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java连接mysql底层封装详解

2019-11-07 18:12 1696 查看

本文实例为大家分享了java连接mysql底层封装代码，供大家参考，具体内容如下

连接数据库

package com.dao.db;

import java.sql.Connection;
import java.sql.SQLException;

/**
* 数据库连接层MYSQL
* @author Administrator
*
*/
public class DBConnection {

/**
* 连接数据库
* @return
*/
public static Connection getDBConnection()
{
// 1. 注册驱动
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// 获取数据库的连接
try {
Connection conn = java.sql.DriverManager.getConnection("jdbc:mysql://localhost/mysql?useUnicode=true&characterEncoding=utf-8", "root", "root");
return conn;
} catch (SQLException e1) {
e1.printStackTrace();
}
return null;
}

}

数据层封装

package com.dao.db;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Types;
import java.util.ArrayList;
import java.util.HashMap;

/**
* MYSQL数据库底层封装
* @author Administrator
*
*/
public class DBManager {

private PreparedStatement pstmt;
private Connection conn;
private ResultSet rs;

/**
* 打开数据库
*/
public DBManager() {
conn = DBConnection.getDBConnection();
}

/**
* 执行修改添加操作
* @param coulmn
* @param type
* @param sql
* @return
* @throws SQLException
*/
public boolean updateOrAdd(String[] coulmn, int[] type, String sql) throws SQLException
{
if(!setPstmtParam(coulmn, type, sql))
return false;
boolean flag = pstmt.executeUpdate()>0?true:false;
closeDB();
return flag;
}
/**
* 获取查询结果集
* @param coulmn
* @param type
* @param sql
* @throws SQLException
*/
public DataTable getResultData(String[] coulmn, int[] type, String sql) throws SQLException
{
DataTable dt = new DataTable();

ArrayList<HashMap<String, String>>list = new ArrayList<HashMap<String, String>>();

if(!setPstmtParam(coulmn, type, sql))
return null;
rs = pstmt.executeQuery();
ResultSetMetaData rsmd = rs.getMetaData();//取数据库的列名
int numberOfColumns = rsmd.getColumnCount();
while(rs.next())
{
HashMap<String, String> rsTree = new HashMap<String, String>();
for(int r=1;r<numberOfColumns+1;r++)
{
rsTree.put(rsmd.getColumnName(r),rs.getObject(r).toString());
}
list.add(rsTree);
}
closeDB();
dt.setDataTable(list);
return dt;
}

/**
* 参数设置
* @param coulmn
* @param type
* @throws SQLException
* @throws NumberFormatException
*/
private boolean setPstmtParam(String[] coulmn, int[] type, String sql) throws NumberFormatException, SQLException
{
if(sql== null) return false;
pstmt = conn.prepareStatement(sql);
if(coulmn != null && type != null && coulmn.length !=0 && type.length !=0 )
{
for (int i = 0; i<type.length; i++) {
switch (type[i]) {
case Types.INTEGER:
pstmt.setInt(i+1, Integer.parseInt(coulmn[i]));
break;
case Types.BOOLEAN:
pstmt.setBoolean(i+1, Boolean.parseBoolean(coulmn[i]));
break;
case Types.CHAR:
pstmt.setString(i+1, coulmn[i]);
break;
case Types.DOUBLE:
pstmt.setDouble(i+1, Double.parseDouble(coulmn[i]));
break;
case Types.FLOAT:
pstmt.setFloat(i+1, Float.parseFloat(coulmn[i]));
break;
default:
break;
}
}
}
return true;
}

/**
* 关闭数据库
* @throws SQLException
*/
private void closeDB() throws SQLException
{
if(rs != null)
{
rs.close();
}
if(pstmt != null)
{
pstmt.close();
}
if(conn != null)
{
conn.close();
}

}
}

数据集封装

package com.dao.db;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
* 数据集封装
* @author Administrator
*
*/
public class DataTable {

public String[] column;//列字段
public String[][] row; //行值
public int rowCount = 0;//行数
public int colCoun = 0;//列数

public DataTable() {
super();
}

public DataTable(String[] column, String[][] row, int rowCount, int colCoun) {
super();
this.column = column;
this.row = row;
this.rowCount = rowCount;
this.colCoun = colCoun;
}

public void setDataTable(ArrayList<HashMap<String, String>> list) {
rowCount = list.size();
colCoun = list.get(0).size();
column = new String[colCoun];
row = new String[rowCount][colCoun];
for (int i = 0; i < rowCount; i++) {
Set<Map.Entry<String, String>> set = list.get(i).entrySet();
int j = 0;
for (Iterator<Map.Entry<String, String>> it = set.iterator(); it
.hasNext();) {
Map.Entry<String, String> entry = (Map.Entry<String, String>) it
.next();
row[i][j] = entry.getValue();
if (i == rowCount - 1) {
column[j] = entry.getKey();
}
j++;
}
}
}

public String[] getColumn() {
return column;
}

public void setColumn(String[] column) {
this.column = column;
}

public String[][] getRow() {
return row;
}

public void setRow(String[][] row) {
this.row = row;
}

public int getRowCount() {
return rowCount;
}

public void setRowCount(int rowCount) {
this.rowCount = rowCount;
}

public int getColCoun() {
return colCoun;
}

public void setColCoun(int colCoun) {
this.colCoun = colCoun;
}

}

测试Demo

package com.bussiness.test;

import java.sql.SQLException;
import java.sql.Types;

import com.dao.db.DBManager;
import com.dao.db.DataTable;

public class TestBusIness{

static String searchSql = "select * from score";
static String insertSql = "insert into score(name, age, score)values(?,?,?)";
static String deleteSql = "delete from score where id = ?";
static String updateSql = "update score set name = ? where id = ?";

public static void main(String[] args) {
intsertData();
searchData();
}

private static void intsertData()
{
DBManager dm = new DBManager();
String[] coulmn = new String[]{"wyf2", "23", "89.5"};
int[] type = new int[]{Types.CHAR, Types.INTEGER, Types.DOUBLE};

try {
boolean flag = dm.updateOrAdd(coulmn, type, insertSql);
if(flag)
System.out.println("插入成功");
} catch (SQLException e) {
e.printStackTrace();
}
}
private static void searchData()
{
DBManager dm = new DBManager();
String[] coulmn = null;
int[] type = null;

try {
DataTable dt = dm.getResultData(coulmn, type, searchSql);
if(dt != null && dt.getRowCount()> 0){
for(int i = 0; i<dt.getRowCount(); i++)
{
for(int j = 0; j<dt.getColCoun(); j++)
System.out.printf(dt.getRow()[i][j]+"\t");
System.out.println();
}
}
else
System.out.println("查询失败");
} catch (SQLException e) {
e.printStackTrace();
}
}
}

以上就是本文的全部内容，希望对大家的学习有所帮助

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