3.12

所花时间：2.5h

代码量：100

博客量：1

了解的知识点：1.练习安卓连接数据库

2.参照Android连接Mysql数据库教程以及增删改查_android 访问 mysql 增删查改 源码-CSDN博客

package com.example.mysqlconnectiontest;

 

import android.annotation.SuppressLint;

import android.os.Handler;

import android.os.Message;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.TextView;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

 

public class MainActivity extends AppCompatActivity {

    private Button button;

    private TextView textView;

    private static final int TEST_USER_SELECT = 1;

    int i =0;

    @SuppressLint("HandlerLeak")

    private Handler handler = new Handler(){

        @Override

        public void handleMessage(Message msg) {

            String user;

            switch (msg.what){

                case TEST_USER_SELECT:

                    Test test = (Test) msg.obj;

                    user = test.getUser();

                    System.out.println("***********");

                    System.out.println("***********");

                    System.out.println("user:"+user);

                    textView.setText(user);

                    break;

            }

        }

    };

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        button = (Button) findViewById(R.id.bt_send);

        textView = (TextView) findViewById(R.id.tv_response);

    }

 

    @Override

    protected void onStart() {

        super.onStart();

        button.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View view) {

                //执行查询操作

                //通多点击buttoni自增长查询对应id的name

                if (i<=3){//因为数据库我就添加了三个数据条数，所以进行判断使其可以循环查询

                    i++;

                }

                else{

                    i=1;

                }

                //连接数据库进行操作需要在主线程操作

                new Thread(new Runnable() {

                    @Override

                    public void run() {

                        Connection conn = null;

                        conn =(Connection) DBOpenHelper.getConn();

                        String sql = "select name from test_one where id='"+i+"'";

                        Statement st;

                        try {

                            st = (Statement) conn.createStatement();

                            ResultSet rs = st.executeQuery(sql);

                            while (rs.next()){

                               //因为查出来的数据试剂盒的形式，所以我们新建一个javabean存储

                                Test test = new Test();

                                test.setUser(rs.getString(1));

                                Message msg = new Message();

                                msg.what =TEST_USER_SELECT;

                                msg.obj = test;

                                handler.sendMessage(msg);

                            }

                            st.close();

                            conn.close();

                        } catch (SQLException e) {

                            e.printStackTrace();

                        }

                    }

                }).start();

            }

        });

    }

}