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;

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;
}

}