时间:2021-07-01 10:21:17 帮助过:30人阅读
package com.xuliugen.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DBUtil {
public static Connection getConn() {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/你的数据库名称", "你的账号", "你的密码");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
public static PreparedStatement prepareStmt(Connection conn, String sql) {
PreparedStatement pstmt = null;
try {
pstmt = conn.prepareStatement(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return pstmt;
}
public static ResultSet executeQuery(Statement stmt, String sql) {
ResultSet rs = null;
try {
rs = stmt.executeQuery(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return rs;
}
public static void close(Connection conn, Statement stmt,
PreparedStatement preStatement, ResultSet rs) {
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
stmt = null;
}
if (preStatement != null) {
try {
preStatement.close();
} catch (SQLException e) {
e.printStackTrace();
}
preStatement = null;
}
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
rs = null;
}
}
}
(2)使用preparedStatement插入数据的数据库:
public boolean saveComment(Comment comment) {
Connection connection = DBUtil.getConn();
String sql = "insert into comment values (null,?,?,?,?)";
PreparedStatement preparedStatement = null;
boolean flag = false;
try {
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, comment.getCommenttext() + "");
preparedStatement.setString(2, comment.getCommenttime() + "");
preparedStatement.setString(3, comment.getUserid() + "");
preparedStatement.setString(4, comment.getArticleid() + "");
int isOk = preparedStatement.executeUpdate();
if (isOk > 0) {
return !flag;
} else {
return flag;
}
} catch (SQLException e) {
e.printStackTrace();
}
DBUtil.close(connection, null, preparedStatement, null);
return flag;
}
(3)使用preparedStatement选择数据,读取数据:
public List getCommentDetail(int userid, int articleid) {
Connection connection = DBUtil.getConn();
String sql = "select * from comment c where c.userid=? and c.articleid=?";// 编写sql语句,第一个字段不需要插入,是自动增加的
PreparedStatement preparedStatement = null;
List commentList = new ArrayList();
try {
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, userid);
preparedStatement.setInt(2, articleid);
//这里的产讯不需要传入sql语句
ResultSet rs = preparedStatement.executeQuery();
// 判断是否为空
if (rs.next()) {
while (rs.next()) {// 将信息迭代到list中
Comment comment = new Comment();
comment.setCommentid(rs.getInt("commentid"));
comment.setCommenttext(rs.getString("commenttext"));
comment.setCommenttime(rs.getString("commenttime"));
comment.setUserid(rs.getInt("userid"));
comment.setArticleid(rs.getInt("articleid"));
commentList.add(comment);
}
} else {
return null;
}
} catch (SQLException e) {
e.printStackTrace();
}
DBUtil.close(connection, null, preparedStatement, null);
return commentList;
}
(4)使用Statement操作数据库:
public List getArticleMessage() {
Connection connection = DBUtil.getConn();
String sql = "select * from article";// 编写sql语句,第一个字段不需要插入,是自动增加的
Statement statement = null;
List articleList = new ArrayList();
try {
statement = connection.createStatement();
ResultSet rs = statement.executeQuery(sql);
//判断是否为空
if (rs.next()) {
while (rs.next()) {//将信息迭代到list中
Article article = new Article();
article.setTitle(rs.getString("title"));
article.setContext(rs.getString("context"));
article.setArticleTime(rs.getString("articletime"));
article.setUserid(rs.getInt("userid"));
article.setArticleid(rs.getInt("articleid"));
articleList.add(article);
}
} else {
return null;
}
} catch (SQLException e) {
e.printStackTrace();
}
DBUtil.close(connection, statement, null, null);
return articleList;
}