Mysql api函式：具體的api操作

package com.fasterry.dao;

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

import
 
 org.hibernate.hql.internal.ast.tree.IsNotNullLogicOperatorNode;
import org.omg.CosNaming.NamingContextExtPackage.StringNameHelper;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.PreparedStatement;

public class Mysql {

    private static volatile Mysql instance = null;
    public static final String
 
 url = "jdbc:mysql://localhost:3306/Evaluation";
    public String db = "company?autoReconnect=true";
    public static final String driver = "com.mysql.jdbc.Driver";
    public static final String user = "zhouchenglin";
    public static final String password = "zhouchenglin";
    public Connection connection =
 
 null;
    public PreparedStatement pstmt = null;
    public ResultSet resultSet = null;

    public static Mysql getInstance() {
        if (instance == null) {
            synchronized (Mysql.class) {
                if (instance == null) {
                    instance = new Mysql();
                }
            }
        }
        return instance;
    }

    public Mysql() {
        try {
            // 指定連線型別
            Class.forName(driver);

            // 獲取連線
            connection = (Connection) DriverManager.getConnection(url, user, password);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public int queryCount(String sql,List<Object> params) throws SQLException{
        int count = 0;
        int index = 1;
        pstmt = (PreparedStatement) connection.prepareStatement(sql);
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        // 返回查詢結果
         resultSet= pstmt.executeQuery();
         count  = resultSet.getFetchSize();
         return count;
    }
    public Map<String, Object> queryOne(String sql, List<Object> params) throws SQLException {
        Map<String, Object> map = new HashMap<String, Object>();    
        int index = 1;
        pstmt = (PreparedStatement) connection.prepareStatement(sql);
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        resultSet = pstmt.executeQuery();// 返回查詢結果
        ResultSetMetaData metaData = resultSet.getMetaData();
        int col_len = metaData.getColumnCount();
        while (resultSet.next()) {
            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 = "";
                }
                map.put(cols_name, cols_value);
            }
        }
        return map;
    }

    public void insertData(String sql, List<Object> params) throws SQLException {
        Map<String, Object> map = new HashMap<String, Object>();
        int index = 1;
        pstmt = (PreparedStatement) connection.prepareStatement(sql);
        if (params != null && !params.isEmpty()) {
            for (int i = 0; i < params.size(); i++) {
                pstmt.setObject(index++, params.get(i));
            }
        }
        pstmt.executeUpdate();
    }

    public List<Map<String, Object>> queryMore(String sql, List<Object> params) throws SQLException {
        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        int index = 1;
        pstmt = (PreparedStatement) connection.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;
    }


    protected void finalize() throws Throwable {
        super.finalize();
        connection.close();
    }
}

mysqlAPi封裝：通過將sql語句放在sql.properties檔案裡面，來將所有的sql語句放在同一個檔案裡面，來操作。

package com.fasterry.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import org.apache.taglibs.standard.lang.jstl.test.beans.PublicInterface2;

import com.fasterry.dao.*;
import com.fasterry.test.test;

import net.sf.json.JSON;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class MysqlAPI {

    private Mysql mysql;
    private Properties prs;

    /**
     * 建構函式，初始化sql.properties
     * 
     * @throws IOException
     */
    public MysqlAPI() throws IOException {
        prs = new Properties();
        InputStream inputStream = test.class.getResourceAsStream("../properties/sql.properties");
        mysql = Mysql.getInstance();
        prs.load(inputStream);
        inputStream.close();

    }

    /**
     * 向資料庫插入一條資料
     * 
     * @param sqlKey
     *            key的值，通過尋找sql.propertie檔案來獲得對應的sql
     * @param params
     *            插入的資料
     * @return 插入失敗的返回值
     */
    public String InsertData(String sqlKey, List<Object> params) {
        String sql = prs.getProperty(sqlKey);
        String error = null;
        try {
            mysql.insertData(sql, params);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            error = "插入失敗";
        }
        return error;
    }

    public int queryCount(String sqlKey, List<Object> params) {
        String sql = prs.getProperty(sqlKey);
        int count   = 0;
        try {
            count   = mysql.queryCount(sql, params);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();            
        }
        return count;
    }

    /**
     * 查詢一條資料，並返回json物件
     * 
     * @param sqlKey
     *            sql.properties檔案裡面的key
     * @param params
     *            要查詢的引數
     * @return json物件
     */
    public JSONObject queryOne(String sqlKey, List<Object> params) {
        JSONObject json = null;
        String sql = prs.getProperty(sqlKey);
        Map<String, Object> map = new HashMap<String, Object>();
        try {
            map = mysql.queryOne(sql, params);
            json = JSONObject.fromObject(map);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return json;
    }

    /**
     * 查詢多條資料，並返回json物件
     * 
     * @param sqlKey
     *            sql.properties檔案裡面的key
     * @param params
     *            要查詢的引數
     * @return json物件
     */
    public JSONArray queryMore(String sqlKey, List<Object> params) {
        JSONArray json = null;
        String sql = prs.getProperty(sqlKey);
        try {
            List<Map<String, Object>> list = mysql.queryMore(sql, params);
            json = JSONArray.fromObject(list);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return json;
    }

    /**
     * 尋找指定字串的個數
     * 
     * @param str
     *            指定字串
     * @param key
     *            要查詢的字元
     * @return key的個數
     */
    public int findKeyString(String str, String key) {
        int num = 0;
        while (str.indexOf(key) != -1) {
            num++;
            str = str.substring(str.indexOf(key) + key.length());
        }

        return num;
    }

}

sql.properties

#/*********************user表*****************
insertUser=insert into user(name,password) values(?,?)
queryUserInfo=select name,password,age from user 
queryUserPassword=select password from user where name=?
queryUserName=select count(*) from user where name=?

我個人覺得將sql語句放在同一個檔案裡面來操作比較好，這樣更加方便的管理sql語句。