package cn.netjava.pojo;

public class UserInfo {
private int id;
private String name;
private String pwd;
private int age;

@Override
public String toString() {
    return "UserInfo [id=" + id + ", name=" + name + ", pwd=" + pwd + ", age="
            + age + "]";
}
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getPwd() {
    return pwd;
}
public void setPwd(String pwd) {
    this.pwd = pwd;
}
public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}

}

package cn.netjava.factory;

import java.sql.Connection;
import java.sql.DriverManager;

public class Connect2DBFactory {
    public static Connection getDBConnection() {
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/blogsystem";
            String user = "root";
            String password = "netjava";
            conn = DriverManager.getConnection(url, user, password);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return conn;
    }
}

package cn.netjava.session;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import cn.netjava.factory.Connect2DBFactory;
import cn.netjava.pojo.UserInfo;

public class NetJavaSession {
    /**
     * 解析出保存對(duì)象的sql語句
     *
     * @param object
     *            ：需要保存的對(duì)象
     * @return：保存對(duì)象的sql語句
     */
    public static String getSaveObjectSql(Object object) {
        // 定義一個(gè)sql字符串
        String sql = "insert into ";
        // 得到對(duì)象的類
        Class c = object.getClass();
        // 得到對(duì)象中所有的方法
        Method[] methods = c.getMethods();
        // 得到對(duì)象中所有的屬性
        Field[] fields = c.getFields();
        // 得到對(duì)象類的名字
        String cName = c.getName();
        // 從類的名字中解析出表名
        String tableName = cName.substring(cName.lastIndexOf(".") + 1,
                cName.length());
        sql += tableName + "(";
        List<String> mList = new ArrayList<String>();
        List vList = new ArrayList();
        for (Method method : methods) {
            String mName = method.getName();
            if (mName.startsWith("get") && !mName.startsWith("getClass")) {
                String fieldName = mName.substring(3, mName.length());
                mList.add(fieldName);
                System.out.println("字段名字----->" + fieldName);
                try {
                    Object value = method.invoke(object, null);
                    System.out.println("執(zhí)行方法返回的值：" + value);
                    if (value instanceof String) {
                        vList.add("\"" + value + "\"");
                        System.out.println("字段值------>" + value);
                    } else {
                        vList.add(value);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        for (int i = 0; i < mList.size(); i++) {
            if (i < mList.size() - 1) {
                sql += mList.get(i) + ",";
            } else {
                sql += mList.get(i) + ") values(";
            }
        }
        for (int i = 0; i < vList.size(); i++) {
            if (i < vList.size() - 1) {
                sql += vList.get(i) + ",";
            } else {
                sql += vList.get(i) + ")";
            }
        }

        return sql;
    }

    public static List getDatasFromDB(String tableName, int Id) {

        return null;

    }

    /**
     * 將對(duì)象保存到數(shù)據(jù)庫中
     *
     * @param object
     *            ：需要保存的對(duì)象
     * @return：方法執(zhí)行的結(jié)果;1:表示成功，0:表示失敗
     */
    public int saveObject(Object object) {
        Connection con = Connect2DBFactory.getDBConnection();
        String sql = getSaveObjectSql(object);
        try {
            // Statement statement=(Statement) con.createStatement();
            PreparedStatement psmt = con.prepareStatement(sql);
            psmt.executeUpdate();
            return 1;
        } catch (SQLException e) {
            e.printStackTrace();
            return 0;
        }
    }

    /**
     * 從數(shù)據(jù)庫中取得對(duì)象
     *
     * @param arg0
     *            ：對(duì)象所屬的類
     * @param id
     *            ：對(duì)象的id
     * @return:需要查找的對(duì)象
     */
    public Object getObject(String className, int Id) {
        // 得到表名字
        String tableName = className.substring(className.lastIndexOf(".") + 1,
                className.length());
        // 根據(jù)類名來創(chuàng)建Class對(duì)象
        Class c = null;
        try {
            c = Class.forName(className);

        } catch (ClassNotFoundException e1) {

            e1.printStackTrace();
        }
        // 拼湊查詢sql語句
        String sql = "select * from " + tableName + " where Id=" + Id;
        System.out.println("查找sql語句：" + sql);
        // 獲得數(shù)據(jù)庫鏈接
        Connection con = Connect2DBFactory.getDBConnection();
        // 創(chuàng)建類的實(shí)例
        Object obj = null;
        try {

            Statement stm = con.createStatement();
            // 得到執(zhí)行查尋語句返回的結(jié)果集
            ResultSet set = stm.executeQuery(sql);
            // 得到對(duì)象的方法數(shù)組
            Method[] methods = c.getMethods();
            // 遍歷結(jié)果集
            while (set.next()) {
                obj = c.newInstance();
                // 遍歷對(duì)象的方法
                for (Method method : methods) {
                    String methodName = method.getName();
                    // 如果對(duì)象的方法以set開頭
                    if (methodName.startsWith("set")) {
                        // 根據(jù)方法名字得到數(shù)據(jù)表格中字段的名字
                        String columnName = methodName.substring(3,
                                methodName.length());
                        // 得到方法的參數(shù)類型
                        Class[] parmts = method.getParameterTypes();
                        if (parmts[0] == String.class) {
                            // 如果參數(shù)為String類型，則從結(jié)果集中按照列名取得對(duì)應(yīng)的值，并且執(zhí)行改set方法
                            method.invoke(obj, set.getString(columnName));
                        }
                        if (parmts[0] == int.class) {
                            method.invoke(obj, set.getInt(columnName));
                        }
                    }

                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return obj;
    }
}

package cn.netjava.tester;

import cn.netjava.pojo.UserInfo;
import cn.netjava.session.NetJavaSession;

public class Tester {
    public static void main(String args[]) {
        //獲得NetJavaSession對(duì)象
        NetJavaSession session = new NetJavaSession();
        //創(chuàng)建一個(gè)UserInfo對(duì)象
        UserInfo user = new UserInfo();
        //設(shè)置對(duì)象的屬性
        user.setId(6988);
        user.setAge(44);
        user.setPwd("pwd");
        user.setName("champion");
        //將對(duì)象保存到數(shù)據(jù)庫中
        String sql = session.getSaveObjectSql(user);
        System.out.println("保存對(duì)象的sql語句：" + sql);
        //查找對(duì)象
        UserInfo userInfo = (UserInfo) session.getObject(
                "cn.netjava.pojo.UserInfo", 6988);
        System.out.println("獲取到的信息：" + userInfo);

    }
}