Eclipse下 Java對MySQL數據庫操作

1. 下載Mysql驅動。

Link:http://dev.mysql.com/downloads/connector/j/

2.加載JDBC

在Eclipse中，選中相應的工程，Properties->Java Build path->add external jars->ok.

3.JDBC操作數據庫的一般步驟

注冊驅動 (只做一次)

 

Class.forName(“com.mysql.jdbc.Driver”);

 

建立連接(Connection)

 

Connection conn = DriverManager.getConnection(url, user, password);

url格式：JDBC:子協議:子名稱//主機名:端口/數據庫名？屬性名=屬性值&…

User,password可以用“屬性名=屬性值”方式告訴數據庫；

 

example：

String url="jdbc:mysql://localhost:3306/test";

Connection conn;

conn = DriverManager.getConnection(url,"root","root");

創建執行SQL的語句(Statement)

 

執行語句

 

Statement是一個SQL執行器，可以用來執行一個靜態的SQL語句。

Statement st = conn.createStatement();

st.executeQuery(sql);

 

example：

Statement stmt = conn.createStatement(); //創建Statement對象
String sql= "select * from writers";
ResultSet rs = stmt.executeQuery(sql);

執行存儲過程

CallableStatement（從PreperedStatement擴展來）

cs = connection.prepareCall(“{call psname(?,?,?)}”);

cs.registerOutParameter(index, Types.INTEGER);

cs.setXXX(i, xxxx);

cs.executeUpdate();

int id=cs.getInt(index);

 

處理執行結果(ResultSet)

 

ResultSet表示一個查詢結果集。

ResultSet rs = statement.executeQuery(sql);

While(rs.next()){

 rs.getString(“col_name”);

 rs.getInt(“col_name”);

 //…

}

釋放資源

 

釋放資源的順序是ResultSet, Statement,Connection；

Connection在使用完成后，必須關閉，ResultSet, Statement無所謂，只要Connection關閉了，它們也會被自動關閉（但資源不是立即被釋放）。

Connection的使用原則是盡量晚創建，盡量早的釋放。

 

 

 

 

例子：

package com.jdbc;

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 connect {
    
      private Connection conn = null;
      private Statement stmt = null;
      private PreparedStatement preparedStatement = null;
      private ResultSet rs = null;
      
      
    public void readDataBase()  throws Exception{
        
        try{
            Class.forName("com.mysql.jdbc.Driver");
             System.out.println("成功加載MySQL驅動！");
        }catch(ClassNotFoundException e1){
            System.out.println("找不到MySQL驅動!");
            e1.printStackTrace();
        }

        String url="jdbc:mysql://localhost:3306/test";    //JDBC的URL    
       

        
        try {

             //調用DriverManager對象的getConnection()方法，獲得一個Connection對象
                conn = DriverManager.getConnection(url,"root","root");
                //創建一個Statement對象
                stmt = conn.createStatement(); //創建Statement對象
                System.out.println("成功連接到數據庫！");
                
                String sql= "select * from writers";
                rs = stmt.executeQuery(sql);
                writeMetaData(rs);
                writeResultSet(rs);
                
                String sql2= "insert into writers values(?,?)";
                preparedStatement=conn.prepareStatement(sql2);
                
                preparedStatement.setString(1, "11");
                preparedStatement.setString(2, "TestEmail");
                preparedStatement.executeUpdate();
                
                rs = stmt.executeQuery(sql);
                writeMetaData(rs);
                writeResultSet(rs);
                
                
        } catch (Exception e) {
              throw e;
        } 
    }
    
    private void writeMetaData(ResultSet rs)throws SQLException{
        System.out.println("The columns in the table are: ");
        
        System.out.println("Table: " + rs.getMetaData().getTableName(1));
        for  (int i = 1; i<= rs.getMetaData().getColumnCount(); i++){
          System.out.print( rs.getMetaData().getColumnName(i)+"\t");
        }
        System.out.println();
    }
    public void writeResultSet(ResultSet rs) throws SQLException{
        
        while(rs.next()){
            System.out.print(rs.getString(1)+"\t");
            System.out.print(rs.getString(2));
            System.out.println();
        }
        
    }
      private void close() {
            try {
              if (rs != null) {
                rs.close();
              }

              if (stmt != null) {
                stmt.close();
              }

              if (conn != null) {
                conn.close();
              }
            } catch (Exception e) {

            }
          }
}

 

main：

import com.jdbc.connect;
public class Main {

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        connect ms= new connect();
        ms.readDataBase();
    }

}