JDBC常见操作

JDBC介绍

JDBC是一种用于执行SQL语句的Java API，可以为多种关系数据库提供统一访问，JDBC对Java程序员而言是API，对与实现数据库连接服务的提供商而言是接口模型。

添加依赖

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.34</version>
</dependency>

普通查找(未关连接)

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Test {
    public static final String URL = "jdbc:mysql://localhost:3306/test";
    public static final String USER = "root";
    public static final String PASSWORD = "123456";
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection(URL, USER, PASSWORD);
        Statement stmt = conn.createStatement();
        // 查找数据库
        ResultSet rs = stmt.executeQuery("SELECT * FROM user");
        while (rs.next()) {
            System.out.println("姓名: " + rs.getString("name")+"，年龄:"+rs.getInt("age"));
        }
    }
}

普通删除(未关连接)

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class Test {
    public static final String URL = "jdbc:mysql://localhost:3306/test";
    public static final String USER = "root";
    public static final String PASSWORD = "123456";
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection(URL, USER, PASSWORD);
        Statement stmt = conn.createStatement();
        // 增，删，改方法，返回影响的行数
        int rs = stmt.executeUpdate("DELETE FROM user WHERE name='fei'");
        if (rs > 0) {
            System.out.println("更新成功！");
        } else {
            System.out.println("更新失败！");
        }
    }
}

预编译查找

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
public class Test {
    public static final String URL = "jdbc:mysql://localhost:3306/test";
    public static final String USER = "root";
    public static final String PASSWORD = "123456";
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement prestate = null;
        ResultSet rs = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USER, PASSWORD);
            // 预编译执行对象
            prestate = conn.prepareStatement("SELECT * FROM user WHERE name=? AND age=?");
            prestate.setString(1, "fei");
            prestate.setInt(2, 22);
            rs = prestate.executeQuery();
            while (rs.next()) {
                System.out.println("姓名: " + rs.getString("name") + "，年龄:" + rs.getInt("age"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 关闭连接
            close(conn, prestate, rs);
        }
    }
    private static void close(Connection con, Statement sta, ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        try {
            if (sta != null) {                
                sta.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        try {
            if (con != null) {
                con.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}