20170416总结

JDBC通用DAO：

         

public <T> T get(Class<T> clazz,String sql,Object ... args) throws SQLException {
        T entity = null;

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        jdbcUtils = new JDBCUtils();
        try {
            //1.得到ResultSet对象
            connection = jdbcUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            for (int i=0;i<args.length;i++){
                preparedStatement.setObject(i+1,args[i]);
            }
            resultSet = preparedStatement.executeQuery();
            //2.得到ResultSetMetaData对象
            ResultSetMetaData rsmd = resultSet.getMetaData();
            //3.创建一个Map<String,Object> 对象，键：SQL查询的列的别名 值：列的值
            Map<String,Object> map = new HashMap<>();
            //4.处理结果集，利用ResultSetMetaData填充 3 对应的Map对象
            while (resultSet.next()){
                for (int i=0;i<rsmd.getColumnCount();i++){
                    String columnLable = rsmd.getColumnLabel(i + 1);
                    Object columnValues = resultSet.getObject(columnLable);

                    map.put(columnLable,columnValues);
                }
            }

            //5.若Map不为空集，利用反射创建clazz对应的对象
            if (map.size() > 0){
                 entity = clazz.newInstance();
                //5.遍历Map对象，利用反射未Class对象的对应的属性赋值
                for (Map.Entry<String,Object> entry : map.entrySet()){
                    String filedName = entry.getKey();
                    Object value = entry.getValue();
                    ReflectionUtils.setFieldValue(entity,filedName,value);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,preparedStatement,connection);
        }
//        System.out.println("传入的sql值为：" + sql);

        return entity;
    }

JDBC工具类：

  

package com.carzyit.jdbc;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

import static com.sun.org.apache.xalan.internal.utils.SecuritySupport.getContextClassLoader;

/**
 * Created by lenovo on 2017/4/11.
 */
public class JDBCUtils {
    private String driver;
    private String url;
    private String user;
    private String pass;
    public  Connection getConnection() throws Exception {

            InputStream in = getClass().getResourceAsStream("mysql.properties");
            Properties properties = new Properties();
            properties.load(in);
            driver = properties.getProperty("driver");
            url = properties.getProperty("url");
            user = properties.getProperty("user");
            pass = properties.getProperty("pass");

            //加载驱动
            Class.forName(driver);
            Connection connection = DriverManager.getConnection(url,user,pass);

        return connection;
    }

    /**
     * 执行SQL语句，使用PreparedStatement，使用可变参数进行输入
     * @param sql
     * @param args
     * @throws SQLException
     */
    public void update(String sql,Object... args) throws SQLException {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        try {
            connection = getConnection();
            preparedStatement = connection.prepareStatement(sql);
            for (int i=0;i<args.length;i++){
                preparedStatement.setObject(i + 1,args[i]);
            }
            preparedStatement.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            releaseDB(null,preparedStatement,connection);
        }
    }

    public ResultSet query(String sql) throws Exception {
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        connection = getConnection();
        statement = connection.createStatement();
        resultSet = statement.executeQuery(sql);

        return resultSet;
    }

    public int update(String sql) throws Exception {

        Connection connection = null;
        Statement statement = null;

        connection = getConnection();
        statement = connection.createStatement();

        return  statement.executeUpdate(sql);
    }

    public static void releaseDB(ResultSet resultSet, Statement statement, Connection connection) throws SQLException {
        if (resultSet != null){
            resultSet.close();
        }

        if (statement != null){
            statement.close();
        }

        if (connection != null){
            connection.close();
        }
    }
}

mysql.properties文件

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/array
user=root
pass=root

mysql其他测试操作

package com.carzyit.jdbc;


import com.sun.corba.se.spi.ior.ObjectKey;

import java.sql.*;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

/**
 * 常用数据库操作集合
 * Created by lenovo on 2017/4/11.
 */
public class JDBCTest {
    private JDBCUtils jdbcUtils;
    private Student student;

    /**
     * 使用ResultSetMetaData获取JDBC元数据对象
     * @throws SQLException
     */
    public void testResultSetMetaData() throws SQLException {

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        String sql = "SELECT flow_id flowId,type,id_card idCard,exam_card examCard,student_name studentName," +
                "location,grade From testgrad WHERE flow_id = ?";

        jdbcUtils = new JDBCUtils();
        try {

            connection = jdbcUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1,3);

            resultSet = preparedStatement.executeQuery();

            Map<String,Object> map = new HashMap<String,Object>();

            //1.得到ResultSetMetaData对象
            ResultSetMetaData rsmd = resultSet.getMetaData();
            while (resultSet.next()){
                //2.打印每一列的列名，放入map集合中
                for (int i=0;i<rsmd.getColumnCount();i++){
                    String columnLable = rsmd.getColumnLabel(i + 1);
                    Object columnValue = resultSet.getObject(columnLable);//getObject不用指定类型

                    map.put(columnLable,columnValue);
                }
            }
            Class clazz = Student.class;//实例化为Student对象
            Object object = clazz.newInstance();
            for (Map.Entry<String,Object> entry : map.entrySet()){
                String filedName = entry.getKey();
                Object fileValues = entry.getValue();
                //利用反射机制获取集合元素
                ReflectionUtils.setFieldValue(object,filedName,fileValues);
            }
            System.out.println(object);//输出实例化对象的集合
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,preparedStatement,connection);
        }
    }

    /**
     * *********掌握************
     * 目前最通用的查询方法！！！！！！！！利用反射机制得到类的属性
     * @param clazz
     * @param sql
     * @param args
     * @param <T>
     * @return
     * @throws SQLException
     */
    public <T> T get(Class<T> clazz,String sql,Object ... args) throws SQLException {
        T entity = null;

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        jdbcUtils = new JDBCUtils();
        try {
            //1.得到ResultSet对象
            connection = jdbcUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            for (int i=0;i<args.length;i++){
                preparedStatement.setObject(i+1,args[i]);
            }
            resultSet = preparedStatement.executeQuery();
            //2.得到ResultSetMetaData对象
            ResultSetMetaData rsmd = resultSet.getMetaData();
            //3.创建一个Map<String,Object> 对象，键：SQL查询的列的别名 值：列的值
            Map<String,Object> map = new HashMap<>();
            //4.处理结果集，利用ResultSetMetaData填充 3 对应的Map对象
            while (resultSet.next()){
                for (int i=0;i<rsmd.getColumnCount();i++){
                    String columnLable = rsmd.getColumnLabel(i + 1);
                    Object columnValues = resultSet.getObject(columnLable);

                    map.put(columnLable,columnValues);
                }
            }

            //5.若Map不为空集，利用反射创建clazz对应的对象
            if (map.size() > 0){
                 entity = clazz.newInstance();
                //5.遍历Map对象，利用反射未Class对象的对应的属性赋值
                for (Map.Entry<String,Object> entry : map.entrySet()){
                    String filedName = entry.getKey();
                    Object value = entry.getValue();
                    ReflectionUtils.setFieldValue(entity,filedName,value);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,preparedStatement,connection);
        }
//        System.out.println("传入的sql值为：" + sql);

        return entity;
    }

    public Customers getCustomers(String sql,Object... args) throws SQLException {
        Customers customers = null;

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        jdbcUtils = new JDBCUtils();
        try {
            connection = jdbcUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            for (int i=0;i<args.length;i++){
                preparedStatement.setObject(i+1,args[i]);
            }
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
                customers = new Customers();
                customers.setId(resultSet.getInt(1));
                customers.setName(resultSet.getString(2));
                customers.setEmail(resultSet.getString(3));
                customers.setBirth(resultSet.getDate(4));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,preparedStatement,connection);
        }
        System.out.println("传入的sql值为：" + sql);
        return customers;
    }

    /**
     * 使用PrepareStatement进行登录验证，将有效解决SQL注入问题
     */
    public String testSQLInjection2(String username,String password) throws SQLException {
        String flag = null;
        String sql = "SELECT * FROM zengjiqiang WHERE  username = ? AND password = ?";//符号记得别用中文，否则出错很难找到！！！！
        System.out.println(sql);
        jdbcUtils = new JDBCUtils();

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        try {
            connection = jdbcUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);

            preparedStatement.setString(1,username);
            preparedStatement.setString(2,password);
            resultSet = preparedStatement.executeQuery();
            if (resultSet.next()){
                System.out.println("登录成功！");
                flag = "登录成功!!!";
            }else {
                System.out.println("用户名或者密码错误！");
                flag = "用户名或者密码错误！";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,preparedStatement,connection);
        }
        return flag;
    }

    /**
     * 使用Statement进行登录验证，可以进行SQL注入，不安全
     * @throws SQLException
     */
    public void testSQLInjection() throws SQLException {
        String username = "a' or password = ";
        String password = " or '1'='1 ";
        String sql = "select * from zengjiqiang where  username= '" + username + "' and password = '"+ password + "'";
        System.out.println(sql);
        jdbcUtils = new JDBCUtils();

        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            connection = jdbcUtils.getConnection();
            statement = connection.createStatement();
            resultSet = statement.executeQuery(sql);
            if (resultSet.next()){
                System.out.println("登录成功！");
            }else {
                System.out.println("用户名或者密码错误！");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,statement,connection);
        }
    }

    public String registerTest(String username,String password) throws SQLException {
        String flag = null;
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        String sql = "insert into zengjiqiang(username,password) values(?,?)";
        jdbcUtils = new JDBCUtils();
        try {
            connection = jdbcUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,username);
            preparedStatement.setString(2,password);
            preparedStatement.executeUpdate();
            flag = "注册成功！";
        } catch (Exception e) {
            e.printStackTrace();
            flag = "注册失败！";
        }finally {
            jdbcUtils.releaseDB(null,preparedStatement,connection);
        }
        return flag;
    }


    /**
     * 使用PreparedStatement执行插入
     * @throws SQLException
     */
    public void testPrepareStatement() throws SQLException {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        String sql = "insert into customers(name,email,birth) values(?,?,?)";
        jdbcUtils = new JDBCUtils();
        try {
            connection = jdbcUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,"李达康");
            preparedStatement.setString(2,"12345@163.com");
            preparedStatement.setDate(3,new Date(new java.util.Date().getTime()));//传入时间的时候要特别注意
            preparedStatement.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(null,preparedStatement,connection);
        }
    }

    /**
     * 根据某一列的信息查询所有对象的数据；例如：根据准考证号或者身份证号查询成绩
     * @throws Exception
     */
    public void getStudentInfo() throws Exception {
        //1.得到查询类型
        int searchType = getSearchTypeFromConsole();
        //2.具体查询学生信息
        Student student = searchStudent(searchType);
        //3.打印学生信息
        printStudent(student);
    }

    /**
     * 打印学生信息：存在打印具体信息，
     * @param student
     */
    private void printStudent(Student student) {
        if (student != null){
            System.out.println(student);
        }else {
            System.out.println("无查找结果！");
        }

    }

    /**
     * 具体查询学生信息的，返回一个Student对象，若不存在，则返回null
     * @param searchType
     * @return
     */
    private Student searchStudent(int searchType) throws Exception {
        String sql = "SELECT * FROM TestGrad WHERE ";
//        String sql = "SELECT flowid, type, idcard, examcard,studentname, location, grade FROM TestGrad WHERE ";
        Scanner scanner = new Scanner(System.in);
        //1.根据searchType，提示用户输入
        //1.1若searchType为1，提示：请输入身份证号，若为2：请输入准考证号
        if (searchType == 1){
            System.out.print("请输入准考证号：");
            String examCard = scanner.next();
            sql = sql + "examcard = '" + examCard + "'";
        }else {
            System.out.print("请输入身份证号:");
            String idCard = scanner.next();
            sql = sql + "idCard = '" + idCard + "'";
        }
        //2.执行查询
        Student student = getStudent(sql);

        //3、存在返回查询结果
        return student;
    }

    /**
     * 使用PrepareStatement进行查询操作
     * 根据传入的Sql 返回student对象,
     * @param sql
     * @param args
     * @return
     */
    private Student getStudent(String sql,Object... args) throws SQLException {
        Student student = null;

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        jdbcUtils = new JDBCUtils();
        try {
            connection = jdbcUtils.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            for (int i=0;i<args.length;i++){
                preparedStatement.setObject(i+1,args[i]);
            }
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
                student = new Student();
                student.setFlowId(resultSet.getInt(1));
                student.setType(resultSet.getInt(2));
                student.setIdCard(resultSet.getString(3));
                student.setExamCard(resultSet.getString(4));
                student.setStudentName(resultSet.getString(5));
                student.setLocation(resultSet.getString(6));
                student.setGrade(resultSet.getInt(7));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,preparedStatement,connection);
        }
        System.out.println("传入的sql值为：" + sql);
        return student;
    }

    /**
     * 使用Statement进行查询操作
     * 根据传入的Sql 返回student对象,
     * @return
     */
    private Student getStudent(String sql) throws SQLException {

        Student student = null;

        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        jdbcUtils = new JDBCUtils();
        try {
            connection = jdbcUtils.getConnection();
            statement = connection.createStatement();
            resultSet = statement.executeQuery(sql);
            while (resultSet.next()){
                student = new Student(
                        resultSet.getInt(1),
                        resultSet.getInt(2),
                        resultSet.getString(3),
                        resultSet.getString(4),
                        resultSet.getString(5),
                        resultSet.getString(6),
                        resultSet.getInt(7));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,statement,connection);
        }
        System.out.println("传入的sql值为：" + sql);
        return student;
    }

    /**
     * 从控制台读入一个整数，确定要查询的类型
     * @return 1.用身份证查询 2.用准考证号查询， 其他的无效，并提示用户重新输入
     */
    private int getSearchTypeFromConsole() {
        System.out.println("1.用准考证号查询 2.用身份证查询");
        Scanner scanner = new Scanner(System.in);
        int type = scanner.nextInt();
        if (type != 1 && type != 2){
            System.out.print("输入错误请重新输入");
            throw new RuntimeException();
        }
        return type;
    }

    /**
     * 使用Statement执行插入语句；非常麻烦，注意与PrepareStatement执行插入的区别
     * @throws Exception
     */
    public void addNewStudent() throws Exception {
        student = getStudentFromConsole();
//        addNewStudent(student);
        addNewStudent2(student);
    }

    private Student getStudentFromConsole(){

        Scanner scanner = new Scanner(System.in);
        student = new Student();

        System.out.print("FlowId: ");
        student.setFlowId(scanner.nextInt());

        System.out.print("Type: ");
        student.setType(scanner.nextInt());

        System.out.print("IdCard:");
        student.setIdCard(scanner.next());

        System.out.print("ExamCard:");
        student.setExamCard(scanner.next());

        System.out.print("StudentName: ");
        student.setStudentName(scanner.next());

        System.out.print("Location:");
        student.setLocation(scanner.next());

        System.out.print("Grade: ");
        student.setGrade(scanner.nextInt());

        return  student;
    }

    public void addNewStudent(Student student) throws Exception {
        //1.准备一条sql语句：
        String sql = "INSERT INTO TestGrad VALUES(" + student.getFlowId()
                + "," + student.getType() + ",'" + student.getIdCard() + "','"
                + student.getExamCard() + "','" + student.getStudentName()
                + "','" + student.getLocation() + "'," + student.getGrade()
                + ")";

        jdbcUtils.update(sql);
    }

    /**
     * 使用PrepareStatement
     * @param student
     * @throws SQLException
     */
    public void addNewStudent2(Student student) throws SQLException {
        jdbcUtils = new JDBCUtils();
        String sql = "insert into testgrad(flowid,type,idcard,examcard,studentname,location,grade) values(?,?,?,?,?,?,?)";
        jdbcUtils.update(sql,student.getFlowId(),student.getType(),
                student.getIdCard(),student.getExamCard(), student.getStudentName(),
                student.getLocation(),student.getGrade());
    }

    /**
     * 使用Statement查询数据库的左右信息（查询四六级所有信息）
     * @throws SQLException
     */
    public void allTotalInfo() throws SQLException {
        String sql = null;
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;
        jdbcUtils = new JDBCUtils();
//        sql = "delete from customers where id = 1";//删除第一条记录
//        sql = "update customers set name = 'Tom' where id = 2";//查询id为2的记录
        sql = "select flowid ,type,idcard,examcard,studentname,location,grade from testgrad";//查询所有结果

        try {
            connection = jdbcUtils.getConnection();
            statement = connection.createStatement();
            resultSet = statement.executeQuery(sql);
            while (resultSet.next()){
                int id = resultSet.getInt("flowid");
                int grad = resultSet.getInt("type");
                String idnumber = resultSet.getString("idcard");
                String ticketnumber = resultSet.getString("examcard");
                String name = resultSet.getString("studentname");
                String area = resultSet.getString("location");
                int score = resultSet.getInt("grade");
                System.out.println("流水号：" + id);
                System.out.println("四级/六级：" + grad);
                System.out.println("身份证号：" + idnumber);
                System.out.println("准考证号：" + ticketnumber);
                System.out.println("姓名：" + name);
                System.out.println("区域：" + area);
                System.out.println("得分：" + score);
                System.out.println();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            jdbcUtils.releaseDB(resultSet,statement,connection);
        }
    }
}

关于properties文件存放的位置：

      一般放在和引用此properties文件的类的包下，然后使用如下代码引用：（相对路径的应用方法）

     

     InputStream in = getClass().getResourceAsStream("mysql.properties");
     Properties properties = new Properties();
     properties.load(in);

    使用绝对路径引用一直出错！！！！！将properties文件放在工程根目录一直引用失败！！！！后续将继续解决路径问题！！！