【java】使用文本文档IO流代替数据库实现增删改查
实现效果是这样的
可以看到包含了增删改查和写入全部功能
直接上源码
复制粘贴然后在源码的根目录上创建一个Teacher.txt就可以直接用啦
主程序
import com.sun.source.tree.IfTree;
import java.io.*;
import java.util.Scanner;
public class TManageSystem
{
public String ManagerID = "admin";
public String ManagerPassword = "123456";
public static TeacherTable table = new TeacherTable(10);
public static void main(String[] args)
{
TManageSystem TM = new TManageSystem();
TM.readDBTable();
TM.head();
Scanner scanner = new Scanner(System.in);
System.out.println("请输入账号");
String loginID = scanner.nextLine();
//System.out.println(loginID);
System.out.println("请输入密码");
String loginPassword = scanner.nextLine();
while (!loginID.equals("admin") && !loginPassword.equals("123456"))
{
System.out.println("登录失败，账号或密码错误");
System.out.println("请重新输入账号");
loginID = scanner.nextLine();
System.out.println("请重新输入密码");
loginPassword = scanner.nextLine();
}
System.out.println("登录成功");
table.showTable();
System.out.println("功能介绍：\n" +
"增 insert into 教师姓名 教师年龄 工号 职位 系别 主要科目 电话 地址（中间用空格隔开）;\n"
+ "删 delect where 工号;\n" + "改 update 教师姓名 教师年龄 工号 职位 系别 主要科目 电话 地址 where 工号（中间用空格隔开）;\n"
+ "查 select where 工号（工号不写就是全部）;\n" +
"写入文件 writer;\n" +
"查看全部 selectAll;\n"
+ "退出系统 exit;");
String listen = "";
// table.addRow(new String[]{"教师姓名"," 教师年龄"," 工号"," 职位 ","系别"," 主要科目 ","电话 ","地址"});
while (!listen.equals("exit"))
{
listen = scanner.nextLine();
if (listen.isEmpty())
{
System.out.println("请输入命令");
}
else if (!listen.substring(listen.length() - 1, listen.length()).equals(";"))
{
System.out.println("指令最后要以 ; 结尾");
}
else
{
TM.Lexer(listen);
}
//System.out.println(listen.substring(listen.length()-1,listen.length()));
}
}
public void Writer(){
table.delectEmptyLine();
try {
BufferedWriter out = new BufferedWriter(new FileWriter("Teacher.txt"));
String temp = "";
for (int i = 1; i < table.table.length; i++)
{
if (table.table[i][0].equals("0"))
{
break;
}
for (int j = 0; j < table.table[0].length; j++)
{
if (!table.table[i][j].equals("0"))
{
temp+= table.table[i][j];
}
}
temp+=".\n";
}
out.write(temp);
out.close();
System.out.println("写入成功！");
table.index = 1;
readDBTable();
} catch (IOException e) {
System.out.println(e);
}
}
public void head()
{//填充表
table.head(new String[]{"姓名", "年龄", "ID", "职称", "系别", "课程", "电话", "地址"});
//table.addRow(new String[]{"老王", "18", "ax1122", "班主任", "计算机", "c语言设计", "15905967002", "北京海定"});
}
public void Lexer(String syntax)
{//语法分析器
String temp = "";
String[] elements = getElemetStr(syntax);
String[] temp2 = new String[8];
int index = 0;
for (int i = 0; i < elements.length; i++)
{
switch (elements[i])
{
case "writer ":
Writer();
return;
case "insert ":
for (int j = 2; j <= 9; j++)
{
// System.out.println(index + "" + j);
temp2[index++] = elements[j];
}
//System.out.println(index);
table.addRow(temp2);
System.out.println("添加了一行");
return;
case "delect ":
table.delete(elements[2]);
return;
case "update ":
for (int j = 1; j <= 8; j++)
{
temp2[index++] = elements[j];
}
index = 0;
table.update(elements[10], temp2);
return;
case "select ":
table.select(elements[2]);
return;
case "selectAll ":
table.showTable();
return;
}
}
System.out.println("找不到命令，请重新输入");
}
public void readDBTable()
{
try (FileReader fw = new FileReader("Teacher.txt"))
{
BufferedReader bufReader = new BufferedReader(fw);
String line;
String[] Row = new String[8];
String temp = "";
String bolen = "";
int i = 0;
int j = 0;
while (bufReader.ready())
{
//System.out.println("已读");
line = bufReader.readLine();
bolen = line.substring(i, i + 1);
while (!bolen.equals("."))
{//若当前读取的字符不为‘.’则输出一行
//System.out.println(bolen);
if (!bolen.equals(" "))
{
bolen = line.substring(i, i + 1);
temp += line.substring(i, ++i);
}
else
{
bolen = line.substring(i, i + 1);
// System.out.println(temp);
Row[j++] = temp;
temp = "";
}
}
i = 0;
j = 0;
table.addRow(Row);
}
}
catch (IOException e)
{
//throw new RuntimeException(e);
}
}
public String[] getElemetStr(String line)
{
int i = 0;//当前字符的角标
int j = 0;//当前元素的角标
String[] tempArr = new String[20];
for (int o = 0; o < tempArr.length; o++)
{
tempArr[o] = "";
}
String bolen = "";
String temp = "";
while (!bolen.equals(";"))
{
if (!bolen.equals(" "))
{
bolen = line.substring(i, i + 1);
temp += line.substring(i, ++i);
}
else
{
bolen = line.substring(i, i + 1);
tempArr[j++] = temp;
temp = "";//初始化
}
}
if (j == 0)
{
tempArr[j++] = temp;
}
if (bolen.equals(";"))
{
tempArr[j++] = temp.substring(0, temp.length() - 1) + " ";
temp = "";//初始化
i++;
}
String[] temp2 = new String[j];
for (int k = 0; k < tempArr.length; k++)
{
if (!tempArr[k].equals(""))
{
temp2[k] = tempArr[k];
}
}
for (int l = 0; l < temp2.length; l++)
{
//System.out.print(temp2[l]);
}
System.out.println();
return temp2;
}
}
表的实现
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
public class TeacherTable
{
public static String[][] table;
public static int index = 1;
//initial able
public TeacherTable(int n)
{
table = new String[n][8];
for (int i = 0; i < table.length; i++)
{
for (int j = 0; j < table[0].length; j++)
{
table[i][j] = "0";
}
}
}
//初始化表头
public void head(String[] head)
{
for (int i = 0; i < head.length; i++)
{
table[0][i] = head[i];
}
index++;
}
//show table
public void showTable()
{
delectEmptyLine();
System.out.println(table[1][2]);
for (int i = 0; i <= table.length - 1; i++)
{
for (int j = 0; j <= table[0].length - 1; j++)
{
//System.out.print(table[i][j] + "");
if (!table[i][j].equals("0"))
{
System.out.print(table[i][j] + "|");
}else return;
}
System.out.println();
}
}
public int foundRowInID(String ID)
{
for (int i = 1; i <= table[0].length; i++)
{
if (table[i][2].equals(ID))
{
//System.out.println(i);
return i;
}
}
return -1;
}
private int getEmptyLine()
{
for (int i = 0; i < table.length; i++)
{
//System.out.println(table[i][0]);
if (table[i][0].equals("0"))
{
return i;
}
}
return -1;
}
public void addRow(String[] values)
{
if (values.length > table[0].length)
{
System.out.println("添加的列超过索引");
return;
}
String temp = "";
for (int i = 0; i < values.length; i++)
{
table[index][i] = values[i];
temp += values[i];
}
//System.out.println("表格" + index);
index++;
}
public void update(String ID, String[] values)
{//通过工号修改
if (foundRowInID(ID) == -1)
{
System.out.println("找不到工号，重新输入");
return;
}
for (int i = 0; i < table.length; i++)
{//找到工号所在行
if (!table[i][2].equals(""))
{
if (table[i][2].equals(ID))
{
for (int j = 0; j < table[0].length; j++)
{//修改列
table[i][j] = values[j];
}
return;
}
}
else
{
return;
}
}
}
public void delete(String ID)
{
int bolen = foundRowInID(ID);
if (bolen == -1)
{
System.out.println("找不到工号，请重新输入");
return;
}
for (int i = 0; i < table[0].length; i++)
{
table[bolen][i] = "0";
}
System.out.println("删除成功，改变一行");
delectEmptyLine();
index--;
}
public void select(String ID)
{
System.out.println(foundRowInID(ID));
if (foundRowInID(ID) != -1)
{
for (int i = 0; i < table[0].length; i++)
{
System.out.print(table[foundRowInID(ID)][i] + "|");
}
System.out.println();
}
else
{
System.out.println("找不到工号，请重新输入");
}
}
public void delectEmptyLine()
{
int bolen = getEmptyLine();
if (bolen == -1)
{
return;
}
String[] temp = new String[table[0].length];
//System.out.println("列宽"+table[0].length);
// System.out.println("行高"+table.length);
for (int i = bolen; i < table.length - 1; i++)
{
for (int j = 0; j < table[0].length; j++)
{
temp[j] = table[i + 1][j];
table[i][j] = temp[j];
}
}
}
}