Exception{
Statement st = ConnFactory.getConn().createStatement();
Scanner sc = new Scanner(System.in);
String id = sc.nextLine();
String name = sc.nextLine();
int age = Integer.parseInt(sc.nextLine());
//String sql = "insert into stud values('P2001','kobe',25) ";
String sql = "insert into stud values('"+id+"','"+name+"',"+age+") ";
System.out.println(sql);
st.execute(sql);
ConnFactory.getConn().close();
}

@Test //容易被黑：如输入name值为: a' or '1'='1
public void login() throws Exception{
Statement st = ConnFactory.getConn().createStatement();
Scanner sc = new Scanner(System.in);
String id = sc.nextLine();
String name = sc.nextLine();
//String sql = "select count(*) from stud where id='P2001' and name='kobe'  ";
String sql = "select count(*) from stud where id='"+id+"' and name='"+name+"'  ";
System.out.println(sql);
ResultSet rs = st.executeQuery(sql);
rs.next();
int n = rs.getInt(1);
if(n<=0){
System.out.println("登录失败...");
}else{
System.out.println("登录成功....");
}

ConnFactory.getConn().close();
}

//////综上：如果sql语句由程序内部直接指定，那么用Statement没问题。////

//采用PrepareStatement
@Test //不会被黑：如输入name值为: a' or '1'='1
public void login2() throws Exception{
Connection con = ConnFactory.getConn();
Scanner sc = new Scanner(System.in);
String id = sc.nextLine();
String name = sc.nextLine();

//创建预处理语句对象
String sql = "select count(*) from stud where id=? and name=?  ";//凡是用户输入的地方，用“?”号(称占位符)填入
PreparedStatement pst = con.prepareStatement(sql);
//给占位设置值---设置参数
pst.setString(1, id); //给第1个参数设置
pst.setString(2, name); //给第2个参数设置

ResultSet rs = pst.executeQuery();//这里不能传参数sql

rs.next();
int n = rs.getInt(1);
if(n<=0){
System.out.println("登录失败...");
}else{
System.out.println("登录成功....");
}

con.close();
}

@Test//演示批处理函数
public void testExecuteBatch() throws Exception{
Connection con = ConnFactory.getConnection();
Statement st = con.createStatement();
String sql = "insert into stud values('1011','五毛',25,'成都')";
st.addBatch(sql);
sql = "insert into stud values('1012','六毛',26,'重庆')";
st.addBatch(sql);
sql = "insert into stud values('1013','七毛',26,'深圳')";
st.addBatch(sql);
int[] sum = st.executeBatch();
for(int x:sum){
System.out.println(x);
}
con.close();
}

@Test//演示批处理函数
public void testExecuteBatch2() throws Exception{
Connection con = ConnFactory.getConnection();
String sql = "insert into stud values(?,?,?,?)";
PreparedStatement pst = con.prepareStatement(sql);
pst.setString(1, "1014");
pst.setString(2, "小粒子");
pst.setInt(3, 27);
pst.setString(4, "天津");
pst.addBatch();
int[] sum = pst.executeBatch();
for(int x:sum){
System.out.println(x);
}
}

DELIMITER $$

USE `mydata`$$

DROP PROCEDURE IF EXISTS `p4`$$

CREATE DEFINER=`root`@`localhost` PROCEDURE `p4`(IN m INT,OUT num INT)
BEGIN
SELECT * FROM stud WHERE age > m;
SELECT COUNT(*) INTO num FROM stud;
END$$

DELIMITER ;

@Test
public void testProcess() throws Exception{
Connection con = ConnFactory.getConnection();
String sql = "call p4(?,?)";
CallableStatement cst = con.prepareCall(sql);
cst.setInt(1, 25);
cst.registerOutParameter(2, Types.INTEGER);
ResultSet rs = cst.executeQuery();
while(rs.next()){
System.out.println(rs.getString(1)+","+rs.getString(2)+","+rs.getInt(3)+","+rs.getString(4));
}
int num = cst.getInt(2);
System.out.println(num);
}