Java--jdbc--orm-- List-- Json

DB_Select_Demo.java

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package com.syc.test.DB;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.ArrayList;import java.util.List;import com.syctest.bean.UpdateListBean;public class DB_Select_Demo {public static void main(String[] args) {System.out.println(selectDB());}public static List<UpdateListBean> selectDB() {Connection conn = null;Statement st = null;ResultSet rs = null;List<UpdateListBean> list=new ArrayList<UpdateListBean>();String text = "00";// mysql的加载JDBC驱动程序try {Class.forName("com.mysql.jdbc.Driver");} catch (ClassNotFoundException e) {System.out.println("驱动加载错误");e.printStackTrace();}// 与mysql数据库建立连接try {conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/sva_rec", "root", "mysql");} catch (SQLException e) {System.out.println("数据库链接错误");e.printStackTrace();}// 创建Statementtry {st = conn.createStatement();// 创建一个JDBC声明String query ="SELECT dt, year,month FROM date_drv ORDER BY dt,MONTH DESC LIMIT 1,10";rs = st.executeQuery(query);while (rs.next()) {UpdateListBean ulBean=new UpdateListBean();ulBean.setYear(rs.getString("year"));ulBean.setDt(rs.getString("dt"));ulBean.setMonth(rs.getString("month"));list.add(ulBean);}} catch (SQLException e1) {System.out.println("数据操作错误");e1.printStackTrace();}// 关闭数据库try {if (rs != null) {rs.close();rs = null;}if (st != null) {st.close();st = null;}if (conn != null) {conn.close();conn = null;}} catch (Exception e) {System.out.println("数据库关闭错误");e.printStackTrace();}return list;}}

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UpdateList2Json.java

package com.syctest.JSON;import java.util.ArrayList;import java.util.List;import net.sf.json.JSONArray;import com.syc.test.DB.DB_Select_Demo;import com.syctest.bean.UpdateListBean;public class UpdateList2Json {public static void main(String[] args) {UpdateList2Json();}private static void UpdateList2Json() {List<UpdateListBean> list = new ArrayList<UpdateListBean>();list = DB_Select_Demo.selectDB();for (int i = 0; i < list.size(); i++) {// System.out.println(list.get(i).getYear()+" "+list.get(i).getMonth()+" "+list.get(i).getDt()// );}for (int i = 0; i < list.size(); i++) {int maxNum = Integer.parseInt(list.get(0).getMonth());int objNum = Integer.parseInt(list.get(i).getMonth()) * 100/ maxNum;System.out.println(maxNum + " " + objNum);list.get(i).setRate(String.valueOf(objNum));}for (int i = 0; i < list.size(); i++) {System.out.println(list.get(i).getYear() + " "+ list.get(i).getMonth() + " " + list.get(i).getDt() + " "+ list.get(i).getRate());}JSONArray ja = JSONArray.fromObject(list);System.out.println(ja.toString());}}

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UpdateListBean.java

package com.syctest.bean;public class UpdateListBean {public String rate;public String getRate() {return rate;}public void setRate(String rate) {this.rate = rate;}public String year;public String getYear() {return year;}public void setYear(String year) {this.year = year;}public String getMonth() {return month;}public void setMonth(String month) {this.month = month;}public String getDt() {return dt;}public void setDt(String dt) {this.dt = dt;}public String month;public String dt;}

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