List<bean>转换Jsonarray知识心得

使用基本的jdbc连接mysql，获取数据。

创建实体类user:

package com.json;

public class user {
    private int id;
private String username;
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
private String password;
private score score;

public user() {
    super();
}
public user(String username, String password, com.json.score score) {
    super();
    this.username = username;
    this.password = password;
    this.score = score;
}
public score getScore() {
    return score;
}
public void setScore(score score) {
    this.score = score;
}
public String getUsername() {
    return username;
}
public void setUsername(String username) {
    this.username = username;
}
public String getPassword() {
    return password;
}
public void setPassword(String password) {
    this.password = password;
}

}

创建utildao工具类:

package com.json;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class utildao {
    public static Connection getConnection(){
        Connection conn=null;
        String url="jdbc:mysql://localhost:3306/test";
        try {
        Class.forName("com.mysql.jdbc.Driver");
        conn=DriverManager.getConnection(url,"用户名","密码");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            System.out.println("数据库驱动加载出错");
        }catch (SQLException e) {
            e.printStackTrace();
            System.out.println("数据库出错");
        }
        return conn;
    }
    public static void close(ResultSet rs,PreparedStatement p,Connection conn){
        try {
            rs.close();
            p.close();
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
            System.out.println("数据库关闭出错");
        }
    }
    public static void main(String[] args) {
        System.out.println(utildao.getConnection());
    }
}

创建查询:

package com.json;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class jsonjiexi {
    public static ResultSet getjson(){
        Connection conn=null;
        PreparedStatement p=null;
        ResultSet rs=null;
        try {
        conn=utildao.getConnection();
        String sql="select * from userone";
        p=conn.prepareStatement(sql);
        rs=p.executeQuery();
        while(rs.next()){
            //utildao.close(rs, p, conn);
            //System.out.println("查询结束，关闭");
            return rs;
        }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
    
}

最后main方法类:

package com.json;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class huoqujson {
    public static void main(String[] args) throws SQLException {
        //注释掉此段为,将jdbc获取的resultset转换为list集合
        /*List list=new ArrayList();
        ResultSet rs=jsonjiexi.getjson();
        ResultSetMetaData md=rs.getMetaData();
        int num=md.getColumnCount();
        while(rs.next()){
            Map rowData=new HashMap();
            for(int i=1;i<=num;i++){
                rowData.put(md.getColumnName(i),rs.getObject(i));
            }
            list.add(rowData);
        }
        System.out.println(list.toString());*/
        //这段实现了将jdbc获取的数据，赋值给实体类，添加进List，最后转换为jsonarray
        user us=new user();
        List<user> list=new ArrayList<user>();
        ResultSet rs=jsonjiexi.getjson();
        while(rs.next()){
            us.setId(rs.getInt("id"));
            us.setUsername(rs.getString("name"));
            us.setPassword(rs.getString("pwd"));
            System.out.println(us.getId()+":"+us.getUsername()+":"+us.getPassword());
        }
        list.add(us);
        JSONArray array=JSONArray.fromObject(list);
        System.out.println(array.toString());
        }
        
    }

编写期间遇到的错误，在Main方法执行之后，由于没有导入某些jar包报的错误：

commons-lang-2.4.jar不加这个包 
java.lang.NoClassDefFoundError: org/apache/commons/lang/exception/NestableRuntimeException

commons-logging-1.1.1.jar不加这个包 
java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory 

commons-beanutils-1.8.0.jar不加这个包 

java.lang.NoClassDefFoundError: org/apache/commons/beanutils/DynaBean
commons-collections.jar 不加这个包
java.lang.NoClassDefFoundError: org/apache/commons/collections/map/ListOrderedMap
ezmorph-1.0.4.jar不加这个包
java.lang.NoClassDefFoundError: net/sf/ezmorph/Morpher
json-lib-2.3-jdk15.jar不加这个包
java.lang.NoClassDefFoundError: net/sf/json/JSONObject