Java基礎--JDBC-反射等__Java

User類

package com.JDBCTest;import java.util.Date;public class User {private Integer id;private String username;private String address;private Date birthday;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}}

介面類

package com.JDBCTest;import java.sql.ResultSet;import java.sql.SQLException;@FunctionalInterfacepublic interface ResultSetExtractor {//函數泛型public  Object extractData(ResultSet rs) throws SQLException; }

反射類

package com.JDBCTest;import java.lang.reflect.Method;import java.util.Date;public class ReflectUtil {   /** * 設定對象的參數 */public static void setValue(String name,Object value,Object obj){try {Class clz = obj.getClass();String tname = value.getClass().getTypeName();Method method = clz.getDeclaredMethod("set"+name, Class.forName(tname));method.invoke(obj, value);} catch (Exception e) {e.printStackTrace();}}//public static void main(String[] args) {//User user = new User();//ReflectUtil.setValue("Id", "7", user);//ReflectUtil.setValue("Username", "tt", user);//ReflectUtil.setValue("Address", "上海", user);//} }

實作類別

package com.JDBCTest;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.util.ArrayList;import java.util.LinkedList;import java.util.List;public class Session {private static final String url = "jdbc:mysql://119.254.106.50:3309/test?useUnicode=true&characterEncoding=utf8";private static final String user = "rw_all_db";private static final String password = "rw_all_db";/** * 擷取單條資料 */public <T>T query(String sql,ResultSetExtractor extractor){try {Class.forName("com.mysql.jdbc.Driver");Connection connection = DriverManager.getConnection(url, user, password);PreparedStatement statement = connection.prepareStatement(sql);ResultSet rs = statement.executeQuery();rs.next();return (T)extractor.extractData(rs);} catch (Exception e) {return null;} finally {//關閉串連}}/** * 帶參數擷取單條資料 */public <T>T query(String sql,ResultSetExtractor extractor,Object...params){try {Class.forName("com.mysql.jdbc.Driver");Connection connection = DriverManager.getConnection(url, user, password);PreparedStatement statement = connection.prepareStatement(sql);if(params!=null && params.length > 0){for (int i = 0; i < params.length; i++) {Object object = params[i];statement.setObject(i+1, object);}}ResultSet rs = statement.executeQuery();rs.next();return (T)extractor.extractData(rs);} catch (Exception e) {return null;}}/** * 帶參數擷取多條資料 */public <T>List<T> queryList(String sql,ResultSetExtractor extractor,Object...params){try {Class.forName("com.mysql.jdbc.Driver");Connection connection = DriverManager.getConnection(url, user, password);PreparedStatement statement = connection.prepareStatement(sql);if(params!=null && params.length > 0){for (int i = 0; i < params.length; i++) {Object object = params[i];statement.setObject(i+1, object);}}ResultSet rs = statement.executeQuery();List<T> lists = new ArrayList<>();while (rs.next()) {lists.add((T)extractor.extractData(rs));}return lists;} catch (Exception e) {return null;}}/** * 反射 */public <T>List<T> queryList(String sql,Class clz,Object...params){try {Class.forName("com.mysql.jdbc.Driver");//擷取連線物件Connection connection = DriverManager.getConnection(url, user, password);//執行預先處理對象PreparedStatement statement = connection.prepareStatement(sql);//設定參數if(params!=null && params.length > 0){for (int i = 0; i < params.length; i++) {Object object = params[i];statement.setObject(i+1, object);}}//結果集ResultSet rs = statement.executeQuery();//拿到擷取sql語句 select ***from 這段的列明ResultSetMetaData metaData = rs.getMetaData();int count = metaData.getColumnCount();//定義個集合儲存這些列名LinkedList<String> colunmNames = new LinkedList<>();for (int i = 0; i < count; i++) {colunmNames.add(metaData.getColumnName(i+1));//解析儲存}//定義容器，裝載資料List<T> lists = new ArrayList<>();while (rs.next()) {//執行個體化對象T obj = (T)clz.newInstance();for (String string: colunmNames) {//講資料庫對應的列明轉換成javabean中對應的屬性名稱，首字母轉大寫,因為setUsername//columnToProperty()講資料庫列名轉換成駝峰命名規則，create_time ---createTime//create_time --columnToProperty--createTime--toUpperCaseFirst---CreateTimeString colunmName = string.substring(0, 1).toUpperCase() + string.substring(1);//調用反射，給屬性賦值ReflectUtil.setValue(colunmName, rs.getObject(colunmName), obj);}//將資料放入集合中lists.add(obj);}return lists;} catch (Exception e) {return null;}}public static void main(String[] args) {Session session = new Session();//測試一：單條資料//String sql = "select id,username,address from user where id = 1";//User user1 = session.query(sql, new ResultSetExtractor() {////@Override//public User extractData(ResultSet rs) throws SQLException {//User user = new User();//user.setId(rs.getInt("id"));//user.setUsername(rs.getString("username"));//user.setAddress(rs.getString("address"));//return user;//}//});//System.out.println(user1.getId()+"=>"+user1.getAddress()+"=>"+user1.getUsername());//測試二：帶參數單條資料//String sql = "select id,username,address from user where id = ?";//User user1 = session.query(sql, new ResultSetExtractor() {////@Override//public User extractData(ResultSet rs) throws SQLException {//User user = new User();//user.setId(rs.getInt("id"));//user.setUsername(rs.getString("username"));//user.setAddress(rs.getString("address"));//return user;//}//},5);//System.out.println(user1.getId()+"=>"+user1.getAddress()+"=>"+user1.getUsername());//測試三：帶參數多條資料String sql = "select id,username,address from user where address = ?";//List<User> list = session.queryList(sql, new ResultSetExtractor() {////@Override//public User extractData(ResultSet rs) throws SQLException {//User user = new User();//user.setId(rs.getInt("id"));//user.setUsername(rs.getString("username"));//user.setAddress(rs.getString("address"));//return user;//}//},"北京");////for (User user1 : list) {//System.out.println(user1.getId()+"=>"+user1.getAddress()+"=>"+user1.getUsername());//}//lamad函數改寫//List<User> list1 = session.queryList(sql, (rs) -> {//User user = new User();//user.setId(rs.getInt("id"));//user.setUsername(rs.getString("username"));//user.setAddress(rs.getString("address"));//return user;}//,"北京");////for (User user1 : list1) {//System.out.println(user1.getId()+"=>"+user1.getAddress()+"=>"+user1.getUsername());//}//反射測試List<User> list = session.queryList(sql,User.class,"上海");for (User user1 : list) {System.out.println(user1.getId()+"=>"+user1.getAddress()+"=>"+user1.getUsername());}  }}