jdbc_连接数据库

1、例一：

package com.vince.jdbc;

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

public class JdbcDemo{
 public final static String URL = "jdbc:mysql://localhost:3306/test";
 //用户名
 public final static String USERNAME = "root";
 //密码
 public final static String PASSWORD = "admin";
 
 public final static String DRIVER = "com.mysql.jdbc.Driver"; 
 
 public static void main(String[] args) {
  insert();
//  update();
//  delete();
 }
 
public static void insert(){
 try {
  /*1、加载驱动*/
  Class.forName(DRIVER);
    /*2、连接数据库*/
   Connection cnn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
     //3、构造SQL语句
    String sql = "insert into emp1 values(3,'小栏','女',9000,29,0,1);";
  //4、构造一个Statement实例(用来发送SQL语句的载体)
    Statement state= cnn.createStatement();   
  //5、执行SQL语句
    state.executeUpdate(sql);
    //6、关闭连接
    state.close();
  cnn.close();  
  System.out.println("success.");  
  
 } catch (ClassNotFoundException e) {
  System.out.println("加载失败");
  e.printStackTrace();
 } catch (SQLException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 } 
}  
 }

例二：

package com.vince.jdbc;

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

public class JdbcDemo{
 public final static String URL = "jdbc:mysql://localhost:3306/test";
 //用户名
 public final static String USERNAME = "root";
 //密码
 public final static String PASSWORD = "admin";
 
 public final static String DRIVER = "com.mysql.jdbc.Driver"; 

 public static void main(String[] args) {
//  insert();
  select();
//  update();
//  delete();
 }
 
public static void insert(){
 try {
  /*1、加载驱动*/
  Class.forName(DRIVER);
    /*2、连接数据库*/
   Connection cnn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
     //3、构造SQL语句
    String sql = "insert into emp1 values(3,'小栏','女',9000,29,0,1);";
  //4、构造一个Statement实例(用来发送SQL语句的载体)
    Statement state= cnn.createStatement();   
  //5、执行SQL语句
    state.executeUpdate(sql);
    //6、关闭连接
    state.close();
  cnn.close();  
  System.out.println("success."); 
/*添删改都是一样的，把sql语句一改就可以了*/ 
  
 } catch (ClassNotFoundException e) {
  System.out.println("加载失败");
  e.printStackTrace();
 } catch (SQLException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 } 
} 
    public static void select(){
  try {
   Class.forName(DRIVER);
   Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
   String sql = "select * from emp1 ";
   Statement state = conn.createStatement();
   //执行查询并返回结果集
   ResultSet rs = state.executeQuery(sql);
   while(rs.next()){
    int id = rs.getInt(1);
    String name=rs.getString(2); 
    String gender=rs.getString(3);
    float age=rs.getFloat(4);
    System.out.println(id+name+gender+age);   
    
   }   
  } catch (ClassNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } 
     
    } 
}

例三：使用PreparedStatement插入数据

package com.vince.jdbc;

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

public class PreparedStatement_demo { 
 //数据库连接地址
 public final static String URL = "jdbc:mysql://localhost:3306/test"; //用户名
 public final static String USERNAME = "root";
 //密码
 public final static String PASSWORD = "admin"; 
 public final static String DRIVER = "com.mysql.jdbc.Driver";  
 /**
  * 使用
  * @param PreparedStatement插入数据
  */
 public static void insert(Person p){
  
  try {
   Class.forName(DRIVER);
   Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
   String sql = "insert into emp1(id,name,gendar,salary,age)values(?,?,?,?,?)";
   PreparedStatement ps = conn.prepareStatement(sql);
   //设置占位符对应的值
   ps.setInt(1, p.getId());
   ps.setString(2, p.getName());
   ps.setString(3, p.getGendar());
   ps.setFloat(4,p.getSalary());
   ps.setFloat(5,p.getAge());
   
   
   
   ps.executeUpdate();
   
   ps.close();
   conn.close();
   
   
  } catch (ClassNotFoundException e) {
   e.printStackTrace();
  } catch (SQLException e) {
   e.printStackTrace();
  }
  
 }

 public static void main(String[] args) {
  Person p = new Person(7,"小黑","男",5000,30);
      insert(p);
//  update(p);
//  delete(3);
// p = findById(2);
  System.out.println(p);
 }

}

-----------------------

同文件夹新建一个Person类

package com.vince.jdbc;

public class Person {
 private int id;
 private String name;
 private String gendar;
 private float salary;
 private int age;
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public String getGendar() {
  return gendar;
 }
 public void setGendar(String gendar) {
  this.gendar = gendar;
 }
 public float getSalary() {
  return salary;
 }
 public void setSalary(float salary) {
  this.salary = salary;
 }
 public int getAge() {
  return age;
 }
 public void setAge(int age) {
  this.age = age;
 } 
 
 public Person(int id, String name, String gendar, float salary ,int age) {
  super();
  this.id = id;
  this.name = name;
  this.gendar = gendar;
  this.salary = salary;
  this.age= age;
 } 
 
}