jdbc中对mysql数据库操作的简单封装--（仅做备忘记录）

Posted 2021-01-13

本次使用jdbc中的mysql-connector-java-5.1.47-bin.jar的连接包，下载这个jar包放在javaee项目的WEB-INF/lib目录下，再把它作为外包jar包进入到libraries中，这样就可以使用mysql的jdbc接口了。

自己封装的代码中引入了两个自己字义的Exception:
SqlSecureException.java

package com.myproweb.exception;

public class SqlSecureException extends Exception {

    /**
     * 
     */
    private static final long serialVersionUID = -185202535331616389L;

}

SqlErrorException.java

package com.myproweb.exception;

public class SqlSecureException extends Exception {

    /**
     * 
     */
    private static final long serialVersionUID = -185202535331616389L;

}

最后封装代码如下：

package com.myproweb.utils;

import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import com.myproweb.exception.SqlErrorException;
import com.myproweb.exception.SqlSecureException;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;

public class MysqlDatabaseConnection {

    private static String mysql_username = "root";
    private static String mysql_password = "";
    private static String mysql_connection_url = "jdbc:mysql://localhost:3306/javadb";
    private static Connection mysql_connection;
    private static Boolean check_fileds_safety = true;

    static {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    private static Boolean validateValueString(String value_string) {
        value_string = value_string.toLowerCase();
        String validateString="‘|or|and|;|-|--|+|,|like|//|/|*|%|#";
        String[] validateStrings = validateString.split("\|");
        for (int i = 0; i < validateStrings.length; i++) {
            if (value_string.indexOf(validateStrings[i]) >= 0) {
                return false;
            }
        }
        return true;
    }
    private static String getSqlValue(Object obj) throws SqlSecureException {
        String sql_value_string = null;
        if (obj instanceof String) {
            if(check_fileds_safety){
                if(validateValueString(obj.toString().trim())) {
                    sql_value_string = "‘" + obj.toString().trim() + "‘";
                }else {
                    throw new SqlSecureException();
                }
            }else {
                sql_value_string = "‘" + obj.toString().trim() + "‘";
            }
        }

        if (obj instanceof Integer) {
            sql_value_string = ((Integer) obj).toString();
        }

        if (obj instanceof Long) {
            sql_value_string = ((Long) obj).toString();
        }

        if (obj instanceof Float) {
            sql_value_string = ((Float) obj).toString();
        }

        if (obj instanceof Double) {
            sql_value_string = ((Double) obj).toString();
        }
        return sql_value_string;
    }

    private static String getWheresSqlString(Map<String, Object[]> wheres) throws SqlErrorException, SqlSecureException {
        String where_string = "";
        for (String key : wheres.keySet()) {
            Object[] condition = wheres.get(key);
            String value_string = getSqlValue(condition[0]);
            if (condition.length == 1) {
                if (null != value_string) {
                    if ("".equals(where_string)) {
                        where_string += " " + key.trim() + "=" + value_string + " ";
                    } else {
                        where_string += "and " + key.trim() + "=" + value_string + " ";
                    }

                }
            }

            if (condition.length == 2) {
                if (!(condition[1] instanceof String)) {
                    throw new SqlErrorException("key words error[0001]!");
                }
                String judgement_condition = condition[1].toString().trim();
                if ("=".equals(judgement_condition) || "<=".equals(judgement_condition)
                        || ">=".equals(judgement_condition) || "!=".equals(judgement_condition)
                        || "<>".equals(judgement_condition)) {
                    if (null != value_string) {
                        if ("".equals(where_string)) {
                            where_string += " " + key.trim() + judgement_condition + value_string + " ";
                        } else {
                            where_string += "and " + key.trim() + judgement_condition + value_string + " ";
                        }

                    }
                } else {
                    throw new SqlErrorException("key words error[0002]!");
                }
            }

            if (condition.length == 3) {
                if (!(condition[2] instanceof String) || !(condition[1] instanceof String)) {
                    throw new SqlErrorException("key words error[0001]!");
                }
                String and_or_string = condition[2].toString().toUpperCase();
                String judgement_condition = condition[1].toString().trim();
                if (("AND".equals(and_or_string) || "OR".equals(and_or_string)) && ("=".equals(judgement_condition)
                        || "<=".equals(judgement_condition) || ">=".equals(judgement_condition)
                        || "!=".equals(judgement_condition) || "<>".equals(judgement_condition))) {
                    if (!"".equals(where_string)) {
                        where_string += and_or_string + ‘ ‘;
                    }
                    if (null != value_string) {
                        where_string += key.trim() + judgement_condition + value_string + ‘ ‘;
                    }
                } else {
                    throw new SqlErrorException("key words error[0002]!");
                }
            }
        }
        if ("".equals(where_string)) {
            throw new SqlErrorException("key words error[0003]!");
        }
        return where_string;
    }

    /**
     * 是否设置对字符值进行安全检查
     * @param is_fields_safety  true:进行安全检查  false:不进行安全检查
     */
    public static void setFieldsSecure(Boolean is_fields_safety) {
        check_fileds_safety=is_fields_safety;
    }

    // 连接数据库边接
    public static Connection getConnection() throws SQLException {
        if (null != mysql_connection) {
            close(mysql_connection);
        }
        mysql_connection = (Connection) DriverManager.getConnection(mysql_connection_url, mysql_username,
                mysql_password);
        return mysql_connection;
    }

    /**
     * 通用的删除、更新、删除函数
     * @param sql_string delete or update or insert sql语句
     * @return sql操作影响的行数
     * @throws SQLException
     */
    public static int commonDeleteOrUpdateOrInsert(String sql_string) throws SQLException {
        Connection connection = getConnection();
        Statement statement = (Statement) connection.createStatement();
        int result = statement.executeUpdate(sql_string);
        close(connection);
        close(statement);
        return result;
    }

    /**
     * 通用的查询函数
     * @param sql_string  select sql语句
     * @return 把查询的结果集放到一个二唯数组中
     * @throws SQLException
     */
    public static ArrayList<ArrayList<Object>> commonQuery(String sql_string) throws SQLException {
        Connection connection = getConnection();
        Statement statement = (Statement) connection.createStatement();
        ResultSet resultSet = statement.executeQuery(sql_string);
        ArrayList<ArrayList<Object>> arraylist = new ArrayList<ArrayList<Object>>();
        int column_count =resultSet.getMetaData().getColumnCount();
        while(resultSet.next()) {
            ArrayList<Object> tmp_arraylist = new ArrayList<Object>();
            for(int i=1 ;i<=column_count ; i++) {
                tmp_arraylist.add(resultSet.getObject(i));
            }
            arraylist.add(tmp_arraylist);
        }
        close(resultSet);
        close(statement);
        close(connection);
        return arraylist;
    }

    /**
     * 实现一个简单sql插入的封装
     * 
     * @param table_name 表名
     * @param values     要插入的值
     * @return 返回Statement执行的结果
     * @throws SQLException
     * @throws SqlSecureException 
     */
    public static int simplyInsert(String table_name, Map<String, Object> values) throws SQLException, SqlSecureException {
        String sql_string = "insert into " + table_name;
        String fields_string = "";
        String values_string = "";
        for (String key : values.keySet()) {
            fields_string += key.trim() + ‘,‘;
            Object obj = values.get(key);
            String t_value_string = getSqlValue(obj);
            if (null != t_value_string) {
                values_string += t_value_string + ",";
            }
        }
        fields_string = fields_string.substring(0, fields_string.length() - 1);
        values_string = values_string.substring(0, values_string.length() - 1);
        sql_string = sql_string + "(" + fields_string + ") value(" + values_string + ")";
        return commonDeleteOrUpdateOrInsert(sql_string);
    }

    /**
     * 实现一个简单sql更新封装
     * @param table_name 表名
     * @param values 更新的值 
     * @param wheres 更新的条件
     * @return 返回受影响的行数
     * @throws SqlErrorException
     * @throws SQLException
     * @throws SqlSecureException 
     */
    public static int simplyUpdate(String table_name, Map<String, Object> values, Map<String, Object[]> wheres) throws SqlErrorException, SQLException, SqlSecureException {
        String sql_string="update "+table_name+" set ";
        String update_string ="";
        for(String key:values.keySet()) {
            update_string+=key+"="+getSqlValue(values.get(key))+",";
        }

        if("".equals(update_string)) {
            throw new SqlErrorException("update string is error!");
        }
        update_string = update_string.substring(0, update_string.length() - 1);
        String where_string = getWheresSqlString(wheres);
        sql_string+=update_string+" where "+where_string;
        return commonDeleteOrUpdateOrInsert(sql_string);
    }

    /**
     * 实现一个简单sql查询一条结果封装
     * @param table_name 表名
     * @param fields 字符集
     * @param wheres 条件
     * @return 返回一行结果
     * @throws SqlErrorException
     * @throws SQLException
     * @throws SqlSecureException
     */
    public static Map<String,Object> simplyQueryRow(String table_name, String[] fields, Map<String, Object[]> wheres)
            throws SqlErrorException, SQLException, SqlSecureException {
        String sql_string = "select ";
        String fields_string = "";
        if (fields.length == 0) {
            throw new SqlErrorException("fileds do not allowed empty!");
        }
        for (String field : fields) {
            fields_string += field + ",";
        }
        fields_string = fields_string.substring(0, fields_string.length() - 1);
        sql_string += fields_string + " from " + table_name + " where ";
        String where_string = getWheresSqlString(wheres);
        sql_string += where_string+" limit 1";
        ArrayList<ArrayList<Object>> resultSet = commonQuery(sql_string);
        Map<String,Object> result = new HashMap<String,Object>();

        ArrayList<Object> filst_row = resultSet.get(0);
        if(null != filst_row) {
            int column_size =filst_row.size();
            if(column_size==fields.length) {
                for(int i=0;i < fields.length ; i++) {
                    result.put(fields[i], filst_row.get(i));
                }
            }else {
                throw new SqlErrorException("fileds and result is error!");
            }
        }
        return result;
    }

    /***
     * 一个简单的删除封装
     * @param table_name  表名
     * @param wheres 条件集
     * @return 返回受影响的行
     * @throws SqlErrorException
     * @throws SQLException
     * @throws SqlSecureException
     */
    public static int simplyDelete(String table_name, Map<String, Object[]> wheres)
            throws SqlErrorException, SQLException, SqlSecureException {
        String sql_string = "delete from " + table_name + " where ";
        String where_string = getWheresSqlString(wheres);
        sql_string += where_string;
        return commonDeleteOrUpdateOrInsert(sql_string);
    }

    // 关闭 结果集 sql预声明 连接
    public static void close(Object obj) throws SQLException {
        if (null == obj) {
            return;
        }
        if (obj instanceof ResultSet) {
            ((ResultSet) obj).close();
        }
        if (obj instanceof Statement) {
            ((Statement) obj).close();
        }
        if (obj instanceof Connection) {
            ((Connection) obj).close();
        }
        obj = null;
    }
}

简单使用实例如下
比如操作表：

CREATE TABLE `customer` (
  `id` int(8) unsigned NOT NULL AUTO_INCREMENT,
  `username` varchar(20) NOT NULL COMMENT ‘用户名‘,
  `password` varchar(20) NOT NULL COMMENT ‘密码‘,
  `gender` int(1) NOT NULL DEFAULT ‘0‘ COMMENT ‘性别‘,
  PRIMARY KEY (`id`),
  UNIQUE KEY `customer_id` (`id`) USING BTREE,
  KEY `customer_username` (`username`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=44 DEFAULT CHARSET=utf8 COMMENT=‘用户表‘;

MysqlDatabaseConnection.simplyInsert 方法示例：

HashMap<String,Object> customer = new HashMap<String,Object>();
        customer.put("username", "admin");
        customer.put("password", "123123123");
        customer.put("gender", new Integer(1));
        try {
            int result = MysqlDatabaseConnection.simplyInsert("customer",customer );
            System.out.println(result);
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (SqlSecureException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

MysqlDatabaseConnection.simplyDelete 方法示例：

Map<String,Object []> wheres = new HashMap<String,Object []>();
        wheres.put("id", new Object[] {new Integer(6),"<=","and"});
        wheres.put("username", new Object[] {"jack","=","or"});
        try {
            int result = MysqlDatabaseConnection.simplyDelete("customer", wheres);
            System.out.println(result);
        } catch (SqlErrorException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (SqlSecureException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

MysqlDatabaseConnection.simplyQueryRow 方法示例：

Map<String,Object []> wheres = new HashMap<String,Object []>();
        wheres.put("id", new Object[] {new Integer(37),"=","and"});
        try {
            Map<String,Object>rowResult = MysqlDatabaseConnection.simplyQueryRow("customer", new String[] {"id","username","password","gender"}, wheres);
            for(String key:rowResult.keySet()) {
                System.out.println(key+":"+rowResult.get(key));
            }
        } catch (SqlErrorException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SqlSecureException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

MysqlDatabaseConnection.simplyUpdate 方法示例：

Map<String,Object> values = new HashMap<String,Object>();
        Map<String,Object[]> wheres = new HashMap<String,Object[]>();

        values.put("username", "admin1");
        values.put("password", "nihao");

        wheres.put("id", new Object[] {new Integer(31)});
        try {
            int result = MysqlDatabaseConnection.simplyUpdate("customer", values, wheres);
            System.out.println(result);
        } catch (SqlErrorException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (SqlSecureException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

以上内容仅做个人备忘用