mysql之jdbc

Posted 2020-12-14 今进

JDBC java数据库连接 用来操纵mysql数据库服务器的一套api接口。
大部分是接口。

java jdbc 各种关系数据库
mysql oracle sqlserver db2

jdbc操作mysql步骤
1)下载mysql jdbc驱动jar文件包。 mysql-xxxx.jar
mysql-connector-java-8.0.20.zip

2) 解压mysql-connector-java-8.0.20.zip 找到 mysql-connector-java-8.0.20.jar

3) 建立java项目，添加mysql-connector-java-8.0.20.jar依赖

4) 编写测试代码
package org.beiyou;

import java.sql.*;

public class Test {
public static void main(String[] args) throws ClassNotFoundException, SQLException {
String driver = "com.mysql.cj.jdbc.Driver";
String url = "jdbc:mysql://localhost:33068/db?serverTimezone=PRC&useUnicode=true&characterEncoding=utf8";
String username = "root";
String password = "root";

//加载驱动
Class.forName("com.mysql.cj.jdbc.Driver");

//建立数据库连接
Connection conn = DriverManager.getConnection(url,username,password);

PreparedStatement pst = conn.prepareStatement("select id,name,address from stu");
ResultSet rs = pst.executeQuery();
while(rs.next()){
String v = rs.getString(3);
System.out.println(v == null ? "地址未填写" : v);
}
conn.close();
}

public static void one(String[] args) throws SQLException {
Connection conn = DriverManager.getConnection("jdbc:mysql:/db?user=root&serverTimezone=PRC");
//System.out.println(conn);
//conn.createStatement().execute("create table aa(a int)");
//conn.createStatement().execute("drop table if exists a1,a2,a3,a4,a5,a6,aa");
//PreparedStatement ps = conn.prepareStatement("show tables");
PreparedStatement ps = conn.prepareStatement("show full tables from `db` where table_type = ‘BASE TABLE‘");

ResultSet rs = ps.executeQuery();
while(rs.next()){
System.out.println(rs.getString(1));
}
rs.close();
ps.close();
}
}

//加载驱动
Class.forName("com.mysql.cj.jdbc.Driver"); mysql8 serveTimezone=PRC

Class.forname("com.mysql.jdbc.Driver"); mysql5.6 5.5 5.1 user= password= useUnicode=true&characterEncoding=utf8

//建立数据库连接
Connection conn = DriverManager.getConnection(url,username,password);

 

java.sql.*;
DriverManager

 

1)Statement 语句对象

Connection conn = new DbUtil().getConn();
//Statement
try {
Statement s = conn.createStatement();
//s.execute() create drop grant revoke
//s.executeQuery() show select
//s.executeUpdate() insert delete update
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}

java jdbc mysql 插入数据时，返回自增id值
select max(id) from users ;
2)PreparedStatement

 

3).CallableStatement
delimiter $$
create procedure booknewadd(id int,in bn varchar(30),out s int,inout n int)
begin
insert into booknew values(id,bn);
select count(*) into s from booknew;
set n = n * n;
end$$
delimiter ;

CallableStatement cs = conn.prepareCall("{call booknewadd(?,?,?,?)}");
cs.setInt(1,2);
cs.setString(2,"《mysql数据库技术》");
cs.registerOutParameter(3, Types.INTEGER);
cs.setInt(4,11);
cs.registerOutParameter(4, Types.INTEGER);
int i = cs.executeUpdate();
System.out.println(cs.getInt(3));
System.out.println(cs.getInt(4));
System.out.println(i);

编写DbUtil.java类， 工具类

DbUtil du = new DbUtil();
du.add(String sql,HashMap<String,Object>);
du.add(String sql,Object...objs);
du.execute(String sql,int id);

package com.fz.util;

import java.sql.*;
import java.util.*;

/**
* Created by webrx on 2017-08-16.
*/
public class DbUtil {
private String driver = "com.mysql.jdbc.Driver"; // 数据库驱动类
private String url = "jdbc:mysql://localhost:3306/oadb?useUnicode=true&characterEncoding=utf8&useSSL=true";// url
private String uid = "root"; // 账号
private String pwd = "123";// 密码
private int port = 3306;
private Connection conn = null;
private int currpage = 1;
private int pagesize = 5;
private int recordcount = 0;
private int pagecount = 0;
private String dbname = "oadb";
private String host = "localhost";

public void connect(String host, String user, String password, int port, String dbname) {
this.host = host;
this.url = url;
this.uid = user;
this.pwd = password;
this.dbname = dbname;
this.port = port;
this.url = String.format("jdbc:mysql://%s:%d/%s?useUnicode=true&characterEncoding=utf8&useSSL=true",this.host,this.port,this.dbname);
try {
Class.forName(driver);
this.conn = DriverManager.getConnection(url, uid, pwd);
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}

public String getPk(String tablename) {
String pk = null;
DatabaseMetaData dbmd;
try {
dbmd = this.conn.getMetaData();
ResultSet rs = dbmd.getPrimaryKeys(this.dbname, null, tablename);
if (rs.next()) {
pk = rs.getString(4);
}
} catch (SQLException e) {
e.printStackTrace();
}
return pk;
}

public int add(String sql, Object[] values) {
int num = 0;
PreparedStatement pst;
try {
pst = this.conn.prepareStatement(sql);
int i = 0;
for (Object o : values) {
pst.setObject(++i, o);
}
num = pst.executeUpdate();
pst.close();
} catch (SQLException e) {
e.printStackTrace();
}
return num;
}

public int insert(String tablename, Map<String, Object> m) {
int num = 0;
StringBuilder n = new StringBuilder();
StringBuilder v = new StringBuilder();
for (String k : m.keySet()) {
v.append("?,");
n.append(k + ",");
}
String sql = String.format("insert into %s(%s) values(%s)", tablename, n.toString().subSequence(0, n.length() - 1), v.toString().subSequence(0, v.length() - 1));
PreparedStatement pst;
try {
pst = this.conn.prepareStatement(sql);
int i = 0;
for (Object o : m.values()) {
pst.setObject(++i, o);
}
num = pst.executeUpdate();
pst.close();
} catch (SQLException e) {
e.printStackTrace();
}
return num;
}

public int deleteById(String tablename, Object id) {
int num = delete(tablename, this.getPk(tablename) + "=" + id);
return num;
}

public int delete(String tablename, String where) {
int num = 0;
String sql = String.format("delete from %s where %s", tablename, where);
try {
PreparedStatement pst = this.conn.prepareStatement(sql);
num = pst.executeUpdate();
pst.close();
} catch (SQLException e) {
e.printStackTrace();
}
return num;
}

public int delete(String tablename) {
int num = delete(tablename, "1=1");
return num;
}

public Map<String, Object> queryById(String tablename, Object id) {
Map<String, Object> m = new HashMap<String, Object>();
String sql = String.format("select * from %s where %s", tablename, this.getPk(tablename) + "=‘" + id+"‘");
try {
PreparedStatement pst = this.conn.prepareStatement(sql);
ResultSet rs = pst.executeQuery();
if (rs.next()) {
ResultSetMetaData rsmd = rs.getMetaData();
int cc = rsmd.getColumnCount();
for (int i = 1; i <= cc; i++) {
String name = rsmd.getColumnLabel(i);
m.put(name, rs.getObject(name));
}
}
} catch (SQLException e) {
e.printStackTrace();
}
return m;
}

public int update(String tablename, Map<String, Object> m) {
int num = 0;
String pk = this.getPk(tablename);
if (m.containsKey(pk)) {
num = update(tablename, m, pk + "=‘" + m.get(pk)+"‘");
} else {
num = update(tablename, m, "1=1");
}
return num;
}

public int update(String tablename, Map<String, Object> m, String where) {
int num = 0;
StringBuilder s = new StringBuilder();
for (String k : m.keySet()) {
s.append(k + "=?,");
}
String sql = String.format("update %s set %s where %s", tablename, s.toString().subSequence(0, s.length() - 1), where);
PreparedStatement pst;
try {
pst = this.conn.prepareStatement(sql);
int i = 0;
for (Object o : m.values()) {
pst.setObject(++i, o);
}
num = pst.executeUpdate();
pst.close();
} catch (SQLException e) {
e.printStackTrace();
}
return num;
}

public void close() {
if (this.conn != null) {
try {
this.conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}

public int getCurrpage() {
return currpage;
}

public void setCurrpage(int currpage) {
this.currpage = currpage;
}

public int getPagesize() {
return pagesize;
}

public void setPagesize(int pagesize) {
this.pagesize = pagesize;
}

public int getRecordcount() {
return recordcount;
}

public void setRecordcount(int recordcount) {
this.recordcount = recordcount;
}

public int getPagecount() {
return pagecount;
}

public void setPagecount(int pagecount) {
this.pagecount = pagecount;
}

/**
* host localhost
* user root
* pwd 123
* port 3306
*/
public DbUtil() {
try {
Properties pro = new Properties();
pro.load(DbUtil.class.getClassLoader().getResourceAsStream("db.properties"));
this.driver = pro.getProperty("db.driver");
Class.forName(this.driver);
this.url = pro.getProperty("db.url");
this.uid = pro.getProperty("db.user");
this.pwd = pro.getProperty("db.password");
this.conn = DriverManager.getConnection(this.url, this.uid, this.pwd);
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}

public DbUtil(String host,String user,String password,String dbname) {
this.host = host;
this.uid = user;
this.pwd = password;
this.url = String.format("jdbc:mysql://%s:3306/%s?useUnicode=true&characterEncoding=utf8&useSSL=true",this.host,this.dbname);
try {
Class.forName(driver);
this.conn = DriverManager.getConnection(url, uid, pwd);
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}

public Connection getConn() {
return this.conn;
}

public int count(String tablename, String where) {
int num = 0;
String sql = String.format("select count(*) from %s where %s", tablename, where);
try {
PreparedStatement pst = this.conn.prepareStatement(sql);
ResultSet rs = pst.executeQuery();
if (rs.next()) {
num = rs.getInt(1);
}
rs.close();
pst.close();
} catch (SQLException e) {
e.printStackTrace();
}
return num;
}

public List<Map<String, Object>> query(String tablename, String field) {
return query(tablename, field, "1=1", "");
}

public List<Map<String, Object>> query(String tablename) {
return query(tablename, "*", "1=1", "");
}

public List<Map<String, Object>> query(String tablename, String field, String where, String order) {
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
String sql = String.format("select %s from %s where %s %s", field, tablename, where, order);
PreparedStatement pst;
try {
pst = this.conn.prepareStatement(sql);
ResultSet rs = pst.executeQuery();
ResultSetMetaData rsmd = rs.getMetaData();
while (rs.next()) {
Map<String, Object> m = new HashMap<String, Object>();
int cc = rsmd.getColumnCount();
for (int i = 1; i <= cc; i++) {
String name = rsmd.getColumnLabel(i);
m.put(name, rs.getObject(name));
}
list.add(m);
}
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}

public List<Map<String, Object>> page(int currpage, String tablename, String where, String order) {
return page(currpage, tablename, "*", where, order);
}

public List<Map<String, Object>> page(int currpage, String tablename, String order) {
return page(currpage, tablename, "*", "where 1=1", order);
}

public List<Map<String, Object>> page(int currpage, String tablename) {
return page(currpage, tablename, "*", "where 1=1", "");
}

public List<Map<String, Object>> page(int currpage, String tablename, String fields, String where, String order) {
this.currpage = currpage;
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
String sql = String.format("select %s from %s %s %s limit ?,?", fields, tablename, where, order);
String qqq = String.format("select count(*) c from %s %s", tablename, where);
try {
// 分页信息
PreparedStatement qpst = this.conn.prepareStatement(qqq);
ResultSet qrs = qpst.executeQuery();
if (qrs.next()) {
this.recordcount = qrs.getInt("c");
this.pagecount = this.recordcount % this.pagesize == 0 ? this.recordcount / this.pagesize : this.recordcount / this.pagesize + 1;
}
if (this.currpage < 1)
this.currpage = 1;
if (this.currpage > this.pagecount)
this.currpage = this.pagecount;

// 分页结果信息
PreparedStatement pst = this.conn.prepareStatement(sql);
pst.setInt(1, this.currpage * this.pagesize - this.pagesize);
pst.setInt(2, this.pagesize);
ResultSet rs = pst.executeQuery();
ResultSetMetaData rsmd = rs.getMetaData();
while (rs.next()) {
Map<String, Object> m = new HashMap<String, Object>();
int cc = rsmd.getColumnCount();
for (int i = 1; i <= cc; i++) {
String name = rsmd.getColumnLabel(i);
m.put(name, rs.getObject(name));
}
list.add(m);
}
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}

public String pagebootstrap() {
StringBuilder s = new StringBuilder();
s.append("<ul class="pagination">");
int start = 1;
int end = 10;

if (this.currpage >= 7) {
start = this.currpage - 5;
end = this.currpage + 4;
}
if (this.currpage != 1) {
s.append(String.format("<li><a class="prev" href="?p=%d">上一页</a></li>", this.currpage - 1));
}
for (int i = start; i <= end; i++) {
if (i > this.pagecount)
break;
if (this.currpage == i) {
s.append(String.format("<li class="active"><a href="javascript:void(0)">%d</a></li>", i));
continue;
}
s.append(String.format("<li><a href="?p=%d">%d</a></li>", i, i));
}
if (this.currpage < this.pagecount) {
s.append(String.format("<li><a class="next" href="?p=%d">下一页</a></li>", this.currpage + 1));
}
s.append("</ul>");
return s.toString();
}

public String pageinfo() {
StringBuilder s = new StringBuilder();
s.append("<div class="page">");
int start = 1;
int end = 10;

if (this.currpage >= 7) {
start = this.currpage - 5;
end = this.currpage + 4;
}
if (this.currpage != 1) {
s.append(String.format("<a class="prev" href="?p=%d">上一页</a>", this.currpage - 1));
}
for (int i = start; i <= end; i++) {
if (i > this.pagecount)
break;
if (this.currpage == i) {
s.append(String.format("<span>%d</span>", i));
continue;
}
s.append(String.format("<a href="?p=%d">%d</a>", i, i));
}
if (this.currpage < this.pagecount) {
s.append(String.format("<a class="next" href="?p=%d">下一页</a>", this.currpage + 1));
}
s.append("</div>");
return s.toString();
}

}