java删除impl代码 java中impl

java对所有mongodb表进行增删改查表名怎么设置

一、MongoDB数据库参数配置

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1、推荐使用mongodb.cfg.properties配置，则在构造MongoDBService对象的时候只需调用无参构造方法即可自动完成配置。

2、如果没有通过mongodb.cfg.properties，会采用程序指定的默认配置。

// 定义默认配置，1、IP地址 2、端口号 3、用户名 4、密码 5、配置文件位置名 6、数据库名    private static final String MONGODB_ADDRESS = "127.0.0.1";    private static final int MONGODB_PORT = 27017;    private static final String MONGODB_USERNAME = "root";    private static final String MONGODB_PASSWORD = "";    private static final String MONGODB_RESOURCE_FILE = "mongodb.cfg.properties";    private static final String MONGODB_DBNAME = "test";    private static final String MONGODB_COLLECTIONNAME = "test";

3、通过有参构造方法构造MongoDBService对象或通过get/set方法，指定数据库及集合，优先级最高。

//有参构造方法，指定数据库名与集合名    public MongoDBServiceImpl(String dbName, String collName) {        this.dbName = dbName;        this.collName = collName;        try {            db = getDb();        } catch (Throwable e) {            e.printStackTrace();        }    }    //无参构造方法，返回配置文件配置的数据库对象引用，如果配置文件中没有设置则返回默认数据库对象引用    public MongoDBServiceImpl() {        getDb();    }    /*     * 获取数据库对象，3种情况（优先级从高到低）：span style="white-space: pre" /span *1、构造方法指定2、配置文件指定3、默认数据库span style="white-space: pre" /span *（情况2、3在MongoDButil中设置）     */    public DB getDb() {        if (this.db == null) {            if (this.dbName == null) {                this.db = MongoDBUtil.getDB();            } else {                this.db = MongoDBUtil.getDBByName(this.dbName);            }        }        return this.db;    }         /*     * 获取集合对象，3种情况（优先级从高到低）：         *1、构造方法指定2、配置文件指定3、默认数据库     *（情况2、3在MongoDButil中设置）     */    public DBCollection getCollection() {        if(this.collName != null){            return db.getCollection(this.collName);        }        else {            return MongoDBUtil.getDBCollection();        }    }

二、方法简介（具体实现参看MongoDBServiceImpl接口实现类）

1、获取基本信息或对象:

(1)、获取数据库名： getDbName()

(2)、设置数据库名（指定数据库）： setDbName(String dbName)

(3)、获取集合名： getCollName()

(4)、设置集合名（指定集合）： setCollName(String collName)

(5)、获取数据库对象： getDb()

2、数据插入方式：

(1)、插入单条数据： insert(DBObject obj)

(2)、插入多条数据： insertBatch(List list)void

3、数据删除方式：

(1)、删除单条数据： delete(DBObject obj)

(2)、删除多条数据： deleteBatch(List list)

4、数量统计方式：

(1)、获取集合中数据数量： getCollectionCount()

(2)、获取符合条件的数据数量： getCount(DBObject obj)

5、查找数据：

(1)、查找所有数据： findAll()

(2)、查找符合条件的数据： find(DBObject obj)

(3)、查找符合条件的数据并排序： find(DBObject query, DBObject sort)

(4)、查找符合条件的指定数量的数据并排序：find(DBObject query, DBObject sort, int start, int limit)

(5)、由ID查找数据： getById(String id)

6、更新数据 ：update(DBObject setFields, DBObject whereFields) void

7、打印List： printListDBObj(List list)

测试代码：（@Test）

public class testMongoService {    //使用mongodb.cfg.properties中配置的数据库与集合，如未指定，使用MongoDBUtil中默认的数据库与集合    MongoDBService mongoDBService1 = new MongoDBServiceImpl();         //测试插入数据    @Test    public void testInsert(){        //数据一，包括用户名、密码，地址信息（省份、城市），爱好[…]        BasicDBList dbList1 = new BasicDBList();        dbList1.add("basketball");        dbList1.add("music");        dbList1.add("web");        DBObject dbObject1 = new BasicDBObject("username","insert1")            .append("age", 18)            .append("address", new BasicDBObject("province","广东").append("city", "广州"))            .append("favourite", dbList1);        //数据二        BasicDBList dbList2 = new BasicDBList();        dbList2.add("football");        dbList2.add("music");        DBObject dbObject2 = new BasicDBObject("username","insert2")            .append("age", 18)            .append("address", new BasicDBObject("province","陕西").append("city", "西安"))            .append("favourite", dbList2);        //数据三        BasicDBList dbList3 = new BasicDBList();        dbList3.add("Linux");        DBObject dbObject3 = new BasicDBObject("username","insert3")            .append("age", 18)            .append("address", new BasicDBObject("province","河北").append("city", "保定"))            .append("favourite", dbList3);        //数据四        BasicDBList dbList4 = new BasicDBList();        dbList4.add("swim");        dbList4.add("android");        DBObject dbObject4 = new BasicDBObject("username","insert4")            .append("age", 18)            .append("address", new BasicDBObject("province","四川").append("city", "成都"))            .append("favourite", dbList4);        //数据五        DBObject dbObject5 = new BasicDBObject("username", "insert5")            .append("age", 28)            .append("address", new BasicDBObject("city", "杭州"));        mongoDBService1.printListDBObj(mongoDBService1.findAll());        System.out.println("——————————————————insert collection——————————————————");        Listdbobject list = new ArrayListdbobject();        list.add(dbObject1);        list.add(dbObject2);        list.add(dbObject3);        list.add(dbObject5);        mongoDBService1.insertBatch(list);        System.out.println("——————————————————insert one——————————————————");        mongoDBService1.insert(dbObject4);        mongoDBService1.printListDBObj(mongoDBService1.findAll());    }         //测试查询数据    @Test    public void testFind(){        DBObject dbObject = new BasicDBObject("username","insert1");        System.out.println("数量：" + mongoDBService1.getCollectionCount());        System.out.println("username=java的数据数量：" + mongoDBService1.getCount(dbObject));        System.out.println("——————————————————find all——————————————————");        mongoDBService1.printListDBObj(mongoDBService1.findAll());        System.out.println("——————————————————find obj——————————————————");        mongoDBService1.printListDBObj(mongoDBService1.find(dbObject));        System.out.println("——————————————————find sort——————————————————");        mongoDBService1.printListDBObj(mongoDBService1.find(new BasicDBObject(), new BasicDBObject("age", 1)));        System.out.println("——————————————————find sort limit——————————————————");        mongoDBService1.printListDBObj(mongoDBService1.find(new BasicDBObject(), new BasicDBObject("age", 1), 1, 2));    }     //测试数据更新    @Test    public void testUpdate(){        BasicDBObject newDocument = new BasicDBObject("$set",new BasicDBObject("age",11));                         BasicDBObject searchQuery = new BasicDBObject().append("username", "insert2");             mongoDBService1.printListDBObj(mongoDBService1.find(searchQuery));        System.out.println("——————————————————update——————————————————");        mongoDBService1.update(newDocument, searchQuery);        mongoDBService1.printListDBObj(mongoDBService1.find(searchQuery));    }         //测试数据删除    @Test    public void testDelete(){        DBObject dbObject1 = new BasicDBObject("username", "insert1");        DBObject dbObject2 = new BasicDBObject("username", "insert2");        DBObject dbObject3 = new BasicDBObject("username", "insert3");        DBObject dbObject4 = new BasicDBObject("username", "insert4");        DBObject dbObject5 = new BasicDBObject("username", "insert5");        Listdbobject list = new ArrayListdbobject();        list.add(dbObject1);        list.add(dbObject2);        list.add(dbObject3);        list.add(dbObject4);        mongoDBService1.printListDBObj(mongoDBService1.findAll());        System.out.println("——————————————————delete list——————————————————");        mongoDBService1.deleteBatch(list);        System.out.println("——————————————————delete one——————————————————");        mongoDBService1.delete(dbObject5);        //System.out.println("——————————————————delete all——————————————————");        //mongoDBService1.delete(new BasicDBObject());        mongoDBService1.printListDBObj(mongoDBService1.findAll());    }}/dbobject/dbobject/dbobject/dbobject

测试结果：

源代码：（完整项目文件下载链接：点击打开链接）

MongoDBServiceImpl.java

public class MongoDBServiceImpl implements MongoDBService {    private String dbName;    private String collName;    private DB db;         //有参构造方法，指定数据库名与集合名    public MongoDBServiceImpl(String dbName, String collName) {        this.dbName = dbName;        this.collName = collName;        try {            db = getDb();        } catch (Throwable e) {            e.printStackTrace();        }    }    //无参构造方法，返回配置文件配置的数据库对象引用，如果配置文件中没有设置则返回默认数据库对象引用    public MongoDBServiceImpl() {        getDb();    }    /*     * 获取数据库对象，3种情况（优先级从高到低）：     *1、构造方法指定2、配置文件指定3、默认数据库     *（情况2、3在MongoDButil中设置）     */    public DB getDb() {        if (this.db == null) {            if (this.dbName == null) {                this.db = MongoDBUtil.getDB();            } else {                this.db = MongoDBUtil.getDBByName(this.dbName);            }        }        return this.db;    }         /*     * 获取集合对象，3种情况（优先级从高到低）：     *1、构造方法指定2、配置文件指定3、默认数据库     *（情况2、3在MongoDButil中设置）     */    public DBCollection getCollection() {        if(this.collName != null){            return db.getCollection(this.collName);        }        else {            return MongoDBUtil.getDBCollection();        }    }     public DBObject map2Obj(Mapstring, object="" map) {        DBObject obj = new BasicDBObject();        if (map.containsKey("class") map.get("class") instanceof Class)            map.remove("class");        obj.putAll(map);        return obj;    }    //插入数据    public void insert(DBObject obj) {        getCollection().insert(obj);    }    //插入多条数据    public void insertBatch(Listdbobject list) {        if (list == null || list.isEmpty()) {            return;        }        Listdbobject listDB = new ArrayListdbobject();        for (int i = 0; i list.size(); i++) {            listDB.add(list.get(i));        }        getCollection().insert(listDB);    }    //删除数据    public void delete(DBObject obj) {        getCollection().remove(obj);    }    //删除多条数据    public void deleteBatch(Listdbobject list) {        if (list == null || list.isEmpty()) {            return;        }        for (int i = 0; i list.size(); i++) {            getCollection().remove(list.get(i));        }    }    //获取集合中的数据数量    public long getCollectionCount() {        return getCollection().getCount();    }    //查找符合条件的数据数量    public long getCount(DBObject obj) {        if (obj != null)            return getCollection().getCount(obj);        return getCollectionCount();    }    //查找符合条件的数据    public Listdbobject find(DBObject obj) {        DBCursor cur = getCollection().find(obj);        return DBCursor2list(cur);    }         //查找符合条件的数据并排序    @Override    public Listdbobject find(DBObject query, DBObject sort) {        DBCursor cur;        if (query != null) {            cur = getCollection().find(query);        } else {            cur = getCollection().find();        }        if (sort != null) {            cur.sort(sort);        }        return DBCursor2list(cur);    }     //查找符合条件的数据并排序，规定数据个数    @Override    public Listdbobject find(DBObject query, DBObject sort, int start,            int limit) {        DBCursor cur;        if (query != null) {            cur = getCollection().find(query);        } else {            cur = getCollection().find();        }        if (sort != null) {            cur.sort(sort);        }        if (start == 0) {            cur.batchSize(limit);        } else {            cur.skip(start).limit(limit);        }        return DBCursor2list(cur);    }         //将DBCursor转化为listdbobject    private Listdbobject DBCursor2list(DBCursor cur) {        Listdbobject list = new ArrayListdbobject();        if (cur != null) {            list = cur.toArray();        }        return list;    }     //更新数据    public void update(DBObject setFields, DBObject whereFields) {        getCollection().updateMulti(whereFields, setFields);    }    //查询集合中所有数据    public Listdbobject findAll() {        DBCursor cur = getCollection().find();        Listdbobject list = new ArrayListdbobject();        if (cur != null) {            list = cur.toArray();        }        return list;    }     //由ID获取数据    public DBObject getById(String id) {        DBObject obj = new BasicDBObject();        obj.put("_id", new ObjectId(id));        DBObject result = getCollection().findOne(obj);        return result;    }     public String getDbName() {        return dbName;    }     public void setDbName(String dbName) {        this.dbName = dbName;        this.db = MongoDBUtil.getDBByName(this.dbName);    }     public String getCollName() {        return collName;    }     public void setCollName(String collName) {        this.collName = collName;    }    @Override    public void printListDBObj(Listdbobject list) {        // TODO Auto-generated method stub        for(DBObject dbObject: list){            System.out.println(dbObject);        }    }       }/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/dbobject/string,

MongoDBUtil.java

public class MongoDBUtil {    // 定义默认配置，1、IP地址 2、端口号 3、用户名 4、密码 5、配置文件位置名 6、数据库名    private static final String MONGODB_ADDRESS = "127.0.0.1";    private static final int MONGODB_PORT = 27017;    private static final String MONGODB_USERNAME = "root";    private static final String MONGODB_PASSWORD = "";    private static final String MONGODB_RESOURCE_FILE = "mongodb.cfg.properties";    private static final String MONGODB_DBNAME = "test";    private static final String MONGODB_COLLECTIONNAME = "test";    // 定义静态变量，1、Mongo对象（代表数据库连接）2、DB对象（代表数据库）3、集合名4、数据库相关配置映射集合5、已获取的数据库连接    private static Mongo mongo;    private static DB db;    private static DBCollection collection;    private static Mapstring, string="" cfgMap = new HashMapstring, string=""();    private static Hashtablestring, db="" mongoDBs = new Hashtablestring, db=""();     /**     * 初始化Mongo的数据库     */    static {        init();    }     /**     * 获取配置文件中配置的DB对象     */    public static DB getDB() {        return db;    }     /**     * 获取配置文件中配置的DBCollection对象     */    public static DBCollection getDBCollection() {        return collection;    }     /**     * 根据数据库名称,得到数据库 如果不存在,则创建一个该名称的数据库,并设置用户名和密码为配置文件中的参数值     *     * @param dbName     * @return DB     */    @SuppressWarnings("deprecation")    public static DB getDBByName(String dbName) {        DB db = mongo.getDB(dbName);        if (!mongoDBs.contains(db)) {            System.out.println("add");            db.addUser(cfgMap.get("mongo.db.username"),                    cfgMap.get("mongo.db.password").toCharArray());            mongoDBs.put(dbName, db);        }        return db;    }     // ————————————————————————————————————初始化过程————————————————————————————————————    /**     * 获取配置文件mongedb.cfg.properties的文件对象     */    public static File getConfigFile() {        String path = MongoDBUtil.class.getResource("/").getPath();        String fileName = path + MONGODB_RESOURCE_FILE;        System.out.println(fileName);        File file = new File(fileName);        if (file.exists()) {            return file;        }        return null;    }     /**     * 通过mongedb.cfg.properties配置文件初始化配置映射集合，如果没有编写配置文件，则加载程序指定的默认配置     */    @SuppressWarnings("unchecked")    private static void initCfgMap() {        File file = getConfigFile();        if (file != null) {            Properties p = new Properties();            try {                p.load(new FileInputStream(file));                for (Enumeration enu = p.propertyNames(); enu.hasMoreElements();) {                    String key = (String) enu.nextElement();                    String value = (String) p.getProperty(key);                    cfgMap.put(key, value);                }            } catch (IOException e) {                System.out.println("加载Mongo配置文件失败!");                e.printStackTrace();            }        } else { // 如果没有编写配置文件，则加载默认配置            cfgMap.put("mongo.db.address", MONGODB_ADDRESS);            cfgMap.put("mongo.db.port", String.valueOf(MONGODB_PORT));            cfgMap.put("mongo.db.username", MONGODB_USERNAME);            cfgMap.put("mongo.db.password", MONGODB_PASSWORD);            cfgMap.put("mongo.db.dbname", MONGODB_DBNAME);            cfgMap.put("mongo.db.collectionname", MONGODB_COLLECTIONNAME);        }    }     /**     * 初始化Mongo的数据库（将db指向相应对象引用，将collection指向相应对象引用，通过mongoDBs记录现有数据库对象）     */    @SuppressWarnings("deprecation")    private static void init() {        initCfgMap();        try {            String address = cfgMap.get("mongo.db.address");            int port = Integer.parseInt(cfgMap.get("mongo.db.port").toString());            String dbName = cfgMap.get("mongo.db.dbname");            String username = cfgMap.get("mongo.db.username");            String password = cfgMap.get("mongo.db.password");            String collectionName = cfgMap.get("mongo.db.collectionname");            mongo = new Mongo(address, port);            if (dbName != null !"".equals(dbName)) {                db = mongo.getDB(dbName);                if (username != null !"".equals(username)) {                    db.addUser(username, password.toCharArray());                    if (collectionName != null !"".equals(collectionName)) {                        collection = db.getCollection(collectionName);                    }                }                mongoDBs.put(dbName, db);            }        } catch (Exception e) {            e.printStackTrace();        }    } }

关于java 连接数据库实现增删改查的具体功能代码。

首先你得确定你的数据库连接是通过什么形式连接的，hibernate还是原生态的jdbc 还是spring；

如果是只有hibernate，那么你得通过加载配置文件得到sessionFactory,然后得到session

如果spring，那么同样也需要注入sessionfactory到你的dao

如果是jdbc方式，那么你就按照原生态jdbc写法

总之，在你构造DAO时，得有数据源。这样才能操纵你的数据库

如果搞懂了这些问题，那么你的第一个，第三个问题就迎刃而解了。至于第二问题，我没明白你什么意思！

处理删除操作时出现 Unknown entity: java.lang.Integer

看一下--------SubjectAction

public String deleteSubject(){

isubjectbiz.deleteSubject(subjectId);

return SUCCESS;

}

subjectId 是否是用struts2 自动从页面封装过来的 还是你使用request获取的 首先你输出一下有没有值 然后如果是request获取的 必须要把它转换成integer 其次如果有值 且为integer 这时你就要检查你的数据库隐射文件是否正确 一级一级排除

JAVA 实现数据库增删改查的Dao和DaoImpl的写法

package org.dao;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.sql.SQLException;

import java.util.Date;

import org.dbc.DBManageer;

import org.dbc.DBUtil;

import org.vo.CardInfo;

public class CardInfoDao {

public void testResultSetMetaData() {

String sql = "select * from cardinfo";

Connection con = new DBUtil().getConnection();

PreparedStatement ps = null;

ResultSetMetaData rsmd = null;

ResultSet rs = null;

try {

ps = con.prepareStatement(sql);

rs = ps.executeQuery();

rsmd = rs.getMetaData();

for (int i = 1; i rsmd.getColumnCount(); i++) {

System.out.print(" 数据类型名:" + rsmd.getColumnClassName(i));

System.out.print(" 别名:" + rsmd.getColumnLabel(i));

System.out.print(" 列名:" + rsmd.getColumnName(i));

System.out.print(" 数据类型:" + rsmd.getColumnTypeName(i));

System.out.println(" 数据类型:" + rsmd.getColumnType(i));

}

while (rs.next()) {

// 通过反射可以对VO对象(CardInfo)自动赋值

// for(...)

// CardInfo ci=new CardInfo();

// ci.setId(rs.getInt(columnIndex))

/*

* CardInfo ca = new CardInfo(); Class cc = ca.getClass();

*/

/*Class? c = Class.forName("org.vo.CardInfo");

CardInfo ca = (CardInfo) c.newInstance();

ca.setCardId(rs.getString("cardId"));

ca.setCustomerName(rs.getString("customerName"));

ca.setCurrentMoney(rs.getFloat("currentMoney"));

ca.setOpenDate(rs.getDate("openDate"));

System.out.println(ca);//ok */

//加载一个CardInfo类

Class c = Class.forName("org.vo.CardInfo");

Object o = c.newInstance(); //获得它的一个实例

//定义String类的对象数组

Class[] params = new Class[] { String.class};

//定义float类的对象数组

Class[] floatparams = new Class[] { float.class};

//定义Date(util)类的对象数组

Class[] dateparams = new Class[] { Date.class};

//获得setCardId方法

Method me = c.getMethod("setCardId", params);

//实例方法的参数

Object []ostr = new Object[]{rs.getString("cardId")};

//如果底层方法是静态的，那么可以忽略指定的 obj 参数。该参数可以为 null。

//如果底层方法所需的形参数为 0，则所提供的 args 数组长度可以为 0 或 null。

//o 调用方法的对象 ostr 方法调用的参数

me.invoke(o, ostr);

//获得setCustomerName方法

Method name = c.getMethod("setCustomerName", params);

Object []cusname = new Object[]{rs.getString("customerName")};

name.invoke(o,cusname);

//获得setCurrentMoney方法

Method money = c.getMethod("setCurrentMoney", floatparams);

Object []cusmoney = new Object[]{rs.getFloat("currentMoney")};

money.invoke(o,cusmoney);

//获得setOpenDate方法

Method date = c.getMethod("setOpenDate",dateparams);

Object []openDate = new Object[]{rs.getDate("openDate")};

date.invoke(o, openDate);

//打印

System.out.println(o);

}

} catch (SQLException e) {

e.printStackTrace();

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (InstantiationException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (SecurityException e) {

e.printStackTrace();

}catch (IllegalArgumentException e) {

e.printStackTrace();

} catch (NoSuchMethodException e) {

e.printStackTrace();

} catch (InvocationTargetException e) {

e.printStackTrace();

}

}

public void showResultSet() {

String sql = "select * from cardinfo";

Connection con = new DBManageer().getConnection();

PreparedStatement ps = null;

try {

ps = con.prepareStatement(sql, ResultSet.TYPE_SCROLL_SENSITIVE,

ResultSet.CONCUR_UPDATABLE);

ResultSet rs = ps.executeQuery();

System.out.println("---依次读取------");

while (rs.next()) {

CardInfo ca = new CardInfo();

ca.setCardId(rs.getString("cardId"));

ca.setCustomerName(rs.getString("customerName"));

ca.setCurrentMoney(rs.getFloat("currentMoney"));

ca.setOpenDate(rs.getDate("openDate"));

System.out.println(ca);

}

System.out.println("---倒读------");

while (rs.previous()) {

CardInfo ca = new CardInfo();

ca.setCardId(rs.getString("cardId"));

ca.setCustomerName(rs.getString("customerName"));

ca.setCurrentMoney(rs.getFloat("currentMoney"));

ca.setOpenDate(rs.getDate("openDate"));

System.out.println(ca);

}

rs.absolute(3);// 定位倒第几行

rs.updateString("customerName", "star");

// rs.updateRow();

rs.beforeFirst();

while (rs.next()) {

CardInfo ca = new CardInfo();

ca.setCardId(rs.getString("cardId"));

ca.setCustomerName(rs.getString("customerName"));

ca.setCurrentMoney(rs.getFloat("currentMoney"));

ca.setOpenDate(rs.getDate("openDate"));

System.out.println(ca);

}

} catch (SQLException e) {

e.printStackTrace();

}

}

}

java如何实现对数据表里面的数据删除(最好给个具体代码范例)

连接数据库

public class DBManager {

//定义数据库连接的URL

private static final String URL="jdbc:sqlserver://localhost:1433;database=j1105";

//定义数据库的用户名

private static final String USERNAME = "sa";

//定义数据库密码

private static final String PASSWORD = "sa";

//定义一个连接的引用,使用单例模式

private static Connection conn = null;

//使用静态块来注册驱动

//类加载时自动执行代码块

static {

//反射com.microsoft.sqlserver.jdbc.SQLServerDriver.class

try {

Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");

} catch (ClassNotFoundException e) {

e.printStackTrace();

}

}

//获得连接

//在程序使用过程中始终只有1个对象存在

//使用单例模式来给Connection赋值

public static Connection getConnection(){

if(conn == null){

try {

conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);

} catch (SQLException e) {

e.printStackTrace();

}

}

return conn;

}

/**

* 关闭的一些操作 , 优化

* @param conn

* @param stat

* @param rs

*/

public static void close(Connection conn,Statement stat,ResultSet rs){

try{

if(conn != null){

conn.close();

}

if(stat != null){

stat.close();

}

if(rs != null){

rs.close();

}

}catch(SQLException e){

e.printStackTrace();

}

}

/**

* 重写上面的方法,在只有2个参数的情况下关闭

* @param conn

* @param stat

*/

public static void close(Connection conn,Statement stat){

try{

if(conn != null){

conn.close();

}

if(stat != null){

stat.close();

}

}catch(SQLException e){

e.printStackTrace();

}

}

public static void main(String[] args){

Connection conn = DBManager .getConnection();

System.out.println(conn);

}

}

接口

public interface IStudentDao {

public void deleteStudent(int xh);

}

实现

public class StudentDAOimpl implements IStudentDao {

public void deleteStudent(int xh) {

try{

String sql = "delete from tb_student where xh = ?";

PreparedStatement ps = conn.prepareStatement(sql);

ps.setInt(1, xh);

ps.executeUpdate();

System.out.println("成功删除");

}catch(SQLException e){

e.printStackTrace();

}

}

}