下面来介绍一下如何通过Java，来连接数据库，并对数据库进行crud操作。
在连接数据库之前，首先我们必须要有一个jar包
，该包，通过bulid path,将jar包导入进去。打开SQLyog，创建一个数据库，并向里面添加表student ,并且属性值，这是我建立的表；

在eclipse中，创建一个web项目，并在里面创建一个包，添加一个search 的类，该类封装了获取数据库的连接还有增删改查的方法，以后便于我们直接调用，
首先是的代码：
public class search {
private Connection con ;
private PreparedStatement ps;
private static String url = “jdbc:mysql://localhost:3306/graduation?useUnicode=true&characterEncoding=utf-8”; //graduation是你的要连接的数据库
private static String root = “root”;//数据库的用户名
private static String password = “root”;//数据库的密码，根据一开始你设置的密码

///连接数据库的方法
public Connection getConnection(){
try {
if(con==null){
Class.forName(“com.mysql.jdbc.Driver”);//通过反射连接数据库
con= DriverManager.getConnection(url,root,password);
}
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return con;
}
////增删改,在=增删改中，返回num是影响的行数，所以返回的类型是int类型
public int Line(String sql,Object[] obj) {
int num =-1;
try {
num = -1;
con = getConnection();
ps = con.prepareStatement(sql);
//替换占位符
if(obj!=null&&obj.length>0){
for (int i = 0; i < obj.length; i++) {
ps.setObject((i+1), obj[i]);
}
}
num = ps.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
//close(con,ps,null);
}
return num;
}
//查找，在查找的时候，返回的是一个ResultSet的结果集合

public ResultSet update(String sql,Object[] objs) throws SQLException{ResultSet rs =null;con = getConnection();ps = con.prepareStatement(sql);if(objs!=null&&objs.length>0){for (int i = 0; i < objs.length; i++) {ps.setObject(i+1, objs[i]);}}rs = ps.executeQuery();return rs;
}}

在创建一个接口，UserDao
public interface UserDao {

List<entity> selectBy();  //查询
int updateEntity(entity e);  //修改
int InsertInto(entity e);//增加
int DeleteInto(int i); //删除
List<entity> LimitSearch(Integer i,Integer j);//分页查询
List<entity> LikeSearch(String str); //模糊查询

}

之后创建一个类，继承search类，实现UserDao接口
public class UserDaoimpl extends search implements UserDao {

//查询
public List<entity> selectBy() {List<entity> list = new ArrayList<entity>();String sql = "select * from pet";try {ResultSet rs = super.update(sql, null);while(rs.next()){entity u = new entity();u.setId(rs.getInt("id"));u.setName(rs.getString("name"));u.setHealth(rs.getInt("health"));u.setLove(rs.getInt("love"));u.setStrain(rs.getString("strain"));list.add(u);}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return list;
}//修改
public int updateEntity(entity e) {// TODO Auto-generated method stubString sql = "update pet set name=?,health=?,love=?,strain = ?where id =?";Object[] objs = {e.getName(),e.getHealth(),e.getLove(),e.getStrain(),e.getId()};int num=super.Line(sql,objs);return num;
}
//增加
public int InsertInto(entity e) {int  num=0;String sql = "insert into pet(id,name,health,love,strain) values(?,?,?,?,?)";Object[] obj = {e.getId(),e.getName(),e.getHealth(),e.getLove(),e.getStrain()};num = super.Line(sql,obj);return num;
}//删除
public int DeleteInto(int i) {String sql = "delete from pet where id=?";Object[] obj = {i};int num = super.Line(sql, obj);return num;
}///分页查询
public List<entity> LimitSearch(Integer i,Integer j) {List<entity> list = new ArrayList<entity>();try{String sql = "select * from pet limit ?,?";Object[] obj = {(i-1)*j,j};ResultSet rs = super.update(sql, obj);;while(rs.next()){entity u = new entity();u.setId(rs.getInt("id"));u.setName(rs.getString("name"));u.setHealth(rs.getInt("health"));u.setLove(rs.getInt("love"));u.setStrain(rs.getString("strain"));list.add(u);}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return list;
}//模糊查询
public List<entity> LikeSearch(String str) {List<entity> list = new ArrayList<entity>();try{String sql = "select * from pet where name like ?";Object[] obj = {str};ResultSet rs = super.update(sql, obj);while(rs.next()){entity u = new entity();u.setId(rs.getInt("id"));u.setName(rs.getString("name"));u.setHealth(rs.getInt("health"));u.setLove(rs.getInt("love"));u.setStrain(rs.getString("strain"));list.add(u);}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return list;
}

在创建一个entity类，用来获取数据库的属性，这里属性要和刚才创建表的属性要一样
public class entity implements Serializable{

private int id;
private String name;
private int health;
private int love;
private String strain;
public int getId() {return id;
}
public void setId(int id) {this.id = id;
}
public String getName() {return name;
}
public void setName(String name) {this.name = name;
}
public int getHealth() {return health;
}
public void setHealth(int health) {this.health = health;
}
public int getLove() {return love;
}
public void setLove(int love) {this.love = love;
}
public String getStrain() {return strain;
}
public void setStrain(String strain) {this.strain = strain;
}public String toString() {return "entity [id=" + id + ", name=" + name + ", health=" + health+ ", love=" + love + ", strain=" + strain + "]";
}
public entity(int id, String name, int health, int love, String strain) {super();this.id = id;this.name = name;this.health = health;this.love = love;this.strain = strain;
}
public entity() {super();
}

}

之后建立一个测试类Text类

public static void main(String[] args) {
UserDao userdao = new UserDaoimpl();
// List userList = userdao.selectBy();
// System.out.println(userList);
//entity e = new entity();
// e.setId(1); //这里的id由于是主键，所以下面的id是不能重复的
// e.setName(“小白”);
// e.setHealth(100);
// e.setLove(60);
// e.setStrain(“狗”);
// userdao.InsertInto(e);
// entity e2 = new entity();
// e2.setId(2);
// e2.setName(“小黄”);
// e2.setHealth(120);
// e2.setLove(70);
// e2.setStrain(“猫”);
// userdao.InsertInto(e2);
entity e6 = new entity();
e6.setId(6);
e6.setName(“花泽类”);
e6.setHealth(100);
e6.setLove(100);
e6.setStrain(“虫子”);
userdao.InsertInto(e6);//添加数据到数据库中
//userdao.DeleteInto(2); //根据id = 2删除语句
//下面两条语句是模糊查询
entity e = new entity();
List userList = userdao.LikeSearch(“花%”);
//
System.out.println(userList);
}

}

这以上就是如何通过java连接数据库，并对数据库进行操作