JAVA JBDC连接MySql数据库示例心得一

①–>下载MySql数据库驱动解压获得JAR文件导入编写的Java程序中
下图中1是复制过来的驱动文件，2是导入的文件，要导入才可以用。

②–> 连接数据库，数据查询，数据更新

A是数据库对应的数据类如下：

package com.jdbc;public class A {    private int id;    private String name;    private String password;    private String email;    public A() {    }    public A(int id, String name, String password, String email) {        this.id = id;        this.name = name;        this.password = password;        this.email = email;    }    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    public String getEmail() {        return email;    }    public void setEmail(String email) {        this.email = email;    }    @Override    public String toString() {        return "A [id=" + id + ", name=" + name + ", password=" + password + ", email=" + email + "]";    }}

jdbc.properties是数据库配置文件：

driver=com.mysql.jdbc.Driverjdbcurl=jdbc:mysql://localhost:3306/demodb?useUnicode=true&characterEncoding=utf-8&useSSL=falseuser=rootpassword=123456

JDBCTools是JDBC工具类，包括数据库连接，数据更新如下：

package com.jdbc;import java.io.IOException;import java.io.InputStream;import java.lang.reflect.Field;import java.lang.reflect.Method;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.HashMap;import java.util.Map;import java.util.Properties;import com.mysql.jdbc.Statement;public class JDBCTools {    /**     * 获取数据库连接     * */    public Connection GetConnection() throws IOException, SQLException, ClassNotFoundException {        //使用配置文件方式连接数据库        Properties properties = new Properties();        //获取流        InputStream in = this.getClass().getClassLoader().getResourceAsStream("jdbc.properties");        properties.load(in);        String driver = properties.getProperty("driver");        String jdbcurl = properties.getProperty("jdbcurl");        String user = properties.getProperty("user");        String password = properties.getProperty("password");        Class.forName(driver);        return DriverManager.getConnection(jdbcurl, user, password);    }    /**     * 数据获取     * */    public <T> T get(Class<T> clazz,String sql,Object ...obj){        T eneity = null;        Connection conn = null;        PreparedStatement preparedStatement = null;        ResultSet resultSet = null;        ResultSetMetaData setMetaData = null;        try {            conn = GetConnection();            preparedStatement = conn.prepareStatement(sql);            for(int i=0;i<obj.length;i++){                preparedStatement.setObject(i+1, obj[i]);            }            resultSet = preparedStatement.executeQuery();//得到结果集            //得到ResultSetMetaData对象            setMetaData = resultSet.getMetaData();            //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> values = new HashMap<String, Object>();            //处理结果集，利用ResultSetMetaData填充对应的Map对象            if(resultSet.next()){                for(int i=0;i<setMetaData.getColumnCount();i++){                    String columnLabel = setMetaData.getColumnLabel(i+1);//得到列名                    Object columnValue = resultSet.getObject(i+1);                    System.out.println(columnValue.getClass().getName());                    //System.out.println(columnLabel+":"+columnValue);                    //键列名与对应的值存入Map对象                    values.put(columnLabel, columnValue);                }                if(values.size()>0){                    //若Map不为空集，利用反射创建clazz对应的对象                    eneity = clazz.newInstance();                    //遍历Map对象，取出对应的属性的值                    for(Map.Entry<String, Object> entry:values.entrySet()){                        String fieldName = entry.getKey();                        Object value = entry.getValue();                        //利用反射保存数据                        SetValues(eneity, fieldName, value);                    }                }            }            return eneity;        } catch (Exception e) {            e.printStackTrace();        } finally{            //关闭连接            release(resultSet, (Statement) preparedStatement, conn);        }        return eneity;    }    /**     * 保存数据库数据到对应的JAVA类中     * */    public <T> void SetValues(T t,String fieldName,Object value){        //将传过来的值首字母大写        String methodName = fieldName.substring(0, 1).toUpperCase()+ fieldName.substring(1);         Method method = null;         try {            //获取该类下的所有属性值            Field field = t.getClass().getDeclaredField(fieldName);            //初始化变量类型数组            Class[] parameterTypes = new Class[1];            //获取该属性值的变量类型对象            parameterTypes[0] = field.getType();              //传入方法名称及方法的类型获取该方法的对象            method = t.getClass().getMethod("set"+methodName,parameterTypes);            //获取传人的值的变量类型            method.invoke(t,value);         } catch (Exception e) {           e.printStackTrace();         }    }    /**     * 执行SQL的方法,包含insert,delete,updata     * sql="insert into A (id,name,password,email) values(?,?,?,?);";     * ?号代表条件值     * */    public void Updata(String sql,Object ...obj){        Connection conn = null;        PreparedStatement preparedStatement= null;        try {            conn = GetConnection();            preparedStatement = conn.prepareStatement(sql);            for(int i=0;i<obj.length;i++){                preparedStatement.setObject(i+1, obj[i]);            }            preparedStatement.executeUpdate();        } catch (Exception e) {            e.printStackTrace();        } finally{            release(null, (Statement) preparedStatement, conn);        }    }    /**     * 关闭数据库     * */    public static void release(ResultSet rs, Statement sm, Connection conn) {        if (rs != null) {            try {                rs.close();            } catch (SQLException e) {                e.printStackTrace();            }        }        if (sm != null) {            try {                rs.close();            } catch (SQLException e) {                e.printStackTrace();            }        }        if (conn != null) {            try {                rs.close();            } catch (SQLException e) {                e.printStackTrace();            }        }    }}

测试代码：

JDBCTools jdbcTools = new JDBCTools();        A a = jdbcTools.get(A.class, sql6, 3);        System.out.println(a);