个人4/28总结博客

Android 连接数据库

package com.example.mysql;

import android.util.Log;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.HashMap;

//数据库工具类：连接数据库用、获取数据库数据用
public class DBUtils {
private static String driver = "com.mysql.jdbc.Driver";// MySql驱动
private static String user = "root";// 用户名
private static String password = "sise";// 密码

private static Connection getConn(String dbname){
Connection connection = null;
try{
Class.forName(driver);// 动态加载类
String ip = "172.17.9.108"; // 写成本机地址，不能写成localhost
// 尝试建立到给定数据库URL的连接
connection = DriverManager.getConnection("jdbc:mysql://" + ip
+ ":3306/" + dbname, user, password);
}catch (Exception e){
Log.i("DBUtils","Exception");
e.printStackTrace();
}
return connection;
}

public static HashMap<String, Object> getAllInfo(){
HashMap<String, Object> map = new HashMap<>();
// 根据数据库名称，建立连接
Connection connection = getConn("test");
try {
String sql = "select * from users;";
if (connection != null){// connection不为null表示与数据库建立了连接
PreparedStatement ps = connection.prepareStatement(sql);
if (ps != null){
// 执行sql查询语句并返回结果集
ResultSet rs = ps.executeQuery();
if (rs != null){

while (rs.next()){
// String rsm = rs.getMetaData().getColumnName(1);
// Log.i("DBUtils","记录rsm ：" + rsm);
// 通过字段检索
String id = rs.getString("nums");
String name = rs.getString("name");
String passw = rs.getString("passw");
int age = rs.getInt("age");
String adress = rs.getString("adress");
Log.i("DBUtils","记录全 ：" + id + name + passw + age + adress);
map.put(id,","+name+","+passw+","+age+","+adress);
}
connection.close();
ps.close();
return map;
}else {
Log.i("DBUtils","结果为空");
return null; }
}else {
Log.i("DBUtils","sql");
return null; }
}else {
Log.i("DBUtils","连接失败");
return null; }
}catch (Exception e){
e.printStackTrace();
Log.e("DBUtils","异常：" + e.getMessage());
return null;
}

}
public static HashMap<String, Object> getInfoByName(String names){
HashMap<String, Object> map = new HashMap<>();
// 根据数据库名称，建立连接
Connection connection = getConn("test");
try {
// mysql简单的查询语句。这里是根据users表的name字段来查询某条记录
String sql = "select * from users where name = ? ;";
if (connection != null){ // connection不为null表示与数据库建立了连接
PreparedStatement ps = connection.prepareStatement(sql);
if (ps != null){
// 设置上面的sql语句中的？的值为name
// ps.setString(1, names);
ps.setNString(1,names);
// 执行sql查询语句并返回结果集
ResultSet rs = ps.executeQuery();
// rs.beforeFirst();
if (rs != null && rs.next()){
Log.i("DBUtils","记录 count ：" + rs.getMetaData().getColumnCount());
rs.previous();
while (rs.next()){
// 通过字段检索
String id = rs.getString("nums");
String name = rs.getString("name");
String passw = rs.getString("passw");
int age = rs.getInt("age");
String adress = rs.getString("adress");
Log.i("DBUtils","记录全 ：" + id + name + passw + age + adress);
map.put(id,","+name+","+passw+","+age+","+adress);
}
connection.close();
ps.close();
return map;
}else {
Log.i("DBUtils","结果为空");
return null; }
}else {
Log.i("DBUtils","sql");
return null; }
}else {
Log.i("DBUtils","连接失败");
return null; }
}catch (Exception e){
e.printStackTrace();
Log.e("DBUtils","异常：" + e.getMessage());
return null;
}

}
}