MySQL database connection and additions and deletions to change Java code implementation (PreparedStatement version)

Database:

CREATE TABLE t1 (ID int primary key NOT NULL Auto_increment,name varchar (+), password varchar); insert INTO T1 (name,pass Word) VALUES (' admin ', ' 123 '); INSERT into T1 (Name,password) VALUES (' Zhangsan ', ' 123 '); INSERT into T1 (Name,password) VALUES (' Lisi ', ' 123 ');

Java code:

Mysqlconnection.java Code:

Package Com.dbdao.mysql;import Java.sql.connection;import Java.sql.drivermanager;import java.sql.PreparedStatement ; Import Java.sql.resultset;import Java.sql.sqlexception;import Org.junit.test;public class Mysqlconnection {// Create database driver name private static string driver_class= "Com.mysql.jdbc.Driver";//Database link address private String url= "jdbc:mysql:// Localhost:3306/test ";//database user name private string user=" root ";//Database Password private string password=" 11 ";//Database link private Connection con=null;//prepare to declare SQL statement private PreparedStatement pstmt=null;//result set private ResultSet rs=null;//affect line number private int i;/* * Create driver * */static{try {class.forname (driver_class);} catch (ClassNotFoundException e) {//TODO auto-generated catch B Locke.printstacktrace ();}} /* * Load Driver * */@Testpublic void GetConnect () {//TODO auto-generated method stubtry {con=drivermanager.getconnection (URL, u SER, password);} catch (SQLException e) {//TODO auto-generated catch Blocke.printstacktrace ();} Determine if the database is loaded successfully if (con!=null) {System.out.println ("Database loaded successfully! ");} Else{system.out.pRINTLN ("Database load failed! ");}} /* * Execute SQL statement * */public void Dosql (String sql,object[] Object) {//TODO auto-generated method stub//determine if the SQL statement exists if (Sql!=nul L) {//Load drive getconnect ();//Determine if an object array exists if (object==null) {//If not present, create one to prevent null pointer exceptions object=new object[0];} try {//Declare a prepared SQL statement pstmt=con.preparestatement (SQL);//Assign a value of object one by one for (int i=0;i<object.length;i++) { Pstmt.setobject (i+1, Object[i]);} Execute declaration of SQL statement Pstmt.execute ();} catch (SQLException e) {//TODO auto-generated catch Blocke.printstacktrace ();}} ELSE{SYSTEM.OUT.PRINTLN ("SQL statement does not exist!") ");}} /* * Get result set * */public ResultSet getrs () {try {//Get result set method Rs=pstmt.getresultset ();} catch (SQLException e) {//TODO Auto-gener Ated catch Blocke.printstacktrace ();} Return result set return RS; /* * Gets the number of rows affected * */public int getupdatecount () {//TODO auto-generated method Stubtry {//Get Influence line number methods I=pstmt.getupdatecount ();} C Atch (SQLException e) {//TODO auto-generated catch Blocke.printstacktrace ();} Returns the number of rows affected return I;} /* * Close method * */public void Getclose () {//TODO auto-generated method stub//Close ResultSet try {//Result set Close method Rs.close ();} catch (SQLException e) {//TODO auto-generated catch Blocke.printstacktrace ();} finally{//close declared SQL statement try {//close declaration of SQL statement Method Pstmt.close ();} catch (SQLException e) {//TODO auto-generated catch Blocke.printstacktrace ();} finally{//Uninstall Drive try {//Drive Unload Method Con.close ();} catch (SQLException e) {//TODO auto-generated catch Blocke.printstacktrace ();}} }}}

Loginservice.java Code:

Package Com.service;import Java.sql.resultset;import Java.sql.sqlexception;import org.junit.test;import Com.dbdao.mysql.mysqlconnection;public class Loginservice {//import mysqlconnection classes Mysqlconnection mysqlCon=new Mysqlconnection ();//Prepare the SQL statement private String sql;//affect the number of rows (after the data change, affecting the number of rows is greater than 0, equal to 0 o'clock is not changed, so that if the change fails, then affect the number of rows must be negative) private int i=-1  ;//result set private ResultSet rs;/* * * * */@Testpublic void Insert () {//TODO auto-generated method stub//Create SQL statement sql= "Insert into T1 (Name,password) VALUES (?,?) "; /Create an Object array object[] object=new object[]{"admin", "123456"};//Execute SQL Statement mysqlcon.dosql (SQL, object);//Gets the number of rows affected i= Mysqlcon.getupdatecount ();//Determine if the insertion succeeds if (i!=-1) {System.out.println ("Data insertion succeeded! ");} ELSE{SYSTEM.OUT.PRINTLN ("Data insertion failed!") ");} Close link mysqlcon.getclose ();} /* * Delete data * */@Testpublic void Delete () {//TODO auto-generated method stub//Create SQL statement sql= "Delete from T1 where id=?"; /Create an Object array object[] object=new object[]{3};//Execute SQL statement mysqlcon.dosql (SQL, object);//Gets the number of rows affected I=mysqlcon.getupdatecount ();//Determine if the deletion succeeds if (i!=-1) {System.out.println ("Data deletion succeeded!") ");} ELSE{SYSTEM.OUT.PRINTLN ("Data deletion failed!") ");} Close link mysqlcon.getclose ();} /* * UPDATE data * */@Testpublic void update () {//TODO auto-generated method stub//Create SQL statement sql= "update t1 set password=? where NA Me=? "; /Create an Object array object[] object=new object[]{"One", "admin"};//Execute SQL Statement mysqlcon.dosql (SQL, object);//Gets the number of rows affected i= Mysqlcon.getupdatecount ();//Determine if the data is updated successfully if (i!=-1) {System.out.println ("Data Update succeeded! ");} ELSE{SYSTEM.OUT.PRINTLN ("Data update failed!") ");} Close link mysqlcon.getclose ();} /* * TRAVERSE data * */@Testpublic void Select () {//TODO auto-generated method stub//Create SQL statement sql= "SELECT * from T1";//Execute SQL statement MYSQLC On.dosql (SQL, NULL);//Get result set rs=mysqlcon.getrs ();//Determine if the result set is empty if (rs!=null) {try {//moves the cursor to the end of the result set, note that rs.afterlast () cannot be used here Otherwise, a null value. Rs.last ();//Gets the result set row number I=rs.getrow ();//Determines whether the result set exists if (i>0) {//moves the cursor to the end of the result set Rs.beforefirst ();//loops through all rows while (Rs.next () {//traverse the contents of each line element string name=rs.getstring ("name"); String password=rs.getstring ("password");//Print the result System.out.println in the console ("Name:" +name+ "Password:" +password);}} ELSE{SYSTEM.OUT.PRINTLN ("The result set is empty! ");}} Catch (SQLException e) {//TODO auto-generated catch Blocke.printstacktrace ();}} ELSE{SYSTEM.OUT.PRINTLN ("Result set does not exist! ");} Close link mysqlcon.getclose ();}}

MySQL database connection and additions and deletions to change Java code implementation (PreparedStatement version)