本週首先暫時結束了java高階知識,進入了資料庫的學習:
java進階部分:
1.多執行緒:執行緒執行階段(多個執行緒操作共享變數) ;
鎖機制,關鍵字有synchronize( (悲觀)死鎖,,wait,notify,notifyAll;
2.網路程式設計: UDP資料廣播(資料傳送者只需傳送一個拷貝,交換器 與 Json資料格式,語法規則:JSON物件{"屬性名稱":"屬性值"}
JSON外掛程式:- Json-lib
- Gson
- Jackson
- FastJSON - alibaba
;
資料庫部分:(採用mysql5.5資料庫,以及navicat圖形工具對其操作)
系統指令(以管理者身分運作)
: #啟動服務
net start mysql
#停止服務
# # #排列
mysql -uroot -p密碼
#
#退出mysql指令 #修改密碼
備份資料庫執行個體 mysqldump -uroot -proot mydb > d:/mydb.sql
#備份表 mysqldump -uroot -proot mydb tbuser > d:/tbuser.sql
: --顯示資料庫執行個體
show databases;
--建立資料庫執行個體
create database mydb;
# user mydb;
語句
(not null unique)
DDL(資料庫定義語言:用來建立資料庫、資料庫物件和定義其列):create、desc(檢視表格結構) 、alter、drop
中註解時(資料庫操縱語言中:增約 修正值 DCL(資料庫控制語言:控制權限)revork,grant;
2. 外鍵約束
3. 不為空限制
5. 檢查約束(mysql暫不支援)
# 6.資料類型、運算子
FROM 目標表
## 【WHERE 查詢條件】
【GROUP BY 欄位名稱】
詢問條件】
【LIMIT [偏移行,]记录行数】
单表查询:模糊查询(“%”,“_”),聚合函数
多表查询:等值连接,外连接
mysql函数的使用。
import java.io.Serializable; /** * 工作详情类 * @author NIUXUYUAN */ public class Jobs implements Serializable{ /** * */ private static final long serialVersionUID = 1L; private String id; //id private String experience; //工作经验 private String city; //工作地点 private String industry; //行业 private String detail; //工作详情 private String company; //公司 private String jobname; //职位 public Jobs(String id, String experience, String city, String industry, String detail, String company, String jobname) { super(); this.id = id; this.experience = experience; this.city = city; this.industry = industry; this.detail = detail; this.company = company; this.jobname = jobname; } @Override public String toString() { return "Jobs [id=" + id + ", experience=" + experience + ", city=" + city + ", industry=" + industry + ", detail=" + detail + ", company=" + company + ", jobname=" + jobname + "]"; } public String toString(int i) { return experience+city+industry+detail+company+jobname; } public Jobs() { // TODO Auto-generated constructor stub } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getExperience() { return experience; } public void setExperience(String experience) { this.experience = experience; } public String getCity() { return city; } public void setCity(String city) { this.city = city; } public String getIndustry() { return industry; } public void setIndustry(String industry) { this.industry = industry; } public String getDetail() { return detail; } public void setDetail(String detail) { this.detail = detail; } public String getCompany() { return company; } public void setCompany(String company) { this.company = company; } public String getJobname() { return jobname; } public void setJobname(String jobname) { this.jobname = jobname; } }
import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.util.ArrayList; import java.util.List; public class AddJobs { static List<Jobs> list = new ArrayList<>(); File file = new File("jobs"); /** * 输入数据 * @throws IOException */ public void input() throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("以id/experience/education/city/industry/detail/company/jobname格式填入:"); String msg = ""; while(!(msg = br.readLine()).equalsIgnoreCase("quit")) { add(msg); } br.close(); } /** * 将数据变为Jobs对象存入list集合 * @param msg */ private void add(String msg) { String[] s = msg.split("/"); Jobs job = new Jobs(s[0], s[1], s[2], s[3], s[4], s[5], s[6]); list.add(job); } private void checkFile() throws FileNotFoundException, IOException, ClassNotFoundException { if(file.length()>0) { ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file)); List<Jobs> temp = (List<Jobs>)ois.readObject(); if(temp!=null) { list.clear(); for(Jobs t:temp) { list.add(t); } } ois.close(); } } public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException { AddJobs aj = new AddJobs(); if(!aj.file.exists()) { aj.file.createNewFile(); } aj.checkFile(); aj.input(); ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(aj.file)); oos.writeObject(list); oos.close(); } }
import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStreamReader; import java.io.ObjectInputStream; import java.util.ArrayList; import java.util.List; public class Query { static List<Jobs> list = new ArrayList<>(); File file = new File("jobs"); /** * 查看file文件,将数据导入list集合 * @throws FileNotFoundException * @throws IOException * @throws ClassNotFoundException */ private void checkFile() throws FileNotFoundException, IOException, ClassNotFoundException { if(file.length()>0) { ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file)); List<Jobs> temp = (List<Jobs>)ois.readObject(); if(temp!=null) { list.clear(); for(Jobs t:temp) { list.add(t); } } ois.close(); } } public void check() throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("请输入experience/education/city/industry/detail/company/jobname的某些信息"); String msg = br.readLine(); String[] s = msg.split("/"); String regex = ""; for (String str : s) { regex += "[\\s\\S]*" + str + "[\\s\\S]*"; } List<Jobs> temp = new ArrayList<>(); for (Jobs j : list) { msg = j.toString(1); if(msg.matches(regex)) { temp.add(j); } } System.out.println("结果"); for (Jobs jobs : temp) { System.out.println(jobs); } } public static void main(String[] args) throws FileNotFoundException, ClassNotFoundException, IOException { Query q = new Query(); q.checkFile(); q.check(); } }
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