jdbc 封装增删改查以及映射查找（UserInfo） android-servlet-mysql

package com.Jdbcutil;

import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class JdbcUtils {
//定义数据库的用户名
private final String USERNAME = "root";
//定义数据库用户密码
private final String PASSWORD = "1234";
//定义数据库的地址
private final String URL = "jdbc:mysql://localhost:3306/test";

// //黄金屋用户名
// private final String USERNAME = "zxyquser";
// //黄金屋密码
// private final String PASSWORD = "1234rfvcxzaqwer$#@!";
// //黄金屋数据库
// private final String URL = "jdbc:mysql://172.17.1.10:3306/DBEN_BASE"+
// "?useUnicode=true&characterEncoding=utf8";

//定义数据库驱动
private final String DRIVER = "com.mysql.jdbc.Driver";
//定义数据库连接
private Connection conn;
//定义sql语句的执行对象
private PreparedStatement pstmt;
//定义查询返回的结果的集合
private ResultSet resultSet;
public JdbcUtils() {
try {
Class.forName(DRIVER);
System.out.println("注册驱动成功");

} catch (Exception e) {
// TODO: handle exception
}
}
/**
* 定义获得数据库连接
*/
public Connection getConnection(){
try {
conn = DriverManager.getConnection(URL,USERNAME,PASSWORD);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}

/**
* 完成对数据库表的添加删除和修改功能
* @param sql
* @param params
* @return
* @throws SQLException
*/
public boolean updateByPreparedStatement(String sql,List<Object> params)
throws SQLException{

boolean flag = false;
int result = -1;//表示当用户执行添加删除和修改的时候所影响数据库的行数
pstmt = conn.prepareStatement(sql);
int index = 1;
if(params != null && !params.isEmpty()){
for(int i=0;i<params.size();i++){
pstmt.setObject(index++, params.get(i));
}
}
result = pstmt.executeUpdate();
flag = result > 0 ? true : false;
return flag;
}

/**
* 查询返回单条记录
* @return
* @throws SQLException
*/
public Map<String,Object> findSimpleResult(String sql,List<Object> params)throws SQLException{
Map<String,Object> map = new HashMap<String,Object>();
int index = 1;
pstmt = conn.prepareStatement(sql);
if(params !=null && !params.isEmpty()){
for(int i = 0;i<params.size();i++){
pstmt.setObject(index++, params.get(i));
}
}
resultSet = pstmt.executeQuery();//返回查询结果
ResultSetMetaData metaData = resultSet.getMetaData();
int con_len = metaData.getColumnCount();//获得列的名称
while(resultSet.next()){
for(int i =0;i<con_len;i++){
String cols_name = metaData.getColumnName(i+1);
Object cols_value = resultSet.getObject(cols_name);
if(cols_value == null){
cols_value = "";
}
map.put(cols_name, cols_value);
}

}
return map;
}

/**
* 查询返回多条记录
*/
public List<Map<String,Object>> findMoreResult(String sql,List<Object> params)
throws SQLException{
List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
int index = 1;
pstmt = conn.prepareStatement(sql);
if(params != null && !params.isEmpty()){
for(int i = 0;i<params.size(); i++){
pstmt.setObject(index++, params.get(i));
}
}
resultSet = pstmt.executeQuery();
ResultSetMetaData metaData = resultSet.getMetaData();
int cols_len = metaData.getColumnCount();
while(resultSet.next()){
Map<String,Object> map = new HashMap<String, Object>();
for(int i=0;i<cols_len;i++){
String cols_name = metaData.getColumnName(i+1);
Object cols_value = resultSet.getObject(cols_name);
if(cols_value == null){
cols_value = "";
}
map.put(cols_name, cols_value);
}
list.add(map);
}
return list;
}
/**
* //jdbc的封装可以用反射机制来封装
* @param sql
* @param params
* @param cls
* @return
* @throws SQLException
* @throws NoSuchFieldException
* @throws SecurityException
* @throws InstantiationException
* @throws IllegalAccessException
*/

public <T> T findSimpleRefResult(String sql,List<Object> params,Class<T> cls)
throws SQLException, NoSuchFieldException, SecurityException, InstantiationException, IllegalAccessException{
T resultObject = null;
int index = 1;
pstmt = conn.prepareStatement(sql);
if(params != null && !params.isEmpty()){
for(int i = 0;i<params.size(); i++){
pstmt.setObject(index++, params.get(i));
}
}
resultSet = pstmt.executeQuery();
ResultSetMetaData metaData = resultSet.getMetaData();
int col_len = metaData.getColumnCount();
while(resultSet.next()){
//通过反射机制创建实例
resultObject = cls.newInstance();
for(int i=0;i<col_len;i++){
String cols_name = metaData.getColumnName(i+1);
Object cols_value = resultSet.getObject(cols_name);
if(cols_value == null){
cols_value = "";
}
Field field = cls.getDeclaredField(cols_name);
field.setAccessible(true);//打开javabean的访问private权限
field.set(resultObject, cols_value);
}
}
return resultObject;
}

/**
* 通过反射机制访问数据库
* @param sql
* @param params
* @param cls
* @return
* @throws Exception
*/
public <T> List<T> findMoreRefResult(String sql,List<Object> params,
Class<T> cls)throws Exception{
List<T> list = new ArrayList<T>();
int index = 1;
pstmt = conn.prepareStatement(sql);
if(params != null && !params.isEmpty()){
for(int i = 0;i<params.size(); i++){
pstmt.setObject(index++, params.get(i));
}
}
resultSet = pstmt.executeQuery();
ResultSetMetaData metaData = resultSet.getMetaData();
int col_len = metaData.getColumnCount();
while(resultSet.next()){
T resultObject = cls.newInstance();
for(int i=0;i<col_len;i++){
String cols_name = metaData.getColumnName(i+1);
Object cols_value = resultSet.getObject(cols_name);
if(cols_value == null){
cols_value = "";
}
Field field = cls.getDeclaredField(cols_name);
field.setAccessible(true);//打开javabean的访问private权限
field.set(resultObject, cols_value);
}
list.add(resultObject);
}
return list;
}

/**
* 关闭数据库
*/
public void releaseConn(){
if(resultSet != null){
try {
resultSet.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(pstmt != null){
try {
pstmt.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(conn != null){
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
JdbcUtils jdbcUtils = new JdbcUtils();
jdbcUtils.getConnection();
// String sql = "insert into userinfo(username,pswd) values(?,?)";
// List<Object> params = new ArrayList<Object>();
// params.add("jack1");
// params.add("admin1");
// try {
// boolean flag = jdbcUtils.updateByPreparedStatement(sql, params);
// System.out.println(flag);
// } catch (SQLException e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// }

//查询多条记录
String sql = "select * from userinfo";
List<Object> params = new ArrayList<Object>();
try {
System.out.println(jdbcUtils.findMoreResult(sql, params));
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}