package com.tly.dbutil;import java.io.IOException;import java.util.Properties;public class Config {  private static Properties prop = new Properties();    static{        try {      //加載dbconfig.properties配置文件      prop.load(Config.class.getResourceAsStream("dbconfig.properties"));    } catch (IOException e) {      // TODO Auto-generated catch block      e.printStackTrace();    }  }    //設(shè)置常量  public static final String CLASS_NAME = prop.getProperty("CLASS_NAME");  public static final String DATABASE_URL = prop.getProperty("DATABASE_URL");  public static final String SERVER_IP = prop.getProperty("SERVER_IP");  public static final String SERVER_PORT = prop.getProperty("SERVER_PORT");  public static final String DATABASE_SID = prop.getProperty("DATABASE_SID");  public static final String USERNAME = prop.getProperty("USERNAME");  public static final String PASSWORD = prop.getProperty("PASSWORD");  }

CLASS_NAME=com.mysql.jdbc.DriverDATABASE_URL=jdbc:mysqlSERVER_IP=localhostSERVER_PORT=3306DATABASE_SID=employeesUSERNAME=rootPASSWORD=1

package com.employees.dbutil;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;public class DBConn {  //三屬性、四方法    //三大核心接口  private Connection conn = null;  private PreparedStatement pstmt = null;  private ResultSet rs = null;    //四個(gè)方法  //method1: 創(chuàng)建數(shù)據(jù)庫的連接  public Connection getConntion(){        try {      //1: 加載連接驅(qū)動(dòng)，Java反射原理      Class.forName(Config.CLASS_NAME);      //2:創(chuàng)建Connection接口對(duì)象，用于獲取MySQL數(shù)據(jù)庫的連接對(duì)象。三個(gè)參數(shù)：url連接字符串  賬號(hào) 密碼      String url = Config.DATABASE_URL+"://"+Config.SERVER_IP+":"+Config.SERVER_PORT+"/"+Config.DATABASE_SID;      conn = DriverManager.getConnection(url,Config.USERNAME,Config.PASSWORD);    } catch (ClassNotFoundException e) {      e.printStackTrace();    } catch (SQLException e) {      e.printStackTrace();    }      return conn;  }      //method2：關(guān)閉數(shù)據(jù)庫的方法  public void closeConn(){    if(rs!=null){      try {        rs.close();      } catch (SQLException e) {        e.printStackTrace();      }    }    if(pstmt!=null){      try {        pstmt.close();      } catch (SQLException e) {        e.printStackTrace();      }    }    if(conn!=null){      try {        conn.close();      } catch (SQLException e) {        e.printStackTrace();      }    }  }    //method3: 專門用于發(fā)送增刪改語句的方法  public int execOther(PreparedStatement pstmt){    try {      //1、使用Statement對(duì)象發(fā)送SQL語句      int affectedRows = pstmt.executeUpdate();      //2、返回結(jié)果      return affectedRows;    } catch (SQLException e) {      e.printStackTrace();      return -1;    }  }  //method4: 專門用于發(fā)送查詢語句  public ResultSet execQuery(PreparedStatement pstmt){    try {      //1、使用Statement對(duì)象發(fā)送SQL語句      rs = pstmt.executeQuery();      //2、返回結(jié)果      return rs;    } catch (SQLException e) {      e.printStackTrace();      return null;    }  }}

package com.employees.dao;import java.io.InputStream;import java.lang.reflect.Method;import java.lang.reflect.ParameterizedType;import java.sql.Connection;import java.sql.Date;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import com.employees.dbutil.DBConn;public class BaseDAO<T> {    DBConn conn = new DBConn();  private Connection connection = null;    @SuppressWarnings("unused")  private Class<T> persistentClass;    @SuppressWarnings("unchecked")  public BaseDAO() {    initConnection();    //獲得參數(shù)化類型        ParameterizedType type = (ParameterizedType)getClass().getGenericSuperclass();    persistentClass = (Class<T>)type.getActualTypeArguments()[0];  }      /**   * 獲得數(shù)據(jù)庫連接   */  public void initConnection() {    connection = conn.getConntion();        }      /**   * 保存   */  public void save(T entity) throws Exception{    //SQL語句,insert into table name (    String sql = "insert into " + entity.getClass().getSimpleName().toLowerCase() + "(";        //獲得帶有字符串get的所有方法的對(duì)象    List<Method> list = this.matchPojoMethods(entity,"get");        Iterator<Method> iter = list.iterator();        //拼接字段順序 insert into table name(id,name,email,    while(iter.hasNext()) {      Method method = iter.next();      sql += method.getName().substring(3).toLowerCase() + ",";    }        //去掉最后一個(gè),符號(hào)insert insert into table name(id,name,email) values(    sql = sql.substring(0, sql.lastIndexOf(",")) + ") values(";        //拼裝預(yù)編譯SQL語句insert insert into table name(id,name,email) values(?,?,?,    for(int j = 0; j < list.size(); j++) {      sql += "?,";    }    //去掉SQL語句最后一個(gè),符號(hào)insert insert into table name(id,name,email) values(?,?,?);    sql = sql.substring(0, sql.lastIndexOf(",")) + ")";        //到此SQL語句拼接完成,打印SQL語句    System.out.println(sql);        //獲得預(yù)編譯對(duì)象的引用    PreparedStatement statement = connection.prepareStatement(sql);        int i = 0;    //把指向迭代器最后一行的指針移到第一行.    iter = list.iterator();    while(iter.hasNext()) {      Method method = iter.next();      //此初判斷返回值的類型,因?yàn)榇嫒霐?shù)據(jù)庫時(shí)有的字段值格式需要改變,比如String,SQL語句是'"+abc+"'      if(method.getReturnType().getSimpleName().indexOf("String") != -1) {        statement.setString(++i, this.getString(method, entity));      } else if(method.getReturnType().getSimpleName().indexOf("Date") != -1){        statement.setDate(++i, this.getDate(method, entity));      } else if(method.getReturnType().getSimpleName().indexOf("InputStream") != -1) {        statement.setAsciiStream(++i, this.getBlob(method, entity),1440);      } else {        statement.setInt(++i, this.getInt(method, entity));      }    }    //執(zhí)行    conn.execOther(statement);    //關(guān)閉連接    conn.closeConn();  }      /**   * 修改   */  public void update(T entity) throws Exception{    String sql = "update " + entity.getClass().getSimpleName().toLowerCase() + " set ";        //獲得該類所有g(shù)et方法對(duì)象集合    List<Method> list = this.matchPojoMethods(entity,"get");        //臨時(shí)Method對(duì)象,負(fù)責(zé)迭代時(shí)裝method對(duì)象.    Method tempMethod = null;        //由于修改時(shí)不需要修改ID,所以按順序加參數(shù)則應(yīng)該把Id移到最后.    Method idMethod = null;    Iterator<Method> iter = list.iterator();    while(iter.hasNext()) {      tempMethod = iter.next();      //如果方法名中帶有ID字符串并且長(zhǎng)度為2,則視為ID.      if(tempMethod.getName().lastIndexOf("Id") != -1 && tempMethod.getName().substring(3).length() == 2) {        //把ID字段的對(duì)象存放到一個(gè)變量中,然后在集合中刪掉.        idMethod = tempMethod;        iter.remove();      //如果方法名去掉set/get字符串以后與pojo + "id"想符合(大小寫不敏感),則視為ID      } else if((entity.getClass().getSimpleName() + "Id").equalsIgnoreCase(tempMethod.getName().substring(3))) {        idMethod = tempMethod;        iter.remove();              }    }        //把迭代指針移到第一位    iter = list.iterator();    while(iter.hasNext()) {      tempMethod = iter.next();      sql += tempMethod.getName().substring(3).toLowerCase() + "= ?,";    }        //去掉最后一個(gè),符號(hào)    sql = sql.substring(0,sql.lastIndexOf(","));        //添加條件    sql += " where " + idMethod.getName().substring(3).toLowerCase() + " = ?";        //SQL拼接完成,打印SQL語句    System.out.println(sql);        PreparedStatement statement = this.connection.prepareStatement(sql);        int i = 0;    iter = list.iterator();    while(iter.hasNext()) {      Method method = iter.next();      //此初判斷返回值的類型,因?yàn)榇嫒霐?shù)據(jù)庫時(shí)有的字段值格式需要改變,比如String,SQL語句是'"+abc+"'      if(method.getReturnType().getSimpleName().indexOf("String") != -1) {        statement.setString(++i, this.getString(method, entity));      } else if(method.getReturnType().getSimpleName().indexOf("Date") != -1){        statement.setDate(++i, this.getDate(method, entity));      } else if(method.getReturnType().getSimpleName().indexOf("InputStream") != -1) {        statement.setAsciiStream(++i, this.getBlob(method, entity),1440);      } else {        statement.setInt(++i, this.getInt(method, entity));      }          }        //為Id字段添加值    if(idMethod.getReturnType().getSimpleName().indexOf("String") != -1) {      statement.setString(++i, this.getString(idMethod, entity));    } else {      statement.setInt(++i, this.getInt(idMethod, entity));    }        //執(zhí)行SQL語句    statement.executeUpdate();                //關(guān)閉預(yù)編譯對(duì)象        statement.close();                //關(guān)閉連接        connection.close();  }      /**   * 刪除   */  public void delete(T entity) throws Exception{    String sql = "delete from " + entity.getClass().getSimpleName().toLowerCase() + " where ";        //存放字符串為"id"的字段對(duì)象    Method idMethod = null;        //取得字符串為"id"的字段對(duì)象    List<Method> list = this.matchPojoMethods(entity, "get");    Iterator<Method> iter = list.iterator();    while(iter.hasNext()) {      Method tempMethod = iter.next();      //如果方法名中帶有ID字符串并且長(zhǎng)度為2,則視為ID.      if(tempMethod.getName().lastIndexOf("Id") != -1 && tempMethod.getName().substring(3).length() == 2) {        //把ID字段的對(duì)象存放到一個(gè)變量中,然后在集合中刪掉.        idMethod = tempMethod;        iter.remove();      //如果方法名去掉set/get字符串以后與pojo + "id"想符合(大小寫不敏感),則視為ID      } else if((entity.getClass().getSimpleName() + "Id").equalsIgnoreCase(tempMethod.getName().substring(3))) {        idMethod = tempMethod;        iter.remove();              }    }        sql += idMethod.getName().substring(3).toLowerCase() + " = ?";        PreparedStatement statement = this.connection.prepareStatement(sql);        //為Id字段添加值    int i = 0;    if(idMethod.getReturnType().getSimpleName().indexOf("String") != -1) {      statement.setString(++i, this.getString(idMethod, entity));    } else {      statement.setInt(++i, this.getInt(idMethod, entity));    }            //執(zhí)行    conn.execOther(statement);    //關(guān)閉連接    conn.closeConn();  }      /**   * 通過ID查詢   */  public T findById(Object object) throws Exception{    String sql = "select * from " + persistentClass.getSimpleName().toLowerCase() + " where ";        //通過子類的構(gòu)造函數(shù),獲得參數(shù)化類型的具體類型.比如BaseDAO<T>也就是獲得T的具體類型    T entity = persistentClass.newInstance();        //存放Pojo(或被操作表)主鍵的方法對(duì)象    Method idMethod = null;        List<Method> list = this.matchPojoMethods(entity, "set");    Iterator<Method> iter = list.iterator();        //過濾取得Method對(duì)象    while(iter.hasNext()) {      Method tempMethod = iter.next();      if(tempMethod.getName().indexOf("Id") != -1 && tempMethod.getName().substring(3).length() == 2) {        idMethod = tempMethod;      } else if((entity.getClass().getSimpleName() + "Id").equalsIgnoreCase(tempMethod.getName().substring(3))){        idMethod = tempMethod;      }    }    //第一個(gè)字母轉(zhuǎn)為小寫    sql += idMethod.getName().substring(3,4).toLowerCase()+idMethod.getName().substring(4) + " = ?";        //封裝語句完畢,打印sql語句    System.out.println(sql);        //獲得連接    PreparedStatement statement = this.connection.prepareStatement(sql);        //判斷id的類型    if(object instanceof Integer) {      statement.setInt(1, (Integer)object);    } else if(object instanceof String){      statement.setString(1, (String)object);    }        //執(zhí)行sql,取得查詢結(jié)果集.    ResultSet rs = conn.execQuery(statement);        //記數(shù)器,記錄循環(huán)到第幾個(gè)字段    int i = 0;            //把指針指向迭代器第一行    iter = list.iterator();        //封裝    while(rs.next()) {      while(iter.hasNext()) {        Method method = iter.next();        if(method.getParameterTypes()[0].getSimpleName().indexOf("String") != -1) {          //由于list集合中,method對(duì)象取出的方法順序與數(shù)據(jù)庫字段順序不一致(比如:list的第一個(gè)方法是setDate,而數(shù)據(jù)庫按順序取的是"123"值)          //所以數(shù)據(jù)庫字段采用名字對(duì)應(yīng)的方式取.          this.setString(method, entity, rs.getString(method.getName().substring(3).toLowerCase()));        } else if(method.getParameterTypes()[0].getSimpleName().indexOf("Date") != -1){          this.setDate(method, entity, rs.getDate(method.getName().substring(3).toLowerCase()));        } else if(method.getParameterTypes()[0].getSimpleName().indexOf("InputStream") != -1) {          this.setBlob(method, entity, rs.getBlob(method.getName().substring(3).toLowerCase()).getBinaryStream());        } else {          this.setInt(method, entity, rs.getInt(method.getName().substring(3).toLowerCase()));        }        }    }        //關(guān)閉結(jié)果集    rs.close();            //關(guān)閉預(yù)編譯對(duì)象    statement.close();        return entity;  }      /**   * 過濾當(dāng)前Pojo類所有帶傳入字符串的Method對(duì)象,返回List集合.   */  private List<Method> matchPojoMethods(T entity,String methodName) {    //獲得當(dāng)前Pojo所有方法對(duì)象    Method[] methods = entity.getClass().getDeclaredMethods();        //List容器存放所有帶get字符串的Method對(duì)象    List<Method> list = new ArrayList<Method>();        //過濾當(dāng)前Pojo類所有帶get字符串的Method對(duì)象,存入List容器    for(int index = 0; index < methods.length; index++) {      if(methods[index].getName().indexOf(methodName) != -1) {        list.add(methods[index]);      }    }        return list;  }      /**   * 方法返回類型為int或Integer類型時(shí),返回的SQL語句值.對(duì)應(yīng)get   */  public Integer getInt(Method method, T entity) throws Exception{    return (Integer)method.invoke(entity, new Object[]{});  }    /**   * 方法返回類型為String時(shí),返回的SQL語句拼裝值.比如'abc',對(duì)應(yīng)get   */  public String getString(Method method, T entity) throws Exception{    return (String)method.invoke(entity, new Object[]{});  }    /**   * 方法返回類型為Blob時(shí),返回的SQL語句拼裝值.對(duì)應(yīng)get   */  public InputStream getBlob(Method method, T entity) throws Exception{    return (InputStream)method.invoke(entity, new Object[]{});  }      /**   * 方法返回類型為Date時(shí),返回的SQL語句拼裝值,對(duì)應(yīng)get   */  public Date getDate(Method method, T entity) throws Exception{    return (Date)method.invoke(entity, new Object[]{});  }      /**   * 參數(shù)類型為Integer或int時(shí),為entity字段設(shè)置參數(shù),對(duì)應(yīng)set   */  public Integer setInt(Method method, T entity, Integer arg) throws Exception{    return (Integer)method.invoke(entity, new Object[]{arg});  }    /**   * 參數(shù)類型為String時(shí),為entity字段設(shè)置參數(shù),對(duì)應(yīng)set   */  public String setString(Method method, T entity, String arg) throws Exception{    return (String)method.invoke(entity, new Object[]{arg});  }    /**   * 參數(shù)類型為InputStream時(shí),為entity字段設(shè)置參數(shù),對(duì)應(yīng)set   */  public InputStream setBlob(Method method, T entity, InputStream arg) throws Exception{    return (InputStream)method.invoke(entity, new Object[]{arg});  }      /**   * 參數(shù)類型為Date時(shí),為entity字段設(shè)置參數(shù),對(duì)應(yīng)set   */  public Date setDate(Method method, T entity, Date arg) throws Exception{    return (Date)method.invoke(entity, new Object[]{arg});  }}

package com.employees.dao;import java.util.ArrayList;import java.util.List;import com.employees.po.Employees;public class EmployeesDao extends BaseDAO<Employees> {  // 添加員工信息的操作  public boolean addEmployees(final Employees employees) throws Exception {    save(employees);    return true;  }  // 將員工信息添加到表格中  public List<Employees> addEmployees(int id) throws Exception {    List<Employees> lstEmployees = new ArrayList<Employees>();    Employees employees = findById(id);    // 將當(dāng)前封轉(zhuǎn)好的數(shù)據(jù)裝入對(duì)象中    lstEmployees.add(employees);    return lstEmployees;  }  public void deleteEmp(final Employees entity) throws Exception {    this.delete(entity);  }  public void updateEmp(final Employees entity) throws Exception {    this.update(entity);  }}

package com.employees.dao;import org.junit.Test;import com.employees.po.Employees;public class EmployeesDaoTest {  @Test  public void testAdd() throws Exception {    Employees emp = new Employees();    emp.setPname("tly");    emp.setPsex("男");    emp.setPbeliefs("xxxxx");    emp.setPaddr("天河");    emp.setPhobby("打籃球");    emp.setPsubject("計(jì)算機(jī)");    emp.setPtel("123456");    EmployeesDao dao = new EmployeesDao();    dao.addEmployees(emp);  }  @Test  public void testUpdate() throws Exception {    EmployeesDao dao = new EmployeesDao();    Employees emp = dao.findById(14);    emp.setPtel("999999");    dao.updateEmp(emp);  }  @Test  public void testdelete() throws Exception {    EmployeesDao dao = new EmployeesDao();    Employees emp = dao.findById(15);    dao.deleteEmp(emp);  }}