jbdc总结

1.使用纯java方式连接数据库

2.使用Statement添加信息

package com.sql;

/**
 * 使用Statement添加宠物
 */
import java.sql.*;

public class Demo1 {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement ps = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {// 加载驱动
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            System.out.println("建立连接失败");
        }

        try {// 创建连接对象
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/hello", "root", "123456");
            stmt = conn.createStatement();// 创建sql操作对象
            String name = "佩奇";
            int health = 40;
            int love = 90;
            String strain = "哈士奇";

            StringBuffer sbSql = new StringBuffer("insert into dog (name,health,love,strain) values ( '");
            sbSql.append(name + "',");
            sbSql.append(health + ",");
            sbSql.append(love + ",'");
            sbSql.append(strain + "')");
            // 打印拼接后的sql
            System.out.println(sbSql.toString());

            stmt.execute(sbSql.toString());
            // System.out.println("插入成功");
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println("建立连接失败");
        } finally {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }

        }

    }
}

View Code

3.使用Statement更新信息

package com.sql;

/**
 * 使用Statement更新宠物
 */
import java.sql.*;

public class Demo1 {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement ps = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {// 加载驱动
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            System.out.println("建立连接失败");
        }

        try {// 创建连接对象
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/hello", "root", "123456");
            stmt = conn.createStatement();// 创建sql操作对象
            String sql = "update dog set health=140,love=100 where name='佩奇'";

            int t = stmt.executeUpdate(sql);
            if (t > 0)
                System.out.println("修改成功");

            // System.out.println("插入成功");
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println("建立连接失败");
        } finally {
            try {
                conn.close();
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }

        }

    }
}

View Code

4.用·Statement查询信息

package com.sql;

/**
 * 使用Statement查询宠物
 */
import java.sql.*;

public class Demo1 {
    public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/hello", "root", "123456");
            stmt = conn.createStatement();
            rs = stmt.executeQuery("select * from dog");
            while (rs.next()) {
                System.out.print(rs.getString(1) + "\t");
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                rs.close();// 结果集关闭
                stmt.close();// 语句关闭
                conn.close();// 连接关闭
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}

View Code

 5.用prepaedStatement防止SQL注入

package com.sql;

/**
 * 消除SQL注入隐患
 */
import java.sql.*;
import java.util.*;

public class Demo1 {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/hello", "root", "123456");

            System.out.println("*************************");
            System.out.println("        宠物主人                                ");
            System.out.println("*************************");
            Scanner input = new Scanner(System.in);
            System.out.println("输入姓名");
            String name = input.next();
            System.out.println("输入密码");
            String pass = input.next();
            String sql = "select* from master where name=? and password=?";
            ps = conn.prepareStatement(sql);
            ps.setString(1, name);
            ps.setString(2, pass);
            System.out.println(sql);
            // 结果
            rs = ps.executeQuery();
            if (rs.next()) {
                System.out.println(rs.getString(1) + " " + rs.getString(2));
            } else {
                System.out.println("登陆失败");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                rs.close();
                ps.close();
                conn.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    }
}

View Code

 可以处理多条数据：

package com.sql;

import java.sql.*;
import java.util.*;

/**
 * @author Administrator 演示示例5：SQL注入隐患
 */
public class Demo1 {

    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/hello?useUnicode=true&characterEncoding=utf-8", "root", "123456");

            System.out.println("*************************");
            System.out.println("        宠物主人                                ");
            System.out.println("*************************");

            Map<String, String> paraMap = new HashMap<String, String>();
            paraMap.put("name", "王志");
            paraMap.put("password", "123456");

            String name = paraMap.get("name");
            String password = paraMap.get("password");

            String sql = "select * from master where 1=1 ";

            List<String> paraList = new ArrayList<String>();
            if (name != null && name.length() > 0) {
                sql += " and name = ? ";
                paraList.add(name);
            } // end of if

            if (password != null && password.length() > 0) {
                sql += " and password = ? ";
                paraList.add(password);
            } // end of if

            System.out.println(sql);

            pstmt = conn.prepareStatement(sql);

            for (int i = 0; i < paraList.size(); i++) {// 逐条演绎
                System.out.println(paraList.get(i));
                pstmt.setObject(i + 1, paraList.get(i));
            }

            // 注意：使用预编译语句不需要传入sql
            rs = pstmt.executeQuery();

            if (rs.next()) {
                // System.out.println(rs.getString(2));
                System.out.print("登录成功，欢迎您");
            } else {
                System.out.print("登录失败");
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                rs.close();
                pstmt.close();
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}

View Code

//标准版逐条演绎

package com.sql;

import java.sql.*;
import java.util.*;

/**
 * @author Administrator 演示示例5：SQL注入隐患
 */
public class Demo1 {

    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/hello?useUnicode=true&characterEncoding=utf-8", "root", "123456");

            System.out.println("*************************");
            System.out.println("        宠物主人                                ");
            System.out.println("*************************");

            Map<String, String> paraMap = new HashMap<String, String>();//容器
            paraMap.put("name", "王志");
            paraMap.put("password", "123456");

            paraMap.put("name", "王志");
            paraMap.put("password", "123456");
            for(int nn=0;nn<paraMap.size();nn++){
            String name = paraMap.get("name");//获取name
            String password = paraMap.get("password");//获取password

            String sql = "select * from master where 1=1 ";

            List<String> paraList = new ArrayList<String>();//String容器 存储sql语句
            if (name != null && name.length() > 0) {
                sql += " and name = ? ";
                paraList.add(name);
            } // end of if

            if (password != null && password.length() > 0) {
                sql += " and password = ? ";
                paraList.add(password);
            } // end of if

            System.out.println(sql);

            pstmt = conn.prepareStatement(sql);

            for (int i = 0; i < paraList.size(); i++) {// 逐条演绎
                System.out.println(paraList.get(i));
                pstmt.setObject(i + 1, paraList.get(i));
            }

            // 注意：使用预编译语句不需要传入sql
            rs = pstmt.executeQuery();

            if (rs.next()) {
                // System.out.println(rs.getString(2));
                System.out.print("登录成功，欢迎您");
            } else {
                System.out.print("登录失败");
            }
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                rs.close();
                pstmt.close();
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}

View Code

6.使用PreparedStatement更新宠物 

package com.sql;

import java.sql.*;
import java.util.*;

/**
 * @author Administrator 演示示例5：SQL注入隐患
 */
public class Demo1 {

    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/hello?useUnicode=true&characterEncoding=utf-8", "root", "123456");
            // 更新狗狗的数据到数据库
            String sql = "update dog set health=?, love =?, strain=? where name='佩奇'";
            ps = conn.prepareStatement(sql);
            ps.setInt(1, 80);
            ps.setInt(2, 100);
            ps.setString(3, "小狗小狗");
            int t = ps.executeUpdate();
            if (t > 0) {
                System.out.println("成功");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                ps.close();
                // rs.close();
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}

View Code