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.Driver
jdbcurl=jdbc:mysql://localhost:3306/demodb?useUnicode=true&characterEncoding=utf-8&useSSL=false
user=root
password=123456JDBCTools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);