JDBC_ORM原理JAVA277-279

本文主要是介绍JDBC_ORM原理JAVA277-279，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

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一、S03E277_01JDBC_ORM原理、使用Object数组存储一条记录

引用表emp

#右击该properties文件--properties--Resource--Text file encoding，选中other,选择其它编码方式。
#如UTF-8或GBK,这样就能在properties里面输入中文，而不会自动转成Unicode了。#java中的properties文件是一种配置文件，主要用于表达配置信息。
#文件类型为*.properties，格式为文本文件，文件内容是"键=值"的格式。
#在properties文件中，可以用"#"来作注释#MySQL连接配置
mysqlDriver=com.mysql.jdbc.Driver
mysqlURL=jdbc:mysql://localhost:3306/sorm
mysqlUser=root
mysqlPwd=mysql#Oracle连接配置
#...

package com.test.orm;import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;public class JDBCUtil {static Properties pros = null;  //可以帮助读取和处理资源文件中的信息static {    //加载JDBCUtil类的时候调用pros = new Properties();try {pros.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("db.properties"));} catch (IOException e) {e.printStackTrace();}}public static Connection getMysqlConn(){try {Class.forName(pros.getProperty("mysqlDriver"));return DriverManager.getConnection(pros.getProperty("mysqlURL"),pros.getProperty("mysqlUser"),pros.getProperty("mysqlPwd"));} catch (Exception e) {e.printStackTrace();return null;}}//可以重载多个，这里就懒得写了public static void close(ResultSet rs,Statement st,Connection conn){try {if (rs!=null) {rs.close();}} catch (SQLException e) {e.printStackTrace();}try {if (st!=null) {st.close();}} catch (SQLException e) {e.printStackTrace();}try {if (conn!=null) {conn.close();}} catch (SQLException e) {e.printStackTrace();}}
}

package com.test.orm;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;/*** 使用Object[]来封装一条记录* 使用List<Object[]>存储多条记录*/
public class Demo01 {public static void main(String[] args) {Connection conn = JDBCUtil.getMysqlConn();PreparedStatement ps = null;ResultSet rs = null;List <Object[]> objsList = new ArrayList<Object[]>();try {ps = conn.prepareStatement("select empname,salary,age from emp where id > ?");ps.setObject(1, 1); //从1开始算参数rs = ps.executeQuery();while (rs.next()) {Object[] objs = new Object[3];  //一个Object数组封装了一条记录的信息！objs[0] = rs.getString(1);objs[1] = rs.getDouble(2);objs[2] = rs.getInt(3);objsList.add(objs);}} catch (SQLException e) {e.printStackTrace();} finally {JDBCUtil.close(rs, ps, conn);}for (Object[] objs : objsList) {System.out.println(objs[0]+"--"+objs[1]+"--"+objs[2]);}}
}

二、S03E278_01JDBC_ORM原理、Map封装一条记录、Map和List封装多条记录

package com.test.orm;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;/*** 使用Map存储一条记录中的多行* 使用List<Map>存储各行中的多行* 使用Map<Map>存储各行中的多行*/
public class Demo02 {/*** 使用Map存储一条记录中的多行*/public static void test01(){Connection conn = JDBCUtil.getMysqlConn();PreparedStatement ps = null;ResultSet rs = null;Map<String,Object> row = new HashMap<String,Object>();  //使用一个Map封装一条记录try {ps = conn.prepareStatement("select empname,salary,age from emp where id = ?");ps.setObject(1, 1); //从1开始算参数rs = ps.executeQuery();while (rs.next()) {row.put("empname", rs.getObject(1));row.put("salary", rs.getObject(2));row.put("age", rs.getObject(3));}} catch (SQLException e) {e.printStackTrace();} finally {JDBCUtil.close(rs, ps, conn);}System.out.println("Map存储单行的多列：");//遍历Map，就是遍历这一行的多列的信息for (String key : row.keySet()) {System.out.print(key+"--"+row.get(key)+"\t");}System.out.println();}/*** 使用List<Map>存储各行中的多行*/public static void test02(){Connection conn = JDBCUtil.getMysqlConn();PreparedStatement ps = null;ResultSet rs = null;//List封装List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();try {ps = conn.prepareStatement("select empname,salary,age from emp where id > ? order by empname");ps.setObject(1, 1); //从1开始算参数rs = ps.executeQuery();while (rs.next()) {Map<String,Object> row = new HashMap<String,Object>();  //使用一个Map封装一条记录row.put("empname", rs.getObject(1));row.put("salary", rs.getObject(2));row.put("age", rs.getObject(3));list.add(row);  //Map加入List}} catch (SQLException e) {e.printStackTrace();} finally {JDBCUtil.close(rs, ps, conn);}System.out.println("List存储各行的多列：");//遍历listfor (Map<String, Object> map : list) {//遍历Map，就是遍历这一行的多列的信息for (String key : map.keySet()) {System.out.print(key+"--"+map.get(key)+"\t");}System.out.println();}}/*** 使用Map<Map>存储各行中的多行*/public static void test03(){Connection conn = JDBCUtil.getMysqlConn();PreparedStatement ps = null;ResultSet rs = null;//Map封装Map<String,Map<String,Object>> maps = new HashMap<String,Map<String,Object>>();try {ps = conn.prepareStatement("select empname,salary,age from emp where id > ? order by empname");ps.setObject(1, 1); //从1开始算参数rs = ps.executeQuery();while (rs.next()) {Map<String,Object> row = new HashMap<String,Object>();  //使用一个Map封装一条记录row.put("empname", rs.getObject(1));row.put("salary", rs.getObject(2));row.put("age", rs.getObject(3));maps.put(rs.getString(1), row); //Map加入Map}} catch (SQLException e) {e.printStackTrace();} finally {JDBCUtil.close(rs, ps, conn);}System.out.println("Map存储各行的多列：");//遍历Mapfor (String empname : maps.keySet()) {Map<String,Object> row = maps.get(empname);//遍历Map，就是遍历这一行的多列的信息for (String key : row.keySet()) {System.out.print(key+"--"+row.get(key)+"\t");}System.out.println();}}public static void main(String[] args) {test01();   //单条test02();   //多行test03();   //多行}
}

三、S03E279_01JDBC_ORM原理、使用javabean对象封装一条记录

package com.test.orm;import java.sql.Date;public class Emp {  //表结构和类对应private Integer id; //尽量用包装类private String empname;private Double salary;private Date birthday;private Integer age;private Integer depId;public Emp() {}public Emp(String empname, Double salary, Integer age) {super();this.empname = empname;this.salary = salary;this.age = age;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getEmpname() {return empname;}public void setEmpname(String empname) {this.empname = empname;}public Double getSalary() {return salary;}public void setSalary(Double salary) {this.salary = salary;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public Integer getDepId() {return depId;}public void setDepId(Integer depId) {this.depId = depId;}
}

package com.test.orm;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;/*** 使用Javabean对象存储一条记录中的多行* 使用List<Javabean>存储各行中的多行*/
public class Demo03 {/*** 使用Javabean对象存储一条记录中的多行*/public static void test01(){Connection conn = JDBCUtil.getMysqlConn();PreparedStatement ps = null;ResultSet rs = null;Emp emp = null;try {ps = conn.prepareStatement("select empname,salary,age from emp where id = ?");ps.setObject(1, 1); //从1开始算参数rs = ps.executeQuery();while (rs.next()) {emp = new Emp(rs.getString(1), rs.getDouble(2), rs.getInt(3));System.out.println("Javabean对象存储一条记录中的多行");System.out.println(emp.getEmpname()+"--"+emp.getSalary()+"--"+emp.getAge());}} catch (SQLException e) {e.printStackTrace();} finally {JDBCUtil.close(rs, ps, conn);}}/*** 使用List<Javabean>存储各行中的多行*/public static void test02(){Connection conn = JDBCUtil.getMysqlConn();PreparedStatement ps = null;ResultSet rs = null;//List封装List<Emp> list = new ArrayList<Emp>();try {ps = conn.prepareStatement("select empname,salary,age from emp where id > ? order by empname");ps.setObject(1, 1); //从1开始算参数rs = ps.executeQuery();while (rs.next()) {Emp emp = new Emp(rs.getString(1), rs.getDouble(2), rs.getInt(3)); list.add(emp);}} catch (SQLException e) {e.printStackTrace();} finally {JDBCUtil.close(rs, ps, conn);}System.out.println("List存储各行的多列：");//遍历listfor (Emp emp : list) {System.out.println(emp.getEmpname()+"--"+emp.getSalary()+"--"+emp.getAge());}}public static void main(String[] args) {test01();   //单条test02();   //多行}
}

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