使用注解将JDBC结果集映射到Java对象，jdbcjava,SamplePojo.j

使用注解将JDBC结果集映射到Java对象，jdbcjava,SamplePojo.j

SamplePojo.java

import javax.persistence.Column;import javax.persistence.Entity;@Entitypublic class SamplePojo {    @Column(name="User_Id")    private int id;    @Column(name="User_Name")    private String name;    @Column(name="Address")    private String address;    @Column(name="Gender")    private boolean gender;    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 getAddress() {        return address;    }    public void setAddress(String address) {        this.address = address;    }    public boolean isGender() {        return gender;    }    public void setGender(boolean gender) {        this.gender = gender;    }    @Override    public String toString() {        return  "id: " + id + "\n" +                 "name: " + name + "\n"+                "address: " + address + "\n" +                "gender: " + (gender ? "Male" : "Female") + "\n\n";    }}

ResultSetMapper.java

import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;import javax.persistence.Column;import javax.persistence.Entity;import org.apache.commons.beanutils.BeanUtils;public class ResultSetMapper<T> {    @SuppressWarnings("unchecked")    public List<T> mapRersultSetToObject(ResultSet rs, Class outputClass) {        List<T> outputList = null;        try {            // make sure resultset is not null            if (rs != null) {                // check if outputClass has 'Entity' annotation                if (outputClass.isAnnotationPresent(Entity.class)) {                    // get the resultset metadata                    ResultSetMetaData rsmd = rs.getMetaData();                    // get all the attributes of outputClass                    Field[] fields = outputClass.getDeclaredFields();                    while (rs.next()) {                        T bean = (T) outputClass.newInstance();                        for (int _iterator = 0; _iterator < rsmd                                .getColumnCount(); _iterator++) {                            // getting the SQL column name                            String columnName = rsmd                                    .getColumnName(_iterator + 1);                            // reading the value of the SQL column                            Object columnValue = rs.getObject(_iterator + 1);                            // iterating over outputClass attributes to check if any attribute has 'Column' annotation with matching 'name' value                            for (Field field : fields) {                                if (field.isAnnotationPresent(Column.class)) {                                    Column column = field                                            .getAnnotation(Column.class);                                    if (column.name().equalsIgnoreCase(                                            columnName)                                            && columnValue != null) {                                        BeanUtils.setProperty(bean, field                                                .getName(), columnValue);                                        break;                                    }                                }                            }                        }                        if (outputList == null) {                            outputList = new ArrayList<T>();                        }                        outputList.add(bean);                    }                } else {                    // throw some error                }            } else {                return null;            }        } catch (IllegalAccessException e) {            e.printStackTrace();        } catch (SQLException e) {            e.printStackTrace();        } catch (InstantiationException e) {            e.printStackTrace();        } catch (InvocationTargetException e) {            e.printStackTrace();        }        return outputList;    }}

使用方法

import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.List;public class SampleMain {    public static void main(String ...args){    try {        ResultSetMapper<SamplePojo> resultSetMapper = new ResultSetMapper<SamplePojo>();        ResultSet resultSet = null;        // simple JDBC code to run SQL query and populate resultSet - START        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");        String database = "jdbc:odbc:AkDb";         Connection connection = DriverManager.getConnection( database ,"","");        PreparedStatement statement = connection.prepareStatement("SELECT * FROM UsersSample");        resultSet = statement.executeQuery();        // simple JDBC code to run SQL query and populate resultSet - END        List<SamplePojo> pojoList = resultSetMapper.mapRersultSetToObject(resultSet, SamplePojo.class);        // print out the list retrieved from database        if(pojoList != null){            for(SamplePojo pojo : pojoList){                System.out.println(pojo);            }        }else{            System.out.println("ResultSet is empty. Please check if database table is empty");        }        connection.close();    } catch (ClassNotFoundException e) {        e.printStackTrace();    } catch (SQLException e) {        e.printStackTrace();    }    }}