JAVA课程设计_CSDN博客收集和整理程序_数据库连接类
这个类是这个课程设计中的一个类，非独立运行（但是测试连接数据库可以独立运行,main方法和构造函数已经注释，需要测试把注释去掉）。
使用用法：如果配置不变，即数据库为Mysql，在本地上并且端口为3306（连接需要下载JDBC mysql的连接包），登录用户名为ROOT，没有密码。并且数据库名称为blogcheckdb，如果有改变可以使用set方法改变。使用时使用connect方法连接数据库。
连接需要使用数据库，稍后给出数据库文件。注意，没有数据库请 不要连接
本类按照需求写了非常多的方法用作接口，详细使用请看注释。
import java.sql.*;
public class DBC {
Connection con;// 连接
Statement stmt;
ResultSet rs;// 返回值
String ip = "127.0.0.1";
String port = "3306";
String DBname = "blogcheckdb";
String url = "jdbc:mysql://" + ip + ":" + port + "/" + DBname
+ "?characterEncoding=utf8";// 数据库链接
String user = "root";// 数据库用户名
String password = null;// 数据库密码
/*public DBC() throws SQLException {
this.connect();
try {// 连接JDBC驱动
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException ce) {
System.out.println("SqlException:" + ce.getMessage());
System.out.println("加载驱动失败");
}
con = DriverManager.getConnection(url, user, password);
stmt = con.createStatement();
// this.connect();
// this.selectnews();
// this.deleteclass(13);
// this.insertnews(1, 1552, 122, 0, 9, 0, 0, 17, true);
// this.updatanews(9, 1552, 122, 1, 9, 1, 1, 19, true);
// this.selectclass();
// this.selectallstudent();
// this.insertclass("网络121");
// this.closeDB();
}*/
public void connect() {
try {// 连接JDBC驱动
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException ce) {
System.out.println("SqlException:" + ce.getMessage());
System.out.println("加载驱动失败");
}
try {
con = DriverManager.getConnection(url, user, password);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
stmt = con.createStatement();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/* public static void main(String[] args) throws SQLException {
new DBC();
}*/
public void insertclass(String classname) {// 插入班级
try {
int a = stmt.executeUpdate("insert into class(classname) values('"
+ classname + "')");
if (a != 0)
System.out.println("插入班级" + classname + "成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void insertstudents(String studentname, String blogurl, int classno) {// 插入学生
try {
int a = stmt
.executeUpdate("insert into students(studentname,url,classno) values('"
+ studentname
+ "','"
+ blogurl
+ "',"
+ classno
+ ")");
if (a != 0)
System.out.println("插入学生" + studentname + "成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public String[][] selectallstudent() {// 查询所有学生号码和姓名和URL，0为学生名，1学号，2为url
int studentcount;// 人数
String[][] Studentname = null;
try {
rs = stmt.executeQuery("SELECT count(*) count FROM Students");
rs.next();
studentcount = Integer.parseInt(rs.getString("count"));
Studentname = new String[3][studentcount];
rs = stmt.executeQuery("select * FROM students");
// rs.next();
for (int i = 0; i < studentcount && rs.next(); i++) {
Studentname[0][i] = rs.getString("studentname");
Studentname[1][i] = rs.getString("studentno");
Studentname[2][i] = rs.getString("url");
// System.out.print(Studentname[0][i]);
// System.out.print(Studentname[1][i]);
// System.out.println(Studentname[2][i]);
}
// System.out.println(studentcount);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return Studentname;
}
public String[][] selectclassstudent(int classno) {// 查询班级内学生，0为学生名，1学号，2为url
int studentcount;// 人数
String[][] Student = null;
try {
rs = stmt
.executeQuery("SELECT count(*) count FROM Students where classno ='"
+ classno + "'");
rs.next();
studentcount = Integer.parseInt(rs.getString("count"));
Student = new String[3][studentcount];
rs = stmt.executeQuery("select * FROM students");
for (int i = 0; i < studentcount && rs.next(); i++) {
Student[0][i] = rs.getString("studentname");
Student[1][i] = rs.getString("studentno");
Student[2][i] = rs.getString("url");
}
// System.out.println(studentcount);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return Student;
}
public String[][] selectclass() {// 查询班级,0为班级名称，1为班级号码
int classcount;// 人数
String[][] classm = null;
try {
rs = stmt.executeQuery("SELECT count(*) count FROM class");
rs.next();
classcount = Integer.parseInt(rs.getString("count"));
classm = new String[2][classcount];
rs = stmt.executeQuery("select * FROM class");
// rs.next();
for (int i = 0; i < classcount && rs.next(); i++) {
classm[0][i] = rs.getString("classname");
classm[1][i] = rs.getString("classno");
// Studentname[2][i] = rs.getString("url");
System.out.print(classm[0][i]);
System.out.print(classm[1][i]);
// System.out.println(Studentname[2][i]);
}
// System.out.println(studentcount);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return classm;
}
public String[][] selectnews() {// 查询更新状态，0为学生名，1学号，2为url
int count;// 人数
String[][] classm = null;
try {
rs = stmt
.executeQuery("SELECT count(*) count FROM students a ,news b where a.studentno = b.studentno AND b.new = TRUE");
rs.next();
count = Integer.parseInt(rs.getString("count"));
classm = new String[3][count];
rs = stmt
.executeQuery("SELECT studentname,url,a.studentno FROM students a ,news b where a.studentno = b.studentno AND b.new = TRUE");
// rs.next();
for (int i = 0; i < count && rs.next(); i++) {
classm[0][i] = rs.getString("studentname");
classm[1][i] = rs.getString("studentno");
classm[2][i] = rs.getString("url");
// Studentname[2][i] = rs.getString("url");
System.out.print(classm[0][i]);
System.out.print(classm[1][i]);
System.out.println(classm[2][i]);
}
// System.out.println(studentcount);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return classm;
}
public void deleteclass(int classno) {// 删除班级
try {
rs = stmt
.executeQuery("SELECT count(*) count FROM students where classno = "
+ classno);
rs.next();
int count = Integer.parseInt(rs.getString("count"));
int student[] = new int[count];
rs = stmt
.executeQuery("SELECT studentno FROM students where classno = "
+ classno);
for (int i = 0; i < count; i++) {
rs.next();
student[i] = Integer.parseInt(rs.getString("studentno"));
}
for (int i = 0; i < count; i++) {
this.deletestudent(student[i]);
}
int a = stmt.executeUpdate("DELETE FROM class where classno = '"
+ classno + "'");// 删除学生
if (a != 0)
System.out.println("删除班级" + classno + "成功！");
rs.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void deletestudent(int studentno) {// 删除学生
try {
rs = stmt
.executeQuery("SELECT count(*) count FROM news where studentno = "
+ studentno);
rs.next();
int i = Integer.parseInt(rs.getString("count"));
while (i > 0) {
i--;
this.deletenews(studentno);// 删除更新状态
}
int a = stmt
.executeUpdate("DELETE FROM students where studentno = '"
+ studentno + "'");// 删除学生
if (a != 0)
System.out.println("删除学生" + studentno + "成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void deletenews(int studentno) {// 删除更新状态
try {
int a = stmt.executeUpdate("DELETE FROM news where studentno = "
+ studentno);
if (a != 0)
System.out.println("删除更新状态" + studentno + "成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void insertnews(int studentno, int accesscount, int credits,
int rank, int originalcount, int reprintcount, int translatecount,
int commentcount, boolean news) {// 插入更新状态
try {
rs = stmt
.executeQuery("SELECT count(*) count FROM news where studentno = "
+ studentno);
rs.next();
int i = Integer.parseInt(rs.getString("count"));
while (i > 0) {
i--;
this.deletenews(studentno);// 删除更新状态
}
int a = stmt
.executeUpdate("insert into news(studentno,accesscount,credits,rank,originalcount,reprintcount,translatecount,commentcount,new) values("
+ studentno
+ ","
+ accesscount
+ ","
+ credits
+ ","
+ rank
+ ","
+ originalcount
+ ","
+ reprintcount
+ ","
+ translatecount
+ ","
+ commentcount + "," + news + ")");// 删除学生
if (a != 0)
System.out.println("插入更新状态" + studentno + "成功！");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void updatanews(int studentno, int accesscount, int credits,
int rank, int originalcount, int reprintcount, int translatecount,
int commentcount, boolean news) {// 更新更新状态
try {
rs = stmt
.executeQuery("SELECT count(*) count FROM news where studentno = "
+ studentno);
rs.next();
int i = Integer.parseInt(rs.getString("count"));
if (i == 0) {
this.insertnews(studentno, accesscount, credits, rank,
originalcount, reprintcount, translatecount,
commentcount, news);// 删除更新状态
} else {
int a = stmt.executeUpdate("UPDATE news set studentno = "
+ studentno + ",accesscount = " + accesscount
+ ",credits = " + credits + ",rank = " + rank
+ ",originalcount = " + originalcount
+ ",reprintcount = " + reprintcount
+ ",translatecount = " + translatecount
+ ",commentcount = " + commentcount + ",new = " + news);//
if (a != 0)
System.out.println("更新状态" + studentno + "成功！");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void closeDB() throws SQLException {// 关闭数据库连接
// rs.close();
stmt.close();
con.close();
}
/////////////////////////////////////////////系统生成get方法和set方法//////////////////////////////////////////////////////
public String getIp() {
return ip;
}
public void setIp(String ip) {
this.ip = ip;
}
public String getPort() {
return port;
}
public void setPort(String port) {
this.port = port;
}
public String getDBname() {
return DBname;
}
public void setDBname(String dBname) {
DBname = dBname;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
// ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
}