JDBC优化
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内容图文
一.什么是dao 二.dao模式实现 三.dao优化 定义包的模式如下： TecDao package dao;import java.sql.SQLException;import java.util.List;import pojo.TecPojo;public interface TecDao {public int insert(TecPojo tec)throws SQLException;public int delet
一.什么是dao
二.dao模式实现
三.dao优化
定义包的模式如下：
TecDao
package dao;
import java.sql.SQLException;
import java.util.List;
import pojo.TecPojo;
public interface TecDao {
public int insert(TecPojo tec)throws SQLException;
public int delete(int id)throws SQLException;
public int update(TecPojo tec)throws SQLException;
public List query(TecPojo tec)throws SQLException;
}
TecDaoImpl
package dao.impl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import dao.TecDao;
import pojo.TecPojo;
import util.SQLUtil;
public class TecDaoImpl implements TecDao{
public int insert(TecPojo tec) throws SQLException {
Connection conn = SQLUtil.getConnection();
String sql = "insert into tec (name,age,gender,job,createDate)values(?,?,?,?,?)";
PreparedStatement state = conn.prepareStatement(sql);
state.setString(1, tec.getName());
state.setInt(2, tec.getAge());
state.setString(3, tec.getGender());
state.setString(4, tec.getJob());
state.setString(5, tec.getCreateDate());
int result = state.executeUpdate();
if(result>0){
System.out.println("Yes");
}
return result;
}
public int update(TecPojo tec) throws SQLException {
Connection conn = SQLUtil.getConnection();
String sql = "update tec set name = ?,age = ? where id = 11";
PreparedStatement state = conn.prepareStatement(sql);
state.setString(1, tec.getName());
state.setInt(2, tec.getAge());
int result = state.executeUpdate();
if(result>0){
System.out.println("Yes");
}
return result;
}
public List query(TecPojo tec) throws SQLException {
Connection conn = SQLUtil.getConnection();
String sql = "select * from tec";
PreparedStatement state = conn.prepareStatement(sql);
ResultSet resultset = state.executeQuery();
ArrayList list = new ArrayList();
TecPojo tp = null;
while(resultset.next()){
tp = new TecPojo();
tp.setId(resultset.getInt("id"));
tp.setName(resultset.getString("name"));
tp.setAge(resultset.getInt("age"));
tp.setGender(resultset.getString("gender"));
tp.setJob(resultset.getString("job"));
tp.setCreateDate(resultset.getString("createDate"));
list.add(tp);
}
for(int i = 0;i<list.size();i++){
System.out.println(list.get(i));
}
return list;
}
public int delete(int id) throws SQLException {
Connection conn = SQLUtil.getConnection();
String sql = "delete from tec where id = "+id;
PreparedStatement state = conn.prepareStatement(sql);
int result = state.executeUpdate();
if(result>0){
System.out.println("Yes");
}
return result;
}
}
TecPojo
package pojo;
public class TecPojo {
private int id;
private String name;
private int age;
private String gender;
private String job;
private String createDate;
public TecPojo(String name, int age, String gender, String job, String createDate) {
super();
this.name = name;
this.age = age;
this.gender = gender;
this.job = job;
this.createDate = createDate;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String toString() {
return id+" "+name+" "+age+" "+gender+" "+job+" "+createDate;
}
public TecPojo() {
super();
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public String getCreateDate() {
return createDate;
}
public void setCreateDate(String createDate) {
this.createDate = createDate;
}
}
SQLUtil
package util;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
public class SQLUtil {
private static String url;
private static String user;
private static String password;
private static String driver;
static{
try {
Properties pro = new Properties();
InputStream ins = SQLUtil.class.getResourceAsStream("/sqlconfig.properties");
pro.load(ins);
url = pro.getProperty("url");
user = pro.getProperty("user");
password = pro.getProperty("password");
driver = pro.getProperty("driver");
Class.forName(driver);
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection getConnection(){
Connection conn = null;
try {
conn = DriverManager.getConnection(url,user,password);
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
}
Test
package util;
import java.sql.SQLException;
import dao.impl.TecDaoImpl;
import pojo.TecPojo;
public class Test {
public static void main(String[] args) {
SQLUtil util = new SQLUtil();
TecPojo tp = new TecPojo("bb",22,"man","teacher","2016-4-6");
TecDaoImpl tdi = new TecDaoImpl();
try {
// tdi.insert(tp);
// tdi.update(tp);
tdi.query(tp);
// tdi.delete(12);
} catch (SQLException e) {
e.printStackTrace();
}
}
}
此时发现，TecDaoImpl的方法有多次重复，于是对重复的方法再次进行封装
SQLTemplete
package util;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class SQLTemplete {
public static int update(String sql,Object...object)throws SQLException{
Connection conn = SQLUtil.getConnection();
PreparedStatement state = conn.prepareStatement(sql);
for(int i=0;i<object.length;i++){
state.setObject(i+1, object[i]);
}
int result = state.executeUpdate();
return result;
}
public static ResultSet query(String sql,Object...object)throws SQLException{
Connection conn = SQLUtil.getConnection();
PreparedStatement state = conn.prepareStatement(sql);
for(int i=0;i<object.length;i++){
state.setObject(i+1, object[i]);
}
ResultSet resultset = state.executeQuery();
return resultset;
}
}
TecDaoImpl
package dao.impl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import dao.TecDao;
import pojo.TecPojo;
import util.SQLTemplete;
import util.SQLUtil;
public class TecDaoImpl implements TecDao{
public int insert(TecPojo tec) throws SQLException {
String sql = "insert into tec (name,age,gender,job,createDate)values(?,?,?,?,?)";
int result = SQLTemplete.update(sql, tec.getName(),tec.getAge(),tec.getGender(),tec.getJob(),tec.getCreateDate());
if(result>0){
System.out.println("Yes");
}
return result;
}
public int update(TecPojo tec) throws SQLException {
String sql = "update tec set name = ?,age = ? where id = 11";
int result = SQLTemplete.update(sql, tec.getName(),tec.getAge());
if(result>0){
System.out.println("Yes");
}
return result;
}
public List query(TecPojo tec) throws SQLException {
String sql = "select * from tec";
ResultSet resultset = SQLTemplete.query(sql);
ArrayList list = new ArrayList();
TecPojo tp = null;
while(resultset.next()){
tp = new TecPojo();
tp.setId(resultset.getInt("id"));
tp.setName(resultset.getString("name"));
tp.setAge(resultset.getInt("age"));
tp.setGender(resultset.getString("gender"));
tp.setJob(resultset.getString("job"));
tp.setCreateDate(resultset.getString("createDate"));
list.add(tp);
}
for(int i = 0;i<list.size();i++){
System.out.println(list.get(i));
}
return list;
}
public int delete(int id) throws SQLException {
String sql = "delete from tec where id = "+id;
int result = SQLTemplete.update(sql);
if(result>0){
System.out.println("Yes");
}
return result;
}
}
这样实现了更彻底的封装，TecDaoImpl类里没有直接和数据库联系，用SQLTemplete类实现对数据库的操作，从而达到业务逻辑和数据访问之间的分离。
内容总结
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