标签：查找 cad 基本 sel hashset 数据 out stat ref
apache的dbutils包
一对多
package com.cn.bean;
import java.util.HashSet;
import java.util.Set;
public class Department {
private String id;
private String name;
private Set employees = new HashSet();
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set getEmployees() {
return employees;
}
public void setEmployees(Set employees) {
this.employees = employees;
}
}
package com.cn.bean;
public class Employee {
private String id;
private String name;
private double salary;
private Department department;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
}
package com.cn.dao;
import java.sql.SQLException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import com.cn.bean.Department;
import com.cn.bean.Employee;
import com.cn.utils.JdbcUtils;
public class DepartmentDao {
/*
* create table department(
* id varchar(40) primary key, name varchar(40)
* );
* create table employee(
* id varchar(40) primary key, name varchar(40),
* salary double, department_id varchar(40), on delete set null 这个叫做级联，就是如果删除部门的话，会把外键设置为空，具体参考mysql的api
* constraint department_id_FK foreign key(department_id) references department(id) ) on delete set null;;
*/
// 把员工的信息添加到部门中，因为员工的数量无法判断，所以用循环
public void add(Department d) throws SQLException {
// 把department对象的数据插入到department表
QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
String sql = "insert into department(id,name) values(?,?)";
Object params[] = { d.getId(), d.getName() };
qr.update(sql, params);
// 把department对象中维护的所有员工插入到员工表，并且更新员工表的外键列，说明员工的部门
// 因为这里是department的dao，所有employee不能重新定义，直接调用department中的getEmployee方法即可
Set<Employee> set = d.getEmployees();
for (Employee e : set) {
sql = "insert into employee(id,name,salary,department_id) values(?,?,?,?)";
params = new Object[] { e.getId(), e.getName(), e.getSalary(),
d.getId() };
qr.update(sql, params);
}
}
// 查询某个部门下面有多少员工
public Department find(String id) throws SQLException {
// 找部门表，查询部门的基本信息
QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
String sql = "select * from department where id=?";
Department d = (Department) qr.query(sql, id, new BeanHandler(
Department.class));
// 查找员工表，找到部门下面的所有员工
sql = "select * from employee where id=? ";
List list = (List) qr.query(sql, id,
new BeanListHandler(Employee.class));
d.getEmployees().addAll(list); //addAll方法可以添加另外个集合，注意不能用add方法，因为添加进去的是个list集合，而不是员工信息
return d;
}
//删除某个部门
public void delete(String id) throws SQLException {
QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
String sql ="delete from department where id=?";
qr.update(sql, id);
}
}
package com.cn.service;
import java.sql.SQLException;
import org.apache.commons.dbutils.QueryRunner;
import org.junit.Test;
import com.cn.bean.Department;
import com.cn.bean.Employee;
import com.cn.dao.DepartmentDao;
import com.cn.utils.JdbcUtils;
//一对多
public class BService {
//添加
public void add() throws SQLException {
Department d = new Department();
d.setId("111");
d.setName("开发部");
Employee e1 = new Employee();
e1.setId("1");
e1.setName("aa");
e1.setSalary(10000);
Employee e2 = new Employee();
e2.setId("2");
e2.setName("bb");
e2.setSalary(10000);
d.getEmployees().add(e1);
d.getEmployees().add(e2);
DepartmentDao dao = new DepartmentDao();
dao.add(d);
}
@Test
public void find() throws SQLException {
DepartmentDao dao = new DepartmentDao();
Department d=dao.find("111");
System.out.println(d);
}
@Test
public void delete() throws SQLException {
DepartmentDao dao = new DepartmentDao();
dao.delete("111");
}
}
package com.cn.utils;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
//连接池
public class JdbcUtils {
private static DataSource ds;
static {
try {
Properties prop = new Properties();
prop.load(JdbcUtils.class.getClassLoader().getResourceAsStream(
"dbcpconfig.properties"));
BasicDataSourceFactory factory = new BasicDataSourceFactory();
ds = factory.createDataSource(prop);
} catch (Exception e) {
e.printStackTrace();
}
}
public static DataSource getDataSource() {
return ds;
}
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
}
然后就上dbcp的配置文件 并且记得导入相关的包：数据库、dbcp、dbutils
多对多
package com.cn.bean;
import java.util.HashSet;
import java.util.Set;
public class Teacher {
private String id;
private String name;
private double salary;
private Set students = new HashSet();
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
public Set getStudents() {
return students;
}
public void setStudents(Set students) {
this.students = students;
}
}
package com.cn.bean;
import java.util.HashSet;
import java.util.Set;
public class Student {
private String id;
private String name;
private Set teachers = new HashSet();
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set getTeachers() {
return teachers;
}
public void setTeachers(Set teachers) {
this.teachers = teachers;
}
}
package com.cn.dao;
import java.sql.SQLException;
import java.util.List;
import java.util.Set;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import com.cn.bean.Student;
import com.cn.bean.Teacher;
import com.cn.utils.JdbcUtils;
//多对多
public class TeacherDao {
// 把学生的信息存入到老师中
public void add(Teacher t) throws SQLException {
// 取出老师，存入老师表
QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
String sql = "insert into teacher(id,name,salary) values(?,?,?)";
Object params[] = { t.getId(), t.getName(), t.getSalary() };
qr.update(sql, params);
// 取出老师的所有学生，存入学生表
Set<Student> set = t.getStudents();
for (Student s : set) {
sql = "insert into student(id,name) value(?,?)";
params = new Object[] { s.getId(), s.getName() };
qr.update(sql, params);
// 更新中间表，说明老师和学生的关系
sql = "insert into teacher_student(teacher_id,student_id) values(?,?)";
params = new Object[] { t.getId(), s.getId() };
qr.update(sql, params);
}
}
// 查找某个老师的所有学生
public Teacher find(String id) throws SQLException {
QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
// 找老师表，找出老师的基本信息
String sql = "select * from teacher where id=?";
Teacher t = (Teacher) qr.query(sql, id, new BeanHandler(
Teacher.class));
/*
* 找出老师的所有学生 从中间表去找， 中间表里面学生的id和student中的id必须相同 然后判断中间表里面老师的id和传递的id是否相同
* 因为传递的id里面学生的信息是一样的
*/
sql = "select s.* from teacher_student as ts,student as s where ts.teacher_id=? and ts.student_id=s.id";
List list = (List) qr
.query(sql, id, new BeanListHandler(Student.class));
t.getStudents().addAll(list);
return t;
}
public void delete(String id) throws SQLException {
QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
String sql ="delete from teacher where id=?";
qr.update(sql, id);
}
}
package com.cn.service;
import java.sql.SQLException;
import org.junit.Test;
import com.cn.bean.Student;
import com.cn.bean.Teacher;
import com.cn.dao.TeacherDao;
//多对多
public class AService {
/*
create table teacher(
id varchar(40) primary key,
name varchar(40),
salary double
);
create table student(
id varchar(40) primary key,
name varchar(40)
);
create table teacher_student(
teacher_id varchar(40),
student_id varchar(40),
primary key(teacher_id,student_id), on delete cascade 如果用这个的话，那么删除的话会把该表全部删除
constraint teacher_id_Fk foreign key(teacher_id) references teacher(id) on delete cascade,
constraint student_id_Fk foreign key(student_id) references student(id)
);
*/
@Test
public void add() throws SQLException {
Teacher t = new Teacher();
t.setId("1");
t.setName("老张");
t.setSalary(100000);
Student s1 = new Student();
s1.setId("1");
s1.setName("aaa");
Student s2 = new Student();
s2.setId("2");
s2.setName("bbb");
t.getStudents().add(s1);
t.getStudents().add(s2);
TeacherDao dao = new TeacherDao();
dao.add(t);
}
@Test
public void findTeacher() throws SQLException {
TeacherDao dao = new TeacherDao();
Teacher t=dao.find("1");
System.out.println(t);
}
}
package com.cn.utils;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
//连接池
public class JdbcUtils {
private static DataSource ds;
static {
try {
Properties prop = new Properties();
prop.load(JdbcUtils.class.getClassLoader().getResourceAsStream(
"dbcpconfig.properties"));
BasicDataSourceFactory factory = new BasicDataSourceFactory();
ds = factory.createDataSource(prop);
} catch (Exception e) {
e.printStackTrace();
}
}
public static DataSource getDataSource() {
return ds;
}
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
}
标签：查找 cad 基本 sel hashset 数据 out stat ref
原文地址：http://www.cnblogs.com/zengjiao/p/7900868.html
