java 控制台输出的系统要用的数据库的增删改查。

package com.list

/*

* Author: qcq

* Date:2015/7/20

* E-mail:qinchuanqing918@163.com

* */

import java.io.BufferedReader

import java.io.File

import java.io.FileReader

import java.io.FileWriter

import java.io.IOException

import java.util.HashMap

import java.util.Map

import java.util.Scanner

import java.util.Set

public class Query {

class Person {

public String Id/*should be sure this is unique*/

public String name

public int age

public boolean sex/*true for man, false for girl*/

@Override

public String toString() {

return Id + " " + name + " " + age + " " + (sex? "M" : "F")

}

}

private Map<String, Person>people

private String fileName

public Query(String fileName){

people = new HashMap<String, Person>()

this.fileName = fileName

if(!initial()){

System.out.println("The initial procedure failed may be because wrong"

+ "store file path, please checkit, and rerun this program.")

}

}

private boolean initial(){

boolean flag = false

try {

File file = new File(fileName)

if (!file.exists()){

System.out.println("The file not exist, we will create it for you")

file.createNewFile()

}

BufferedReader reader = new BufferedReader(new FileReader(fileName))

String line = reader.readLine()

while(null != line &&!line.equals("")){

String[] splitLine = line.split(" +")

if (splitLine.length <4){

System.out.println("The information not enough")

return flag

}

Person temp = new Person()

temp.Id = splitLine[0]

temp.name = splitLine[1]

temp.age = Integer.valueOf(splitLine[2])

temp.sex = splitLine[3].equals("M")? true:false

people.put(temp.Id, temp)

line = reader.readLine()

}

flag = true

} catch (IOException e) {

e.printStackTrace()

}

return flag

}

public boolean writeInFile(){

boolean flag = false

try {

FileWriter writer = new FileWriter(fileName)

Set<String>key = people.keySet()

for (String keyIndex: key){

writer.write(people.get(keyIndex).toString() + "\n")

}

} catch (IOException e) {

e.printStackTrace()

}

return flag

}

/**/

public boolean add(){

return false

}

public boolean delete(){

return false

}

public boolean query(){

return false

}

public boolean update(){

return false

}

public static void main(String[] args){

Query data = new Query("temp.txt")/*here should define the file name*/

Scanner in = new Scanner(System.in)

System.out.println("Here you can choice which option:\n"

+ "quit: for quit"

+ "a: for add"

+ "d: for delete"

+ "u: for update"

+ "q: for query")

String option = in.next()

label:

while(null != option &&!option.equals("")){

switch (option){

case "quit" : break label

case "a" :

/*here add the function*/

data.add()

break

case "d" :

/*here add the function*/

data.delete()

break

case "u":

/*here add the function*/

data.update()

break

case "q" :

/*here add the function*/

data.query()

break

default:

break label

}

}

if (null != in){

in.close()

}

}

}

首先得确定你的数据库连接是通过什么形式连接的，hibernate还是原生态的jdbc 还是spring；

如果是只有hibernate，那么你得通过加载配置文件得到sessionFactory,然后得到session

如果spring，那么同样也需要注入sessionfactory到你的dao

如果是jdbc方式，那么你就按照原生态jdbc写法

总之，你构造DAO时，得有数据源。这样才能 *** 纵数据库

字段说明：

用户的id 假设是 uid

要修改的内容是 content

sql语句：

update 表名 set content='修改后的内容' where uid='你传过来的用户id'

但这样的话，表的设计肯定是有问题的。

一般一个用户可以对应多个内容，所以这样的话就会修改该用户的多个内容，应该还需要一个内容的唯一 id，一般会有一个 id 字段，主键自增。

这样修改的时候的 where 条件应该至少有两个：id 和 uid

id 是为了保证只修改到一条内容，且是指定的内容；

uid 是为了保证该内容是同一个创作的（当然前端直接传 uid 是不安全的，应该通过 session 和 token 后端再转成用户的 uid)

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