BeanUtils

今日学习目标 :

1. 可以说出BeanUtils的做用
2. 可以使用BeanUtils封装数据
3. 可以编写XML综合案例

 

 

1. BeanUtils (*****了解*****)

JavaBean 介绍 :

       JavaBean 它是一个简单的Java类, 这个类拥有 get 和 set 方法便可. 但要求这个类必须有一个公开的空参构造方法.

       后期开发中, 这个类通常会保存在名为 domain 或者 beans 包中.

 

 

BeanUtils 介绍 :

       在 Servlet 中通常须要获取页面提交的form表单中的数据, 而后封装到一个JavaBean上.

       这样咱们须要书写大量的 getParameter 获取提交的参数, 同时还要使用 JavaBean 的 setParameter 方法把数据所有封装到对象上.

       因而 Apache 公司给咱们提供了能够快速获取页面数据, 并将数据封装到JavaBean对象上的方式.

 

       BeanUtils 类的功能是把一个Map集合中的数据, 封装到一个 JavaBean 上. 使用BeanUtils工具类中的populate方法就能够把Map集合中的数据封装到指定的bean上.Map中的key名称必须和bean对象的属性名称保持一致.

 

Request 请求 -> getParameter -> getParameterMap(); -> populate 填充 -> JavaBean 类的对象.

 

 

 

BeanUtils 做用 :

       能够为JavaBean的属性设置值, 获取值, 并经过Map为JavaBean的数值赋值.

 

 

连接 : http://commons.apache.org/proper/commons-beanutils/download_beanutils.cgi

 

连接 : http://commons.apache.org/proper/commons-logging/download_logging.cgi

 

 

BeanUtils 是 Apache commons组件的成员之一，主要用于简化JavaBean封装数据的操做。它能够给JavaBean封装一个字符串数据，也能够将一个表单提交的全部数据封装到JavaBean中。

       使用第三方工具，须要导入jar包：

             

      

	方法	描述
BeanUtils对象	populate(Object bean, Map<String,String[]> properties)	将Map数据封装到指定Javabean中，通常用于将表单的全部数据封装到javabean
setProperty(Object obj,String name,Object value)	设置属性值
getProperty(Object obj,String name)	得到属性值

 

1. 提供JavaBean User ，并提供对应的构造方法

 

1. package cn.itcast.domain;
2.  
3. public class User {
4.        // 属性
5.        private String id;
6.        private String username;
7.        private String pwd;
8.        private int age;
9.        private float scores;
10.  
11.        public User(String id, String username, String pwd, int age, float scores) {
12.               super();
13.               this.id = id;
14.               this.username = username;
15.               this.pwd = pwd;
16.               this.age = age;
17.               this.scores = scores;
18.        }
19.  
20.        public User() {
21.               super();
22.        }
23.       
24.        @Override
25.        public String toString() {
26.               return "User [id=" + id + ", username=" + username + ", pwd=" + pwd + ", age=" + age + ", scores=" + scores
27.                            + "]";
28.        }
29.        public int getAge() {
30.               return age;
31.        }
32.        public float getScores() {
33.               return scores;
34.        }
35.        public void setAge(int age) {
36.               this.age = age;
37.        }
38.        public void setScores(float scores) {
39.               this.scores = scores;
40.        }
41.        public String getId() {
42.               return id;
43.        }
44.        public String getUsername() {
45.               return username;
46.        }
47.        public String getPwd() {
48.               return pwd;
49.        }
50.        public void setId(String id) {
51.               this.id = id;
52.        }
53.        public void setUsername(String username) {
54.               this.username = username;
55.        }
56.        public void setPwd(String pwd) {
57.               this.pwd = pwd;
58.        }
59. }

 

 

1. 功能1：设置属性
2. 功能2：得到属性

 

1. import org.apache.commons.beanutils.BeanUtils;
2. import org.junit.Test;
3.  
4. public class BeanUtilsDemo01 {
5.        @Test
6.        public void demo01() throws Exception {
7.               User user = new User();
8.              
9.               // 设置
10.               BeanUtils.setProperty(user, "id", "u001");
11.               BeanUtils.setProperty(user, "username", "Jack");
12.               BeanUtils.setProperty(user, "pwd", "123456");
13.               BeanUtils.setProperty(user, "age", 18);
14.               BeanUtils.setProperty(user, "scores", 99.5f);
15.              
16.               System.out.println(user);
17.        }
18.       
19.        @Test
20.        public void demo02() throws Exception {
21.               User user = new User("u001", "Jack", "123456", 18, 99.5f);
22.              
23.               String id = BeanUtils.getProperty(user, "id");
24.               String username = BeanUtils.getProperty(user, "username");
25.               String pwd = BeanUtils.getProperty(user, "pwd");
26.               String age = BeanUtils.getProperty(user, "age");
27.               String scores = BeanUtils.getProperty(user, "scores");
28.              
29.               System.out.println(id + ", " + username + ", " + pwd + ", " + age + ", " + scores);
30.        }
31. }

 

 

1. 功能3：封装表单数据，使用Map 模拟 request.getParameterMap()

1. import java.util.HashMap;
2. import java.util.Map;
3.  
4. import org.apache.commons.beanutils.BeanUtils;
5.  
6. public class BeanUtilsDemo02 {
7.        public static void main(String[] args) throws Exception {
8.              
9.               // 功能3 : 封装表单数据, 使用 Map 模拟 request.getParameterMap();
10.               // 需求 : 将数据封装到 JavaBean 对象中
11.               User user = new User();
12.               BeanUtils.populate(user, Request.getParameterMap());
13.               System.out.println(user);
14.        }
15. }
16.  
17. class Request {
18.        // 方法
19.        public static Map<String, Object> getParameterMap() {
20.               HashMap<String, Object> map = new HashMap<String, Object>();
21.               map.put("id", "u001");
22.               map.put("username", "Jack");
23.               map.put("pwd", "123456");
24.               map.put("age", 18);
25.               map.put("scores", 99.5f);
26.               return map;
27.        }
28. }

 

 

 

 

1. 综合案例1 (*****练习*****)

  读取XML中的配置文件信息,使用BeanUtils工具类建立JavaBean对象,将XML中的数据保存到JavaBean类的属性中.

 

 

xml文件 :

 

<?xml version="1.0" encoding="UTF-8"?>

<beans>

    <bean className="cn.itcast.bean.Employee">

       <property name="id" value="1"></property>

       <property name="name" value="张三"></property>

       <property name="salary" value="20000.00"></property>

    </bean>

    <bean className="cn.itcast.bean.Student">

       <property name="name" value="翠花"></property>

       <property name="age" value="18"></property>

       <property name="gender" value="女"></property>

       <property name="score" value="99.5f"></property>

    </bean>

</beans>

 

 

建立两个 JavaBean 类 :

 

1. package cn.itcast.domain;
2.  
3. public class Employee {
4.        // 属性
5.        private int id;
6.        private String name;
7.        private double salary;
8.       
9.        // 构造方法重载
10.        public Employee(int id, String name, double salary) {
11.               super();
12.               this.id = id;
13.               this.name = name;
14.               this.salary = salary;
15.        }
16.       
17.        @Override
18.        public String toString() {
19.               return "Employee [id=" + id + ", name=" + name + ", salary=" + salary + "]";
20.        }
21.  
22.        // setter & getter
23.        public Employee() {
24.               super();
25.        }
26.        public int getId() {
27.               return id;
28.        }
29.        public String getName() {
30.               return name;
31.        }
32.  
33.        public double getSalary() {
34.               return salary;
35.        }
36.       
37.        public void setId(int id) {
38.               this.id = id;
39.        }
40.        public void setName(String name) {
41.               this.name = name;
42.        }
43.        public void setSalary(double salary) {
44.               this.salary = salary;
45.        }
46. }

 

 

1. package cn.itcast.domain;
2.  
3. public class Student {
4.        // 属性
5.        private String name;
6.        private int age;
7.        private char gender;
8.        private float score;
9.        public Student(String name, int age, char gender, float score) {
10.               super();
11.               this.name = name;
12.               this.age = age;
13.               this.gender = gender;
14.               this.score = score;
15.        }
16.        public Student() {
17.               super();
18.        }
19.        @Override
20.        public String toString() {
21.               return "Student [name=" + name + ", age=" + age + ", gender=" + gender + ", score=" + score + "]";
22.        }
23.        public String getName() {
24.               return name;
25.        }
26.        public int getAge() {
27.               return age;
28.        }
29.        public char getGender() {
30.               return gender;
31.        }
32.        public float getScore() {
33.               return score;
34.        }
35.        public void setName(String name) {
36.               this.name = name;
37.        }
38.        public void setAge(int age) {
39.               this.age = age;
40.        }
41.        public void setGender(char gender) {
42.               this.gender = gender;
43.        }
44.        public void setScore(float score) {
45.               this.score = score;
46.        }
47. }

 

解析 xml 并实现为 JavaBean 对象赋值 :

 

1. import java.util.List;
2.  
3. import org.apache.commons.beanutils.BeanUtils;
4. import org.dom4j.Document;
5. import org.dom4j.Element;
6. import org.dom4j.io.SAXReader;
7.  
8. @SuppressWarnings("all")
9. public class BeanUtilsDemo03 {
10.        public static void main(String[] args) throws Exception {
11.              
12.               // 1. 建立一个 SAXReader 解析器
13.               SAXReader saxReader = new SAXReader();
14.               // 2. 读取 xml 文档, 获取 docuemnt 对象
15.               Document document = saxReader.read("employee.xml");
16.               // 3. 获取根标签
17.               Element rootElement = document.getRootElement();
18.               // 4. 获取beans标签下的子标签bean
19.               List<Element> beanElements = rootElement.elements();
20.               // 5.1 遍历集合, 获取集合中的 bean 标签
21.               for (Element bean : beanElements) {
22.                     // 5.2 获取bean标签中的className属性值
23.                     String className = bean.attributeValue("className");
24.                     // System.out.println(className);
25.                     // 5.3 根据className字符串, 使用反射技术, 建立一个该类的实例对象
26.                     Class<?> cls = Class.forName(className);
27.                     Object obj = cls.newInstance();
28.                     // 5.4 获取 bean 标签的 property 标签
29.                     List<Element> propElements = bean.elements();
30.                     // 5.5 遍历集合, 获取集合中的每个 property 标签
31.                     for (Element prop : propElements) {
32.                            // 5.6 获取 prop 标签中的 name 和 value 属性值
33.                            String name = prop.attributeValue("name");
34.                            String value = prop.attributeValue("value");
35.                            // System.out.println(name + " = " + value);
36.                            // 5.7 使用 BeanUtils 工具给对象的相应属性设置数值
37.                            BeanUtils.setProperty(obj, name, value);
38.                     }
39.                     System.out.println(obj);
40.               }
41.        }
42. }

 

 

 

 

 

 

 

1. 综合案例2 (*****练习*****)

 

student.xml

<?xml version="1.0" encoding="UTF-8"?>

<students>

    <student stuNo="it001">

       <name>章子怡</name>

       <age>20</age>

       <gender>女</gender>

       <score>99</score>

    </student>

    <student stuNo="it002">

       <name>汪峰</name>

       <age>22</age>

       <gender>男</gender>

       <score>100</score>

    </student>

    <student stuNo="it003">

       <name>高圆圆</name>

       <age>18</age>

       <gender>女</gender>

       <score>98</score>

    </student>

</students>

 

 

Student.java

 

1. public class Student {
2.        // 属性
3.        private String stuNo;
4.        private String name;
5.        private int age;
6.        private char gender;
7.        private float score;
8.        public Student(String stuNo, String name, int age, char gender, float score) {
9.               super();
10.               this.stuNo = stuNo;
11.               this.name = name;
12.               this.age = age;
13.               this.gender = gender;
14.               this.score = score;
15.        }
16.        public Student() {
17.               super();
18.        }
19.        @Override
20.        public String toString() {
21.               return "Student [stuNo=" + stuNo + ", name=" + name + ", age=" + age + ", gender=" + gender + ", score=" + score
22.                            + "]";
23.        }
24.        public String getStuNo() {
25.               return stuNo;
26.        }
27.        public String getName() {
28.               return name;
29.        }
30.        public int getAge() {
31.               return age;
32.        }
33.        public char getGender() {
34.               return gender;
35.        }
36.        public float getScore() {
37.               return score;
38.        }
39.        public void setStuNo(String stuNo) {
40.               this.stuNo = stuNo;
41.        }
42.        public void setName(String name) {
43.               this.name = name;
44.        }
45.        public void setAge(int age) {
46.               this.age = age;
47.        }
48.        public void setGender(char gender) {
49.               this.gender = gender;
50.        }
51.        public void setScore(float score) {
52.               this.score = score;
53.        }
54. }

 

StudentDemo01.java

 

1. import java.util.ArrayList;
2. import java.util.List;
3.  
4. import org.apache.commons.beanutils.BeanUtils;
5. import org.dom4j.Document;
6. import org.dom4j.Element;
7. import org.dom4j.io.SAXReader;
8.  
9. @SuppressWarnings("all")
10. public class StudentDemo01 {
11.        public static void main(String[] args) throws Exception {
12.               // 建立一个集合, 存储 Student 类型的对象
13.               ArrayList<Student> list = new ArrayList<Student>();
14.              
15.               // 解析 xml
16.               SAXReader saxReader = new SAXReader();
17.               Document document = saxReader.read("student.xml");
18.               Element rootElement = document.getRootElement();
19.               List<Element> stuElements = rootElement.elements();
20.               for (Element stu : stuElements) {
21.                     // 获取 stuNo 的属性值
22.                     String stuNo = stu.attributeValue("stuNo");
23.                     System.out.println(stuNo);
24.                     // 建立一个学生对象, 并为学生对象的 stuNo 的属性赋值
25.                     Student s = new Student();
26.                     s.setStuNo(stuNo);
27.                     // 再获取 stu 标签下的全部子标签
28.                     List<Element> elements = stu.elements();
29.                     for (Element element : elements) {
30.                            String name = element.getName();   // 获取标签名
31.                            String value = element.getText();  // 获取标签中的文本信息
32.                            System.out.println("\t" + name + " = " + value);
33.                            // 将 name 和 value 赋值给建立的学生对象
34.                            BeanUtils.setProperty(s, name, value);
35.                     }
36.                     // 将建立的 Student 对象添加到集合中
37.                     list.add(s);
38.               }
39.              
40.               // 遍历查看集合
41.               for (Student stu : list) {
42.                     System.out.println(stu);
43.               }
44.        }
45. }

 

输出结果 :