Android Studio 使用JDBC连接MysqL数据库

1.下载mysql-connector-java-5.1.7

（有可能不能用，如果不能用就自己在官网下载吧）
链接：https://pan.baidu.com/s/1j5Qh7p3Y346O1ctOjthZMQ
提取码：04w2
复制这段内容后打开百度网盘手机App，操作更方便哦–来自百度网盘超级会员V1的分享

2.将jar包导入到Android Studio

3.创建数据库连接帮助类

//MysqL数据库的连接辅助类:生成连接、生成数据库操作对象
public class DbOpenHelper {
    private static  final String driver = "com.MysqL.jdbc.Driver";// MysqL驱动
    //192.168.43.65为我电脑的ip，这里要用自己电脑的ip，transportation为我电脑的数据库名，也要换。
    private static  final String url = "jdbc:MysqL://192.168.43.65:3306/transportation?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8";
    private static  final String user = "root";// 用户名
    private static  final String password = "123456";// 密码

    public static Connection conn;//连接对象
    public  static Statement stmt;//命令集
    public  static PreparedStatement pStmt;//预编译命令集
    public  static ResultSet rs;//结果集


    //取得连接的方法
    public  static void getConnection(){
        try {
           Class.forName(driver);
            try {
                conn = DriverManager.getConnection(url,user,password);
            } catch (sqlException e) {
                e.printstacktrace();
            }
        } catch (ClassNotFoundException e) {
            e.printstacktrace();
        }


    }

    //关闭数据库
    public static  void closeAll(){
        if(rs!=null){
            try {
                rs.close();
            } catch (sqlException e) {
                e.printstacktrace();
            }
            rs = null;
        }
        if(stmt!=null){
            try {
                stmt.close();
            } catch (sqlException e) {
                e.printstacktrace();
            }
            stmt = null;
        }
        if(pStmt!=null){
            try {
                pStmt.close();
            } catch (sqlException e) {
                e.printstacktrace();
            }
            pStmt = null;
        }

        if(conn!=null){
            try {
                conn.close();
            } catch (sqlException e) {
                e.printstacktrace();
            }
            conn = null;
        }

    }

}

其中ip要换成自己电脑的IP，打开cmd,执行ipconfig，IPv4地址为此处的IP，数据库名称也要换，以及登录数据库的用户名、密码也要换成自己的。
PS：这里还要打开cmd登录数据库，对数据库允许访问的IP权限进行设置，具体设置方法：

grant all privileges on *.* to 'root'@'ip'identified by '密码'; #授权某个ip的用户可以通过密码访问数据库

此时Android studio就连接上了MysqL数据库了。

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想做一个无线点餐的安卓app 开桌把桌号传到数据库 但是servlet不太会 想请教为什么出错

这是activity传数据的主要代码
package com.systaresto_client;






import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;


import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;


import util.HttpUtil;
import com.systaresto_client.R;
import com.systaresto_client.R.layout;
import com.systaresto_client.R.menu;






import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;


@SuppressLint("NewApi")
public class KaizhuoActivity extends Activity {
 String personNum;
 String tableID;


 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_kaizhuo);
 
 Button openTb = (Button)findViewById(R.id.openTbButton);//caidan
 openTb.setOnClickListener(new OnClickListener() {
 @Override
 public void onClick(View v) {
 
 
 EditText personNumEt = (EditText) findViewById(R.id.personNumEditText02);
 personNum = personNumEt.getText().toString();
 EditText tableIDEt = (EditText) findViewById(R.id.tableNumEditText);
 tableID = tableIDEt.getText().toString(); 
  
 
 // 桌�?�
 if	( tableID.equals("1")){
 showDialog("该桌已开");
 }
 else
 {
 Intent intent = new Intent(); // 调用点菜方法
 // 桌号
 intent.setClass(KaizhuoActivity.this,JiacaiActivity.class);
 Bundle bundle = new Bundle(); 
 bundle.putString("tableID",tableID);
 bundle.putString("personNum",personNum);
 
 intent.putExtras(bundle);
 startActivity(intent); 
 
 List<BasicNameValuePair> params =new LinkedList<BasicNameValuePair>();
 params.add(new BasicNameValuePair("OrderNum", tableID));
 params.add(new BasicNameValuePair("Person",personNum));
 
 UrlEncodedFormEntity entity1=null;
 try {
 entity1 = new UrlEncodedFormEntity(params,HTTP.UTF_8);
 } catch (UnsupportedEncodingException e) {
 e.printStackTrace();
 }
 
 // 请求服务器Servlet的url
 String url = HttpUtil.BASE_URL+"servlet/KaizhuoServlet";
 // 获得HttpPost对象
 HttpPost request = HttpUtil.getHttpPost(url);
 // 为请求设置参数
 request.setEntity(entity1);
 // 获得返回结果
 String result= HttpUtil.queryStringForPost(request);
 System.out.print(result); 
 StrictMode
 .setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
 .detectDiskReads().detectDiskWrites()
 .detectNetwork() // or .detectAll() for all
 // detectable problems
 .penaltyLog().build());
 StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()
 .detectLeakedSqlLiteObjects() // 探测SQLite数据库操作
 .penaltyLog() // 打印logcat
 .penaltyDeath().build());
 finish();
 
 }
  
 }
 });
 
 Button mCancel = (Button)findViewById(R.id.fanhui);
 mCancel.setOnClickListener(new OnClickListener() {
 public void onClick(View v) {
 finish();//这个是关键
 }
 });
 
 Button mainMenu = (Button)findViewById(R.id.zhucaidan);
 mainMenu.setOnClickListener(new OnClickListener() {
 @Override
 public void onClick(View v) {
 
 Intent i=new Intent(KaizhuoActivity.this, MainActivity.class);
 startActivity(i);
 KaizhuoActivity.this.startActivity(i);
 KaizhuoActivity.this.finish();
 }
 });
 }
 
 
 private void showDialog(String msg){
 AlertDialog.Builder builder = new AlertDialog.Builder(this);
 builder.setMessage(msg)
       .setCancelable(false)
       .setNegativeButton("取消", new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int id) {
           }
       })
       .setPositiveButton("添菜", new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int id) {
        	   EditText personNumEt = (EditText) findViewById(R.id.personNumEditText02);
 String personNum = personNumEt.getText().toString();
 EditText tableIDEt = (EditText) findViewById(R.id.tableNumEditText);
 String tableID = tableIDEt.getText().toString(); 
  
        	   
        	   Intent intent = new Intent(); // 调用点菜方法
 // 桌号
 intent.setClass(KaizhuoActivity.this,JiacaiActivity.class);
 Bundle bundle = new Bundle(); 
 bundle.putString("personNum",personNum);
 bundle.putString("tableID",tableID);
 intent.putExtras(bundle);
 startActivity(intent); 
 
           }
       });
 AlertDialog alert = builder.create();
 alert.show();
 }
 


 


 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
 // Inflate the menu; this adds items to the action bar if it is present.
 getMenuInflater().inflate(R.menu.kaizhuo, menu);
 return true;
 }


 
}

 
 
 

 

 
 
 

	

 
 
 

 

 
 
 
这是开桌daoImpl
package dao.impl;


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


import dao.kaizhuoDao;






import util.DBUtil;


import entity.kaizhuo;


public class KaizhuoDaoImpl implements kaizhuoDao {
 String TableId ;
 String PersonNum;
 
 public kaizhuo check(String OrderNum, String Person){
 // 查询SQL语句
 String sql1 =   " select OrderNum,Person,Montant"+
 " from commandinfo7"+
 " where OrderNum=? and Person=? ";
 
 
 // 添加SQL语句
//				String sql2 = " insert into commandinfo7(OrderNum,Person)values(3,3) ";
 // 数据库连接工具类
 DBUtil util = new DBUtil();
 // 获得连接
 Connection conn = util.openConnection(); 
 try {
 // 获得预定义语句
 PreparedStatement pstmt = conn.prepareStatement(sql1);
//					PreparedStatement pstmt2 = conn.prepareStatement(sql2);
 // 设置查询参数 
 pstmt.setString(1, OrderNum);
 pstmt.setString(2, Person);
 
//					 pstmt2.setString(3, OrderNum);
//					 pstmt2.setString(4, Person);
 // 执行查询
 ResultSet rs = pstmt.executeQuery();
 // 判断用户是否存在
 if (rs.next()) {
 // 获得用户信息
 
 
//						OrderNum = rs.getString(1);
//						Person = rs.getString(2);
 float Montant= rs.getFloat(3);
 // 封装用户信息
 kaizhuo k = new kaizhuo();
 
 k.setMontant(Montant);
 k.setOrderNum(OrderNum);
 k.setPerson(Person);
 
 return k;
 
 }else return null;
 }
 catch (SQLException e) {
 e.printStackTrace();
 } finally {
 util.closeConn(conn);
 }
 return null;
 
 
}
 // 保存点餐列表
 public kaizhuo saveKaizhuo(kaizhuo kz) {
 // 添加SQL语句
 String sql = " insert into commandinfo7(OrderNum,Person)values(?,?) ";
 // 数据库连接工具类
 DBUtil util = new DBUtil();
 // 获得连接
 Connection conn = util.openConnection();
 try {
 // 获得预定义语句
 PreparedStatement pstmt = conn.prepareStatement(sql);
 
 // 设置参数
 pstmt.setString(1, kz.getOrderNum());
 pstmt.setString(2, kz.getPerson());
 // 执行更新
 pstmt.executeUpdate();
 } catch (SQLException e) {
 e.printStackTrace();
 } finally {
 util.closeConn(conn);
 }
 return null;
 
 }
 
 
 
 
 
 
 
 
 
 public static void main(String[] args) {
 kaizhuoDao dao = new KaizhuoDaoImpl();
 kaizhuo k = dao.check("3", "1");
 System.out.println(k.getMontant());
 kaizhuo kz = dao.saveKaizhuo(k);
 
 }
 
 
 
}

这是servlet

package servlet;


import java.io.IOException;
import java.io.PrintWriter;


import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import dao.kaizhuoDao;
import dao.impl.KaizhuoDaoImpl;
import entity.kaizhuo;


public class KaizhuoServlet extends HttpServlet { 
 
 public KaizhuoServlet() {
    super();
    
 }
 public void destroy(){
 super.destroy();
 }
 
 private static final long serialVersionUID = 1L;
   
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


 response.setContentType("text/html");
 PrintWriter out = response.getWriter();
 // 桌号
 String OrderNum = request.getParameter("OrderNum");
 // 人数
 String Person = request.getParameter("Person");
 // 获得DAO接口
 kaizhuoDao dao = new KaizhuoDaoImpl(); 
 // 实例化订单类
 kaizhuo k = dao.check(OrderNum, Person);
 kaizhuo kz = new kaizhuo();
 kz.setOrderNum(OrderNum);
 kz.setPerson(Person);
 
 // 设置订单属性 
 k.setPerson(Person); 
 k.setOrderNum(OrderNum);


 dao.saveKaizhuo(kz);
 
 
 out.flush();
 out.close();
 
 }


 
 
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 doGet(request,response);
 }
public void init() throws ServletException{
}




}

 
 
 

 

 
 
 

	

 
 
 

 

 
 
 

开桌 dao

package dao;


import entity.kaizhuo;


public interface kaizhuoDao {
 // 开桌信息
 public kaizhuo check (String OrderNum ,String Person );


 public kaizhuo saveKaizhuo(kaizhuo kz);
}

 
 
 

 

 
 
 

	

  
  
  
 
  
 
  
  
  
entity开桌

  
  
  
 
  
 
  
  
  


 
 
 

 

 
 
 
package entity;





public class kaizhuo {

// 桌号

private String OrderNum;

// 人数

private String Person;

private float Montant;



public float getMontant() {

return Montant;

}

public void setMontant(float montant) {

Montant = montant;

}

public String getOrderNum() {

return OrderNum;

}

public void setOrderNum(String orderNum) {

OrderNum = orderNum;

}

public String getPerson() {

return Person;

}

public void setPerson(String person) {

Person = person;

}





}

DBUtil


package util;





import java.sql.Connection;  

import java.sql.DriverManager;  

  

import java.sql.SQLException;  

 

public class DBUtil {

/*

* 关闭数据库连接

*/

public void closeConn(Connection conn){

try {

conn.close();

} catch (SQLException e) {

e.printStackTrace();

}

}



/*

* 打开数据库连接

*/

public Connection openConnection() {





String url="jdbc:mysql://localhost:3306/systaresto?useUnicode=true&characterEncoding=utf-8";

String	username="root";

String	password="test";

try {

//			prop.load(this.getClass().getClassLoader().getResourceAsStream(

//					"DBConfig.properties"));

Class.forName("com.mysql.jdbc.Driver");







return DriverManager.getConnection(url, username, password);

} catch (Exception e) {

e.printStackTrace();

}





return null;

}





}


 
 
 

 

 
 
 

	
  
  
  
 
  
 
  
  
  


 
 
 

 

 
 
 

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