JDBC从入门到熟练(一)
【摘要】
//最简单的jdbc连接jdbc，记住5个步骤
import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;public class Test1 { public static void main(String[] args)...
//最简单的jdbc连接jdbc，记住5个步骤
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.SQLException;
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public class Test1 {
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public static void main(String[] args) {
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String url="jdbc:sqlserver://localhost:1433;DatabaseName=News2";
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Connection con=null; //链接对象
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try {
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//1加载驱动类，实例化一下
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Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
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con=DriverManager.getConnection(url, "sa", "sa");
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//2.获得连接对象
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if(con!=null){
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System.out.println("数据库链接成功!");
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}
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} catch (ClassNotFoundException e){
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e.printStackTrace();
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} catch (SQLException e) {
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e.printStackTrace();
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}finally{
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try {
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con.close();//关闭链接
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} catch (SQLException e) {
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e.printStackTrace();
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}
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}
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}
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}
在此基础上继续完善：
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.ResultSet;
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import java.sql.SQLException;
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import java.sql.Statement;
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//数据库管理类做好了，可以直接链接+关闭语句对象+关闭链接对象;
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public class DBManager {
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private static Connection con=null;
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private static String driver="com.microsoft.sqlserver.jdbc.SQLServerDriver";
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private static String url="jdbc:sqlserver://localhost:1433;DatabaseName=News";
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private static String sql="insert userInfo values('admin','admin',getdate())";
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private static String user="sa";
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private static String pwd="sa";
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//1.公共方法是获得数据库链接对象
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public static Connection getConnection(){
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try {
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Class.forName(driver);//加,连
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con=DriverManager.getConnection(url,user,pwd);
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} catch (ClassNotFoundException e) {
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e.printStackTrace();
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} catch (SQLException e) {
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e.printStackTrace();
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}
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return con;//非void都需要return
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}
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//关闭所有方法;有3个参数!,省代码了!!!
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public static void closeAll(ResultSet rs,Statement stmt,Connection con){
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try {
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if(rs!=null){
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rs.close();
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}
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if(stmt!=null){
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stmt.close();
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}
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if(con!=null){
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con.close();
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}
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} catch (SQLException e) {
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e.printStackTrace();
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}
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}
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}
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import java.sql.Date;
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//实体类:存储介质
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public class UserInfo {
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private int id;
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private String username;
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private String pwd;
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private Date createtime;
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public UserInfo(int id, String username, String pwd, Date createtime) {
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super();
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this.id = id;
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this.username = username;
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this.pwd = pwd;
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this.createtime = createtime;
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}
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public int getId() {
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return id;
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}
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public void setId(int id) {
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this.id = id;
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}
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public String getUsername() {
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return username;
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}
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public void setUsername(String username) {
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this.username = username;
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}
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public String getPwd() {
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return pwd;
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}
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public void setPwd(String pwd) {
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this.pwd = pwd;
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}
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public Date getCreatetime() {
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return createtime;
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}
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public void setCreatetime(Date createtime) {
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this.createtime = createtime;
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}
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}
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import java.sql.*;
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import java.sql.Date;
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import java.util.*;
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//对UserInfo表的数据库管理类
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public class UserInfoDB {
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//0.声明对象;
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Connection con=null;
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Statement stmt=null; //语句对象
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PreparedStatement pstmt=null;
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int result=0; //受影响的行数
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ResultSet rs=null; //结果集对象
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//这个方法：对UserInfo表的增 删 改方法
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//sql:可以insert update delete
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public int updateUserInfo(String sql){
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try {
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con=DBManager.getConnection();//加连了!!!
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stmt=con.createStatement();//语句对象
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result=stmt.executeUpdate(sql);
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} catch (SQLException e) {
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e.printStackTrace();
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}finally{
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DBManager.closeAll(null, stmt, con);
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}
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return result;
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}
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//ArrayList:是个可变类型的动态集合
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//针对预编译语句对象的公共方法;list:存放的是?参数的个数
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public int updateUserInfo(String sql,List list){
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try {
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con=DBManager.getConnection();//嘉联
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pstmt=con.prepareStatement(sql);//1.得对象
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//2.要赋值;
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for(int i=0;i<list.size();i++){
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pstmt.setObject(i+1,list.get(i));
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}
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result=pstmt.executeUpdate();//3.去执行
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} catch (SQLException e) {
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e.printStackTrace();
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}finally{
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DBManager.closeAll(null, pstmt, con);
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}
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return result;
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}
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//简单的查询
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public List<UserInfo> getUser(String sql){
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List<UserInfo>list=new ArrayList<UserInfo>();
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try {
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con=DBManager.getConnection();
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pstmt=con.prepareStatement(sql);
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rs=pstmt.executeQuery();
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while(rs.next()){
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int id=rs.getInt(1);
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String name=rs.getString(2);
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String pwd=rs.getString("pwd");
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Date date=rs.getDate(4);
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UserInfo user=new UserInfo(id,name,pwd,date);
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list.add(user);
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}
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} catch (SQLException e) {
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e.printStackTrace();
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}finally{
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DBManager.closeAll(rs, pstmt, con);
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}
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return list;
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}
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}
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import java.sql.*;
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import java.util.*;
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public class TestPre {
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public static void main(String[] args) {
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//测试;
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UserInfoDB udb=new UserInfoDB();
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String sql="select * from userInfo";
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List<UserInfo>list=udb.getUser(sql);
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System.out.println("编号\t用户\t密码\t日期");
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for(UserInfo user:list){
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System.out.println(user.getId()+"\t"+user.getUsername()+
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"\t"+user.getPwd()+"\t"+user.getCreatetime());
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}
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}
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}
文章来源: aaaedu.blog.csdn.net，作者：tea_year，版权归原作者所有，如需转载，请联系作者。
原文链接：aaaedu.blog.csdn.net/article/details/52875790
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